Development and validation of reversed-phase HPLC gradient method for the estimation of efavirenz in plasma.

Efavirenz is an anti-viral agent of non-nucleoside reverse transcriptase inhibitor category used as a part of highly active retroviral therapy for the treatment of infections of human immune deficiency virus type-1. A simple, sensitive and rapid reversed-phase high performance liquid chromatographic gradient method was developed and validated for the determination of efavirenz in plasma. The method was developed with high performance liquid chromatography using Waters X-Terra Shield, RP18 50 x 4.6 mm, 3.5 µm column and a mobile phase consisting of phosphate buffer pH 3.5 and Acetonitrile. The elute was monitored with the UV-Visible detector at 260 nm with a flow rate of 1.5 mL/min. Tenofovir disoproxil fumarate was used as internal standard. The method was validated for linearity, precision, accuracy, specificity, robustness and data obtained were statistically analyzed. Calibration curve was found to be linear over the concentration range of 1-300 µg/mL. The retention times of efavirenz and tenofovir disoproxil fumarate (internal standard) were 5.941 min and 4.356 min respectively. The regression coefficient value was found to be 0.999. The limit of detection and the limit of quantification obtained were 0.03 and 0.1 µg/mL respectively. The developed HPLC method can be useful for quantitative pharmacokinetic parameters determination of efavirenz in plasma.

Systematic Approach for the Formulation and Optimization of Solid Lipid Nanoparticles of Efavirenz by High Pressure Homogenization Using Design of Experiments for Brain Targeting and Enhanced Bioavailability.

The nonnucleoside reverse transcriptase inhibitors, used for the treatment of HIV infections, are reported to have low bioavailability pertaining to high first-pass metabolism, high protein binding, and enzymatic metabolism. They also show low permeability across blood brain barrier. The CNS is reported to be the most important HIV reservoir site. In the present study, solid lipid nanoparticles of efavirenz were prepared with the objective of providing increased permeability and protection of drug due to biocompatible lipidic content and nanoscale size and thus developing formulation having potential for enhanced bioavailability and brain targeting. Solid lipid nanoparticles were prepared by high pressure homogenization technique using a systematic approach of design of experiments (DoE) and evaluated for particle size, polydispersity index, zeta potential, and entrapment efficiency. Particles of average size 108.5 nm having PDI of 0.172 with 64.9% entrapment efficiency were produced. Zeta potential was found to be -21.2 mV and the formulation was found stable. The in-vivo pharmacokinetic studies revealed increased concentration of the drug in brain, as desired, when administered through intranasal route indicating its potential for an attempt towards complete eradication of HIV and cure of HIV-infected patients.

Design and evaluation of ocular drug delivery system for controlled delivery of gatifloxacin sesquehydrate: In vitro and in vivo evaluation.

The objective of this investigation was to formulate ocular inserts of gatifloxacin sesquehydrate to achieve controlled drug release. Drug reservoir was prepared using hydrophilic polymers, namely polyvinyl alcohol and polyvinyl pyrrolidone. The rate controlling membrane was prepared using hydrophobic ethyl cellulose by solvent casting method. Ocular inserts were evaluated for uniformity of weight, thickness, drug content, surface pH, percentage moisture absorption, percentage moisture loss, drug excipients compatibility, in vitro release, sterility test, eye irritation, in vivo release, microbiological and stability studies. Ocular inserts complied with all the physico-chemical parameters. Drug excipients compatibility studies demonstrated no interaction between drug and polymer. The in vitro release profile of drug from ocular inserts showed controlled and prolonged release. The release data followed zero order and non-Fickian transport. Ocular inserts passed the test for sterility. Correlation between in vitro and in vivo drug release was found to be strong revealing the efficacy of the formulation. The drug was found to be effective against Staphylococcus aureus and Escherichia coli. The result of accelerated stability study revealed no significant change in drug content of promising formulation.

Chitosan microspheres of aceclofenac: in vitro and in vivo evaluation.

The objective of this investigation was to achieve controlled drug release of Aceclofenac (ACE) microspheres and to minimize local side-effects in the gastrointestinal tract (GIT). Sustained release chitosan microspheres containing ACE were prepared using double-emulsion solvent evaporation method (O/W/O). Chitosan microspheres were prepared by varying drug to polymer ratio (1:3, 1:4, 1:5 and 1:6). Microspheres were characterized for morphology, swelling behavior, mucoadhesive properties, FTIR and DSC study, drug loading efficiency, in vitro release, release kinetics, and in vivo study was performed on rat model. ACE-loaded microspheres were successfully prepared having production yield, 57-70% w/w. Drug encapsulation efficiency was ranging from 53-72% w/w, Scanning electron microscopy (SEM) revealed particle size of microspheres was between 39 and 55 mum. FTIR spectra and DSC thermograms demonstrated no interaction between drug and polymer. The in vitro release profiles of drug from chitosan microspheres showed sustained-release pattern of the drug in phosphate buffer, pH 6.8. In vitro release data showed correlation (r2 > 0.98), good fit with Higuchi/Korsmeyer-Peppas models, and exhibited Fickian diffusion. ACE microspheres demonstrated controlled delivery of aceclofenac and apparently, no G.I.T. erosion was noticed.

Preparation and characterization of spray-dried mucoadhesive microspheres of aceclofenac.

OBJECTIVE: Microencapsulation of the anti-inflammatory drug aceclofenac (ACE) was investigated as a means of controlling drug release and minimizing or eliminating local side effects. METHOD: Microspheres were prepared by a spray-drying technique using solutions of ACE and three polymers, namely, carbopol, chitosan, and polycarbophil, in different weight ratios. RESULTS: The spray-dried mucoadhesive microspheres were characterized in terms of shape (scanning electron microscope), size (6.60-8.40 mum), production yield (34.10-55.62%), and encapsulation efficiency (58.14-90.57%). In vitro release studies were performed in phosphate buffer (pH 6.8) up to 10 hours. The spray-drying process of solutions of ACE with polymeric blends can give prolonged drug release. The in vitro release data were well fit into Higuchi and Korsmeyer-Peppas model and followed Fickian diffusion mechanism. In vivo data showed that the administration of ACE in polymeric microspheres prevented the gastric side effects. CONCLUSION: The formulations here described can be proposed for the oral administration of nonsteroidal anti-inflammatory drugs with minimal side effects on gastric mucosa.