PG, a 33-year-old woman, presents to XYZ Pharmacy with 2 new prescriptions. The prescriptions are:
Folic acid 1 mg, daily
Zonisamide 100 mg, daily for 2 weeks, then increase to 200 mg daily for 3 weeks, then increase to 300 mg daily
Upon receiving the prescriptions, the pharmacist reviews PG?s medication profile for possible drug interactions. The medications that PG is currently taking include the following:
Carbamazepine extended-release tablets 400 mg, twice daily
Carbamazepine 200 mg, as needed for seizures
PG?s profile also notes an allergy to sulfonamides. When questioned by the pharmacist, PG explains that she had an anaphylactic reaction 2 years ago while taking sulfamethoxazole. The pharmacist informs PG that she needs to contact the physician concerning her sulfonamide allergy.Why is the pharmacist concerned about PG?s allergy?