Polypharmacy is widely practiced today. One example is the combination of antidepressants and hypertensive drugs, as it has been found that 57.5% of people with hypertension also develop depression symptoms. The effects of propranolol (a beta blocker) on the metabolism of clomipramine (a tricyclic antidepressant) were investigated to recreate this combination, using rat liver microsomes, HPLC (high performance liquid chromatography), and CMS (compact mass spectrometry). In the experiment, varying quantities of clomipramine, propranolol (inhibitor), NADPH, and rat liver microsome were incubated and diluted in HPLC mobile phase to be loaded onto the CMS fitted with a reverse phase column. Rat liver microsomes have similar metabolizing enzymes as the human liver. Clomipramine in the liver is metabolized by enzymes CYP2D6, CYP1A2, CYP3A4, and CYP2C19. These enzymes catalyze the metabolism of different functional groups on the clomipramine (CYP2D6 catalyzes aromatic hydroxylation, while CYP1A2, CYP2C19, and CYP3A4 drives demethylation of the amino group). The metabolism type we specifically probed was mono-demethylation of the amino group on clomipramine. The results agree with the hypothesized inhibitory effect of propranolol. The concentration of propranolol at 50% inhibition of demethylation under these conditions was found to be 0.66 mM. (IC50=0.66 mM). Concentration of unmetabolized clomipramine increased by 9.3% with increasing concentration of propranolol. Propranolol acts as a substrate for enzymes CYP1A2 and CYP3A4, competing with clomipramine in binding the active sites of the enzymes, thus decreasing the concentration of desmethylated clomipramine while increasing the concentration of clomipramine. This experiment could guide medical practitioners when prescribing antidepressants and hypertensive drugs together.

Drug-drug effects of propranolol and clomipramine in rat liver microsome using HPLC and compact mass spectrometry

Where thousands of chemistry professionals meet to share ideas and advance scientific and technical knowledge. Spring 2023 abstracts, posters, and presentations will launch at the end of March.

ACS Spring 2023

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.