Preliminary evaluation of the in vitro release and in vivo absorption in rabbits of the modified-release dosage forms

Objective: The suitability of the rabbit as an animal model for the primary screening and selection of the pilot scale batches during the early stages of the formulation development was studied.

Materials and methods: Three modified-release formulations of aminophylline consisted of Carbopol® 971P/HPMC K4M (F-I), and HPMC K100M (F-II) or HPMC K4M (F-III) were used. Commercial products were Aminofilin retard 350?mg tablets, Srbolek, Serbia (R-I) and Phyllocontin^® 350, tablets Purdue Frederic, Canada (R-II).

Results: Calculated release rate constants and the ?2 values between R-I/F-I (84.1) and R-II/F-III (83.4) indicated similar in vitro release while the coefficient n showed presence of different mechanisms of release from Anomalous transport, Fickian diffusion to Case-II transport. Higher T_max, was found in the rabbits, dosed with F-II (12.00?h), F-III (10.50?h), and R-II (15.00?h) formulation. The highest C_max (9.22?mg/L) was obtained with F-II, similar lower values was seen for F-I and F-III, while commercial products showed the lowest values R-I (5.58?mg/L) and R-II (4.18?mg/L). Higher AUC values were detected for all three formulations (from 115.90 to 204.06 mgh/L) in relation to commercial products (105.33 and 113.25 mgh/L).

Discussion and conclusion: The results demonstrated a good correlation of Level A (r² = 0.97) for the two formulations (F-I, F-III) and commercial product (R-I) indicates that there is a reasonable assumption that the rabbit might be use as a model for the preliminary comparison of scale up formulations in the early stages of the product development.     

Onychopharmacokinetics of terbinafine hydrochloride penetration from a novel topical formulation into the human nail in vitro

This study determined the onychopharmacokinetics, nail absorption, distribution, and penetration of [¹⁴C]-terbinafine HCl in a new topical formulation into/through the human finger nail using the in vitro finite dose model. This study determined the penetration rate of terbinafine HCl from multiple doses of topical formulation applied daily for 14 days. Results showed that the total dose recovery (mass balance) was almost 100%. The concentration of terbinafine HCl in the deeper nail plate (ventral/intermediate layers) and the cotton-pad nail bed samples after the 14-day treatment were 613?±?145 and (±S.D.) and 27?±?1.2 µg/cm³ (or 1.9?±?0.6 µg/cm³ daily) on average, respectively. In comparison with nail concentration data from the literature for other topical terbinatine formulations, our results show that higher amounts of terbinafine HCl reached the deep nail plate and/or the nail bed after a 14-day topical treatment with this topical formulation in vitro.     

Preparation and characterization of 5-fluorouracil pH-sensitive niosome and its tumor-targeted evaluation: in vitro and in vivo

The purpose of this study was to investigate preparation, characterization and tumor-targeted effect of pH-sensitive niosomes, composed of a nonionic surfactant mixed with cholesteryl hemisuccinate (CHEMS), a derivative of cholesterol (CHOL), as a pH-sensitive molecule.

CHEMS was synthesized with CHOL and succinic acid, the structure of which was analyzed by Mass spectrometry (MS) and ¹H Nuclear magnetic resonance (¹H NMR) spectrum. Niosomes were prepared via film hydration-probe ultrasound method. Both normal niosomes and pH-sensitive niosomes showed spherical morphology under transmission electron microscope (TEM) with a average particle sizes of 172?±?6.2?nm and 153?±?4.7?nm, respectively. The thermotropic behavior, structure changes and interaction of 5-fluorouracil (5-Fu) with other materials were characterized by differential scanning calorimetry (DSC), and the disappearance of the melting peak of drug revealed the fact that drug was encapsulated in niosomes. Bulk-equilibrium reverse-dialysis method was chosen to investigate the behavior of drug release from normal niosomes and pH-sensitive niosomes in different pH medium, and the results showed that the noisome containing CHEMS had a pH-sensitive property. Tumor-targeted effect was proved by the fact that pH-sensitive niosomes showed a remarkable high concentration in tumor site of the mice transplanted with tumor cell.     

Formulation and optimisation of famotidine proniosomes: an in vitro and ex vivo study

The aim of the study was to develop a proniosomal system for famotidine (FAM), a potent H₂ receptor antagonist that could efficiently deliver entrapped drug over a prolonged period of time. The proniosomal system was formulated by selecting various ratios of Span 60 and cholesterol using a coacervation-phase separation method. The formulated systems were characterised for drug excipient compatibility studies by Fourier transform infrared spectroscopy (FTIR), vesicle size determination by the particle size analyser, % drug encapsulation, drug-release profiles, field emission scanning electron microscopy (FESEM) for surface morphology, X-ray diffraction (XRD) and vesicular stability at different storage conditions. By using this method, the % drug loading that resulted by the encapsulation of proniosome was found to be 78%–89%. Increase in cholesterol and surfactant concentration increases encapsulation efficiency, but further increment decreases encapsulation. In vitro drug-release studies showed prolonged release of entrapped famotidine. The highest % cumulative drug release was achieved in formulation FAM2 (96%) in 24 hours. The ex vivo data on the release of famotidine from proniosomal formulations have shown significantly increased per cent release and flux in comparison to the same dose of marketed preparation of famotidine. Stability studies were carried out in refrigerated conditions, and higher drug retention was observed. It is evident from this study that proniosomes are a promising prolonged delivery system for famotidine and have reasonably good stability characteristics.     

Considerations in the development of an in vitro dissolution condition for lacidipine tablets: in vivo pharmacokinetic evaluation

In this study, a new discriminative dissolution condition for lacidipine tablets was developed by the established in vitro–in vivo relationship. Series of dissolution media of phosphate buffer solution (PBS) covering the pH range of 1–7.2 and pH 6.8 PBS containing different concentrations of sodium dodecyl sulfate (SDS), were prepared and used to investigate the dissolution behavior of lacidipine tablets. There was an obvious difference in the dissolution profiles of the both brands in pH 6.8 PBS medium containing 0.1% SDS. The pharmacokinetic study of the two lacidipine tablets was carried out in the healthy beagle dogs at a single dose of 4?mg. Statistical comparison of the AUC_0–24, C_max, and T_max showed a significant difference in the two brand tablets, coinciding with the dissolution performance with pH 6.8 PBS containing 0.1% SDS. The superiority of the proposed system, pH 6.8 PBS containing 0.1% SDS, could serve as a dissolution medium for lacidipine tablets, and more important it could discriminate the in vivo pharmacokinetic behavior for different brands of products. In summary, in vivo pharmacokinetic evaluation is essential to develop an appropriate in vitro dissolution condition for oral solid dosage forms of poorly soluble drugs.     

Preparation and in vitro/in vivo evaluation of azilsartan osmotic pump tablets based on the preformulation investigation

The objective of this study was to design and evaluate azilsartan osmotic pump tablets. Preformulation properties of azilsartan were investigated for formulation design. Azilsartan osmotic pump tablets were prepared by incorporation of drug in the core and subsequent coating with cellulose acetate and polyethylene glycol 4000 as semi-permeable membrane, then drilled an orifice at the center of one side. The influence of different cores, compositions of semipermeable membrane and orifice diameter on azilsartan release were evaluated. The formulation of core tablet was optimized by orthogonal design and the release profiles of various formulations were evaluated by similarity factor (f₂). The optimal formulation achieved to deliver azilsartan at an approximate zero-order up to 14?h. The pharmacokinetic study was performed in beagle dogs. The azilsartan osmotic pump tablets exhibited less fluctuation in blood concentration and higher bioavailability compared to immediate-release tablets. Moreover, there was a good correlation between the in vitro dissolution and in vivo absorption of the tablets. In summary, azilsartan osmotic pump tablets presented controlled release in vitro, high bioavailability in vivo and a good in vitro-in vivo correlation.     

Improved initial burst of estradiol organogel as long-term in situ drug delivery implant: formulation,in vitro and in vivo characterization

Objective: The present investigation was aimed at optimizing of estradiol (E2) loaded l-amino acid derivatives organogel formulations resulting in improved the high initial release problems and sustained release of E2.

Methods: The visco-elastic properties of blank organogels were measured by rheometer. The E2 organogel formulations were optimized using a central composite design. Also, the effect of gelator structure and composition of the gel formulations on release behavior (in vitro and in vivo) had been studied.

Results: The change of the gelator structure could affect significantly the stiffness of the implants. The release behavior of gel without N-Methyl-2-pyrrolidinone (NMP) was controlled by gel corrosion only. While the drug release of the gel with NMP was controlled by both corrosion and diffusion. The high initial release problems of the organogels were improved by optimizing the formulations. The system consisting by N-Lauroyl l-lysine methyl ester (LLM) derivative in the oil indicated the lowest initial drug release, showed a much lower blood drug level and maintained a steady state for nearly 1 month.

Conclusion: Organogels based on l-lysine methyl ester derivative were ideal carriers for long-term parenteral administration of E2.     

Development and in vitro/in vivo evaluation of HPMC/chitosan gel containing simvastatin loaded self-assembled nanomicelles as a potent wound healing agent

The aim of this study was to develop hydroxypropyl methyl cellulose (HPMC)/chitosan gel containing polymeric micelles loaded with simvastatin (Sim) and evaluates its wound healing properties in rats. An irregular full factorial design was employed to evaluate the effects of various formulation variables including polymer/drug ratio, hydration temperature, hydration time, and organic solvent type on the physicochemical characteristics of pluronic F127-cholesterol nanomicelles prepared using the film hydration method. Among single studied factors, solvent type had the most impact on the amount of drug loading and zeta potential. Particle size and release efficiency was more affected by hydration temperature. The optimized formulation suggested by desirability of 93.5% was prepared using 1?mg of Sim, 10?mg of copolymer, dichloromethane as the organic solvent, hydration time of 45?min and hydration temperature of 25?°C. The release of the drug from nanomicelles was found to be biphasic and showed a rapid release in the first stage followed by a sustained release for 96?h. The gel-contained nanomicelles exhibited pseudo-plastic flow and more sustained drug release profile compared to nanomicelles. In excision wound model on normal rats, the wound closure of the group treated by Sim loaded micelles-gel was superior to other groups. Taken together, Sim loaded micelles-gel may represent a novel topical formulation for wound healing.     

Cellulose acetate microspheres as floating depot systems to increase gastric retention of antidiabetic drug: formulation, characterization and in vitro-in vivo evaluation

Gastric emptying is a complex process that is highly variable and makes the in vivo performance of drug delivery systems uncertain. In order to avoid this variability, efforts have been made to increase the retention time of the drug delivery systems for more than 12 hours utilizing floating or hydrodynamically controlled drug delivery systems. The objective of this investigation was to develop a floating, depot-forming drug delivery system for an antidiabetic drug based on microparticulate technology to maintain constant plasma drug concentrations over a prolonged period of time for effective control of blood sugar levels. Formulations were optimized using cellulose acetate as the polymer and evaluated in vitro for physicochemical characteristics and drug release in phosphate buffered saline (pH 7.4), and evaluated in vivo in healthy male albino mice. The shape and the surface morphology of the prepared microspheres were characterized by optical microscopy and scanning electron microscopy. In vitro drug release studies were performed and drug release kinetics were calculated using the linear regression method. Effects of stirring rate during preparation and polymer concentration on the size of microspheres and drug release were observed. The prepared microspheres exhibited prolonged drug release (more than 10 hours) and remained buoyant for over 10 hours. Spherical and smooth-surfaced microspheres with encapsulation efficiency ranging from 73% to 98% were obtained. The release rate decreased and the mean particle size increased at higher polymer concentrations. Stirring speed affected the morphology of the microspheres. This investigation revealed that upon administration, the biocompatible depot-forming polymeric microspheres controlled the drug release and plasma sugar levels more efficiently than plain orally given drug. These formulations, with their reduced frequency of administration and better control over drug disposition, may provide an economic benefit to the user compared with products currently available for diabetes control.     

Chlorogenic acid stabilized nanostructured lipid carriers (NLC) of atorvastatin: formulation,design and in vivo evaluation

The present work was aimed at developing an optimized oral nanostructured lipid carrier (NLC) formulation of poorly soluble atorvastatin Ca (AT Ca) and assessing its in vitro release, oral bioavailability and pharmacodynamic activity. In this study, chlorogenic acid, a novel excipient having synergistic cholesterol lowering activity was utilized and explored in NLC formulation development. The drug-loaded NLC formulations were prepared using a high pressure homogenization technique and optimized by the Box-Behnken statistical design using the Design-Expert software. The optimized NLC formulation was composed of oleic acid and stearic acid as lipid phase (0.9% w/v), poloxamer 188 as surfactant (1% w/v) and chlorogenic acid (0.05% w/v). The mean particle size, polydispersity index (PDI) and % drug entrapment efficiency of optimized NLC were 203.56?±?8.57?nm, 0.27?±?0.028 and 83.66?±?5.69, respectively. In vitro release studies showed that the release of drug from optimized NLC formulations were markedly enhanced as compared to solid lipid nanoparticles (SLN) and drug suspension. The plasma concentration time profile of AT Ca in rats showed 3.08- and 4.89-fold increase in relative bioavailability of developed NLC with respect to marketed preparation (ATORVA® tablet) and drug suspension, respectively. Pharmacodynamic study suggested highly significant (**p?0.01) reduction in the cholesterol and triglyceride values by NLC in comparison with ATORVA® tablet. Therefore, the results of in vivo studies demonstrated promising prospects for successful oral delivery of AT Ca by means of its chlorogenic acid integrated NLC.     

Microemulsion loaded hydrogel as a promising vehicle for dermal delivery of the antifungal sertaconazole: design,optimization and ex vivo evaluation

The purpose of the present study was to develop and optimize sertaconazole microemulsion-loaded hydrogel (STZ ME G) to enhance the dermal delivery and skin retention of the drug. Following screening of various oils for maximum drug solubility, 12 pseudoternary phase diagrams were constructed using oils (Peceol^®, Capryol^® 90), surfactants (Tween^® 80, Cremophor^® EL), a cosurfactant (Transcutol^® P) and water. A 2¹ × 3¹ × 2¹ × 3¹ full factorial design was employed to optimize a ME of desirable characteristics. The MEs were formulated by varying the oil type, oil concentration, surfactant type and surfactant: cosurfactant ratio. Optimized ME formulae F22 [5% Peceol^®, 55% Tween^® 80: Transcutol^® (1:2), 40% water] and F31 [5% Peceol^®, 55% Cremophor^® EL: Transcutol^® (1:2), 40% water] acquired mean droplet size of 75.21 and 8.68?nm, and zeta potential of 34.65 and 24.05?mV, respectively. Since F22 showed higher STZ skin retention during ex vivo studies (686.47?μg/cm²) than F31 (338.11?μg/cm²); hence it was incorporated in 0.5% Carbopol 934 gel to augment STZ skin retention capability. STZ ME G exhibited higher STZ skin retention (1086.1?μg/cm²) than the marketed product “Dermofix^® cream” (270.3?μg/cm²). The antimycotic activity against C.albicans revealed increased zones of inhibition for F22 and STZ ME G (35.75 and 30.5?mm, respectively) compared to Dermofix^® cream (26?mm). No histopathological changes were observed following topical application of STZ ME G on rats’ skin (n?=?9). Overall, the obtained results confirmed that the fabricated formulation could be a promising vehicle for the dermal delivery of STZ.     

Comparison of simple Eudragit microparticles loaded with prednisolone and Eudragit-coated chitosan-succinyl-prednisolone conjugate microparticles: Part I. Particle characteristics and in vitro evaluation as a colonic delivery system

Objective: Simple Eudragit microparticles loaded with prednisolone and chitosan-succinyl-prednisolone conjugate microparticles coated with Eudragit were prepared and characterized in vitro in order to obtain their basic features as a colonic delivery system.

Materials and methods: Both types of microparticles were prepared by the emulsification-solvent evaporation modified somewhat from the previous one. Their particle size, shape and their drug content were investigated, and in vitro release profiles were examined using JP-15 1st fluid (pH 1.2), JP-15 2nd fluid (pH 6.8) and PBS (pH 7.4) as release media. Furthermore, the regeneration of conjugate microparticles from Eudragit-coated microparticles was investigated under the same incubation conditions.

Results: Simple Eudragit S100 (EuS) microparticles (ES-M) were almost spherical, ca. 1.2 μm diameter, and PD content ca. 3.7% (w/w). Conjugate microparticles (CS-M1) and EuS-coated conjugate microparticles (CS-M1/S) had particle sizes of ca. 2.8 and 15.3 μm, respectively, and PD contents of 5.4 and 2.1% (w/w), respectively. ES-M exhibited suppressed release at pH 1.2, gradual release at pH 6.8 and rapid release at pH 7.4. CS-M1 showed no release at pH 1.2, and very slow release at pH 6.8 and 7.4. CS-M1 regenerated poorly from CS-M1/S at pH 6.8.

Conclusions: Simple Eudragit micrparticles and Eudragit-caoted conjugate microparticles, prepared by the present methods, were found in vitro to be possibly useful as the delivery systems of PD to the lower intestine, although there were differences in their release rate and morphological features.     

A pH-independent instantaneous release of flurbiprofen: a study of the preparation of complexes,their characterization and in vitro/in vivo evaluation

In this study, furbiprofen/hydroxypropyl-β-cyclodextrin (HPβCD) inclusion complexes were prepared to improve the drug dissolution and facilitate its application in hydrophilic gels. Inclusion complexes were prepared using a supercritical fluid processing and a conventional optimized co-lypholization method was employed as a reference. The entrapment efficacy and drug loading of both methods were investigated. Evaluation of drug dissolution enhancement was conducted in deionized water as well as buffer solutions of different pH. Carbopol 940 gels of both flurbiprofen and flurbiprofen/HPβCD inclusion complexes, with or without penetration enhancers, were prepared and percutaneous permeation studies were performed using rat abdominal skin samples. Formation of flurbiprofen/HPβCD inclusion complexes was confirmed by Fourier transform-infrared spectroscopy, differential scanning calorimetry, X-ray diffraction and scanning electron microscopy. The results obtained showed that SCF processing produced a higher EE (81.91?±?1.54%) and DL (6.96?±?0.17%) compared with OCL with values of 69.11?±?2.23% and 4.00?±?1.01%, respectively. A marked instantaneous release of flurbiprofen/HPβCD inclusion complexes prepared by SCF processing (103.04?±?2.66% cumulative release within 5?min, a 10-fold increase in comparison with flurbiprofen alone) was observed. In addition, this improvement in dissolution was shown to be pH-independent (the percentage cumulative release at pH 1.2, 4.5, 6.8 and 7.4 at 5?min was 95.19?±?1.71, 101.75?±?1.44, 105.37?±?4.58 and 96.84?±?0.56, respectively). Percutaneous permeability of flurbiprofen-in-HPβCD-in-gels could be significantly accelerated by turpentine oil and was related to the water content in the system. An in vivo pharmacokinetic study showed a 2-fold increase in C_max and a shortened T_max as well as a comparable relative bioavailability when compared with the commercial flurbiprofen Cataplasms (Zepolas^®). With their superior dissolution, these flurbiprofen/HPβCD inclusion complexes prepared by SCF processing could provide improved applications for flurbiprofen.     

Nanostructured lipid carriers loaded with simvastatin: effect of PEG/glycerides on characterization,stability, cellular uptake efficiency and in vitro cytotoxicity

Objective: The aim of this study is to evaluate the use of PEG/glycerides of different HLB; oleoyl macrogol-6-glycerides (Labrafil^® M 1944 CS) and caprylocaproylmacrogol-8-glycerides (Labrasol^®), compared to Labrafac lipophile^® as PEG-free glyceride in the preparation of nanostructured lipid carriers (NLCs). PEG/glycerides are suggested to perform a dual function; as the oily component, and as the PEG-containing substrate required for producing the PEGylated carriers without physical or chemical synthesis.

Methods: Lipid nanocarriers were loaded with simvastatin (SV) as a promising anticancer drug. An optimization study of NLC fabrication variables was first conducted. The effect of lyophilization was investigated using cryoprotectants of various types and concentrations. The prepared NLCs were characterized in terms of particle size (PS), size distribution (PDI), zeta potential (ZP), drug entrapment, in vitro drug release, morphology and drug–excipient interactions. The influence of glycerides?±?PEG on the cytotoxicity of SV was evaluated on MCF-7 breast cancer cells, in addition to the cellular uptake of fluorescent blank NLCs.

Results: The alteration between different oil types had a significant impact on PS, ZP and drug release. Both sucrose and trehalose showed the lowest increase in PS and PDI of the reconstituted lyophilized NLCs. The in vitro cytotoxicity and cellular uptake studies indicated that SV showed the highest antitumor effect on MCF-7 cancer cells when loaded into Labrasol^® NLCs demonstrating a high cellular uptake as well.

Conclusion: The study confirms the applicability of PEG/glycerides in the development of NLCs. Encapsulating SV in Labrasol^®-containing NLC could enhance the antitumor effect of the drug.     

Capsaicin pretreatment enhanced the bioavailability of fexofenadine in rats by P-glycoprotein modulation: in vitro,in situ and in vivo evaluation

Background and objective: Capsaicin is the main pungent principle present in chili peppers has been found to possess P-glycoprotein (P-gp) inhibition activity in vitro, which may have the potential to modulate bioavailability of P-gp substrates. Therefore, purpose of this study was to evaluate the effect of capsaicin on intestinal absorption and bioavailability of fexofenadine, a P-gp substrate in rats.

Methods: The mechanistic evaluation was determined by non-everted sac and intestinal perfusion studies to explore the intestinal absorption of fexofenadine. These results were confirmed by an in vivo pharmacokinetic study of oral administered fexofenadine in rats.

Results: The intestinal transport and apparent permeability (P_app) of fexofenadine were increased significantly by 2.8 and 2.6 fold, respectively, in ileum of capsaicin treated rats when compared to control group. Similarly, absorption rate constant (K_a), fraction absorbed (F_ab) and effective permeability (P_eff) of fexofenadine were increased significantly by 2.8, 2.9 and 3.4 fold, respectively, in ileum of rats pretreated with capsaicin when compared to control group. In addition, maximum plasma concentration (C_max) and area under the concentration-time curve (AUC) were increased significantly by 2.3 and 2.4 fold, respectively, in rats pretreated with capsaicin as compared to control group. Furthermore, obtained results in rats pretreated with capsaicin were comparable to verapamil (positive control) treated rats.

Conclusions: Capsaicin pretreatment significantly enhanced the intestinal absorption and bioavailability of fexofenadine in rats likely by inhibition of P-gp mediated cellular efflux, suggesting that the combined use of capsaicin with P-gp substrates may require close monitoring for potential drug interactions.     

Chitosan-TPP nanoparticles stabilized by poloxamer for controlling the release and enhancing the bioavailability of doxazosin mesylate: in vitro,and in vivo evaluation

Objective: Control the release and enhance the bioavailability of chitosan-doxazosin mesylate nanoparticles (DM-NPs).

Significance: Improve DM bioavailability for the treatment of benign prostatic hyperplasia and hypertension.

Methods: Plackett–Burman design was utilized to screen the variables affecting the quality of DM-NPs prepared by ionic gelation method. The investigated variables were initial drug load (X₁), chitosan percentage (X₂), tripolyphosphate sodium (TPP) percentage (X₃), poloxamer percentage (X₄), homogenization speed (X₅), homogenization time (X₆) and TPP addition rate (X₇). The prepared DM-loaded NPs have been fully evaluated for particle size (Y₁), Zeta potential (Y₂), production yield (Y₃), entrapment efficiency (Y₄), loading capacity (Y₅), initial burst (Y₆), and cumulative drug release (Y₇). Finally, DM pharmacokinetic has been investigated on healthy albino male rabbits by means of non-compartmental analysis.

Results: The combination of variables showed variability of Y₁, Y₂, and Y₃ equal to 122–710?nm, 3.49–23.63?mV, and 47.31–92.96%, respectively. While Y₄ and Y₅, reached 99.87%, and 8.53%, respectively. The prepared NPs revealed that X₂, X₃, and X₄ are the variables that play the important role in controlling the release behavior of DM from the NPs. The in vivo pharmacokinetic results indicated the enhancement in bioavailability of DM by 7 folds compared to drug suspension and the mean residence time prolonged to 23.72?h compared to 4.7?h of drug suspension.

Conclusion: The study proved that controlling the release of DM from NPs enhance its bioavailability and improve the compliance of patients with hypertension or benign prostatic hyperplasia.     

Long-term sustained-released in situ gels of a water-insoluble drug amphotericin B for mycotic arthritis intra-articular administration: preparation,in vitro and in vivo evaluation

Amphotericin B (AMB) was often used in intra-articular injection administration for fungal arthritis, because it could often bring a satisfactory therapeutic efficacy and a minimum systemic toxic side effect. However, because of the multiple operations and the frequent injections, the compliance of the patients was bad. Therefore, to develop a long-term sustained-released preparation of AMB for mycotic arthritis intra-articular administration is of great significance. The purpose of present study was to develop a long-term sustained-released in situ gel of a water-insoluble drug AMB for mycotic arthritis intra-articular administration. Based on the evaluations of the in vitro properties of the formulations, the formulation containing 10% (w/w) ethanol, 15% (w/w) PG, 0.75% (w/w) HA, 5% (w/w) purified soybean oil, 0.03% (w/w) α-tocopherol, 15% (w/w) water and 55% (w/w) glyceryl monooleate was selected as a suitable intra-articular injectable in situ gel drug delivery system for water-insoluble drug AMB. Furthermore, the results of the in vivo study on rabbits showed that the selected formulation was a safe and effective long-term sustained-released intra-articular injectable AMB preparation. Therefore, the presented in situ AMB gel could reduce the frequency of the administration in the AMB treatment of fungal arthritis, and then would get a good patient compliance.     

Lyophilized insulin nanoparticles prepared from quaternized N-aryl derivatives of chitosan as a new strategy for oral delivery of insulin: in vitro,ex vivo and in vivo characterizations

Objective: The purpose of this research was the development, in vitro, ex vivo and in vivo characterization of lyophilized insulin nanoparticles prepared from quaternized N-aryl derivatives of chitosan.

Methods: Insulin nanoparticles were prepared from methylated N-(4-N,N-dimethylaminobenzyl), methylated N-(4 pyridinyl) and methylated N-(benzyl). Insulin nanoparticles containing non-modified chitosan and also trimethyl chiotsan (TMC) were also prepared as control. The effects of the freeze-drying process on physico-chemical properties of nanoparticles were investigated. The release of insulin from the nanoparticles was studied in vitro. The mechanism of the release of insulin from different types of nanoparticles was determined using curve fitting. The secondary structure of the insulin released from the nanoparticles was analyzed using circular dichroism and the cell cytotoxicity of nanoparticles on a Caco-2 cell line was determined. Ex vivo studies were performed on excised rat jejunum using Frantz diffusion cells. In vivo studies were performed on diabetic male Wistar rats and blood glucose level and insulin serum concentration were determined.

Results: Optimized nanoparticles with proper physico-chemical properties were obtained. The lyophilization process was found to cause a decrease in zeta potential and an increase in PdI as well as and a decrease in entrapment efficiency (EE%) and loading efficiency (LE%) but conservation in size of nanoparticles. Atomic force microscopy (AFM) images showed non-aggregated, stable and spherical to sub-spherical nanoparticles. The in vitro release study revealed higher release rates for lyophilized compared to non-lyophilized nanoparticles. Cytotoxicity studies on Caco-2 cells revealed no significant cytotoxicity for prepared nanoparticles after 3-h post-incubation but did show the concentration-dependent cytotoxicity after 24?h. The percentage of cumulative insulin determined from ex vivo studies was significantly higher in nanoparticles prepared from quaternized aromatic derivatives of chitosan. In vivo data showed significantly higher insulin intestinal absorption in nanoparticles prepared from methylated N-(4-N, N-dimethylaminobenzyl) chitosan nanoparticles compared to trimethyl chitosan.

Conclusion: These data obtained demonstrated that as the result of optimized physico-chemical properties, drug release rate, cytotoxicity profile, ex vivo permeation enhancement and increased in vivo absorption, nanoparticles prepared from N-aryl derivatives of chitosan can be considered as valuable method for the oral delivery of insulin.     

Granulated colloidal silicon dioxide-based self-microemulsifying tablets,as a versatile approach in enhancement of solubility and therapeutic potential of anti-diabetic agent: formulation design and in vitro/in vivo evaluation

The current research work was executed with an aim to explore and promote the potential of self-microemusifying drug delivery systems (SMEDDS) in the form of tablets, in order to enhance solubility and oral bioavailability of poorly aqueous soluble drug Repaglinide (RPG). RPG-loaded liquid SMEDDS were developed consisting Labrafil M 1944CS, Kolliphor EL and Propylene glycol, which were then characterized on various parameters. After characterization and optimization, liquid SMEDDS were converted into solid form by adsorbing on Aeroperl® 300 pharma and polyplasdone^TM XL. Further, selection of suitable excipients was done and mixed with prepared solidified SMEDDS powder followed by the preparation of self-microemulsifying tablets (SMET’s) wet granulation–compression method. SMET’s were subjected to differential scanning calorimetry (DSC) and particle X-ray diffraction (RXRD) studies, results of which indicated transformation of crystalline structure of RPG because of dispersion of RPG at molecular level in liquid SMEDDS. This was further assured by micrographs obtained from scanning electron microscope. SMET’s shown more than 85% (30?min) of in vitro drug release in contrast to conventional marketed tablets (13.2%) and pure RPG drug (3.2%). Results of in vivo studies furnished that SMET’s had shown marked decrease in the blood glucose level and prolonged duration of action (up to 8?h) in comparison with conventional marketed tablets and pure RPG drug. In conclusion, SMET’s serves as a promising tool for successful oral delivery of poorly aqueous soluble drug(s) such as RPG.