Abstract:The actylation of sulfanilamide and procainamide in suspensions of isolated rat parenchymal cells was studied in absence and presence of ethanol (33 mM), acetate (0.5–5 mM), citrate (4 mM), pyruvate (4 mM), and L(minus;)carnitine (2 mM). Ethanol treatment enhanced the sulfanilamide acetylation whereas the acetylation of procainamide was considered to be unchanged. Acetate (1–5 mM), citrate, and pyruvate treatment enhanced the acetylation of both sulfanilamide and procainamide. Acetate (4 mM) increased both Kmand Vmaxof both sulfanilamide and procainamide acetylation. Combined treatment with L(minus;)carnitine and either acetate, pyruvate, or citrate enhanced the acetylation rate of sulfanilamide more than acetate, pyruvate, or citrate, respectively alone. In cell suspensions treated with L(minus;)carnitine and acetate or pyruvate, the acetylation kinetics of sulfanilamide changed from zero‐to apparent first‐order. With procainamide as test drug, a further increase of the acetylation rate was found when L(minus;)carnitine was added to citrate or pyruvate. Acetyl‐CoA increased the rate of sulfanilamide acetylation in rat liver homogenates in a dose depende