CYP3A4 and asthma: Epigallocatechin gallate, a constituent of teas, has shown in vitro inhibition of Cytochrome P450 enzymes, including CYP1A2, CYP2C8, CYP2C9, and CYP3A4 (Albassam and Markowitz, 2017) and therefore has potential effects on the majority of conventional asthma drugs.