Possible Interaction: Pentobarbital and Quinine

“Keto derivatives of cholic acid, such as 3a, 7a, dihydroxy-12-keto-5a-cholic acid (sodium salt … methyl ester) are potential modifiers of blood-brain barrier transport and have been shown to promote quinine up-take, enhance the analgesic effect of … and prolong the sleeping time induced by pentobarbital.”

“ Quinine in various concentrations inhibited the hepatic metabolism of pentobarbital in 9000 g supernatant incubation mixtures (KI = 2.9 × 10−5 M), as did quinidine (KI = 7.6 × 10−6 M).”

“ Quinine increased sleeping time in phenobarbitalstimulated and unstimulated mice and in rats, decreased the ld 50 of pentobarbital in mice, and increased the plasma half-life of pentobarbital in goats.”

“The presence of quinine in plasma decreased the extent of protein binding of pentobarbital m plasma from humans, ponies, swine, goats and mice.”

“The results obtained from these experiments indicate that quinine and quinidine alter the duration of action of pentobarbital by inhibition of microsomal enzymes.”

“L-sulpiride (40 mg/kg intraperitoneally) and pimozide (4 mg/kg intraperitoneally), on the other hand, significantly shortened the onset and prolonged the duration of sleep resulting from the interaction of quinine with pentobarbitone.”