Solid lipid nanoparticles of irbesartan: preparation, characterization, optimization and pharmacokinetic studies

Irbesartan is an antihypertensive with limited bioavailability and solid lipid nanoparticles (SLN) is one of the approaches to improve bioavailability. Solid lipid nanoparticles were prepared using glyceryl monostearate by solvent emulsification method followed by probe sonication. Irbesartan loaded SLNs were characterized and optimized by parameters like particle size, zeta potential, surface morphology entrapment efficiency and in vitro release. The optimized formulation was then further evaluated for the pharmacokinetic studies in Wistar rats. Irbesartan-loaded SLN of particle size 523.7 nm and 73.8% entrapment efficiency showed good bioavailability in Wistar rats and also showed optimum stability in the studies. The SLN prepared using glyceryl monostearate by solvent emulsification method leads to improve bioavailability of the drug

Glutaraldehyde cross-linked chitosan microspheres for controlled delivery of Zidovudine

Zidovudine-Chitosan microspheres were prepared by a suspension cross-linking method. The chitosan was dissolved in 2% acetic acid solution and this solution was dispersed in the light liquid paraffin. Span-80 was used as an emulsifier and glutaraldehyde as cross-linking agent. The prepared microspheres were slight yellow, free flowing and characterized by drug loading, infrared spectroscopy (IR), differential scanning colorimetry (DSC) and scanning electron microscopy (SEM). The in-vitro release studies are performed in pH 7.4 buffer solution. Microspheres produced are spherical and have smooth surfaces, with sizes ranging between 60-210 µm, as evidenced by SEM and particle size analysis. The drug loaded microspheres showed up to 60% of entrapment and release was extended up to 18-24 h. Among all the systems studied, the 35% Glutaraldehyde crosslinked, microspheres with 1 : 6 drug/chitosan ratio showed 75% release at 12 h. The infrared spectra and DSC thermograms showed stable character of zidovudine in the drug loaded microspheres and revealed the absence of drug-polymer interactions. Data obtained from in vitro release were fitted to various kinetic models and high correlation was obtained in the Higuchi model. The drug release was found to be diffusion controlled

Chitosan and Enteric Polymer Based Once Daily Sustained Release Tablets of Aceclofenac: In Vitro and In Vivo Studies

The purpose of this study was to develop a once daily sustained release tablet of aceclofenac using chitosan and an enteric coating polymer (hydroxypropyl methylcellulose phthalate or cellulose acetate phthalate). Overall sustained release for 24 h was achieved by preparing a double-layer tablet in which the immediate release layer was formulated for a prompt release of the drug and the sustained release layer was designed to achieve a prolonged release of drug. The preformulation studies like IR spectroscopic and differential scanning calorimetry showed the absence of drug–excipient interactions. The tablets were found within the permissible limits for various physicochemical parameters. Scanning electron microscopy was used to visualize the surface morphology of the tablets and to confirm drug release mechanisms. Good equivalence in the drug release profile was observed when drug release pattern of the tablet containing chitosan and hydroxypropyl methylcellulose phthalate (M-7) was compared with that of marketed tablet. The optimized tablets were stable at accelerated storage conditions for 6 months with respect to drug content and physical appearance. The results of pharmacokinetic studies in human volunteers showed that the optimized tablet (M-7) exhibited no difference in the in vivo drug release in comparison with marketed tablet. No significant difference between the values of pharmacokinetic parameters of M-7 and marketed tablets was observed (p > 0.05; 95% confidence intervals). However the clinical studies in large scale and, long term and extensive stability studies at different conditions are required to confirm these results

Chronotherapeutic drug delivery for early morning surge in blood pressure: A programmable delivery system

The purpose of the study was to develop pulsatile capsule dosage form of valsartan for controlled delivery. In the majority of individuals blood pressure rises in the early morning hours, which lead to serious cardiovascular complications. Formulations with constant/programmable delivery rates make it possible to deliver drug at definite time or controlled rate in chronopharmacokinetic studies. The prepared system contained swellable polymer (l-hydroxypropyl cellulose (L-HPC), xanthan gum, polyethylene oxide or sodium alginate) together with drug tablet and erodible tablet (L-HPC or guar gum) in a pre-coated capsule. Various formulation factors were investigated through series of tests, in vitro dissolution and ex vivo continuous dissolution-absorption studies. We found that the type, amount of polymers and erodible tablet influenced the drug release. The formulation containing 200\ua0mg sodium alginate and erodible tablet (150\ua0mg) containing 50% guar gum and 46% lactose showed 5-6\ua0h lag time and 10 ± 2.1% drug release in initial 6\ua0h following rapid release (99 ± 1.7% release in 12\ua0h) of drug was observed. The continuous dissolution-absorption study conducted using everted rat intestinal segment indicated delay in absorption of drug. Thus this approach can provide a useful means for timed release of valsartan and may be helpful for patients with morning surge