FORMULATION AND IN VITRO EVALUATION OF DRY COATED FLOATING PULSATILE DRUG DELIVERY SYSYTEM OF ENALAPRIL MALEATE

This research work deals with the development and evaluation of a floating pulsatile drug delivery system used in the treatment of hypertension intended as chronopharmacotherapy.  Serious cardiovascular complications have been seen in majority of individuals with early morning-surge in blood pressure. The floating- pulsatile concept can help to deliver the drug at definite place and time when symptoms of disease are more critical. The system consisted of three different parts, a core tablet, containing the active ingredient, an erodible outer shell and a top cover buoyant layer. The dry coated tablet consists in a drug-containing core, coated by a hydrophilic erodible polymer (HPMC E50 and lactose) which is responsible for a lag phase in the onset of pulsatile release. The buoyant layer, prepared with Methocel E50, Carbopol 934P and sodium bicarbonate, provides buoyancy to increase the retention of the oral dosage form in the stomach applied to increase the gastric residence of the dosage form having lag phase followed by a burst release. The developed formulations were evaluated for their buoyancy, in vitro dissolution and various other formulation factors. Results reveal that coating composition affects the lag time. Formulation containing Lactose as filler with 6.67% Crospovidone and coating composition using 30% lactose provide lag time of 4 h with 93.03% drug release in 6 h that shown a sigmoidal release pattern. These values were close to desired objective of producing lag time 4-5 h followed by fast drug release. Quantity and composition of the buoyant layer controls Floating time.