A patient using topical dorzolamide 2% three times daily complains of a persistent bitter taste after each instillation and asks about the drug class. Which statement about dorzolamide is correct?
- A It is a sulfonamide derivative, so cross-reactivity must be considered in patients with sulfonamide hypersensitivity ✓
- B It lowers IOP by increasing uveoscleral outflow through matrix metalloproteinase activation
- C The bitter taste indicates the drop has degraded and the bottle should be discarded
- D It is contraindicated in patients with a history of nephrolithiasis
Correct answer: A. It is a sulfonamide derivative, so cross-reactivity must be considered in patients with sulfonamide hypersensitivity
Explanation
Dorzolamide is a topical carbonic anhydrase inhibitor structurally related to the sulfonamides, so theoretical cross-reactivity in sulfonamide-allergic patients is considered. The bitter taste is a well-known class effect caused by drainage of the drug through the nasolacrimal duct onto the pharyngeal mucosa, not degradation; punctal occlusion reduces it. Nephrolithiasis is a concern with chronic systemic acetazolamide, not topical dorzolamide, whose main local effects are stinging and superficial punctate keratitis.
Reference: Katzung, Basic and Clinical Pharmacology, 16th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.