Introduction: Herbal medicines such as Hypericum (St. John’s wort), Kava‑kava, Ginkgo biloba, Ginseng, Garlic, black Pepper (piperine) and Ephedra are widely used and can produce significant adverse effects and drug interactions. Key concepts for B.Pharm students include CYP450 and P‑glycoprotein modulation, bleeding risk, hepatotoxicity, hypertensive crises, serotonin syndrome, hypoglycaemia and CNS depression or stimulation. Understanding mechanisms, clinical manifestations and perioperative or polypharmacy management is essential for safe dispensing and counselling. This set focuses on pharmacokinetic and pharmacodynamic interactions, monitoring strategies and contraindications. Now let’s test your knowledge with 30 MCQs on this topic.
Q1. What is the primary pharmacokinetic effect of Hypericum (St. John’s wort) that causes reduced plasma levels of many drugs?
- Inhibition of CYP3A4
- Induction of CYP3A4 and P‑glycoprotein
- Inhibition of P‑glycoprotein
- Inhibition of monoamine oxidase
Correct Answer: Induction of CYP3A4 and P‑glycoprotein
Q2. Co‑administration of St. John’s wort with selective serotonin reuptake inhibitors (SSRIs) most commonly risks which adverse event?
- Hypertensive crisis
- Serotonin syndrome
- Severe hepatotoxicity
- Prolonged QT interval
Correct Answer: Serotonin syndrome
Q3. Which herb is most associated with severe hepatotoxicity and has led to regulatory warnings and withdrawals?
- Ginkgo biloba
- Garlic
- Kava‑kava
- Ginseng
Correct Answer: Kava‑kava
Q4. Ginkgo biloba increases bleeding risk primarily through inhibition of which pathway?
- Platelet‑activating factor (PAF)
- Vitamin K epoxide reductase
- Thromboxane A2 synthesis
- Coagulation factor VII synthesis
Correct Answer: Platelet‑activating factor (PAF)
Q5. Which herb can reduce the effectiveness of oral contraceptives by increasing their metabolism?
- Garlic
- Hypericum (St. John’s wort)
- Ginkgo biloba
- Ginseng
Correct Answer: Hypericum (St. John’s wort)
Q6. Piperine from black pepper affects drug pharmacokinetics mainly by which mechanism?
- Inducing CYP2D6 activity
- Inhibiting CYP3A4 and UGT‑mediated glucuronidation
- Activating monoamine oxidase
- Enhancing renal clearance via P‑glycoprotein induction
Correct Answer: Inhibiting CYP3A4 and UGT‑mediated glucuronidation
Q7. Which herb is known for sympathomimetic effects and has been linked to hypertension, tachycardia, stroke and myocardial infarction?
- Ephedra (ma huang)
- Ginkgo biloba
- Kava‑kava
- Garlic
Correct Answer: Ephedra (ma huang)
Q8. Co‑use of garlic supplements with warfarin most likely results in which clinical effect?
- Reduced INR and thrombotic risk
- Increased INR and bleeding risk
- No interaction
- Increased platelet count
Correct Answer: Increased INR and bleeding risk
Q9. Which herbal product may potentiate central nervous system depression when combined with benzodiazepines or alcohol?
- Ginseng
- Kava‑kava
- Ginkgo biloba
- Piperine (black pepper)
Correct Answer: Kava‑kava
Q10. Panax ginseng can interact with antidiabetic drugs primarily by causing which adverse effect?
- Hyperglycaemia due to insulin antagonism
- Hypoglycaemia due to additive glucose‑lowering
- Inhibition of insulin secretion
- No effect on blood glucose
Correct Answer: Hypoglycaemia due to additive glucose‑lowering
Q11. Which herb is most likely to reduce warfarin anticoagulant effect (lower INR) via CYP induction?
- Ginkgo biloba
- Hypericum (St. John’s wort)
- Garlic
- Kava‑kava
Correct Answer: Hypericum (St. John’s wort)
Q12. A patient on SSRIs and St. John’s wort presents with agitation, hyperreflexia, and autonomic instability. The most likely diagnosis is:
- Hypertensive emergency
- Serotonin syndrome
- Neuroleptic malignant syndrome
- Anticholinergic toxicity
Correct Answer: Serotonin syndrome
Q13. Which herbal ingredient is commonly used to enhance absorption of curcumin and other drugs by inhibiting drug‑metabolising enzymes?
- Piperine (black pepper)
- Allicin (garlic)
- Ginkgolide (ginkgo)
- Kavalactone (kava)
Correct Answer: Piperine (black pepper)
Q14. Which herb should be avoided in patients with a history of seizures because it may lower the seizure threshold?
- Ginkgo biloba
- Garlic
- Ephedra
- Ginseng
Correct Answer: Ginkgo biloba
Q15. Which herb’s active constituents act on GABAergic systems and therefore can cause excessive sedation when combined with other CNS depressants?
- Kava‑kava
- Ephedra
- Hypericum (St. John’s wort)
- Ginseng
Correct Answer: Kava‑kava
Q16. Which interaction is of greatest concern when a patient taking monoamine oxidase inhibitors (MAOIs) uses Ephedra?
- Enhanced anticoagulant effect
- Serotonin syndrome
- Hypertensive crisis due to excess catecholamines
- Severe hypoglycaemia
Correct Answer: Hypertensive crisis due to excess catecholamines
Q17. For a patient scheduled for elective surgery, which herbal supplements are typically recommended to be stopped at least 7–14 days preoperatively due to bleeding or sedative risks?
- St. John’s wort and piperine
- Garlic, ginkgo, ginseng and kava‑kava
- Ephedra and piperine
- All herbs are safe and need not be stopped
Correct Answer: Garlic, ginkgo, ginseng and kava‑kava
Q18. Which herb is most likely to interact with statins and certain immunosuppressants by inducing CYP3A4 and reducing their plasma concentrations?
- Hypericum (St. John’s wort)
- Piperine (black pepper)
- Ginkgo biloba
- Kava‑kava
Correct Answer: Hypericum (St. John’s wort)
Q19. A patient on warfarin wishes to start ginseng. What is the most appropriate counselling point?
- No interaction; proceed without changes
- Expect reduced bleeding risk; decrease INR monitoring
- Ginseng may decrease warfarin effect; increase INR monitoring and counsel on bleeding/thrombosis
- Ginseng causes major bleeding and is an absolute contraindication with warfarin
Correct Answer: Ginseng may decrease warfarin effect; increase INR monitoring and counsel on bleeding/thrombosis
Q20. Which herb directly inhibits platelet aggregation and can potentiate the effect of aspirin and clopidogrel?
- Hypericum (St. John’s wort)
- Ginkgo biloba and garlic
- Piperine (black pepper)
- Kava‑kava
Correct Answer: Ginkgo biloba and garlic
Q21. Which herb is contraindicated or used with extreme caution in pregnancy due to uterotonic or stimulant effects and cardiovascular risk?
- Ginseng
- Ephedra
- Ginkgo biloba
- Piperine (black pepper)
Correct Answer: Ephedra
Q22. Which herb’s withdrawal or sudden discontinuation may reduce clearance of drugs previously affected by CYP induction, potentially increasing their levels?
- St. John’s wort
- Garlic
- Ginkgo biloba
- Kava‑kava
Correct Answer: St. John’s wort
Q23. Which herb is associated with taste disturbances, garlic breath, and potential hypotension when combined with antihypertensives?
- Ginseng
- Garlic
- Ginkgo biloba
- Piperine (black pepper)
Correct Answer: Garlic
Q24. A patient on digoxin is concerned about herbal supplements. Which herb most likely reduces digoxin levels via P‑glycoprotein induction?
- Hypericum (St. John’s wort)
- Ginkgo biloba
- Piperine (black pepper)
- Garlic
Correct Answer: Hypericum (St. John’s wort)
Q25. Which herb has been reported to cause liver enzyme elevations and rare acute liver failure prompting regulatory action?
- Kava‑kava
- Ginkgo biloba
- Hypericum (St. John’s wort)
- Piperine (black pepper)
Correct Answer: Kava‑kava
Q26. Which herb can increase plasma concentrations of drugs normally cleared by glucuronidation, risking toxicity?
- Piperine (black pepper)
- Ginseng
- Ephedra
- Ginkgo biloba
Correct Answer: Piperine (black pepper)
Q27. Combining Ephedra with tricyclic antidepressants (TCAs) may lead to which pharmacodynamic interaction?
- Severe sedation and respiratory depression
- Additive sympathomimetic effects causing arrhythmias and hypertension
- Antiplatelet synergy and bleeding
- Enhanced anticoagulation
Correct Answer: Additive sympathomimetic effects causing arrhythmias and hypertension
Q28. Which herb requires caution with antiepileptic drugs due to possible lowering of seizure threshold?
- Ginkgo biloba
- Garlic
- Piperine (black pepper)
- Kava‑kava
Correct Answer: Ginkgo biloba
Q29. Which herb is most likely to interact with cyclosporine or tacrolimus by reducing their blood levels through CYP3A4 induction?
- Hypericum (St. John’s wort)
- Ginkgo biloba
- Garlic
- Piperine (black pepper)
Correct Answer: Hypericum (St. John’s wort)
Q30. What is the best initial counselling for a patient taking multiple prescription medications who wishes to start any of these herbal supplements?
- Herbs are natural and safe; no need to inform healthcare providers
- Start herbal supplements immediately and stop prescription drugs if adverse effects appear
- Consult pharmacist/physician, review drug‑herb interactions, monitor relevant labs and consider stopping high‑risk herbs before surgery
- Only herbal teas are safe; avoid capsules
Correct Answer: Consult pharmacist/physician, review drug‑herb interactions, monitor relevant labs and consider stopping high‑risk herbs before surgery
