Question

a nurse is reviewing the medication list of a client who wants to begin taking oral contraceptives. which of the following client medications should the nurse identify will interfere with the effectiveness of an oral contraceptive?

sumatriptan
carbamazepine
atenolol
glipizide

Explanation:

Identify the clinical question

The question asks which medication from the list will interfere with the effectiveness of oral contraceptives.

Analyze oral contraceptive metabolism

Oral contraceptives (containing estrogen and/or progestin) are metabolized primarily by hepatic cytochrome P450 enzymes, specifically CYP3A4. Medications that induce these enzymes increase the metabolism of oral contraceptives, leading to decreased hormone levels and reduced contraceptive efficacy.

Evaluate the options

• Sumatriptan: A 5-HT1 receptor agonist used for migraines. It does not significantly induce CYP450 enzymes.
• Carbamazepine: An anticonvulsant and mood stabilizer. It is a potent inducer of hepatic enzymes (including CYP3A4), which accelerates the clearance of oral contraceptives, reducing their effectiveness.
• Atenolol: A beta-blocker used for hypertension. It does not induce hepatic enzymes.
• Glipizide: A sulfonylurea used for type 2 diabetes. It does not induce hepatic enzymes.

Formulate clinical recommendation

Carbamazepine is a known hepatic enzyme inducer that decreases the effectiveness of oral contraceptives. Clients taking carbamazepine require an alternative or back-up method of birth control.

Answer:

• Sumatriptan
• Carbamazepine (Correct answer)
• Atenolol
• Glipizide