CYP2C19 and tuberculosis: Pharmacodynamically, INH acts to inhibit CYP3A4 and CYP2C19 enzymes and can elevate VPA levels, although this was not the case with our patient [10]. INH does have MAOi activity, and while the data on its potential to contribute to serotonin toxicity are limited, its essential role in TB treatment complicates traditional psychopharmacologic management [2].