In vivo and in vitro characterization of rifampicine suppositories

Abstract

In this research, rifampicin suppositories were prepared due to the easy use of suppository administration in the elderly and the fact that plasma concentrations are higher than tablets. The suppositories were formulated with 100 mg of rifampicin using different bases, namely Witepsol H15, Witepsol S58, Witepsol E76, Polyethylene glycol PEG (two different formulations) and modified glycerogelatin (MGG) using the melting method. To optimize the drug release rate, different enhancers such as sodium lauryl sulfate (SLS) as an ionic surfactant, as well as Brij 92 as non-ionic surfactants, and Cetrimide as a cationic surfactant in different concentrations were chosen. The highest release of rifampicin was observed with formulations containing 0.4% SLS in Witepsol S58, 1.2% Cetrimide in Witepsol S58 and 0.4% Brij 92 in PEG2. The drug plasma levels after rectal administration were compared to those obtained after oral administration of the same dose. After 4 h, C max of rifampicin was 23.91 ± 2.74 μg/mL for the oral suspension vs. 43.03 ± 1.76 and 28.90 ± 1.37 μg/mL for PEG2 with 0.4% Brij 92 and Witepsol H15 with 1.2% Brij 92 suppositories. The comparative bioavailability of rifampicin from PEG2 with 0.4% Brij 92 and Witepsol H15 with 1.2% Brij 92 suppositories were 207.42 and 148.31% respectively, in relation to that after oral administration.