Tab-in-tab formulation of ramipril and nifedipine for effective anti-hypertensive activity

Background

The aims of this work were to enhance the solubility of nifedipine in acidic medium; to formulate and characterize tab-in-tab dosage form for immediate release of nifedipine and controlled release of ramipril and to avoid the mutual interactions of drugs. This combination appreciably intended to reduce the incidence of peripheral edema and reflex tachycardia.

Methods

Ramipril was firstly wet granulated with a HPMC polymer to form stable granules and then was directly compressed to form a core tablet. Enteric coating was given with a water insoluble polymer to withstand the acidic pH of stomach. Initially, nifedipine microcapsules were prepared, granulated with excipients and then compressed, keeping the inner tablet in between the granules.

Results and discussion

This novel tab-in-tab dosage form allowed the nifedipine to release for stomach-specific absorption and ramipril to the intestine-specific absorption. Distinctive release profiles were obtained for immediate- and controlled-release tab-in-tab formulations, giving better bioavailability with no metabolic side-effects.

Conclusion

Tab-in-tab drug delivery system used to formulate combination drugs with different pharmacokinetic profiles provide reduction in dosage, dosing frequency, reduction in side effects, additive effects and single pill convenience.