Enhanced Oral Bioavailability of Chlormadinone Acetate through a Self-Microemulsifying Drug Delivery System for a...

Chlormadinone acetate (CMA) is a derivative of the naturally secreted hormone progesterone and exhibits reliable contraceptive and non-contraceptive benefits. Although the marketed product of CMA as oral tablets under the trade name Belara® has been highly successful, there is still room for further improvements in oral bioavailability and a reduction in the clinical dose to decrease related adverse effects. In the current study, a CMA-based self-microemulsifying drug delivery system (SMEDDS) was developed using 32% ethyl oleate as an oil phase, 40% Tween-80 as a surfactant, and 12% Transcutol P combined with 16% PEG400 as a cosurfactant, resulting in spherical droplets with a z-average particle size of 38.92 nm and an average zeta potential of - 3.18 mv. The in vitro release rate of CMA from CMA-SMEDDS in different media (distilled water, HCl solution at pH 1.2, phosphate buffers at pH 4.5 and pH 6.8) was significantly faster than that from Belara® in the first 15 min. A pharmacokinetic study in rats showed that the C_max and AUC of CMA-SMEDDS were significantly higher (P < 0.01) than those of Belara®, with a 1.98-fold increase in oral bioavailability. In comparison with Belara®, the developed CMA-SMEDDS showed promising release profiles both in vitro and in vivo, which could potentially be useful in enhancing oral bioavailability and reducing the clinical dose of CMA.