In vitro and in vivo evaluations of a novel pulsed and controlled osmotic pump capsule

For better treatment of circadian cardiovascular events, a novel Propranolol hydrochloride (PNH) delayed-release osmotic pump capsule was developed.

The capsule body was designed of asymmetric membrane and the capsule cap was made impermeable. The physical characteristics of capsule body walls and membrane permeability were compared among different coating solutions.

The formulation with the glycerin and diethyl phthalate (DEP) ratio of 5:4 appeared to be the best. The lag time and subsequent drug release were investigated through assembling the capsule body with capsule caps of different length. WSR N-10 was chosen as the suspending for its moderate expanding capacity. The influence of factors (WSR N-10 content, NaCl content and capsule cap length) on the responses (lag time and drug release rate) was evaluated using central composite design-response surface methodology. A second-order polynomial equation was fitted to the data and actual response values were in good accordance with the predicted ones. The optimized formulation displayed complete drug delivery, zero-order release rate with 4-h lag time. The results of in vivo pharmacokinetics in beagle dogs clearly suggested the controlled and sustained release of PNH from the system and that the relative bioavailability of this preparation was about 1.023 comparing the marketed preparation.

These results indicate that by the adjustment of capsule cap length, PNH could be developed as a novel pulsatile and controlled drug delivery system.