A Srinivasa Rao

A simple, new, precise, accurate and reproducible RP-HPLC method for simultaneous estimation of mefenamic acid, ethamsylate and tranexamic acid in bulk and pharmaceutical formulations. Separation of mefenamic acid, ethamsylate and tranexamic acid was successfully achieved on a Kromasil C8 (250 mm x 4.6mm x 5µ ) in an isocratic mode utilizing Ammonium acetate buffer and methanol (60:40 v/v) at a flow rate of 1.0 mL/min. The method was validated according to ICH guidelines for linearity, sensitivity, accuracy, precision, specificity and robustness. The response was found to be linear in the drug concentration range of 25-75 mg/mL for mefenamic acid ,25-75 mg/mL for ethamsylate 50-150 mg/mL for tranexamic acid. The correlation coefficient was found to be 0.9997 for both the drugs. The limit of detection (LOD) was 0.158,0.2183 and 0.321 for  mefenamic acid, ethamsylate and tranexamic acid respectively. The limit of quantification (LOQ) was 0.527,0.7278 and 1.071 for mefenamic acid, ethamsylate and tranexamic acid respectively. The relative standard deviation (RSD) of six replicates is less than 2%. This HPLC method is applied successfully to the simultaneous quantitative analysis of mefenamic acid, ethamsylate and tranexamic acid in commercial tablets.

Carvedilol is a non selective α and β receptor blocker which undergoes extensive hepatic first pass metabolism by liver and has poor oral bioavailability of 25% - 30%. In the present investigation Carvedilol was formulated as a bilayered buccal adhesive tablets in order to avoid the first-pass effect and decrease the drug loss using two different natural polymers and excipients. Six formulations were made using different concentrations (17%w/w, 35%w/w, 53%w/w) of Pectin and Guar gum. Formulation F5 was selected for further studies of permeability. Three concentrations of SLS (1%, 1.5% & 2%w/w) was used to study the effect of permeation enhancer and improve the permeability of drug. The formulations were tested for % weight variation, hardness, Friability, % Drug content, in-vitro drug release, surface pH, Swelling index and Mucoadhesive strength. Mucoadhesive strength was determined by the modified balance method in grams and was found to be between 23.75±0.332gm to 60.89±0.134gm and Surface pH was found to be 7. In-vitro release studies revealed that as polymer concentration increases from 17% to 53%w/w, rate of drug release was retarded and the data was fitted into pharmacokinetic models. Among all other formulations, formulations (F5) containing 35%w/w Guar gum were found to be best as the release was retarded upto 8 hours and they have good mucoadhesive strength and they follow zero order with non-fickian diffusion mechanism. Formulation F9 (2%w/w SLS) shows more permeability of drug (34%) compared to other formulations.