A 62-year-old man with primary open-angle glaucoma requires addition of a second drug. His records note a documented severe rash with cotrimoxazole taken years ago. Which topical agent should be prescribed with greatest caution?
- A Latanoprost
- B Dorzolamide ✓
- C Brimonidine
- D Pilocarpine
Correct answer: B. Dorzolamide
Explanation
Dorzolamide and brinzolamide are carbonic anhydrase inhibitors structurally related to sulfonamides, so they carry a theoretical risk of cross-reactivity in patients with sulfonamide antibiotic allergy and are conventionally avoided or used cautiously in such patients. Latanoprost, brimonidine and pilocarpine have no sulfonamide moiety. The practical rule taught in Indian ophthalmology courses is to check sulfonamide allergy before prescribing any topical carbonic anhydrase inhibitor.
Reference: Katzung's Basic and Clinical Pharmacology, 15th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.