International Journal of Pharmaceutics (v.265, #1-2)
TITLE PAGE(EDI BOARD) (iii).
Lung-targeting microspheres of carboplatin by B Lu; J.Q Zhang; H Yang (1-11).
Carboplatin (CPt) was incorporated in the gelatin microspheres by the method of emulsion and the drug content determined spectrophotometrically. The arithmetic mean diameter of the microspheres was 13.20 μm with 98% of the microspheres ranging from 5.0 to 28.6 μm. The average carboplatin content was 23.76% and the yield of the microspheres 85.12%. The microspheres were stable for three months when stored at 37 °C/RH 75%, showing insignificant change in appearance and drug content. The in vitro release profile of the microspheres could be described by a biexponential equation, and the release t 1/2 was 49.7 min and 92.04% released in 10 h; while for the original drug, CPt, under the same conditions, 92.15% released in the first half an hour. Very high lung-targeting efficiency in vivo was proved by the results of targeting parameters. The S-180 lung neoplasm models were established by i.v. cancer cells in mice and the number of pulmonary nodules examined for evaluation of the treatment effect. The results of therapeutic tests showed that the antitumour effects were increased by injection of the microspheres compared with the injection of CPt solution: half of the dose in the microspheres showed comparable effect to the original drug.
Keywords: Carboplatin; Gelatin; Lung-targeting drug delivery systems; Antitumour drug;
Preparation and in-vitro release rate of fentanyl–cyclodextrin complexes for prolonged action in epidural analgesia by C Holvoet; J Plaizier-Vercammen; Y Vander Heyden; M Gabriëls; F Camu (13-26).
Fentanyl was complexed with cyclodextrin derivatives with the intention to obtain parenteral solutions able to provide prolonged analgesia following epidural administration. Three cylodextrins (CDs) suitable for parenteral use were used: hydroxypropyl-β-cyclodextrin (HP-β-CD), sulfobutylether-β-cyclodextrin (SBE-7-β-CD), and maltosyl-β-cyclodextrin (malt-β-CD). Analysis of fentanyl was done with HPLC-UV. The inclusion capacity of HP-β-CD was determined from phase-solubility diagrams at pH 6.5, 7.2 and 8.0, and those of SBE-7-β-CD and of malt-β-CD at pH 8.0. Solubility of fentanyl increased linearly (i) as a function of the CD concentration, and (ii) with decreasing pH. Complexation was highest with HP-β-CD and malt-β-CD, much higher than with SBE-7-β-CD, with stability constants at pH 8.0 of 801, 729 and 1309 M−1, respectively. The CD concentration was calculated to obtain a fentanyl–CD formulation, with the desired amount free fentanyl as loading dose in solution and the rest complexed with CD, as reservoir for prolonged action. A suitable membrane and a release-rate apparatus were selected for in-vitro release-rate studies. Best results were obtained with Spectrapor membranes and a home-made release-rate apparatus. Release rate was evaluated in static and dynamic conditions. For both modes, the release rate of fentanyl decreased as a function of CD concentration, due to complex formation of fentanyl, which suggests the possibility to provide prolonged pharmacodynamic effects in vivo.
Keywords: Fentanyl; Cyclodextrins; Epidural use; Inclusion complexation; Prolonged-action formulation; In-vitro release studies in static and dynamic conditions;
Surface characterisation of bags for total parenteral nutrition by tensiometry and atomic force microscopy by Nicola Realdon; Lucio Zennaro; Francesco Perin; Antonio Bettero; Silvia Bortoluzzi; Adelio Rigo; Enrico Ragazzi (27-35).
Bags made of poly-ethylene and poly-vinylchloride and of the copolymer ethylene–vinylacetate were used as containers of perfusion solutions for total parenteral nutrition. The bags were characterised by tensiometry (free energy and its polar and dispersed components) and atomic force microscopy (AFM) before and after various periods of storage of solutions for total parenteral nutrition containing l-aminoacids, electrolytes or glucose. In most of the cases, after storage of these solutions, tensiometric characterisation and atomic force microscopy analysis of the internal surface of bags showed deep modifications which highlight the adsorption of the solutes. The changes of surface characteristics were found to depend on the time of contact, the wettability of the polymer and the compounds present into the solutions, while their concentration has a negligible effect. Generally, the aminoacid solutions produced a higher increase in the polar component even after short storage times. Poly-ethylene and the copolymer ethylene–vinylacetate showed a greater inertia if compared with the poly-vinylchloride bags.
Keywords: Total parenteral nutrition; Tensiometry; Atomic force microscopy; Poly-ethylenevinylacetate; Poly-ethylene; Poly-vinylchloride;
A novel delivery system for amphotericin B with lipid nano-sphere (LNS®) by Hiroshi Fukui; Tomohiro Koike; Akira Saheki; Satoru Sonoke; Junzo Seki (37-45).
A low-dose therapeutic system with a lipid emulsion for amphotericin B (AmB), a potent antifungal drug, was studied. Lipid nano-sphere (LNS®), a small-particle lipid emulsion, was taken up by the liver to a lesser extent than was a conventional lipid emulsion. As a result, LNS yielded higher plasma concentrations of a radiochemical tracer than did the conventional lipid emulsion. LNS was therefore judged to be a suitable carrier for a low-dose therapeutic system for AmB, and LNS incorporating AmB (LNS-AmB) was prepared. LNS-AmB was found to be a homogeneous emulsion with mean particle diameters ranging from 25 to 50 nm. LNS-AmB yielded higher plasma concentrations of AmB than did Fungizone®, a conventional intravenous dosage form of AmB, after intravenous administration to mice, rats, dogs, and monkeys. This difference between LNS-AmB and Fungizone was also observed for constant intravenous infusion. In contrast to Fungizone, LNS-AmB showed a linear relationship between dose and AUC. These pharmacokinetic characteristics of LNS-AmB make it a suitable candidate for an effective low-dose therapeutic system for AmB.
Keywords: Amphotericin B; Nanoemulsions; Lipid emulsion; LNS;
Design and evaluation of an early stage drug release apparatus by D Mukhopadhyay; I.G Tucker (47-54).
This paper describes the design and evaluation of an early stage drug release apparatus (ERA) to determine drug release from pellets at times less than 1 min. The apparatus comprises a stirred sample chamber in which the sample is retained by a BS150 mesh screen (0.106 mm), and a series of jacketed cups containing the medium (80 ml) which are raised and lowered in turn over the fixed sample chamber for specified periods. Three types of early release studies were used: single 60 s study (single cup), 10 s followed by 50 s (two cups) and 10, 20, 30 … 60 s multiple changeover differential release (six cups). The effects of stirrer speed, stirrer position and multiple changeover on drug release from standard paracetamol-alginate pellets were investigated. Drug release rates from non-disintegrating pellets were reproducibly determined. The three types of early release study schemes yielded reproducible drug release data over sampling times less than 1 min. Stirrer speed, and depth, and changeover motion of release cups affected drug release but yielded reproducible results. Release from the standard pellets used to study the apparatus took 3 days to stabilize and remained stable thereafter. The apparatus can be used for screening of pellet formulations of sparingly soluble drugs during their developmental stage and regular quality assurance studies of pellets (>150 mesh size). Along with early release studies of pellets, it could be easily modified to study other types of formulations and for automation.
Keywords: Early stage drug release; Burst release; Release apparatus;
A new index, the core erosion ratio, of compression-coated timed-release tablets predicts the bioavailability of acetaminophen by T Sawada; K Sako; M Fukui; S Yokohama; M Hayashi (55-63).
Although compression-coated tablets are a commonly used timed-release drug delivery technology, their utility is often limited by poor bioavailability. To try to improve the bioavailability of these tablets, the effect of their core composition of compression-coated tablet on in vivo pharmacokinetics was investigated. First, the extent of mass reduction of cores in different compression-coated tablet core formulations was used to establish a new index, the core erosion ratio. The data show that adding excipients with high water solubility to the core results in a greater core erosion ratio. Next, to elucidate the effect of core erosion ratio on in vivo acetaminophen (AAP) release, three compression-coated tablet formulations with similar in vitro AAP release profiles but different core erosion ratios were administered to four fasted dogs. The time for first appearance (TFA) of AAP in plasma did not differ significantly among formulations, indicating that the in vivo lag time was the same for all formulations. In separate experiments, necroscopy revealed that 3 h after oral administration, the tablets were located in the ileum and colon and that all three formulations had identical GI transit times. However, the area under the AAP plasma concentration–time curve was greater in dogs given formulations with larger core erosion ratios. These results suggest that a formulation with a large core erosion ratio can significantly increase in vivo drug release from compression-coated tablets, leading to increased drug absorption from the lower GI tract.
Keywords: Compression-coated tablets; Timed-release formulation; Dogs; Acetaminophen; Core erosion ratio;
Bioavailability of a morphine suppository is increased after intracolostomal administration in colostoma-constructed rabbits by Kazuki Nagasawa; Sumiko Kintsuji; Hirokazu Nakanishi; Katsuhito Nagai; Sadaki Fujimoto (65-73).
This study was performed to assess the pharmacokinetics of morphine and its major metabolites after its rectal or colostomal administration in rectal-resected (ROP) or colostoma-constructed (SOP) rabbits, respectively. The pharmacokinetics of morphine, morphine-3-glucuronide (M3G), and M6G in normal rabbits appeared to be similar to those in human, judging from their plasma concentration–time profiles and the susceptibility of morphine to first-pass metabolism. In SOP, but not ROP, rabbits, the plasma concentrations of morphine, M3G and M6G were significantly increased compared with those in normal rabbits. The AUC of morphine and its metabolites, and the F value of the former in the SOP group were greater than those in the control group, while the elimination half-life (t 1/2) values were comparable in the two groups. In addition, the disposition of morphine and its metabolites after intravenous (i.v.) administration to SOP rabbits was almost the same as that in normal rabbits, suggesting that an increase in the rate of absorption of morphine in SOP rabbits was not due to inflammation at the absorption site caused by operation, but probably due to its increased solubility in loose stools. Therefore, great attention should be paid when morphine suppositories are intracolostomally administered to colostoma-constructed patients.
Keywords: Palliative care; Pharmacokinetics; Morphine suppository; Metabolism; Colostoma; Rabbit;
Effect of side-chain structures on gene transfer efficiency of biodegradable cationic polyphosphoesters by Jun Wang; Shi-Wen Huang; Peng-Chi Zhang; Hai-Quan Mao; Kam W. Leong (75-84).
Cationic polyphosphoesters (PPEs) with different side-chain charge groups were designed and synthesized as biodegradable gene carriers. Poly(N-methyl-2-aminoethyl propylene phosphate) (PPE-MEA), with a secondary amino group (CH2CH2NHCH3) side chain released DNA in several hours at N/P (amino group of polymer to phosphate group of DNA) ratios from 0.5 to 5; whereas PPE-HA, bearing CH2(CH2)4CH2NH2 groups in the side chain, did not release DNA at the same ratio range for 30 days. Hydrolytic degradation and DNA binding results suggested that side chain cleavage, besides the polymer degradation, was the predominant factor affected the DNA release and transfection efficiencies. The side chain of PPE-MEA was cleaved faster than that of PPE-HA, resulting poor cellular uptake and no transgene expression for PPE-MEA/DNA complexes in COS-7 cells at charge ratios from 4 to 12. In contrast, PPE-HA/DNA complexes were stable enough to be internalized by cells and effected gene transfection (3400 folds higher than background at a charge ratio of 12). Interestingly, gene expression levels mediated by PPE-MEA and PPE-HA in mouse muscle following intramuscular injection of complexes showed a reversed order: PPE-MEA/DNA complexes mediated a 1.5–2-fold higher luciferase expression in mouse muscle as compared with naked DNA injection, while PPE-HA/DNA complexes induced delayed and lowered luciferase expression than naked DNA. These results suggested that the side chain structure is a crucial factor determining the mechanism and kinetics of hydrolytic degradation of PPE carriers, which in turn influenced the kinetics of DNA release from PPE/DNA complexes and their transfection abilities in vitro and in vivo.
Keywords: Non-viral gene delivery; Sustained release; Polymeric carrier; Polyphosphoester;
Formation of fine drug particle by cogrinding with cyclodextrins by Arpansiree Wongmekiat; Yuichi Tozuka; Toshio Oguchi; Keiji Yamamoto (85-93).
The purpose of this study was to investigate the effect of moisture condition during cogrinding process on fine drug particle formation. Cogrinding of cyclodextrins (CDs) and pranlukast (PRK) hemihydrate was performed in various moisture conditions at a mixing molar ratio of 2:1 (CDs:PRK) and the formation of PRK submicron particle was investigated. The moisture content in the cogrinding process significantly affected the fine particle formation. More than 90% of pranlukast loaded transformed to submicron particles when coground with α-CD, β-CD or γ-CD containing the specific amount of water for each CD system. Fine particle formation of PRK was considered as a particular phenomenon to cyclodextrins, since the submicron particles could not be formed when d-mannitol, lactose or microcrystalline cellulose (MCC) was used as a cogrinding additive. Moreover, the appearance and disappearance of fine particle formation was found to be reversible depending on the existence of water during the grinding process.
Keywords: Submicron particle; Cyclodextrin; Pranlukast; Cogrinding; Poorly water-soluble drug;
Improvement in the bioavailability of poorly absorbed glycyrrhizin via various non-vascular administration routes in rats by Kazuhiro Sasaki; Shingo Yonebayashi; Motoyuki Yoshida; Kenji Shimizu; Tomaji Aotsuka; Kozo Takayama (95-102).
The purpose of this study was to examine the improvement of the bioavailability of glycyrrhizin (GL) via extra-vascular, i.e. oral, rectal, and nasal routes with or without the aid of an absorption enhancer in place of the vascular intravenous route in rats. Pharmacokinetic behavior following administration via vascular routes, i.e. the intravenous and portal-venous routes was examined in rats. The area under the plasma concentration–time curve (AUC) after administration of GL via the portal vein was decreased slightly, suggesting that the first elimination of GL in the liver may be one of the factors contributing to the low bioavailability after administration via the oral route.When GL was administered orally as a solution (30 mg/kg), the plasma concentration of GL was extremely low. However, after rectal or nasal administration of GL solution (30 mg/kg) with or without sodium caprate, the mean AUC value was remarkably increased compared with oral administration. In particular, the absolute bioavailability of GL after nasal administration was estimated to be approximately 20%, which was approximately 80-fold greater compared with after oral administration despite of the absence of an enhancer. Furthermore, the fatty acids co-administered orally with GL produced an increase in GL absorption in the following order: sodium caprate>sodium laurate>sodium caprylate>sodium oleate. These results indicate that the rectum and nasal cavity are useful administration routes for systemic delivery of GL. It was also found that the fatty acids were enhancers for the absorption of GL.
Keywords: Glycyrrhizin; Absorption enhancer; Fatty acids; Sodium caprate;
Ultrasonication of chitosan and chitosan nanoparticles by E.S.K. Tang; M. Huang; L.Y. Lim (103-114).
The objective of this study was to evaluate the effects of ultrasonication on chitosan molecules and nanoparticles. Molecular weight (M v) of chitosan HCl (M v 146 kDa and degree of deacetylation (DD) 96%) decreased linearly with increasing duration and amplitude of ultrasonication. DD and FTIR absorption were unaffected. X-ray diffraction (XRD) analysis suggested greater chain alignment in the ultrasonicated chitosan samples. Chitosan nanoparticles had mean diameter of 382 nm, polydispersity of 0.53 and zeta potential of 47 mV. Ultrasonication administered at increasing duration or amplitude decreased the mean diameter and polydispersity of the nanoparticles. Zeta potential and FTIR absorbance were unaffected, while XRD suggested a greater disarray of chain alignment in the nanoparticle matrix. Under the transmission electron microscope (TEM), freshly prepared nanoparticles were dense spherical structures which became fragmented after ultrasonication for 10 min at amplitude of 80. Untreated nanoparticle formulation turned turbid upon storage for 3 weeks at ambient conditions due to substantial swelling of the nanoparticles. Ultrasonicated nanoparticle formulation remained clear on storage. Although the particles had also swelled, they were no longer spherical, assuming instead an irregular shape with branching arms. In conclusion, high-intensity ultrasonication induced considerable damage on the chitosan nanoparticles which could affect their function as drug carriers.
Keywords: Chitosan nanoparticles; Ultrasonic; M v; Particle size; TEM; Storage;
Comparative evaluation of the human whole blood and human peripheral blood monocyte tests for pyrogens by S.S Andrade; R.L Silveira; C.A Schmidt; L.Brum Júnior; S.L Dalmora (115-124).
Two different in vitro tests for pyrogens, using human peripheral blood monocytes (PBMNC) and diluted whole blood (WBC), respectively, were applied to different classes of parenteral medicinal products. Many of these products did not have a specified endotoxin limit concentration that was established as the maximum valid dilution to comply with the test. The results of the in vitro tests for pyrogens were compared with the results from the Limulus amoebocyte lysate (LAL) and rabbit pyrogen tests. The Second International Standard for endotoxin was used to calibrate all of the assays and the International Standard for IL-6 was used to calibrate the IL-6 ELISA which provided the readout for the in vitro tests for pyrogens. Preparatory tests were conducted to ensure that the “criteria for validity and precision of the standard curve” were satisfied and that the drugs being tested did not interfere in the tests. The PBMNC/IL-6 test had a detection limit of 0.06 EU/ml and spike recoveries were 62–165%. The whole blood/IL-6 test also had a detection limit of 0.06 EU/ml and spike recoveries were 58–132%. The application to the detection of non-endotoxin pyrogens needs to be evaluated in more detail, but the two in vitro tests for pyrogens showed good agreement overall, both with each other and with the LAL test and the rabbit pyrogen test for the detection of endotoxins.
Keywords: Blood; IL-6; In vitro test; Pyrogens; Monocytes; Quality control;
Design and monitoring of photostability systems for amlodipine dosage forms by G. Ragno; E. Cione; A. Garofalo; G. Genchi; G. Ioele; A. Risoli; A. Spagnoletta (125-132).
Photostability of amlodipine (AML) has been monitored in several pharmaceutical inclusion systems characterized by plurimolecular aggregation of the drug and excipients with high molecular weight. Several formulations including cyclodextrins, liposomes and microspheres have been prepared and characterized. The photodegradation process has been monitored according to the conditions suggested by the ICH Guideline for photostability testing, by using a light cabinet equipped with a Xenon lamp and monitored by spectrophotometry. The formulations herein tested have been found to be able to considerably increase drug stability, when compared with usual pharmaceutical forms. The residual concentration detected in the inclusion complexes with cyclodextrins and liposomes was 90 and 77%, respectively, while a very good value of 97% was found for microspheres, after a radiant exposure of 11,340 kJ m−2.
Keywords: Amlodipine; Photodegradation; Supramolecular systems; Liposomes; Cyclodextrins; Microspheres;
The physical stability of thermally-stressed phospholipid-based emulsions containing methyl, propyl and heptyl parabens as model drugs by Xiaoguang Zhang; Lee E. Kirsch (133-140).
The objectives of the studies presented herein was to investigate the mechanisms of emulsion instability under thermal stress (121 °C) by evaluating the effects of a lipophilic drug dissolved in the internal phase of an oil-in-water (o/w) emulsion on growth rate suppression and the apparent microviscosity. Model drugs used were methyl, propyl and heptyl paraben. The o/w emulsions were prepared using medium chain triglycerides as an internal phase in aqueous glycerol solutions emulsified with phospholipids. Concentrations of paraben in the internal phase varied from 0.2–0.8 M. Microfluidization was used to reduce the droplet size to the submicron range. Microviscosity was calculated from the measured anisotropy of a fluorophore probe (1,6-phenyl-1,3,5-hexatriene) using a modified Perrin’s equation. Emulsion aliquots were subjected to thermal stressed at 121 °C the droplet growth rate was determined from periodic measurements of the mean droplet diameter using photon correlation spectroscopy. The growth rate decreased in the presence of parabens. Maximal growth suppression occurred at paraben concentrations of 0.4 M. However in deference to theoretical predictions of the effects of increasing co-solute concentrations based on Ostwalt ripening, the droplet growth rates increased at concentrations greater than 0.4 M. The logarithm of the growth rate was linearly correlated to the interfacial rigidity (inverse microviscosity) of the emulsion which suggests that coalescence rather than molecular diffusion was primarily responsible for emulsion instability under the conditions studied.
Keywords: Emulsion stability; Phospholipids; Photon correlation spectroscopy; Anisotropy; Fluorescence polarization; Coalescence; Ostwalt ripening; Molecular diffusion; Paraben;
Ternary naproxen:β-cyclodextrin:polyethylene glycol complex formation by Margarita Valero; Carmen Carrillo; Licesio J. Rodrı́guez (141-149).
The aim of this study was to investigate the effect of the presence of the water-soluble polymer polyethylene glycol (PEG)—MW=35000 g/mol—on the complexation of the phototoxic anti-inflammatory drug naproxen, in its sodium salt form, with β-cyclodextrin (β-CD). The data revealed that the polymer does not interact with the uncomplexed naproxen whereas it does with the β-CD.The presence of different proportions of PEG, in the 0–1% (w/w) range, systematically lowers K app of the formation of the naproxen:β-CD inclusion complex. The reason for the decrease in the complexed drug is the presence of other competing equilibria, the first one is an interaction of the polymer with the β-CD, which in turn reduces the amount of free CD available for including the naproxen, and the second is the formation of a naproxen:β-CD:PEG ternary complex with lower affinity than the binary complex. The binding constant of these processes are K 2=(4.5±1.0)×105 M−1 and K 3=870±19 M−1, respectively.In addition the presence of the PEG produces an important change in the driving force of the complex formation. In this case the process is enthalpically unfavoured and entropically favoured; these are typical characteristics of processes governed by hydrophobic interactions.
Keywords: Naproxen; β-Cyclodextrin; Polyethylene glycol;
Transport mechanism(s) of poly (amidoamine) dendrimers across Caco-2 cell monolayers by M. El-Sayed; C.A. Rhodes; M. Ginski; H. Ghandehari (151-157).
The objective of this research was to investigate the mechanism(s) of transport of generation 2 (G2) poly (amidoamine) dendrimers across Caco-2 cell monolayers. The contribution of an energy-dependent process such as adsorptive endocytosis was investigated by determining G2 permeability at 4 and 37 °C. The contribution of P-gp efflux to transport was examined by determining the apical to basolateral (AB) and basolateral to apical (BA) permeability of 14 C -paclitaxel in presence of G2, and by determining AB and BA permeability of G2 in presence of paclitaxel. The permeability of G2 and 14 C -mannitol was investigated in the presence of palmitoyl carnitine to determine the contribution of the paracellular pathway. Permeability of G2 at 4 °C was significantly (P<0.05) lower than that observed at 37 °C. AB and BA permeability of 14 C -paclitaxel did not change in the presence of G2. AB and BA permeability of G2 did not change in the presence of paclitaxel. The permeability of G2 and 14 C -mannitol increased significantly (P<0.05) in the presence of palmitoyl carnitine, and in addition, 14 C -mannitol permeability was increased in presence of G2. The permeability of G2 across Caco-2 cell monolayers appears to involve a combination of paracellular transport and an energy-dependent process, possibly adsorptive endocytosis. G2 dendrimers do not appear to be substrates for the P-gp efflux system.
Keywords: Drug delivery; Oral permeability; Poly (amidoamine) dendrimers;