Certified Medical Assistant (CMA AAMA)PharmacologyHard
A patient reports taking St. John's Wort for depression. The medical assistant should be aware that this herbal supplement can have a significant interaction with which of the following classes of medications?
- ABeta-blockers
- BOral contraceptives
- CAntihistamines
- DAntibiotics
Show answer & explanationAnswer & explanation
Correct answer: B. Oral contraceptives
St. John's Wort is a known potent inducer of certain cytochrome P450 enzymes (CYP3A4), which can significantly decrease the effectiveness of many medications, including oral contraceptives, leading to unintended pregnancy.
Why the other options are wrong
- A. While interactions are possible, the effect on beta-blockers is less clinically significant compared to oral contraceptives.
- C. Antihistamines are generally less affected by St. John's Wort in a clinically significant way compared to OCs.
- D. Some antibiotics can interact with oral contraceptives, but St. John's Wort has a more direct and potent interaction with OCs.
St. John's Wort Interactions
St. John's Wort is a potent enzyme inducer that can reduce the effectiveness of many medications, notably oral contraceptives.
- Induces CYP3A4 enzymes.
- Decreases blood levels of co-administered drugs.
- Other affected drugs include anticoagulants, antiretrovirals, and digoxin.
Memory trick: St. John's Wort: 'OC' no baby, 'OC' no effect.