Thixotropically Based Biodegradable Intradermal Liquid Depot System Bearing Diltiazem Hydrochloride
Conventional treatment requires frequent administration of drugs to maintain effective concentration at the site of action. In the present work an implantable delivery system has been developed which when comes in contact with biological fluid, solidifies immediately and release the drug in a controlled manner for prolonged period of time. Polylactic acid, polyglycolic acid and copolymers of polylactic acid and polyglycolic acid were synthesized and characterized for various physicochemical attributes. IR spectra of the synthesized polymers was determined and it was found to be identical to that reported in the literature. Molecular weight of the polymers was determined with the help of viscosity measurement. Solubility and hydrolysis of the polymers was determined. Drug delivery systems were fabricated using synthesized polymers and characterized in vitro for various parameters. Drug content was estimated by direct measurement of absorbance whilst viscosity was determined using Ostwald viscometer. In vitro release for the formulations was determined for 10 d using dialysis tube diffusion technique, which revealed slow release of drug from formulation. On the basis of in vitro characterization studies, selected formulations were subjected to in vivo performance where drug plasma level was monitored after intradermal administration. In vivo studies revealed sustained release of the entrapped drug from formulations, which is reflected from the persistence of drug in blood for longer period of time.