A nurse is assisting in the care of an adolescent in an outpatient clinic. Complete the following sentence by using the lists of options. The adolescent is at risk for dropdowndue todropdown.

Rationale for correct choices: • pregnancy: The adolescent is taking phenytoin, an antiseizure medication known to induce hepatic enzymes that can reduce the effectiveness of hormonal contraceptives. This interaction increases the risk of unintended pregnancy despite adherence to the oral contraceptive regimen. Monitoring and counseling are essential to ensure adequate contraceptive protection. • a medication interaction: Phenytoin accelerates the metabolism of ethinyl estradiol and drospirenone, the active components in combined oral contraceptives, through induction of cytochrome P450 enzymes. This pharmacokinetic interaction diminishes hormone levels, potentially compromising contraceptive efficacy and increasing the risk for pregnancy. Rationale for incorrect choices: • anaphylaxis: The adolescent has documented allergies to penicillin and sulfa medications, but neither phenytoin nor the combined oral contraceptive contains these allergens. There is no immediate risk of anaphylaxis related to the current medications. • phenytoin toxicity: Laboratory results indicate phenytoin levels are within the therapeutic range. There are no signs of toxicity such as nystagmus, ataxia, or gingival hyperplasia at this time, so the adolescent is not currently at risk for phenytoin toxicity. • their dosing schedule: The adolescent reports adherence to the prescribed phenytoin and oral contraceptive schedule. The risk of contraceptive failure is related to the drug-drug interaction rather than improper timing or missed doses.