Role of cytochrome P450 1A2 in caffeine-herb interactions

Caffeine is widely consumed in foods and beverages and is also used for a variety of medical purposes. Recently years, the consumption of herbal medicines is on the rise among the global population. Although the safety profile of many herbal medicines is promising, accumulated data show evidence of significant interactions of herbs with caffeine, which can place individual patients at great risk. Cytochrome P450 1A2 (CYP1A2) is one of the major P450 enzymes in human liver and accounts for approximately 13% of the total content of this enzyme group. Caffeine is the first-choice substrate for CYP1A2 phenotyping because it is relatively safe and possesses many favorable pharmacokinetic characteristics for a marker substrate. In fact, some studies have reported herbal medicines can induce or inhibit human CYP1A2 activity. Therefore, caffeine pharmacokinetics may be changed by herbs affecting the activity of CYP1A2. Moreover, numerous herb-drug interactions may occur between caffeine and herbal medicines. Therefore, patients taking caffeine-containing medicine and/or coffee drinkers with herbal medicines that interact with CYP1A2 may require proper dosage adjustments upon caffeine ingestion and cessation.