In-vitro Permeation and Pharmaco-dynamic Properties of Gel Formulations Containing Tenoxicam Entrapped Niosomes

Abstract

Niosomes are now widely studied as an alternative to liposomes because they alleviate the disadvantages of liposomes, such as chemical instability, variable purity of phospholipids and high cost. The aim of this work is to formulate and evaluate niosomes as carriers for topical delivery of Tenoxicam, as an anti-inflammatory drug, test their stability and improve their anti-inflammatory effect through niosomal encapsulation with objectives of prolonging its action and avoiding its most side effects. Incorporation of Tenoxicam - entrapped niosomes into gelling agents and increasing their concentrations resulted in a marked decrease in amount of drug permeated from the gel through cellulose membrane and rabbit skin. Polymers used as gelling agents are Carbopol 934 and Carboxy Methyl Cellulose sodium (CMC Na). It was found that permeated amount of Tenoxicam decreased with increasing either concentration of Carbopol 934 from 1% to 2% or concentration of CMC Na from 2% to 4%. Amount of Tenoxicam permeated from cellulose membrane are significantly high compared to the amounts permeated across the skin (p<0.01) from the same formulation. On the other hand, there is an increase in the amount of drug permeated from niosomal gels through rabbit skin, compared to that permeated from control drug gels prepared from the same gelling agents (enhancement effect). Stability study was carried out to detect effect of temperature on leakage of drug from the niosomal vesicles and evaluate the percentage of drug retained in the niosomal vesicles and niosomal gel formulations, respectively at different storage temperature (4 ° C, 25 °C and 37 ° C). The data obtained were compared statistically using one-way analysis of variance (ANOVA), using Tukey-Krammer Multiple Comparison Test. A p-value of 0.05 or less was considered to be significant. Degradation reaction of Tenoxicam was studied using accelerated stability testing, where correlation coefficient (r) was determined according to zero, first and second order equations and the decomposition rate constants were determined according to the most suitable correlation coefficient (r) which was zero-order and temperature of 4 ° C was the best temperature of storage for niosomal formulations.