Formulation and evaluation of thermosensitive biogels for nose to brain delivery of doxepin.

Thermoreversible biogels can serve as effective systems for delivery of drugs through nose with increased nasal residence time. The objective of this study was to use chitosan and glycerophosphate based thermoreversible systems for delivery of doxepin to brain through intranasal administration. Formulations were prepared by admixture of suitable dilutions of chitosan and glycerophosphate with or without polyethylene glycol, followed by addition of the antidepressant doxepin hydrochloride. Both systems were evaluated for gelling characteristics, rheology, mucoadhesion, in vitro release, and ex vivo permeation through sheep nasal mucosa. In vivo efficacy was evaluated in Swiss albino mice through the forced swim test. Nasal tissues of mice subjected to repeated exposure to formulation were evaluated histopathologically. Both formulations gelled rapidly at 37°C, returned to sol state on cooling, and exhibited thixotropy. Addition of polyethylene glycol decreased the glycerophosphate content required for gelation and rendered the formulation isotonic. Both gels showed good mucoadhesion, enhanced drug permeation, and provided prolonged in vitro release at 37°C. Efficacy of the formulation in treated groups was inferred from the measured pharmacodynamic parameter and histopathological reports of formulation treated groups showed no significant local toxicity. The biogels could be potential systems for effective drug delivery to brain via nose.

Three-way, three-period, crossover bioequivalence study of single oral dose of three brands of 300 mg phenytoin sodium tablets marketed in India, on healthy Indian human volunteers.

OBJECTIVE: To compare the bioavailability of two brands of phenytoin sodium tablets available in the Indian market using Eptoin™ as the reference. MATERIALS AND METHODS: A randomized, assessor-blind, three-way crossover design study was carried out over a period of 6 months after approval from the Institutional Review Board (IRB). Twenty-two healthy male participants received a single oral 300 mg oral tablet of either of the formulations with a 2-week washout. Blood samples were collected predose and at regular intervals postdose. Plasma phenytoin levels were estimated by high-performance liquid chromatography. Calculation of Cmax, AUC0-t, and AUC0-∞ was done by the linear trapezoidal rule and 90-110% margin (90% confidence interval (CI)) was used to assess bioequivalence. RESULTS: Twenty volunteers completed the study. It was seen that the log-transformed values of Cmax, AUC0-t, and AUC0-∞ of the test formulations were not within the specified limits. CONCLUSION: Bioinequivalence of available phenytoin brands indicates that switching brands could lead to variations in blood concentrations and thus impact safety and efficacy. If a brand switch is done for any reason, stringent drug-level monitoring is advised.

Preparation and evaluation of chitosan based thermoreversible gels for intraperitoneal delivery of 5-fluorouracil (5-FU).

Sterile thermoreversibly gelling systems based on chitosan- glycerol phosphate were developed for intraperitoneal delivery of the antineoplastic agent 5-FU. The formulation was evaluated for gelling characteristics and in vitro drug release. Drug free gels were evaluated for in vitro cytotoxicity in L-929 mouse fibroblast cells. Drug loaded gels were subjected to acute toxicity studies in Swiss albino mice via intraperitoneal route and efficacy studies via intratumoral injections in subcutaneous colon carcinoma bearing BALB/c mice. The formulations gelled reversibly in 8 min at 37 °C and provided prolonged release of the drug. Drug free systems showed dose dependent cytotoxicity in fibroblast cells, while in vivo studies revealed a 2.8-fold increase in LD50 of 5-FU administered intraperitoneally as the developed system. Tumor volume measurements showed comparable efficacy of 5-FU administered as gel and commercial injection with a greatly improved safety profile of the former as adjudged from mortality and body weight measurements.