In vitro and in vivo evaluation of sustained release suspensions of ibuprofen

Evaluation of amorphous dispersion of a cellulose ester-colophony mix for ibuprofen controlled release processed by HME and spin coating

Recently, there has been a rapid growth of using bio-based materials in pharmaceutical applications, due to their low cost and availability. In this study, natural composition of cellaburate (cellulose-ester) and colophony (pine-resin) was used to prepare films to control ibuprofen release from its amorphous solid dispersion. The effect of two preparation technologies of spin-coating and hot-melt-extrusion was studied on the physicochemical properties and in vitro dissolution/release behavior. Physical stability was evaluated for 12 w at 54 %RH/22 °C. Characterization involved using PLM/DSC/MTDSC/ATRFTIR/TGA/SEM and PXRD. Ibuprofen was amorphously-dispersed at 30 %(w/w) in 35:65 colophony:cellaburate films. Spin-films were more physically stable over 12 w; however, controlled release of ibuprofen was achieved mainly from hot-melt-extruded-films for 5 h. Both films have shown first-order release kinetics; whereby polymeric swelling and relaxation likely governed the release. The successful preparation of cellaburate-colophony platform that has achieved tunable release profiles of poorly water-soluble drug holds the potential for further drug delivery development.

Nanosponge-based pediatric-controlled release dry suspension of Gabapentin for reconstitution

CONTEXT

Gabapentin was selected to formulate oral controlled release dry suspension because of short biological half life of 5-7 h and low bioavailability (60%). Gabapentin is a bitter drug so an attempt was made to mask its taste.

OBJECTIVE

To formulate and evaluate controlled release dry suspension for reconstitution to increase the bioavailability and to control bitter taste of drug.

MATERIALS AND METHODS

Cyclodextrin based nanosponges were synthesized by previously reported melt method. The nanosponge-drug complexes were characterized by FTIR, DSC and PXRD as well as evaluated for taste and saturation solubility. The complexes were coated on Espheres by a suspension layering technique followed by coating with ethyl cellulose and Eudragit RS-100. A dry powder suspension for reconstitution of the microspheres was formulated and evaluated for taste, redispersibility, in vitro dissolution, sedimentation volume, leaching and pharmacokinetics.

RESULTS AND DISCUSSION

The complexes showed partial entrapment of drug nanocavities. Significant decrease in solubility (25%) was observed in the complexes than pure drug in different media. The microspheres of nanosponge complexes showed desired controlled release profile for 12 h. Insignificant drug leaching was observed in reconstituted suspension during storage for 7 days at 45 °C/75% RH. Nanosponges effectively masked the taste of Gabapentin and the coating polymers provided controlled release of the drug and enhanced taste masking. The results of in vivo studies showed increase in bioavailability of controlled release suspension by 24.09% as compared to pure drug.

CONCLUSION

The dry powder suspension loaded with microspheres of nanosponges complexes can be proposed as a suitable controlled release drug delivery for Gabapentin.

pH- and temperature-sensitive polymeric microspheres for drug delivery: the dissolution of copolymers modulates drug release

Most pH-/temperature-responsive polymers for controlled release of drugs are used as cross-linked hydrogels. However, the solubility properties of the linear polymers below and above the lower critical solution temperature (LCST) are not exploited. Here, the preparation and characterization of poly (N-isopropylacrylamide-co-methacrylic acid-co-methyl methacrylate) (poly (NIPAAm-co-MA-co-MM)) and poly (N-isopropylacrylamide-co-acrylamide) (poly (NIPAAm-co-AAm)), known as "smart" polymers (SP), is reported. Both poly (NIPAAm-co-MA-co-MM) and poly (NIPAAm-co-AAm) display pH- and temperature-responsive properties. Poly (NIPAAm-co-MA-co-MM) was designed to be insoluble in the gastric fluid (pH = 1.2), but soluble in the intestinal fluid (pH = 6.8 and 7.4), at the body temperature (37 degrees C). Poly (NIPAAm-co-AAm) was designed to have a lower critical solution temperature (LCST) corresponding to 37 degrees C at pH = 7.4, therefore it is not soluble above the LCST. The solubility characteristics of these copolymers were exploited to modulate the rate of release of drugs by changing pH and/or temperature. These copolymers were solubilized with hydrophobic cellulose acetate butyrate (CAB) and vitamin B(12) (taken as a water soluble drug model system) in an acetone/methanol mixture and dispersed in mineral oil. By a progressive evaporation of the solvent, the liquid droplets were transformed into loaded CAB/SP microspheres. Differential scanning calorimetric studies and scanning electron microscopy analysis demonstrated that the polymeric components of the microspheres precipitated separately during solvent evaporation forming small microdomains. Moreover, vitamin B(12) was found to be molecularly dispersed in both microdomains with no specific affinity for any polymeric component of microspheres. The release of vitamin B(12) was investigated as a function of temperature, pH, and the CAB/SP ratio.

Polymer-coated microparticles for the sustained release of nitrofurantoin

Suspensions of nitrofurantoin (NTF) microparticles for controlled release were investigated in this study. The microparticles were enteric coated with various combinations of the two polymers, cellulose acetate phthalate/cellulose acetate butyrate (CAP/CAB) by a modified solvent evaporation method. Ratios of NTF to the two polymers (NTF/CAP/CAB) ranged from 1.0:1.6:0.4,1.0:1.0:1.0,1.0: 0.4:1.6 to 1.0:0.0:2.0. The encapsulation efficiency, percentage yield, determined by comparing the final mass of the microparticles with the initial mass of the ingredients used, distribution of particle size and the in-vitro dissolution profiles of the microparticles were determined. Based on light photographs for the evaluation of the microparticle morphology, the drug crystals appeared to be encapsulated sufficiently by the enteric polymers. In our study, the microparticles enteric coated with CAP/CAB in the ratio of 0.4:1.6 displayed the most satisfactory in-vitro release profile (reduced release in the simulated gastric fluid and sustained release in the simulated intestinal fluid). Thus, microparticles with NTF/CAP/CAB in the ratio of 1.0:0.4:1.6 were formulated into a suspension for further bioavailability and ulcerogenicity studies in Sprague-Dawley rats, with the suspension of NTF crystals as a control. The bioavailability study was carried out in eight rats fed with either the free NTF or the corresponding microparticles in a cross-over design. The ulcerogenicity study was carried out in three groups of six rats each: one group received no drug treatment; the control group was treated with free NTF; and the third group was treated with enteric-coated NTF microparticles. The bioavailability of NTF from the microparticles was comparable with the control. More importantly, there was notably less ulceration of the gastric mucosa observed after dosing with the microparticle suspension compared with that after the administration of the control suspension.

Polymethyacrylate based microparticulates of insulin for oral delivery: preparation and in vitro dissolution stability in the presence of enzyme inhibitors

The purpose of this investigation was to (a) evaluate the coprecipitation technique for preparing microparticulates of insulin, (b) study the effect of variables such as addition of salts in the precipitating medium and ratio of polymeric solution to volume of precipitating medium on the dissolution and encapsulation efficiency of insulin microparticulates, and (c) evaluate the in-vitro enzymatic dissolution stability of insulin microparticulates in the presence of chicken ovomucoid (CkOVM) and duck ovomucoid (DkOVM) as inhibitors. Insulin dissolved in 0.01 N HCl was mixed with alcohol USP to get a final concentration of 32% v/v. Eudragit L100, a representative polymethyacrylate polymer, was then dissolved in this solution which was transferred to a beaker containing cold water with homogenization to obtain microparticulates. Dissolution studies were carried out in pH 6.8 phosphate buffer using a 100-ml conversion kit in a standard dissolution assembly. Dissolution stability of microparticulates was evaluated in the presence of 0.5 microM trypsin and 0.l microM chymotrypsin at various ratios of CkOVM and DkOVM. The results indicated that insulin microparticulates could be prepared using the coprecipitation technique with high encapsulation efficiency by proper selection of experimental conditions and amount of polymer. Presence of salts in the precipitating medium decreased the dissolution of insulin from the microparticulates. As the ratio of precipitating medium with respect to the polymeric solution was increased, the encapsulation efficiency increased. In dissolution stability experiments, insulin was not detected in the presence of enzymes alone. When CkOVM and DkOVM were incorporated, the stability of insulin increased significantly in a concentration dependent fashion.

Spray-dried microspheres containing ketoprofen formulated into capsules and tablets

In this study, microspheres were prepared by a spray-drying technique using solutions of ketoprofen and two polymers, cellulose acetate butyrate (CAB) and hydroypropylmethylcellulose phthalate (HPMCP), in different weight ratios. Different total concentrations were used in the feed solutions: 3, 6 and 9% w/v. The spray-dried microparticles were characterized in terms of shape (SEM), size (light scattering method), production yield and encapsulation efficiency. They were formulated into capsules; tablets were prepared by direct compression of the microparticles mixed with maltose and, in some cases, hydroypropylmethylcellulose (HPMC). In vitro release studies were performed both at acidic and neutral pHs. The spray-drying process of solutions of ketoprofen with polymeric blends of cellulose derivatives leads to microparticles which, depending on their final formulation (capsules or tablets), can give a rapid or prolonged drug release. The formulations here described can be proposed for the oral administration of NSAIDs.

New controlled-release ibuprofen tablets

Tablets containing two different doses of ibuprofen are realized. The first possesses very fast release kinetics, while the second has slow and linear release kinetics. This allows drug to produce a therapeutic effect quickly and to maintain it for a long time with only one administration unit. Such tablets are obtained by compression of a mixture of two very different kinds of granulates: an ibuprofen-starch granulate and an ibuprofen-Eudragit RS microsphere granulate. Specific proportions of mixtures of them give the described result after compression at particular tablet hardnesses.

Chemical, dissolution stability and microscopic evaluation of suspensions of ibuprofen and sustained release ibuprofen-wax microspheres

Chemical stability studies of suspensions of ibuprofen powder and ibuprofen-wax microspheres were performed using an accelerated stability protocol with a modified high performance liquid chromatography (HPLC) procedure. The variables considered were pH, suspending agents and temperature. The study showed little or no chemical degradation in the different suspending agents after storage for three months. Dissolution stability was examined in suspensions of ibuprofen microspheres made from an optimized formulation with 17% drug loading. The storage temperature were 23, 37 and 45 degrees C. Other variables for the dissolution stability studies were suspending agents, wax types, suspending medium pH and microsphere size. Suspensions of ceresine wax microspheres stored at 37 degrees C showed faster drug release than room temperature storage, but suspensions stored at 45 degrees C showed an opposite effect. Microspheres suspended in syrup and stored at 37 degrees C had faster dissolution rates than microspheres suspended in methylcellulose at the same temperature, possibly as a result of an interaction between the syrup and the microsphere constituents. Suspensions of microcrystalline wax microspheres had better dissolution stability than microspheres made from ceresine wax. Higher suspending medium pH resulted in faster release of drug from the suspended microspheres, but particle size did not significantly affect the dissolution stability.

Comparative evaluation of the severity of gastric ulceration by solid dispersions and coprecipitates of indomethacin

The ulcerogenic activity of indomethacin was studied in rats following single and chronic doses of indomethacin in the form of pure drug, solid dispersions and coprecipitates. Each formulation was administrated as a suspension in a 2% methylcellulose solution. Gastrointestinal ulceration was assessed, four hours after a single dose and 24 hours following the last dose of a chronic four day dosing regimen, by counting the number of lesions and ulcers present. A rating scale was employed to evaluate the severity index. The coprecipitate formulation produced less severe ulceration than the solid dispersion and pure drug. This suggests that the severity of ulceration than the solid dispersion and pure drug. This suggests that the severity of ulceration may be related to the preparation methodology and drug release kinetics.

Cellulose acetate butyrate and polycaprolactone for ketoprofen spray-dried microsphere preparation

Ketoprofen-loaded microspheres made with a polymeric blend were prepared by a spray-drying technique. Organic solutions of two polymers, cellulose acetate butyrate (CAB) and poly(epsilon-caprolactone) (PCL), in different weight ratios, and of ketoprofen (Ket) were prepared and sprayed, in different experimental conditions, achieving drug-loaded microspheres. The obtained spray-dried microspheres were characterized in terms of yield of production, shape, size, surface properties and drug content, and their in vitro drug release behaviours were determined at different pH values.

Morpholinoalkyl ester prodrugs of diclofenac: synthesis, in vitro and in vivo evaluation

Morpholinoalkyl esters (HCl salts) of diclofenac (1) were synthesized and evaluated in vitro and in vivo for their potential use as prodrugs for oral delivery. Prodrugs were freely soluble in simulated gastric fluid (SGF) and pH 7.4 phosphate buffer and showed a minimum of a 2000-fold increase in solubility over the parent drug. All prodrugs were more lipophilic than 1 as indicated by n-octanol/pH 7.4 buffer partition coefficients, but less lipophilic than 1 in terms of n-octanol/SGF partition coefficients. Potentiometrically determined ionization constants (pKas) were in the range of 7.52 to 8.40 at 25 degrees C. The chemical and enzymatic hydrolyses of prodrugs were evaluated in SGF/pH 7.4 phosphate buffer and rat plasma, respectively, at 37 degrees C. All prodrugs were quantitatively hydrolyzed to 1 by either chemical and/or enzymatic means. An increase in carbon chain length rendered the prodrugs more stable at pH 7.4, but less stable in SGF. In general, the esters were hydrolyzed rapidly in rat plasma at 37 degrees C, the half-lives of hydrolysis being in the range of 4.85 to 23.49 min. Based on in vitro results, prodrug 2 was chosen to evaluate solid-state stability, bioavailability, and in vivo ulcerogenicity. At elevated temperatures, the solid-state decomposition of 2 followed biphasic kinetics, with rapid decomposition occurring initially. The extent, but not the rate, of absorption was significantly greater in rats for prodrug 2 than 1 following single dose oral administration. Prodrug 2 was significantly less irritating to gastric mucosa than 1 following single and chronic oral administration in rats.