Development of Clindamycin Loaded Oral Microsponges (Clindasponges) for Antimicrobial Enhancement: In Vitro Characterization and Simulated in Vivo Studies.

Clindamycin phosphate (CLP) is a broad-spectrum antibiotic that is used widely for different types of infections. It has a short half-life and hence it should be taken every six hours to ensure adequate antibiotic blood concentration. On the other hand, microsponges are extremely porous polymeric microspheres, offering the prolonged controlled release of the drug. The present study aims to develop and evaluate innovative CLP-loaded microsponges (named Clindasponges) to prolong and control the drug release and enhance its antimicrobial activity, consequently improving patient compliance. The clindasponges were fabricated successfully by quasi-emulsion solvent diffusion technique using Eudragit S100 (ES100) and ethyl cellulose (EC) as carriers at various drug-polymer ratios. Several variables were optimized for the preparation technique including the type of solvent, stirring time, and stirring speed. The clindasponges were then characterized in terms of particle size, production yield, encapsulation efficiency, scanning electron microscopy, Fourier Transform Infrared Spectroscopy analysis, in vitro drug release with kinetic modeling, and antimicrobial activity study. Moreover, in vivo, pharmacokinetics parameters of CLP from the candidate formula were simulated based on the convolution method and in vitro-in vivo correlation (IVIVC-Level A) was built up successfully. Uniform spherical microsponges with 82.3 µm mean particle size with a porous spongy structure were evident. ES2 batch exhibited the highest production yield and encapsulation efficiency (53.75 and 74.57%, respectively) and it was able to exhaust 94% of the drug at the end of 8 h of the dissolution test. The release profile data of ES2 was best fitted to Hopfenberg kinetic model. ES2 was significantly (p < 0.05) effective against Staphylococcus aureus and Escherichia coli compared to the control. Also, ES2 displayed a twofold increase in the simulated area under the curve (AUC) compared to the reference marketed product.

Optimized Mucoadhesive Coated Niosomes as a Sustained Oral Delivery System of Famotidine.

The objective of this study is to develop an oral formulation of famotidine niosomes coated with a mucoadhesive polymer, chitosan. Famotidine (FMT) has low oral bioavailability of 40-45% and short half-life between 2.5 to 4 h. Famotidine is classified as class IV in BCS because of its low aqueous solubility (0.1% w/v) and low permeability. Thus, FMT was loaded to the bioadhesive coated niosomes to improve its solubility, enhance its oral bioavailability, and sustain FMT release pattern. Different formulations were prepared by thin-film hydration method and characterized in terms of entrapment efficiency, morphological features, vesicle size, and zeta potential. In vitro release and ex vivo permeability of famotidine from the formulations were evaluated. The optimized formula was coated with chitosan and its mucoadhesion and stability in bile salt was tested. The optimized formula showed a high entrapment efficiency of 74%, as well sustained the in vitro release of FMT in the simulated gastric medium and enhanced its permeation through an excised goat's intestinal membrane by 1.4 fold in comparison to FMT control suspension. The mucoadhesive coated formula exhibited a significantly higher (p < 0.05) mucoadhesive efficiency and more stability in the bile salt as compared to the uncoated formula. Therefore, it could be considered as an efficient delivery system to maintain the prolonged release of FMT and improve its oral bioavailability.

Solid dispersion systems for enhanced dissolution of poorly water-soluble candesartan cilexetil: In vitro evaluation and simulated pharmacokinetics studies.

BACKGROUND: Candesartan cilexetil (CC) is a selective angiotensin II receptor antagonist widely used to treat hypertension. CC is a substrate of P-glycoprotein (P-gp), causing its efflux to the intestinal lumen. It is also practically insoluble in water and has low oral bioavailability (14%). Thus, the current study aims to improve the in vitro dissolution of CC by developing solid dispersion systems (SDSs) and corroborating the in vitro results using a simulated pharmacokinetics study. METHODS: The SDSs were prepared using polyvinyl pyrrolidone (PVP) as a water-soluble polymer, Eudragit E100 (EE100) as a pH-dependent soluble carrier, and a combination of these two polymers. The saturation solubility and the dissolution rate studies of the prepared systems in three dissolution media were performed. The optimized system SE-EE5 was selected for further investigations, including DSC, XRD, FTIR, FESEM, DLS, TSEM, IVIVC convolution study, and stability studies. RESULTS: The solubility of CC significantly increased by a factor of 27,037.344 when formulated as a solid dispersion matrix using EE100 at a ratio of 1:5 (w/w) drug to polymer (SE-EE5 SD), compared to the solubility of the pure drug. The mechanism of solubility and dissolution rate enhancement of CC by the optimized SDS was found to be via the conversion of the crystalline CC into the amorphous form as well as nanoparticles formation upon dissolution at a pH below 5. The instrumental analysis tests showed good compatibility between CC and EE100 and there was no chemical interaction between the drug and the polymer. Moreover, the stability tests confirmed that the optimized system was stable after three months of storage at 25°C. CONCLUSION: The utilization of the solid dispersion technique employing EE 100 polymer as a matrix demonstrates significant success in enhancing the solubility, dissolution, and subsequently, the bioavailability of water-insoluble drugs like CC.