Creatinine Metabolism Impairment by an Anticonvulsant Drug, Phenacemide

OBJECTIVE:To report two cases of increased true serum creatinine (Ser) without renal failure caused by an anticonvulsant drug, phenacemide, and to discuss the possible mechanisms.CASE SUMMARY:Two patients treated with phenacemide were investigated for markedly increased Scr and decreased creatinine clearance (Clcr) values. Glomerular filtration rates, as determined by 125I-iothalamate clearance, were normal in both patients and analytical interferences with the Jaffe reaction were excluded. After discontinuation of the drug, phenacemide concentrations became undetectable within 2 days but it took 7–14 days for Scr and Clcr to return to normal values.DISCUSSION:The Scr increase with phenacemide (120–170 percent) was higher than that reported with cimetidine or trimethoprim (10–40 percent) and could not be explained solely by inhibition of the tubular secretion of creatinine. The hypothesis of an overproduction of creatinine caused by phenacemide was ruled out by experimental studies in rats. Creatinine inc...