The Role of Placental Carbonyl Reducing Enzymes in Biotransformation of Bupropion and 4-methylnitrosamino-1-(3-pyridyl)-1-butanone

Background: Bupropion (BUP) has a potential to be an effective pharmacotherapy for smoking cessation during pregnancy. Smoking during pregnancy stimulates placental carbonyl reductases that catalyze the biotransformation of BUP. 4-methylnitrosamino-1-(3-pyridyl)-1-butanone (NNK) is a potent carcinogen of cigarette smoke. Carbonyl reduction of NNK into 4- methylnitrosamino-1-(3-pyridyl)-1-butanol (NNAL) constitutes a major step in NNK detoxification. Thus, placentas of pregnant smokers on BUP therapy can become a site of drug-drug interaction. Therefore, we investigated the effect of continuous exposure to BUP and cigarette smoke on the activity of placental carbonyl reductases in the formation of NNAL from NNK. Methods: The reductive metabolism of NNK was determined using microsomal and cytosolic subcellular fractions of placentas obtained from non-smoking women treated with BUP for depression, and women not exposed to BUP: non-smokers (control) and smokers. The effect of BUP and its metabolites on the reductive metabolism of NNK was investigated using subcellular fractions of control placentas. Results: The formation of NNAL from NNK by placental cytosolic fractions of heavy smokers (≥20 cigarettes per day) was lower than that of control (12.1±3.5 nmol.mgP-1 vs 16.5±6.0 nmol.mgP-1, P
Source: Drug Metabolism Letters - Category: Drugs & Pharmacology Source Type: research