Serum levels of sulpiride enantiomers after oral treatment with racemic sulpiride in psychiatric patients: A pilot study

Sulpiride (SULP), a substituted benzamide with high selectivity for D-2-lik e dopamine receptors, has a chiral structure and is used in most countries as the racemate. In an open pilot study, we investigated 26 inpatients (13 female, 13 male) with schizophrenic or depressive disorder treated with SUL P (mean daily dosage 64-1062 mg) administered orally, either as a monothera py or as an add-on treatment to a stable and unchanged medication for 3-60 days. Serum levels of total SULP and of its enantiomers were measured by hi gh-performance liquid chromatography (HPLC) procedures. Clinically relevant indicators of hepatic and renal function as well as retrospectively assess ed clinical outcome parameters were correlated with serum levels of racemic SULP, L-SULP, D-SULP, and the L:D-SULP ratio. A significant correlation be tween mean daily dosage and serum levels of SULP, L-SULP, and D-SULP emerge d (p < 0.05) which was not influenced by age, gender, diagnosis, hepatic, o r renal function. The ratio of L:D-SULP serum levels was <1 (range 0.66-0.9 7) in all patients. A slight negative correlation between CGI improvement a nd the ratio of L:D-SULP (p < 0.10) and a positive correlation between race mic SULP concentrations and side-effects at endpoint was found (p < 0.05).