title: In vitro effect of haloperidol, chlorpromazine, imipramine and lithium on the erythrocyte catechol-O-methyltransferase.
abstract: Haloperidol, chlorpromazine, imipramine and lithium in concentrations similar to the average therapeutic plasma levels did not exert any in vitro inhibition on the erythrocyte catechol-O-methyltransferase (COMT). The inhibitory effects of haloperidol, chlorpromazine and imipramine were noted first at concentrations 1000-10 000 times their respective average therapeutic plasma levels. Unlike the former three psychotropic drugs, lithium exerted an in vitro inhibition already at a concentration 40 times the average therapeutic plasma level and that in a competitive way. The inhibitory effect of lithium could be neutralized by increasing the magnesium concentration, likewise in a competitive way.
mesh_terms: D002394:Catechol O-Methyltransferase / Q000097:blood*; D065098:Catechol O-Methyltransferase Inhibitors; D002746:Chlorpromazine / Q000494:pharmacology; D004912:Erythrocytes / Q000201:enzymology; D006220:Haloperidol / Q000494:pharmacology; D006801:Humans; D007099:Imipramine / Q000494:pharmacology; D007700:Kinetics; D008094:Lithium / Q000494:pharmacology; D011619:Psychotropic Drugs / Q000494:pharmacology*
chemical_list: D065098:Catechol O-Methyltransferase Inhibitors; D011619:Psychotropic Drugs; D008094:Lithium; D002394:Catechol O-Methyltransferase; D006220:Haloperidol; D007099:Imipramine; D002746:Chlorpromazine