Question

A patient with depression diagnosed 2 years ago presents to your office for follow-up. Although he states his mood is "pretty good most days," he started St. John’s Wort 3 weeks ago based on a recommendation from a friend. He is currently taking an antidepressant that is a CYP3A4 substrate. What is your assessment regarding the drug-herbal interaction?

a) The antidepressant can decrease the metabolism of the St. John’s Wort, possibly increasing the risk of toxicities associated with St. John’s Wort

b) The antidepressant can increase the metabolism of the St. John’s Wort, possibly causing loss of clinical efficacy of St. John’s Wort

c) St. John’s Wort can decrease metabolism of the antidepressant, possibly increasing the risk of toxicities associated with the antidepressant

d) St. John’s Wort can increase metabolism of the antidepressant, possibly causing loss of clinical efficacy of the antidepressant

Answer 1

St. John’s Wort is known to induce CYP3A4, leading to increased metabolism of CYP3A4 substrates, such as certain antidepressants. This could decrease the effectiveness of the antidepressant. The correct multiple-choice answer is that St. John’s Wort can increase metabolism of the antidepressant, reducing its efficacy (option d).

Step-by-step explanation:

The scenario presented describes a patient with a history of depression who has begun taking St. John’s Wort along with a prescribed antidepressant that is a substrate of the cytochrome P450 enzyme CYP3A4. St. John's Wort is known to be an inducer of CYP3A4, which can lead to increased metabolism of medications that are CYP3A4 substrates. As a result, this can decrease the plasma concentration of the antidepressant, potentially reducing its therapeutic efficacy and necessitating adjustments in dosage. Therefore, it is important for this drug-herbal interaction to be managed carefully by the healthcare provider.

The correct answer to the drug-herbal interaction question is: d) St. John’s Wort can increase metabolism of the antidepressant, possibly causing loss of clinical efficacy of the antidepressant. This interaction could undermine the treatment of the patient’s depression, which requires close monitoring and possibly a change in the medication regimen to ensure continued management of the patient's symptoms.