Resin haemoperfusion in levomepromazine poisoning: evaluation of effect on plasma drug and metabolite levels.

Plasma levels of levomepromazine and two of its major metabolites N-desmethyl-levomepromazine and levomepromazine sulphoxide were studied in two poisoned patients treated with resin haemoperfusion at a constant blood flow of 200 ml/min. The mean haemoperfusion clearance of levomepromazine, N-desmethyl-levomepromazine and levomepromazine sulphoxide was 114, 123 and 151 ml/min, respectively, in patient no. 1, and 153, 148 and 184 ml/min, respectively, in patient no. 2. Patient no. 2 had also ingested amitriptyline, and the mean haemoperfusion clearance of amitriptyline and its metabolite nortriptyline was 183 and 183 ml/min respectively. Haemoperfusion did not seem to alter the elimination profile of levomepromazine or the two metabolites in either patient. We conclude that haemoperfusion is of little value in removing levomepromazine, N-desmethyl-levomepromazine or levomepromazine sulphoxide from the body. This is probably due to the large apparent volume of distribution and the high intrinsic hepatic metabolic clearance of these compounds.