International Journal of Pharmaceutics (v.306, #1-2)
TITLE PAGE (EDI BOARD) (iii).
Transfollicular drug delivery—Is it a reality? by Victor M. Meidan; Michael C. Bonner; Bozena B. Michniak (1-14).
Once regarded as merely evolutionary remnants, the hair follicles and sebaceous glands are increasingly recognised as potentially significant elements in the percutaneous drug delivery paradigm. Interest in pilosebaceous units has been directed towards their use as depots for localised therapy, particularly for the treatment of follicle-related disorders such as acne or the alopecias. Furthermore, considerable attention has also been focused on exploiting the follicles as transport shunts for systemic drug delivery. This paper reviews various key facets of this field including; relevant aspects of pilosebaceous anatomy and physiology, the design and efficacy of follicle-targeting formulations and the emergence of quantitative modeling systems. Several novel developments in this area promise to greatly expand our understanding of this field in the near future.
Keywords: Hair follicles; Pilosebaceous units; Transfollicular; Transdermal; Drug delivery;
Microfabricated drug delivery devices by J. Zachary Hilt; Nicholas A. Peppas (15-23).
We review newest developments in the design and fabrication of drug delivery devices based on micropatterned structures. Electronic devices have now reached a stage of dimensions comparable to those of biological macromolecules. This raises exciting possibilities for combining microelectronics and biotechnology to develop new technologies with unprecedented power and versatility. While molecular electronics use the unique self-assembly, switching and dynamic capabilities of molecules to miniaturize electronic devices, nanoscale biosystems use the power of microelectronics to design ultrafast/ultrasmall biocompatible devices, including implants, that can revolutionize the field of bioengineering. Thus, in recent years we have seen an explosion in the field of novel microfabricated and nanofabricated devices for drug delivery. Such devices seek to develop a platform of well controlled functions in the micro- or nano-level. They include nanoparticulate systems, recognitive molecular systems, biosensing devices, and microfabricated and microelectronic devices.
Keywords: Microfabrication; Drug delivery; Microdevice; Microneedle;
Optimisation and characterisation of bioadhesive controlled release tetracycline microspheres by S. Govender; V. Pillay; D.J. Chetty; S.Y. Essack; C.M. Dangor; T. Govender (24-40).
A Box-Behnken experimental design was employed to statistically optimise the formulation parameters of a tetracycline microsphere preparation for maximum bioadhesivity and controlled drug release. The quantitative effect of the formulation parameters at different levels on bioadhesion and drug release could be predicted using polynomial equations. A formulation comprising of 3% (w/w) chitosan, 10% (w/w) tetracycline HCl and 9% (w/v) tripolyphosphate was identified for maximising bioadhesivity and obtaining controlled drug release. The optimal microsphere preparation was subsequently characterised in terms of hydration dynamics, release kinetics, antimicrobial activity, thermal properties, morphology and surface pH. Kinetic models revealed that drug release followed Fickian diffusion while textural analysis showed minimal hydration over the test period. Antimicrobial studies showed that the drug concentrations in the in vitro release samples were above the minimum concentration of drug required for inhibition of Staphylococcus aureus growth. Thermal analyses showed a possible interaction between the drug and polymer. Scanning electron microscopy confirmed the integrity of the microspheres and identified the morphological changes following drug release. Surface pH of the microspheres was similar to salivary pH and did not show extremes in changes over the test period.
Keywords: Bioadhesion; Microspheres; Periodontal therapy; Experimental design; Physicochemical characterisation;
Micro-mechanical properties of drying material bridges of pharmaceutical excipients by Leon Farber; Gabriel I. Tardos; James N. Michaels (41-55).
This work is part of a larger research effort to elucidate the properties and morphology of pharmaceutical granules produced by wet-granulation. In this work, we measure forces exerted by the drying interparticle bridges. The bridges were formed from aqueous solutions of common pharmaceutical excipients both non-polymeric (lactose, mannitol) and polymeric (hydroxypropyl cellulose (HPC), hydroxypropyl methylcellulose (HPMC), polyvinylpyrrolidone (povidone) (PVP)). We also study the morphology, microstructure and crystalline structure of solidifying bridges. We find that the solidifying behavior and final properties of bridges differ dramatically, depending on the composition of the solution. Bridges containing only lactose or mannitol tend to expand upon solidification, pushing the ends of the bridge apart; in contrast, pure HPC, HPMC, or PVP bridges tend to contract. Bridges crystallized from solution of the pure non-polymeric excipients are polycrystalline, brittle, and have low strength; bridges from the polymeric excipients are amorphous, strong and tough. When the polymeric and non-polymeric excipients are used together, behavior closer to either one or the other extreme takes place. This depends on the relative amount of polymer in the bridge. It was also found that the different polymers impart different behavior on the bridge. The observed differences in solidification behavior have important implications for granule formation, drying and ultimate bridge and granule properties; these are discussed at some length in the paper.
Keywords: Granulation; Granules; Lactose; Mannitol; HPC; Binders;
Quality assessment of internet pharmaceutical products using traditional and non-traditional analytical techniques by Benjamin J. Westenberger; Christopher D. Ellison; Andrew S. Fussner; Susan Jenney; Richard E. Kolinski; Terra G. Lipe; Robbe C. Lyon; Terry W. Moore; Larry K. Revelle; Anjanette P. Smith; John A. Spencer; Kimberly D. Story; Duckhee Y. Toler; Anna M. Wokovich; Lucinda F. Buhse (56-70).
This work investigated the use of non-traditional analytical methods to evaluate the quality of a variety of pharmaceutical products purchased via internet sites from foreign sources and compared the results with those obtained from conventional quality assurance methods. Traditional analytical techniques employing HPLC for potency, content uniformity, chromatographic purity and drug release profiles were used to evaluate the quality of five selected drug products (fluoxetine hydrochloride, levothyroxine sodium, metformin hydrochloride, phenytoin sodium, and warfarin sodium). Non-traditional techniques, such as near infrared spectroscopy (NIR), NIR imaging and thermogravimetric analysis (TGA), were employed to verify the results and investigate their potential as alternative testing methods. Two of 20 samples failed USP monographs for quality attributes. The additional analytical methods found 11 of 20 samples had different formulations when compared to the U.S. product. Seven of the 20 samples arrived in questionable containers, and 19 of 20 had incomplete labeling. Only 1 of the 20 samples had final packaging similar to the U.S. products. The non-traditional techniques complemented the traditional techniques used and highlighted additional quality issues for the products tested. For example, these methods detected suspect manufacturing issues (such as blending), which were not evident from traditional testing alone.
Keywords: Analytical chemistry; Chromatography; Chemometrics; Dissolution; Image analysis; Near infrared spectroscopy; Thermal analysis;
Preparation and evaluation of reverse-phase evaporation and multilamellar niosomes as ophthalmic carriers of acetazolamide by Ahmed S. Guinedi; Nahed D. Mortada; Samar Mansour; Rania M. Hathout (71-82).
Niosomes have been reported as a possible approach to improve the low corneal penetration and bioavailability characteristics shown by conventional ophthalmic vehicles. Niosomes formed from Span 40 or Span 60 and cholesterol in the molar ratios of 7:4, 7:6 and 7:7 were prepared using reverse-phase evaporation and thin film hydration methods. The prepared systems were characterized for entrapment efficiency, size, shape and in vitro drug release. Stability studies were carried out to investigate the leaching of drug from niosomes during storage. The intraocular pressure (IOP) lowering activity of acetazolamide niosomal formulations in rabbits was measured using ShiØtz tonometer. Histological examination for the corneal tissues of rabbits receiving niosomal formulations was carried out for assessment of the ocular irritancy of niosomes. The results showed that the type of surfactant, cholesterol content and the method of preparation altered the entrapment efficiency and drug release rate from niosomes. Higher entrapment efficiency was obtained with multilamellar niosomes prepared from Span 60 and cholesterol in a 7:6 molar ratio. Niosomal formulations have shown a fairly high retention of acetazolamide inside the vesicles (approximately 75%) at a refrigerated temperature up to a period of 3 months. Each of the tested acetazolamide niosomes prepared by either method produced a significant decrease in IOP compared to the solution of free drug and plain niosomes. Multilamellar acetazolamide niosomes formulated with Span 60 and cholesterol in a 7:4 molar ratio were found to be the most effective and showed prolonged decrease in IOP. Histological examination of corneal tissues after instillation of niosomal formulation for 40 days showed slight irritation in the substantia propria of the eye which is reversible and no major changes in tissues were observed.
Keywords: Acetazolamide; Niosomes; Non-ionic surfactant vesicles; Ocular irritancy; Ophthalmic; Stability;
Formulation design of a novel fast-disintegrating tablet by Takao Mizumoto; Yoshinori Masuda; Takeshi Yamamoto; Estuo Yonemochi; Katsuhide Terada (83-90).
As our society is becoming increasingly aged, the development of an appropriate dosage form for the elderly patients is mostly desirable. A novel fast-disintegrating tablet was investigated in this study as a user-friendly dosage form for the aged. Advantages of this formulation have sufficient hardness and can be manufactured by commonly used equipment. Saccharides can be divided into high- and low-compressibility categories, and an appropriate material for fast-disintegrating tablets was created by taking advantage of this fact. To improve the compressibility of low-compressibility saccharides, particle modification was conducted by coating and granulating a low-compressibility saccharide with a high one to enable the production of a fast-disintegrating tablet. Another discovery was that the high-compressibility saccharide used as a binder solution was present in an amorphous state after the granulation process. The crystal change from amorphous to crystal state intentionally by a conditioning process after compression enabled to increase tablet hardness by strengthening adhesion between particles. The conditioning process made it possible to achieve sufficient hardness while maintaining the fast disintegration time. As a result, this fast-disintegrating tablet that can be manufactured by commonly used equipment, can be used for the dosing of a wide range drugs.
Keywords: Fast-disintegrating; Saccharide; Compressibility; Amorphous; Conditioning process;
Simultaneous effects of tocopheryl polyethylene glycol succinate (TPGS) on local hair growth promotion and systemic absorption of topically applied minoxidil in a mouse model by Chien-Ho Chen; Ming-Thau Sheu; An-Bang Wu; Keng-Ping Lin; Hsiu-O Ho (91-98).
In this study, topical minoxidil solutions supplemented with TPGS in cosolvent systems of various compositions consisting of water, alcohol, and polyethylene glycol 400 were designed to evaluate the efficacy of promoting hair growth after topical application and the safety in terms of the amount of minoxidil absorbed through the skin into the circulation using C57BL/6J mice as a model. The commercial product of 2% Regaine® was used as the positive control. The role, which sulfotransferase activity plays in hair growth with treatment using minoxidil, was determined as well. The results revealed that the addition of 0.5% TPGS was able to enhance the proliferation of hair, but an increase in the amount of TPGS to 2% led to deterioration in the enhancement of hair growth. At the higher added amount (2.0%) of TPGS, the promotion of hair growth was slightly reduced for both cosolvent formulations F1 (100% water) and F3 (100% PEG 400), whereas it was reduced to a greater extent for the cosolvent formulations F8–F10. In comparison, the influences of cosolvent compositions with TPGS amounts of 0.0 and 2.0% on the promotion of hair growth were similar. On the contrary, variability in the promotion of hair growth by different solvent formulations was minimal when the added amount of TPGS was 0.5%. In general, a relationship between hair growth and sulfotransferase activities after topical application of 2% Regaine® and minoxidil formulations containing various amounts of TPGS was not demonstrated. Plasma concentrations of minoxidil with 2% Regaine® were found to be greater than those of 2% minoxidil in those cosolvent formulations containing various amounts of TPGS, while showing insignificant differences among those 10 cosolvent formulations with a fixed amount of TPGS. A tendency for the plasma concentration of minoxidil to increase after the topical administration of minoxidil formulations containing the higher amount of TPGS (2%) was noted.
Keywords: TPGS; Minoxidil; Topical application; Sulfotransferase; Systemic effect;
Distribution of liposomal breviscapine in brain following intravenous injection in rats by Wenli Lv; Jianxin Guo; Jin Li; Luosheng Huang; Qineng Ping (99-106).
To investigate distribution of breviscapine in brain after intravenous (i.v.) injection of liposomes.Breviscapine liposomes were prepared by rotary evaporation–sonication method. Particle size, encapsulation efficiency and stability of liposomes were respectively examined. In vitro drug release was investigated in 0.9% sodium chloride at 37 °C. Rats were divided into two groups. Liposomes were given to one group and commercial injection (Injectio Breviscapine) was given to the other at a single dose of 28.1 mg kg−1 i.v., respectively. Scutellarin in rat brain at different sampling time was determined by RP-HPLC. The brain concentration–time curves of breviscapine liposomes and commercial injection were constructed and pharmacokinetic parameters were calculated and compared by statistic analysis.The average liposome diameter was 735 ± 59 nm and encapsulation efficiency was 85.1 ± 2.3%. The average accumulative release percentage of breviscapine liposomes in 0.9% sodium chloride was less than 30% within 24 h. The mean concentration–time curves of breviscapine liposomes and commercial injection were both fitted to one-compartment model. There are significant difference of parameter T 1/2 and AUC0–360 between liposome and commercial injection (p < 0.05). T 1/2 of breviscapine liposomes and commercial injection were 23.13 ± 7.71 and 6.27 ± 1.84 min, respectively. The brain AUC ratio of breviscapine liposomes to commercial injection was 443.4 ± 92.3%.Compared with the commercial injection, liposomes delivered more drugs into the brain and have longer elimination time.
Keywords: Breviscapine; Scutellarin; Liposomes; Pharmacokinetics; RP-HPLC;
Melarsoprol–cyclodextrins inclusion complexes by Stéphane Gibaud; Siham Ben Zirar; Pierre Mutzenhardt; Isabelle Fries; Alain Astier (107-121).
Melarsoprol, a water-insoluble drug, is mainly used in the treatment of trypanosomiasis and has demonstrated an in vitro activity on myeloid and lymphoid leukemia derived cell lines. It is marketed as a very poorly tolerated non-aqueous solution (Arsobal®). The aim of our work was to develop melarsoprol–cyclodextrin complexes in order to improve the tolerability and the bioavailability of melarsoprol. Phase-solubility analysis showed AL-type diagrams with β-cyclodextrin (βCD), randomly methylated β-cyclodextrin (RAMEβCD) and hydroxypropyl-β-cyclodextrin (HPβCD), which suggested the formation of 1:1 inclusion complexes. The solubility enhancement factor of melarsoprol (solubility in 250 mM of cyclodextrin/solubility in water) was about 7.2 × 103 with both β-cyclodextrin derivatives. The 1:1 stoichiometry was confirmed in the aqueous solutions by the UV spectrophotometer using Job's plot method. The apparent stability constants K 1:1, calculated from mole–ratio titration plots, were 57 143 ± 4 425 M−1 for RAMEβCD and 50 761 ± 5 070 M−1 for HPβCD. Data from 1H-NMR and ROESY experiments provided a clear evidence of inclusion complexation of melarsoprol with its dithiaarsane extremity inserted into the wide rim of the cyclodextrin torus. Moreover, RAMEβCD had a pronounced effect on the drug hydrolysis and the dissolution rate of melarsoprol. However, the cytotoxic properties of melarsoprol on K562 and U937 human leukemia cell lines was not modified by complexation.
Keywords: Melarsoprol; Methylated-β-cyclodextrin; Hydroxypropyl-β-cyclodextrin; Complexation; Nuclear magnetic resonance; Cytotoxicity;
Enhancement of brain distribution of anticancer agents using ΔG, the 12 kDa active fragment of ZOT by Divya Menon; Chetan S. Karyekar; Alessio Fasano; Ruliang Lu; Natalie D. Eddington (122-131).
The objective of this study was to evaluate the ability of ΔG, the 12 kDa active fragment of ZOT, to increase the brain distribution of MTX and paclitaxel, two commonly used anticancer agents with poor distribution into the brain.As part of dose estimation of ΔG, [14C]-sucrose (40 μCi/kg), a hydrophilic paracellular marker, was co-administered with ΔG (0, 400 and 800 μg/kg) with and without protease inhibitors to male Sprague–Dawley rats (n = 3 per group) via an intracarotid cannula. MTX (50 mg/kg) and [3H]-paclitaxel (120 μCi/kg) were co-administered with the effective doses of ΔG determined from the above study via the intracarotid cannula. Animals were euthanized by carbon dioxide asphyxiation at the specified time periods and brain and plasma samples were analyzed for the respective drug.The brain distribution of [14C]-sucrose was significantly enhanced at both doses of ΔG. A fold enhancement in the B/P ratios of 1.88 and 2.68 was observed at the 400 and 800 μg/kg doses respectively, when the protein was protected from metabolic degradation with PIs. ΔG significantly increased the brain distribution of MTX at each of the doses administered, with over a seven-fold increase at the 600 μg/kg dose. [3H]-paclitaxel brain AUC0–60 min was significantly higher in the presence of ΔG (800 μg/kg with PIs) with a 2.5-fold enhancement in brain exposure.ΔG significantly enhances the brain distribution of MTX (hydrophilic) and paclitaxel (lipophilic) and has the potential to be further developed as adjunct therapy to increase delivery of poorly permeable chemotherapeutic and other CNS targeted compounds.
Keywords: ZOT; ΔG; Blood–brain barrier; Tight junctions; Brain distribution; Permeation enhancer;
Strategies for improving the functionality of an affinity bioreactor by Tanya Wang; Zhiqiang Yang; Emel Emregul; Allan David; Joseph P. Balthasar; Junfeng Liang; Victor C. Yang (132-141).
Heparin employed in extracorporeal blood circulation (ECBC) procedures (e.g. open heart operations) often leads to a high incidence of bleeding complications. Protamine employed in heparin neutralization, on the other hand, can cause severe adverse reactions. We previously developed an approach that could prevent both heparin- and protamine-induced toxic side effects concomitantly. This approach consisted of placing a hollow fiber-based bioreactor device containing immobilized protamine (termed a “protamine bioreactor”) at the distal end of the ECBC procedure. This protamine bioreactor would remove heparin after heparin served its anticoagulant purpose in the ECBC device, thereby eliminating heparin-induced bleeding risks. In addition, this protamine bioreactor would prevent protamine from entering the patients, thereby aborting any protamine-induced toxic effects. Both in vitro and in vivo studies have successfully demonstrated the feasibility of this approach.Despite promises, early findings also revealed two shortcomings that must be overcome for the protamine bioreactor to be applied clinically. The first drawback was that the cyanate ester linkages, involved in conjugating protamine to the bioreactor device, were unstable and prone to hydrolysis, resulting in the leakage of a significant amount of protamine into circulation during application of the protamine bioreactor. The second deficiency was that the capacity of the protamine bioreactor in heparin removal was rather low, owing to the limited surface area of the hollow fibers for protamine immobilization and subsequently heparin adsorption.In this paper, we present novel strategies to overcome these two limitations. A new conjugation method based on the use of 4-(oxyacetyl)phenoxyacetic acid (OAPA) as the activating reagent was employed to yield stable linkages, via the abundant arginine residues of protamine, onto the hollow fibers. Results showed that while the amount of protamine immobilized on each gram of fibers was relatively comparable between the OAPA and the previous CNBr activation methods (7.45 mg/g versus 7.69 mg/g fibers), there was virtually no detectable leaching of immobilized protamine from the bioreactor by the OAPA method, comparing to 35% leaching of protamine by the previous CNBr method following 72 h of storage of the bioreactor in PBS buffer at 37 °C.To improve the capacity and functionality of the protamine bioreactor, two novel approaches were adopted. Long chain and high molecular weight poly-lysine was linked to the hollow fibers, prior to protamine coupling, to create multiple layers of immobilized protamine for subsequent heparin adsorption. In addition, a poly(ethylene glycol) (PEG) chain was inserted between protamine and the hollow fibers to yield a three-dimensional, free dynamic motion for immobilized protamine. Preliminary observations indicated that a four- to five-fold enhancement in heparin adsorption was attained by utilizing each of these new approaches. Aside from their current use, these new strategies can also be employed generically to improve the functionality of any affinity-type bioreactor. Indeed, efforts have been made recently in utilizing these approaches to develop a clinically usable GPIIb/IIIa bioreactor for the treatment of immune thrombocytopenic purpura (ITP)—an autoimmune disease.
Keywords: Protamine bioreactor; Heparin adsorption; Langmuir adsorption isotherm; Poly(ethylene glycol) modification; Polylysine amplification;
Mixed micelles made of poly(ethylene glycol)–phosphatidylethanolamine conjugate and d-α-tocopheryl polyethylene glycol 1000 succinate as pharmaceutical nanocarriers for camptothecin by L. Mu; T.A. Elbayoumi; V.P. Torchilin (142-149).
Micelles from the mixture of poly(ethylene glycol)–phosphatidyl ethanolamine conjugate (PEG–PE) and d-α-tocopheryl polyetheyene glycol 1000 succinate (TPGS) were prepared loaded with the poorly soluble anticancer drug camptothecin (CPT). The solubilization of CPT by the mixed micelles was more efficient than with earlier described micelles made of PEG–PE alone. CPT-loaded mixed micelles were stable upon storage and dilution and firmly retained the incorporated drug. The cytotoxicity of the CPT-loaded mixed micelles against various cancer cells in vitro was remarkably higher than that of the free drug. PEG–PE/TPGS mixed micelles may serve as pharmaceutical nanocarriers with improved solubilization capacity for poorly soluble drugs.
Keywords: Micelles; Mixed micelles; Polymer–lipid conjugates; TPGS; Poorly soluble drugs; Anticancer drugs; Camptothecin;
Author Index Volumes 288-306 (152-178).
Subject Index Volumes 288-306 (179-193).