A nurse is reviewing the list of current medications for a client who is to start a new prescription for carbamazepine. The nurse should identify that which of the following medications interacts with carbamazepine?

A. Estrogen-progestin combination: Carbamazepine induces hepatic enzymes, which can increase the metabolism of estrogen and progestin. This reduces the effectiveness of hormonal contraceptives, increasing the risk of unintended pregnancy. B. Nicotine transdermal system: Nicotine does not have a significant interaction with carbamazepine. The metabolism and pharmacologic effects of nicotine are not substantially altered by enzyme induction from carbamazepine. C. Diphenhydramine: Diphenhydramine is an antihistamine and does not have a major interaction with carbamazepine. Concurrent use does not significantly affect the efficacy or metabolism of either drug. D. Beclomethasone: Inhaled corticosteroids like beclomethasone are minimally affected by carbamazepine because they have limited systemic absorption. No clinically significant interaction is expected.