zero order kinetics

The primary objective of sustained release drug delivery system is to ensure safety and to improve efficacy of drugs as well as patient compliance. Using controlled drug delivery system the drug release pattern can be controlled within narrow therapeutic range, which leads to minimize the side effect and ensure the safety. The aim of the study is to design, characterize and evaluate ciprofloxacin hydrochloride sustained release tablets using various viscosity grades of HPMC. As ciprofloxacin HCl has very short half life (nearly 3½ to 4 hr) hence multidose therapy for conventional tablets, (250 mg, 500 mg twice a day) is necessary to get the desired therapeutic level. Hence in the presence study attempt has been made to formulate the sustained release tablets of ciprofloxacin HCl using different viscosity grades of HPMC i.e. HPMC K4m,  HPMCK15M, HPMC K100M with different drug polymer ratio to reduce the dosing frequency, minimize the flections of plasma drug concentration, evaluation has been done of the prepared formulation and compared with the standard. The prepared granules were free flowing and characterized for drug content, DSC, X-ray diffraction study and FTIR. The X-ray diffraction study & DSC obtained from various formulations showed no interaction within these formulations. The in-vitro release studies were performed using pH 7.4 phosphate buffer for 12 hours from which the different drug polymer ratios are followed zero order kinetics.

  Diltiazem hydrochloride, a calcium channel blocker, is widely used for the treatment of angina pectoris, hypertension and arrhythmias. The usual dose of diltiazem hydrochloride is 180-240 mg/day. The conventional tablet or capsule is administered 3 or 4 times a day due to its low biological half-life of about 3.7 h. The problems of frequent administration and variable low bioavailability (36-50%) after oral administration of conventional tablet or capsules have been attenuated by designing diltiazem hydrochloride in the form of mucoadhesive microspheres. Diltiazem hydrochloride loaded mucoadhesive microspheres were successfully prepared by emulsification-internal gelation technique with a maximum encapsulation efficiency of 99.48± 0.32%.The order of increasing release rate observed with various microspheres was as follows Sodium alginate < Sodium alginate+ NaCMC < Sodium alginate+ HPMC. The order of increasing release rate observed with various cross linking agents was as follows Aluminum chloride < Barium chloride< Calcium chloride. The release behaviour of microspheres, with different cross-linking agents depends upon the valency and size of the cations of the respective cross-linking agent. The dissolution profiles follow zero order kinetics and the mechanism of drug release was governed by peppas model. The in vitro wash-off test indicated that the wash-off was faster at simulated intestinal fluid (phosphate buffer, pH 7.4) than that at simulated gastric fluid (0.1 M HCl, pH 1.2). The mucoadhesive microspheres formulated with sodium alginate+HPMC and calcium chloride showed a satisfactory sustained release profile for 12 hours.