Effect of ethanol on the pharmacokinetics of 2-14C-methaqualone in the rat

Blood concentrations of radioactivity at 2, 3 and 4 hr and tissue concentrations at 4 hr following 2-¹⁴C-methaqualone (25 mg/kg po) administration, were statistically higher in rats simultaneously dosed with ethanol (3 gm/kg po) than in controls receiving only methaqualone. The major route of elimination was biliary excretion and ethanol inhibited the biliary clearance of carbon-14. An inhibition of metabolism by ethanol could not be demonstrated and reduced clearance was attributed to a depression of active secretory processes by ethanol. Consequently, an elevation of plasma concentrations of free drug and an increased uptake of methaqualone into lipoid tissues such as the brain occurred offering an explanation for reports of potentiation following administration of the ethanolmethaqualone combination.