International Journal of Pharmaceutics (v.437, #1-2)
Editorial Board (iii).
Understanding reflection behavior as a key for interpreting complex signals in FBRM monitoring of microparticle preparation processes by Kerstin Vay; Wolfgang Frieß; Stefan Scheler (1-10).
The application of focused beam reflectance measurement (FBRM) was studied in a larger scale PLGA microparticle preparation process for monitoring changes of the particle size and the particles’ surface properties. Further understanding how these parameters determine the chord length distribution (CLD) was gained by means of single object measurements and data of monodisperse microparticles. It was evaluated how the FBRM signal is influenced by the surface characteristics of the tested materials and the measuring conditions. Particles with good scattering properties provided comparable values for the CLD and the particle size distribution. Translucent particles caused an overestimation of the particle size by FBRM, whereas the values for transparent emulsion droplets were too low. Despite a strong dependence of FBRM results on the optical properties of the samples, it is a beneficial technique for online monitoring of microparticle preparation processes. The study demonstrated how changing reflection properties can be used to monitor structural changes during the solidification of emulsion droplets and to detect process instabilities by FBRM.
Keywords: Focus beam reflectance measurement; Microspheres; Particle size analysis;
Supramolecular hydrogels as a universal scaffold for stepwise delivering Dox and Dox/cisplatin loaded block copolymer micelles by Wen Zhu; Yanli Li; Lixin Liu; Yongming Chen; Fu Xi (11-19).
A general and simple method was presented for preparing supramolecular hydrogels to deliver anticancer drugs. In this system, hydrophobic anticancer drug doxorubicin (Dox) was loaded into poly(ethylene glycol)-b-poly(ɛ-caprolactone) (PEG-b-PCL) amphiphilic block copolymer micelles by hydrophobic interaction. The drug loaded micelles were then mixed with α-cyclodextrin (α-CD) solution to generate the hydrogel. The α-CDs were threaded onto the PEG coronae of the micelles, and formed physical crosslinks of the molecular necklaces. Moreover, by mixing solutions of cisplatin complexed poly(ethylene glycol)-b-poly(acrylic acid) (PEG-b-PAA) micelles, Dox loaded PEG-b-PCL micelles and α-CDs together, a dual-drug loaded supramolecular hydrogel was generated. The gelation properties could be tuned by changing concentrations and polymerization degree of the polymers, and by adding PEG homopolymers or Pluronic copolymers as additives. Structures and properties of the drug loaded hydrogels were studied by wide-angle X-ray diffraction (XRD) and rheology measurement, respectively. In vitro drug release in PBS with different pH values was quantified. The erosion of hydrogels produced discrete micelles, from which the free drugs were released. In vitro cytotoxicity studies showed that the Dox loaded hydrogel inhibited the growth of human bladder carcinoma EJ cells, and the dual-drug loaded hydrogel showed even higher cytotoxicity.
Keywords: Block copolymers; Cisplatin; α-Cyclodextrin; Doxorubicin; Drug delivery; Injectable hydrogels;
Development and evaluation of sustained-release clonidine-loaded PLGA microparticles by Amélie Gaignaux; Jonathan Réeff; Florence Siepmann; Juergen Siepmann; Carine De Vriese; Jonathan Goole; Karim Amighi (20-28).
This work describes the encapsulation of a small, hydrophilic molecule (clonidine) into a PLGA matrix to provide sustained release over more than one month after intra-articular administration. The microparticles were prepared using a double emulsion (w1/o/w2) method followed by evaporation of the organic solvent. To optimize the efficiency of encapsulation and the mean size of the microparticles, which was targeted around 30 μm, the following parameters were modulated: the viscosity and the volume of the organic phase, the molecular weight of the polymer, the volume of the internal and external aqueous phases, the drug loading, the concentration of surfactant, and the stirring parameters. Blends of polymers characterized by different molecular weights (34 000–96 000 Da) as well as copolymers of PLGA–PEG were used to enhance the entrapment of the drug. The pH of the aqueous phases was adjusted to obtain suitable encapsulation efficiency. Characterization was made of the physico-chemical properties of the microparticles, such as their crystallinity (DSC and PXRD) and microstructure (SEM). When performing in vitro dissolution studies, controlled release for up to approximately 30 days was achieved with several of the formulations developed. Diffusion was found to be the dominant drug release mechanism at early time points.
Keywords: Poly(d,l-lactide-co-glycolide acid) (PLGA); Microparticles; Clonidine; Encapsulation efficiency; Controlled release; Double emulsion;
ApoE3 mediated polymeric nanoparticles containing curcumin: Apoptosis induced in vitro anticancer activity against neuroblastoma cells by Rohit S. Mulik; Jukka Mönkkönen; Risto O. Juvonen; Kakasaheb. R. Mahadik; Anant R. Paradkar (29-41).
Curcumin, a natural phytoconstituent, is known to be therapeutically effective in the treatment of various cancers such as, breast cancer, lung cancer, pancreatic cancer, brain cancer, etc. However, low bioavailability and photodegradation of curcumin hampers its overall therapeutic efficacy. Anionic polymerization method was employed for the preparation of apolipoprotein-E3 mediated curcumin loaded poly(butyl)cyanoacrylate nanoparticles (ApoE3-C-PBCA) and characterized for size, zeta potential, entrapment efficiency, photostability, morphology, and in vitro release study.ApoE3-C-PBCA were found to be effective against SH-SY5Y neuroblastoma cells compared to curcumin solution (CSSS) and curcumin loaded PBCA nanoparticles (C-PBCA) from in vitro cell culture investigations. Flow cytometry techniques employed for the detection of anticancer activity revealed enhanced activity of curcumin against SH-SY5Y neuroblastoma cells with ApoE3-C-PBCA compared to CSSS and C-PBCA, and apoptosis being the underlying mechanism. Present study revealed that ApoE3-C-PBCA has tremendous potential to develop into an effective therapeutic treatment modality against brain cancer.
Keywords: Curcumin; Neuroblastoma; Flow cytometry; Nanoparticles; Apolipoprotein E3;
Mechanism of freeze-drying drug nanosuspensions by Nae-Oh Chung; Min Kyung Lee; Jonghwi Lee (42-50).
Drug nanoparticles prepared in a liquid medium are commonly freeze-dried for the preparation of an oral dosage in solid dosage form. The freezing rate is known to be a critical parameter for redispersible nanoformulations. However, there has been controversy as to whether a fast or slow freezing rate prevents irreversible aggregation. A systematic investigation is presented herein regarding the effect of both the molecular weight of the cryoprotectant and the freezing rate in order to elucidate the mechanism underlying irreversible aggregation. It was found that irreversible aggregation occurred during drying rather than freezing, although a proper freezing rate is critical. A more homogeneous distribution of the cryoprotectant and drug nanoparticles led to more redispersible powders. Thus, keeping the local concentration distribution of the nanoparticles and cryoprotectant fixed during the freezing step plays a critical role in how the freezing rate affects the redispersibility. The kinetic approach of excluding the tendency of ice crystal growth permitted an explanation of the controversial results. This study will facilitate an in-depth understanding of the aggregation process of nanoparticles or proteins during freeze-drying.
Keywords: Nanoparticles; Nanocrystals; Freeze-drying; Lyophilization; Redispersibility; Cryoprotectant; Freezing rate; Nanosuspension; Nanoformulation; PEG;
Novel lyophilized hydrogel patches for convenient and effective administration of microneedle-mediated insulin delivery by Yuqin Qiu; Guangjiong Qin; Suohui Zhang; Yan Wu; Bai Xu; Yunhua Gao (51-56).
The combination of lyophilized hydrogel patch with microneedle pretreatment provided a sustained insulin release and steady hypoglycemic effect.A lyophilized hydrogel patch system was developed for microneedle-mediated insulin delivery. The matrix of Cross-linked poly(acrylamide-co-acrylic acid) were synthesized by precipitation polymerization. Recombinant human Insulin was loaded into the lyophilized polymer matrix, which can be rehydrated by water. After the hydrated patch was applied to the abdominal skin of diabetic rats after microneedle pretreatment, pharmacodynamics and pharmacokinetics evaluation was performed. The blood samples were collected to monitor blood glucose and serum insulin levels for 12 h. Blood glucose was lowered in proportion to the concentration of insulin loaded in lyophilized hydrogel patches (R 2 = 0.99), with a longer duration of action compared to subcutaneous injection. Stability study confirmed more than 90% of insulin activity was retained in lyophilized hydrogel after 6 months of storage at 4 °C. In conclusion, hydrogel patches were demonstrated to be appropriate drug reservoir for sustained release of insulin with microneedle mediated transdermal delivery.
Keywords: Lyophilized hydrogel; Transdermal drug delivery; Insulin; Microneedle; Diabetes;
Antisolvent crystallisation is a potential technique to prepare engineered lactose with promising aerosolisation properties: Effect of saturation degree by Waseem Kaialy; Ali Nokhodchi (57-69).
Engineered lactose particles were prepared by anti-solvent crystallisation technique using lactose solutions with different saturation degrees. In comparison to commercial lactose, engineered lactose particles exhibited less elongated and more irregular shape (large aggregates composed of smaller sub-units), rougher surface texture, higher specific surface area, and different anomer form. Engineered lactose powders demonstrated smaller bulk density, smaller tap density, and higher porosity than commercial lactose powder. Dry powder inhaler (DPI) formulations containing engineered lactose and salbutamol sulphate as a model drug demonstrated improved drug content homogeneity and higher amounts of drug delivered to lower airway regions. Higher fine particle fraction of drug was obtained in the case of lactose powders with higher porosity, higher specific surface area and higher fine particle content (<5 μm). The results indicated that the higher the saturation degree of lactose solution used during crystallisation the smaller the specific surface area, the higher the amorphous lactose content, and the higher the β-lactose content of engineered lactose particles. Also, lactose powders obtained from lactose solution with higher degree of saturation showed higher bulk and tap densities and smaller porosity. Engineered lactose powders crystallized from lower saturation degree (20% and 30% w/v) deposited higher amounts of drug on lower airway regions. In conclusion, this study demonstrated that it is possible to prepare engineered lactose particles with favourable properties (e.g. higher fine particle fraction and better drug content homogeneity) for DPI formulations by using lactose solutions with lower degree of saturation during crystallisation process.
Keywords: Dry powder inhaler; Saturation; Engineered lactose; Density; Shape; Roughness; Anomer form; Porosity; Homogeneity; Fine particle fraction;
Folate-decorated thermoresponsive micelles based on star-shaped amphiphilic block copolymers for efficient intracellular release of anticancer drugs by Seyed Jamal Tabatabaei Rezaei; Mohammad Reza Nabid; Hassan Niknejad; Ali Akbar Entezami (70-79).
In this study, a new type of folate-decorated thermoresponsive micelles based on the star-shaped amphiphilic block copolymer 4s[poly(ɛ-caprolactone)-b-2s(poly(N-isopropylacrylamide-co-acrylamide)-b′-methoxy poly(ethylene glycol)/poly(ethylene glycol)-folate)] (i.e., 4s[PCL-b-2s(P(NIPAAm-co-AAm)-b′-MPEG/PEG-FA)] (PCIAE-FA)), were developed for the tumor-targeted delivery and temperature-induced controlled release of hydrophobic anticancer drugs. These amphiphilic star copolymers are capable of self-assembling into spherical micelles in aqueous solution with an average diameter of 91 nm. The lower critical solution temperature (LCST) of micelles was around 39.7 °C. The anticancer drug, paclitaxel (PTX), was encapsulated into the micelles. In vitro release studies demonstrated that the drug-loaded delivery system (PTX–PCIAE-FA) is relatively stable at physiologic conditions but susceptible to temperatures above LCST which would trigger the release of encapsulated drugs. The cytotoxicity studies showed that the PTX transported by these micelles was higher than that by the commercial PTX formulation Tarvexol®. The efficacy of this thermoresponsive drug delivery system was also evaluated at temperatures above the LCST; the results demonstrated that the cellular uptake and the cytotoxicity of PTX-loaded micelles increase prominently. These results indicate that these thermoresponsive micelles may offer a very promising carrier to improve the delivery efficiency and cancer specificity of hydrophobic chemotherapeutic drugs.
Keywords: Thermoresponsive; Star block copolymers; Tumor-targeting; Intracellular release;
A novel formulation of solubilised amphotericin B designed for ophthalmic use by D.R. Serrano; H.K. Ruiz-Saldaña; G. Molero; M.P. Ballesteros; J.J. Torrado (80-82).
Amphotericin B (AmB) is a wide spectrum antifungal with low incidence of clinical resistance. However, there are no licensed topical formulations with AmB in most developed countries. Extemporaneous preparations of AmB are frequently prepared from available marketed parenteral formulations. Herein, a solution of AmB with γ-cyclodextrin is described as suitable for topical administration as eye drops. This novel formulation is characterised by its ability to solubilise AmB and to maintain its antifungal activity, physicochemical stability and sterility over 30 days. Antifungal activity against Candida albicans was significantly higher (35%) for the new formulation than that obtained with Fungizone® based extemporaneous prepared suspension. Optimal 0.1% AmB–10% cyclodextrin formulation remained sterile and with an acceptable osmolarity, pH and particle size for ophthalmic use over 4 weeks. Complexation with γ-cyclodextrins improved AmB chemical stability compared to the reference eye drops suspension based on Fungizone®. These results illustrate the feasibility of an ophthalmic AmB formulation easy enough to be licensed or prepared in community and hospital pharmacies.
Keywords: Cyclodextrins; Amphotericin B; Eye drops; Stability; Antifungal activity;
Nanocarriers for dermal drug delivery: Influence of preparation method, carrier type and rheological properties by Julia C. Schwarz; Angelika Weixelbaum; Elisabeth Pagitsch; Monika Löw; Guenter P. Resch; Claudia Valenta (83-88).
Nanocarriers are highly interesting delivery systems for the dermal application of drugs. Based on a eudermic alkylpolyglycosid nanoemulsions, solid lipid nanoparticles (SLN) and nano-structured lipid carriers (NLC) were prepared by ultrasonic dispersion. The ultrasound preparation technique turned out to be convenient and rapid. For reasons of comparison, nanoemulsions were also prepared by high-pressure homogenisation with highly similar physicochemical properties. Cryo electron microscopy was employed to elucidate the microstructure of the ultrasound-engineered nanocarriers. Furthermore, in vitro skin experiments showed excellent skin permeation and penetration properties for flufenamic acid from all formulations. Moreover, ATR-FTIR studies revealed barrier-restorative properties for NLC and SLN. Furthermore, the rheological characteristics of all nanocarriers were determined. In order to increase the viscosity, three different polymers were employed to also prepare semi-solid NLC drug delivery systems. All of them exhibited comparable skin diffusion properties, but may offer improved dermal applicability.
Keywords: Nanoemulsion; Nano-structures lipid carrier (NLC); Solid lipid nanoparticle (SLN); Skin; Flufenamic acid;
Blooming of Irganox 3114® antioxidant onto a medical grade elastomer. Impact of the recrystallization conditions on the antioxidant polymorphism, on the film wettability and on the antioxidant leachability by J. Saunier; V. Mazel; C. Aymes-Chodur; N. Yagoubi (89-99).
Studying the blooming and recrystallization of additives onto the surface of polymer medical devices is of a great interest because it can affect the biocompatibility of the material. The polymorphism of a phenolic antioxidant (Irganox 3114®) used as an additive in medical devices and pharmaceutical packaging was studied: two different polymorphs were characterized by differential scanning measurements, FTIR and X-ray diffraction analyses. Then, the behavior of the additive in medical grade polyurethane films was described: a recrystallization into the stable polymorphic form was observed onto the polymer surface after annealing at different temperatures. The morphology observed depends not only on the additive/polymer ratio but also on the whole amount of additive in the polymer film. Depending on the recrystallization morphology, the wettability with water could be lowered and the leachability of the additives into aqueous media could be favored.
Keywords: Antioxidant; Polyurethane; Blooming; Polymorphism; Wettability; Leachability;
Application of Langmuir–Blodgett film technology on studying the formulation of self-microemulsifying drug delivery system (SMEDDS) by Xi Yang; Man Ge; Tao Wang; Dongqin Quan (100-102).
The polarity of oleic acid, medium-chain triglyceride and their mixtures with different ratios was determined by LB film technology. Then the particle diameter after emulsifying in water when these different oils were mixed with Cremophor EL-35 respectively was assayed. Then three formulations of SMEDDS using different oils were prepared. And their surface pressure–area isotherm curves and Gibbs change (ΔG) were investigated. The results showed that flexibility of LB film was much better when oil with lower polarity was used to prepare the SMEDDS. And this group of SMEDDS which has low Gibbs change (ΔG) was more stable with appropriate composition of oil, surfactant and co-surfactant. It can be concluded that LB film technology could be applied on the preliminary formulation study of SMEDDS. Our study may provide some theoretical basis and methods of formulation selection of SMEDDS.
Keywords: Self-microemulsifying; Langmuir–Blodgett film; Surface pressure–area isotherm; Gibbs change (ΔG);
Solubility and stability of dalcetrapib in vehicles and biological media by Günter Gross; Joseph Tardio; Olaf Kuhlmann (103-109).
Dalcetrapib solubility was determined in aqueous and in non-aqueous vehicles and in biorelevant media. In a pure aqueous environment the solubility was low but could be increased by addition of surfactants or complexing agents. This was also reflected in the solubility seen in simulated gastrointestinal (GI) fluids, with almost no solubility in simulated gastric fluid, but reasonable solubilisation in simulated intestinal fluids containing lecithin and bile salt. Additionally, the stability of dalcetrapib was determined in simulated GI fluids with and without pancreatic lipase. In solutions without lipase, dalcetrapib was slowly hydrolysed, but in the presence of lipase the hydrolysis rate was significantly faster depending on pH and enzyme activity. In biological fluids, dissolved dalcetrapib appeared to behave similarly being rapidly hydrolysed in human intestinal fluids with a half-life below 20 s with no degradation observed in human gastric fluids at low pH. The results provide supportive evidence that absorption is higher under fed conditions and indicate lipase inhibitors might interfere with oral absorption of dalcetrapib.
Keywords: Dalcetrapib; Dalcetrapib solubility; Dalcetrapib stability; Biorelevant media; Biological media; Cholesteryl ester transfer protein (CETP);
In situ injectable nano-composite hydrogel composed of curcumin, N,O-carboxymethyl chitosan and oxidized alginate for wound healing application by Xingyi Li; Shuo Chen; Binjun Zhang; Mei Li; Kai Diao; Zhaoliang Zhang; Jie Li; Yu Xu; Xianhuo Wang; Hao Chen (110-119).
In this paper, an in situ injectable nano-composite hydrogel composed of curcumin, N,O-carboxymethyl chitosan and oxidized alginate as a novel wound dressing was successfully developed for the dermal wound repair application. Nano-curcumin with improved stability and similar antioxidant efficiency compared with that of unmodified curcumin was developed by using methoxy poly(ethylene glycol)-b-poly(ɛ-caprolactone) copolymer (MPEG-PCL) as carrier followed by incorporating into the N,O-carboxymethyl chitosan/oxidized alginate hydrogel (CCS-OA hydrogel). In vitro release study revealed that the encapsulated nano-curcumin was slowly released from CCS-OA hydrogel with the diffusion-controllable manner at initial phase followed by the corrosion manner of hydrogel at terminal phase. In vivo wound healing study was performed by injecting hydrogels on rat dorsal wounds. Histological study revealed that application of nano-curcumin/CCS-OA hydrogel could significantly enhance the re-epithelialization of epidermis and collagen deposition in the wound tissue. DNA, protein and hydroxyproline content in wound tissue from each group were measured on 7th day of post wounding and the results also indicated that combined using nano-curcumin and CCS-OA hydrogel could significantly accelerate the process of wound healing. Therefore, all these results suggested that the developed nano-curcumin/CCS-OA hydrogel as a promising wound dressing might have potential application in the wound healing.
Keywords: In situ gelling system; Nano-curcumin; Cross-linking; Wound healing; In vivo;
Rheological characterization and permeation behavior of poloxamer 407-based systems containing 5-aminolevulinic acid for potential application in photodynamic therapy by Carlos van Hemelrijck; Christel C. Müller-Goymann (120-129).
Topical application of 5-aminolevulinic acid (ALA) in photodynamic therapy is of great interest because of avoiding systemic side effects with such an easy way of application. However, due to ALA's high polarity its dermal bioavailability is rather limited and thus, permeation enhancement of this active is of major interest in research. In a previous study, a semisolid poloxamer 407-based (POX), five-component system (“thermogel”) was developed for permeation enhancement of ALA across isolated human stratum corneum. In the present study, five-component systems of systematically varied compositions were investigated both rheologically and in terms of permeation enhancement. The five-component systems contained water, a fixed combination of 1:1 of isopropyl alcohol (IPA) and dimethyl isosorbide (DMIS) and a fixed ratio of 4:1 of POX to propylene glycol dicaprylocaprate (MIG). Rheological characterization showed that complex viscosity depended on IPA/DMIS and POX/MIG content. The gelation temperature (GT) was strongly influenced by interactions between MIG, IPA and DMIS. Regarding permeation behavior, several systems showing better permeation fluxes than the original “thermogel” were identified. Surprisingly, permeation flux did not inversely correlate with the complex viscosity, showing that permeation behavior may depend on a variety of further physicochemical characteristics including individual composition and microstructure of the respective formulation.
Keywords: Poloxamer 407; 5-Aminolevulinic acid; Photodynamic therapy; Dermal application; Permeation enhancement; Rheology;
Protein based tablets as reversible gelling systems for delayed release applications by Romain Caillard; Muriel Subirade (130-136).
Succinylated β-lactoglobulin (S-β-lg) was previously shown to be efficient as new excipient for the formation of enteric tablets, suitable for several applications including probiotics delivery. This work investigates the mechanisms leading to S-β-lg tablets delayed release. Release kinetics were evaluated in vitro. Fourier transformed infra red spectroscopy (FTIR) was used to visualize the effect of dissolution medium on matrix tablet surface. Results demonstrated that tablets release in simulated gastric fluids (SGF) might be due to water/drug diffusion through an in situ formed gel layer, as revealed by FTIR data. As SGF penetrated the tablet, regardless of protein succinylation rate (50% or 100%), molecular rearrangements occurred, allowing the development of an important band located in the 1621–1623 cm−1 region. This band was characteristic of the formation of protein intermolecular β-sheets. The gel was showed to be reversible in intestinal conditions, allowing delayed release. While the molecular structure of the gel layer was not depending on protein succinylation rate, it appeared that 100% S-β-lg tablets showed slower release. This low release was probably related to 100% S-β-lg lower solubility, lower charge density, and their ability to form stronger intermolecular hydrogen bonds. This work highlights proteins potential for the conception of controlled drug delivery systems.
Keywords: Globular protein; Tablet; Gel; FTIR; Delayed-release;
Mat-pKa calculation tool development for evaluation of acidity constants from solubility profiles—Large study of 41 compounds by Lionel Vidaud; Claude Kugel; Giovanni Boccardi; Stephan Schmidt; Jean-Yves Pommier (137-155).
In the context of the Quantitative Structure–Activity Relationship (QSAR) for new drugs, knowledge and understanding of the behavior of the molecules in solution and simulated media are key points to provide the best formulated compounds. Current analytical determinations can give solubility data and dedicated techniques can provide other physico-chemical constants, such as pKa(s), log P and log D. All of these data represent the capability of the compound to enter into solutions, but correlations between solubility measurements and these constants are not frequently established, to confirm that the compound observed in solution is the expected one. The study presented here, shows how a dedicated software was elaborated and used in a large study of 41 compounds, to retrieve the dissociation constants, starting with the solubility and pH couples of data acquired.
Keywords: pKas calculations; Solubility profiles; Major entity regulating solubility; Identification of compound in solution;
Solid–liquid phase diagrams for the determination of the solid state nature of both polymorphs of (RS)-2-(2-oxo-pyrrolidin-1-yl)-butyramide by Christelle Herman; Benoît Haut; Luc Aerts; Tom Leyssens (156-161).
This work focuses on the determination of the solid state nature of (RS)-2-(2-oxo-pyrrolidin-1-yl)-butyramide (Etiracetam), the racemic intermediate of (S)-2-(2-oxo-pyrrolidin-1-yl)-butyramide, an Active Pharmaceutical Ingredient, marketed under the name Levetiracetam®. It is show how this information can easily be extracted from solid–liquid phase diagrams of the racemic system. As two polymorphs of Etiracetam are known (Forms I and II), the analyses have been performed considering both polymorphs. The solid–liquid phase diagrams are determined experimentally, using Differential Scanning Calorimetry, and theoretically, using the Prigogine–Defay and Schroeder–Van Laar equations. Only the phase diagram involving the polymorph stable at higher temperatures (Form II) can be constructed experimentally. The theoretical phase diagram involving this polymorph compares well with the experimental one, thus allowing the use of theoretical equations for the prediction of the solid–liquid phase diagram involving Form I, which is meta-stable above 30.5 °C. Our findings confirm that both polymorphs are racemic compounds, which is also confirmed by XRPD analysis.
Keywords: Differential scanning calorimetry; Solid–liquid phase diagram; Eutectic point; Racemic modification; Polymorphism;
Establishment of cocrystal cocktail grinding method for rational screening of pharmaceutical cocrystals by Katsuhiko Yamamoto; Shunichirou Tsutsumi; Yukihiro Ikeda (162-171).
Cocrystals (CCs) used in the pharmaceutical industry are defined as complex crystals formed by reaction between an API and a cocrystal former (CCF); unlike salts, CCs do not show proton transfer. Recently, pharmaceutical CCs have been used to improve the drug-likeness of APIs, such as solubility and stability. Grinding is more effective for CC synthesis than crystallization from solution because in the former case, the API can predominantly interact with the CCF without being affected by solvents. However, this method is tedious because the API is ground with only one CCF at a time. We developed a cocktail cocrystal grinding (CCG) method, in which a mixture of CCFs having the same functional group was used. No false negatives/positives were observed in CCG when carbamazepine was used as the model compound. This method could be used to obtain CCs of piroxicam and spironolactone. False negatives were observed for only one compound from among three model compounds, indicating that CCG facilitates efficient CC detection and that it has higher throughput than does the conventional method. Further, CCG is fast and suitable for rational CC screening, and it helps identify the partial structure of CCFs that forms synthons with an API.
Keywords: Cocrystal; Grinding; Drug substance; Amorphous; Crystallinity; Physicochemistry;
Role of chitosan nanoparticles in the oral absorption of Gemcitabine by Katayoun Derakhshandeh; Sahar Fathi (172-177).
Gemcitabine is a known cytotoxic agent with a wide spectrum of antitumor activity. It has been employed in therapeutic regimens for various malignancies such as the lung, ovary, breast, and bladder cancers. It also has been used in the treatment of pancreatic cancer, in combination chemotherapy of non-small cell lung cancer (NSCLC) and in leukemia. Its effect results from incorporation into DNA with subsequent inhibition of cell proliferation. Unfortunately, Gemcitabine is rapidly metabolized by the so-called cytidine-deaminase which limits its efficacy. Because of extensive deamination by intestinal cells, its oral administration results in very low bioavailability. The aim of this study was to introduce an oral formulation of the drug for the first time and improve its physicochemical properties.Chitosan nanoparticles containing were produced based on ionic gelation method and tripolyphosphate (TPP). Physicochemical properties such as particle size and shape, loading efficiency and release rate were evaluated. Oral absorption of both free and nanoparticle-loaded drugs was measured using the rat intestinal sac model.The Gemcitabine-loaded chitosan nanoparticles were spherical with a mean size of 95 ± 8 nm and high drug loading (63%). The nanoparticles showed controlled release pattern characterized by a fast initial release (61%) during the first 8 h, followed by slower and continuous release (74.66%).The absorption study showed that Gemcitabine intestinal transport increased 3–5 folds by loading in chitosan nanocarrier.
Keywords: Gemcitabine; Chitosan; Nanoparticle; Ionic gelation; Intestinal absorption;
Higuchi's equation and beyond: Overview of the formulation and application of a generalized model of drug release from polymeric matrices by John H. Petropoulos; Kyriaki G. Papadokostaki; Merope Sanopoulou (178-191).
An account is presented of modeling and experimental work, which complements, in many useful ways, the excellent coverage, afforded by a recent dedicated issue edited by Siepmann and Peppas (Int. J. Pharm. 2011, 418(1)), of the theoretical background and many ramifications, as well as practical applications, of the Higuchi equation. The main notable feature of the said modeling work is formulation and successful practical application, of an ab initio generalized approach, based on solving the fundamental transport equations applicable to the operation of typical matrix-controlled release (MCR) devices. This approach (i) reduces to the Higuchi equation under the pertinent restrictive conditions but can duly handle most of its more complex ramifications and (ii) can be parameterized (by the use of appropriate data from the literature or from independent experiments) to adapt itself to the physics of the particular matrix–solvent–solute system under consideration; as demonstrated here with examples from our laboratory or from the literature. A distinctive feature of the experimental work is the extensive use of simpler “model” MCR systems, chosen so as to promote better understanding of the effect of various physicochemical parameters and mechanisms on drug MCR rate and kinetics. A concept of MCR device efficiency is also discussed.
Keywords: Higuchi kinetics; Controlled release; Polymer matrix systems; Modeling; Mechanism of transport; Dose rate;
Blood-pool multifunctional nanoparticles formed by temperature-induced phase transition for cancer-targeting therapy and molecular imaging by Keun Sang Oh; Sangmin Lee; Jin Hee Na; Jeong-Yeon Kim; Dong-Eog Kim; Kwangmeyung Kim; Ick Chan Kwon; Soon Hong Yuk; Seo Young Jeong (192-202).
Multifunctional nanoparticles (NPs) were prepared based on temperature-induced phase transition in a molten mixture of Lipiodol®, Tween 80, paclitaxel (PTX), and Pluronic F-68, wherein the Lipiodol®/Tween 80 mixture is used as a solubilizer for PTX, and Pluronic F-68 is used for the stabilization of the molten mixture. The morphology and size distribution of optimized multifunctional NPs were observed using transmittance electron microscopy (TEM) and a particle size analyzer. In the optical imaging of tumor-bearing mice using a near-infrared fluorescence (NIRF) imaging system, the multifunctional NPs were evaluated in terms of a time-dependent excretion profile, in vivo biodistribution and tumor-targeting capability compared to free fluorescence dye. In addition, the prolonged circulation of multifunctional NPs was confirmed by enhancement of the blood-pool in live animals using a micro-CT imaging system, because iodine-containing Lipiodol® has an X-ray enhancement property. Finally, the anti-tumor efficacy of multifunctional NPs was monitored by injecting the multifunctional NPs into the tail veins of tumor-bearing mice. The multifunctional NPs showed excellent tumor targetability and anti-tumor efficacy in tumor-bearing mice, caused by the enhanced permeation and retention (EPR) effect.
Keywords: Multifunctional nanoparticles; Lipiodol®; Pluronic F-68; Temperature-induced phase transition; Cancer-targeting therapy; Molecular imaging;
Development of ligustrazine-loaded lipid emulsion: Formulation optimization, characterization and biodistribution by Lijun Wei; Nirmal Marasini; Gao Li; Chul Soon Yong; Jong Oh Kim; Qizhe Quan (203-212).
Ligustrazine is a traditional Chinese medicine used to treat various cardiovascular and neurovascular complications. However, this compound exhibits rapid first-pass metabolism, a short biological half-life, low stability and potential vascular irritation that restrict its use for long-term therapy. The use of a lipid emulsion as a carrier for intravenous administration of ligustrazine might provide sustained and prolonged release, thereby reducing the frequency of administration and improving patient compliance. The main purpose of our study was to develop a highly stable and sterile optimal formulation of a ligustrazine lipid emulsion (LLE) and to evaluate its pharmacokinetic behavior and tissue distribution in rats. The final optimal formulation consisted of soybean oil (12.0%), oleic acid (0.6%), lecithin (1.0%), poloxamer 188 (0.6%) and glycerol (2.25%). The average particle size, polydispersity index (PDI), zeta-potential and pH of the final product were 215.0 ± 2.5 nm, 0.076 ± 0.033, −40.4 ± 5.3 mV and 7.25 ± 0.05, respectively. The LLE was stable for at least three months at room temperature. In vitro drug release studies of the LLE suggested a sustained release profile, which was further confirmed by in vivo pharmacokinetic studies in rats. The area under the drug concentration–time curve from 0 h to 10 h (AUC 0–10h) for LLE was increased by 1.6-fold compared with that of the commercially available ligustrazine injection (LI), suggesting enhanced bioavailability from the lipid-based emulsion. Furthermore, a tissue distribution study showed significant improvement in the distribution pattern of ligustrazine with a higher AUC 0–180min observed in all tissues for LLE than for LI. In conclusion, LLE, with excellent stability, improved pharmacokinetics and tissue distribution, demonstrates great potential for the delivery of ligustrazine for clinical applications.
Keywords: Ligustrazine; Lipid emulsion; Characterization; Pharmacokinetics; Tissue distribution;
In vitro uptake evaluation in Caco-2 cells and in vivo results in diabetic rats of insulin-loaded PLGA nanoparticles by Nathalie Reix; Audrey Parat; Elodie Seyfritz; Remmelt Van Der Werf; Virginia Epure; Nicolas Ebel; Louis Danicher; Eric Marchioni; Nathalie Jeandidier; Michel Pinget; Yves Frère; Séverine Sigrist (213-220).
PLGA nanoparticles (NPs) are largely developed for biological applications but little is known about their uptake. Therefore, we focused our study on the modalities of insulin-loaded PLGA NPs transport across Caco-2 monolayers, and their hypoglycaemic effect on diabetic rats.Insulin-loaded PLGA NPs were formulated by a double emulsion solvent evaporation process. NPs mean diameter was between 130 and 180 nm. NPs were smooth and spherical with an entrapment efficiency above 80%. Fluorescently labeled NPs were incubated with Caco-2 cells to study the process of uptake and the intracellular fate by flow cytometry and confocal laser scanning microscopy. The kinetic of absorption was time-dependent and occurred by clathrin-mediated endocytosis. The intracellular traffic led to a basolateral exocytosis of NPs.In vitro studies and in vivo intraduodenal administration to diabetic rats showed that NPs were resistant in intestinal conditions long enough to allow both the intestinal absorption of NPs and the delivery of functional insulin in bloodstream. The resulting in vivo hypoglycaemic effect was similar to a long-acting insulin one. As no effect on glycaemia occurred after oral administration, further studies need to be conducted to protect NPs from the degradation occurring at the enteric level.
Keywords: Insulin; PLGA; Nanoparticles; Caco-2 cells; Endocytosis; Exocytosis;
Novel codrugs with GABAergic activity for dopamine delivery in the brain by Nunzio Denora; Tommaso Cassano; Valentino Laquintana; Antonio Lopalco; Adriana Trapani; Concetta Stefania Cimmino; Leonardo Laconca; Andrea Giuffrida; Giuseppe Trapani (221-231).
This study investigates the use of codrugs of the GABAergic agent 2-phenyl-imidazo[1,2-a]pyridinacetamide and dopamine (DA) or ethyl ester L-Dopa (LD) as a strategy to deliver DA and simultaneously activate GABA-receptors in the brain. For this purpose, both DA and LD ethyl ester were linked by carbamate bond to imidazo[1,2-a]pyridine acetamide moieties to yield two DA- and two LD-imidazopyridine derivatives. These compounds were evaluated in vitro to assess their stability, binding affinities and cell membrane transport, and in vivo to assess their bio-availability via microdialysis studies. The two DA derivatives were adequately stable in buffered solution, but underwent cleavage in diluted human serum. By contrast, the LD derivatives were unstable in buffered solution. Receptor binding studies showed that the DA-imidazopyridine carbamates had binding affinity for benzodiazepine receptors in the nanomolar range. Brain microdialysis experiments indicated that intraperitoneal administration of the DA derivatives sustained DA levels in rat striatum over a 4-h period.These results suggest that DA-imidazopyridine carbamates are new DA codrugs with potential application for DA replacement therapy.
Keywords: Blood–brain barrier; Codrugs; Drug targeting; MDCKII-MDR1 cell; Microdialysis; P-glycoprotein;
Prediction of aqueous solubility of drug-like molecules using a novel algorithm for automatic adjustment of relative importance of descriptors implemented in counter-propagation artificial neural networks by Slavica Erić; Marko Kalinić; Aleksandar Popović; Mire Zloh; Igor Kuzmanovski (232-241).
In this work, we present a novel approach for the development of models for prediction of aqueous solubility, based on the implementation of an algorithm for the automatic adjustment of descriptor's relative importance (AARI) in counter-propagation artificial neural networks (CPANN). Using this approach, the interpretability of the models based on artificial neural networks, which are traditionally considered as “black box” models, was significantly improved. For the development of the model, a data set consisting of 374 diverse drug-like molecules, divided into training (n = 280) and test (n = 94) sets using self-organizing maps, was used. Heuristic method was applied in preselecting a small number of the most significant descriptors to serve as inputs for CPANN training. The performances of the final model based on 7 descriptors for prediction of solubility were satisfactory for both training (RMSEP train = 0.668) and test set (RMSEP test = 0.679). The model was found to be a highly interpretable in terms of solubility, as well as rationalizing structural features that could have an impact on the solubility of the compounds investigated. Therefore, the proposed approach can significantly enhance model usability by giving guidance for structural modifications of compounds with the aim of improving solubility in the early phase of drug discovery.
Keywords: Prediction of solubility; Artificial neural network; Relative importance of descriptors;
Characterisation of high dose aerosols from dry powder inhalers by Floris Grasmeijer; Paul Hagedoorn; Henderik W. Frijlink; Anne H. de Boer (242-249).
Developments in high dose dry powder aerosol delivery will increasingly challenge the applicability of currently used aerosol characterisation techniques. With cascade impaction analysis bounce effects can negatively influence stage collection efficiency, especially with increasing impactor loads. In this study the suitability of the multi stage liquid impinger (MSLI) and the Next Generation Impactor (NGI) for the characterisation of dry powder aerosols containing up to 50 mg of drug is evaluated. The occurrence of bounce effects is quantitatively assessed by comparison with data obtained from laser diffraction analysis. The liquid based impaction surfaces of the MSLI largely prevent bounce effects, but the low number of cut-off values associated with this impactor hinders accurate data interpretation. With the NGI, a standard high viscosity plate coating insufficiently reduces bounce effects, causing the fraction <1 μm to be higher than what can maximally be expected based on the primary particle size distribution (PSD) obtained from RODOS dispersion. With this type of impactor, the use of solvent soaked filters as impaction surface is necessary to eliminate bounce effects.
Keywords: Aerosol characterisation; Bounce effects; High dose; Laser diffraction; MSLI; NGI;
Influence on SPF of the quantity of sunscreen product applied by C. Couteau; E. Paparis; S. El-Bourry-Alami; L.J.M. Coiffard (250-252).
It is now a clearly established fact that ultraviolet radiation is involved in the induction of skin cancer such as carcinoma and melanoma. The most efficient means of protection is by using clothes. For uncovered areas, it is essential to apply a sun product. For some time, various authors have been wondering about the inefficiency or indeed the dangerousness of sun products. Cases of sunburn are still just as frequent in children. We have chosen to study the influence of the quantity of sun product applied on the skin on the level of efficiency obtained. Twenty commercially-available products with SPFs varying between 10 and 50+ and belonging to all levels of protection, that is to say “low”, “medium” and “high”, were tested in vitro at 5 different doses (5.0, 7.5, 10.0, 12.5 and 15.0 mg for a surface area of 25 cm2). We were able to demonstrate that there was a polynomial relationship between the SPF and the quantity of product on the skin's surface. It can be seen that when the dose is halved, the SPF is divided by a variable factor according to the product, from 1.5 to 3.8.
Keywords: Amount of sunscreen; Sun protection factor; Sunscreens;
Exploring the fate of liposomes in the intestine by dynamic in vitro lipolysis by Johannes Parmentier; Nicky Thomas; Anette Müllertz; Gert Fricker; Thomas Rades (253-263).
Liposomes are generally well tolerated drug delivery systems with a potential use for the oral route. However, little is known about the fate of liposomes during exposure to the conditions in the gastro-intestinal tract (GIT). To gain a better understanding of liposome stability in the intestine, a dynamic in vitro lipolysis model, which so far has only been used for the in vitro characterisation of other lipid-based drug delivery systems, was applied to different liposomal formulations. Liposome size and phospholipid (PL) digestion were determined as two markers for liposome stability. In addition, the effect of PL degradation on the ability to maintain liposomally incorporated danazol in solution during lipolysis was evaluated in order to address the feasibility of liposomes designed for oral administration. Rate and extend of hydrolysis of PLs mediated by pancreatic enzymes was determined by titration and HPLC. Size of liposomes was determined by dynamic light scattering during incubation in lipolysis medium (LM) and during lipolysis. SPC-based (soy phosphatidylcholine) liposomes were stable in LM, whereas for EPC-3-based (hydrated egg phosphatidylcholine) formulations the formation of aggregates of around 1 μm in diameter was observed over time. After 60 min lipolysis more than 80% of PLs of the SPC-liposomes were digested, but dependent on the liposome concentration only a slight change in size and size distribution could be observed. Although EPC-3 formulations did form aggregates during lipolysis, the lipids exhibited a higher stability compared to SPC and only 30% of the PLs were digested. No direct correlation between liposome integrity assessed by vesicle size and PL digestion was observed. Danazol content in the liposomes was around 5% (mol/mol danazol/total lipid) and hardly any precipitation was detected during the lipolysis assay, despite pronounced lipolytic degradation and change in vesicle size. In conclusion, the tested dynamic in vitro lipolysis model is suitable for the assessment of liposome stability in the intestine. Furthermore, liposomes might be a useful alternative to other lipid based delivery systems for the oral delivery of poorly soluble drugs.
Keywords: Scanning ion occlusion sensing; Dynamic light scattering; Danazol; Bile salts; Liposome stability; In vitro lipolysis;
The delineation of the morphology of charged liposomal vectors via a fractal analysis in aqueous and biological media: Physicochemical and self-assembly studies by Natassa Pippa; Stergios Pispas; Costas Demetzos (264-274).
The present study deals with the physicochemical characterization of DPPC:DPPG (9:1 molar ratio) and DPPC:DODAP (9:1 molar ratio) liposomes, and the determination of their fractal dimension in HPLC-grade water, PBS and in FBS. Light scattering techniques were used in order to extract information on the structure, morphology, size and surface charge of liposomes in an ageing study and their structural response to changes in concentration and temperature. Fluorescence spectroscopy showed that the microviscosity of cationic liposomes changed by an increase of temperature. The fractal dimension, d f , was found equal to 1.8 for reconstituted DPPC:DPPG (9:1) and DPPC:DODAP (9:1) liposomes in aqueous media. Aggregation of reconstituted DPPC:DPPG (9:1) and DPPC:DODAP (9:1) liposomes in FBS was observed. Their fractal dimensions were 1.46 and 2.45, respectively. The first order aggregation kinetics of DPPC:DODAP (9:1) liposomes in the presence of serum proteins was determined; the aggregates of cationic liposomes with serum components remained stable during 20 days with fractal dimension 2.5. The responsiveness of cationic liposomes to changes in temperature in the three dispersion media has revealed the self-assembly and the morphological complexity of cationic vectors. Finally, we suggest that these studies could be used for developing effective advanced drug delivery nano-systems (aDDnSs) based on their fractal characteristics which effectively draw their morphological profile.
Keywords: Charged liposomal vectors; Fractal dimension (d f ); Colloidal stability; Self-assembly; Serum-induced aggregation; Fetal bovine serum (FBS);
Cyclosporin nanosphere formulation for ophthalmic administration by Wahid Khan; Yanir H. Aldouby; Avi Avramoff; Abraham J. Domb (275-276).
Cyclosporin A (CsA) is a widely used anti-inflammatory agent for the management of dry eye disease, and is available commercially as ophthalmic emulsion formulation (RESTASIS®). For increasing efficacy, and for reducing local toxicity including irritation to eyes, CsA nanosphere (CsA-NS) formulation was prepared and evaluated, in this work. CsA-NS formulation was prepared in a pre-concentrate form, which is a homogeneous solution of a CsA in a mixture of surfactants, lipids and solvents and provides nanosphere dispersion when added to aqueous medium. CsA-NS formulation was characterized and adjusted for particle size, pH, and osmolarity, suitable for ophthalmic administration. Thereafter, CsA-NS formulation was evaluated for parameters like irritation to eyes and penetrability of CsA in the rabbit eyes. Results obtained demonstrated that proposed CsA-NS formulation causes less irritation in rabbit eyes, with nearly same CsA penetration in the rabbit eyes in comparison to marketed emulsion formulation.
Keywords: Cyclosporin A; Pro-dispersion; Nanosphere; Dry eye disease;
Preparation and evaluation of antifungal efficacy of griseofulvin loaded deformable membrane vesicles in optimized guinea pig model of Microsporum canis—Dermatophytosis by Nidhi Aggarwal; Shishu Goindi (277-287).
The present study is aimed at the encapsulation of griseofulvin in the deformable membrane vesicles (DMVs) for dermal delivery. Presently, griseofulvin is available only in conventional oral dosage forms that suffer from the issues of poor and highly variable bioavailability, numerous systemic side effects and long duration of treatment. Multi-lamellar drug-loaded DMVs of griseofulvin (Indian Patent Application 208/DEL/2009) were prepared by thin-film hydration method and were optimized for type and concentration of edge activator (EA). The optimized formulation was evaluated for vesicular shape, size, drug entrapment efficiency, drug content, pH, stability, spreadability, ex vivo skin permeation, dermatokinetics, skin sensitivity, in vitro antifungal assay and in vivo antifungal activity against Microsporum canis using guinea pig model for dermatophytosis. The optimized DMVs illustrated remarkably higher drug permeation and skin retention when compared with liposomes. A complete clinical and mycological cure was observed in animals treated with topical griseofulvin formulation in 10 days. The formulation was observed to be non-sensitizing, histopathologically safe, and stable at 5 ± 3 °C, 25 ± 2 °C and 40 ± 2 °C for a period of six months. The results indicated that the topical formulation of DMVs of griseofulvin could be utilized as an alternative to reduce the encumbrance of conventional oral formulations.
Keywords: Anti-fungal; Percutaneous; Permeability; Phospholipids; Site-specific delivery;
Amorphous solid dispersion enhances permeation of poorly soluble ABT-102: True supersaturation vs. apparent solubility enhancement by Kerstin J. Frank; Karin M. Rosenblatt; Ulrich Westedt; Peter Hölig; Jörg Rosenberg; Markus Mägerlein; Gert Fricker; Martin Brandl (288-293).
Amorphous solid dispersions (ASDs) represent a promising formulation approach for poorly soluble drugs. We explored the formulation-related impact of ASDs on permeation rate, apparent solubility and molecular solubility of the poorly soluble drug ABT-102. The influence of fasted state simulated intestinal fluid (FaSSIF) as dispersion medium was also studied.ASDs were prepared by hot-melt extrusion. Permeation rate was assessed by the Caco-2 transwell assay. Cell viability and barrier integrity were assured by AlamarBlue©, TEER and permeability of the hydrophilic marker carboxyfluorescein. Apparent solubility and molecular solubility were evaluated by using centrifugation and inverse dialysis, respectively.The in vitro permeation rate of ABT-102 from aqueous dispersions of the ASD was found 4 times faster than that from the dispersions of the crystals, while apparent solubility and molecular solubility of ABT-102 were increased. Yet, a further increase in apparent solubility due to micellar solubilization as observed when dispersing the ASD in FaSSIF, did not affect molecular solubility or permeation rate.Overall, a good correlation between permeation rate and molecular solubility but not apparent solubility was seen.
Keywords: Permeability; Solid dispersion; Solubility; Supersaturation; FaSSIF;
Microencapsulation of self-microemulsifying systems: Optimization of shell-formation phase and hardening process by A. Zvonar; K. Bolko; M. Gašperlin (294-302).
The preparation of microcapsules with a self-microemulsifying system (SMES) core using a vibrating nozzle technology was improved with regard to process reproducibility and core phase retention. The microcapsule shell was optimized for composition of the alginate–pectin (A/P) ratio and hydrophilic filling agent content. The best-shaped microcapsules with highest encapsulation efficiency for furosemide-loaded SMES were obtained from the shell-formation phase with an A/P ratio of 25:75, containing 10% lactose, which was hardened through a one-step process. Fluid-bed dried microcapsules were examined for their release characteristics and swelling behavior of the polymeric matrix. Incorporation of hydrophilic filling agents in the shell-formation phase was shown to be successful in limiting the leakage of the core phase during the microcapsule production and drying processes. Moreover, the addition of different fillers also allows the drug release profile from Ca-alginate/pectinate microcapsules with a self-microemulsifying core to be modified.
Keywords: Microcapsule; Alginate; Pectin; Drug release; Vibrating nozzle; Furosemide;
Comparison of commercial serum-free media for CHO-K1 cell growth and monoclonal antibody production by Maria Elisa Rodrigues; Ana Rita Costa; Mariana Henriques; Joana Azeredo; Rosário Oliveira (303-305).
The selection of a serum-free medium for a particular process of production using mammalian cells is a critical step for its success. In this study, seven commercially available serum-free media (EX-CELL, ISF-I, CD CHO, CDM4CHO, CHO-III-A, Octomed and HybridoMed) were evaluated and compared for cell growth and monoclonal antibody (mAb) production of a transfected CHO-K1 cell line. In the conditions assayed, EX-CELL and particularly CDM4CHO are the most recommended media for extended biopharmaceutical processes, on account of inducing superior levels of cell proliferation and mAb production, accentuated by a tendency to improve over time. Furthermore, the less positive results obtained with some media emphasize the importance and the impact of the correct medium selection.
Keywords: Serum-free media; CHO cells; Monoclonal antibody; Production; Cell growth;