Which pre-existing condition is the most important contraindication to prescribing topical timolol maleate for open-angle glaucoma?

• A Type 2 diabetes mellitus
• B Bronchial asthma ✓
• C Systemic hypertension on amlodipine
• D Previous cataract surgery

Explanation

Timolol is a non-selective beta blocker that blocks bronchial beta-2 receptors even after topical administration due to nasolacrimal drainage and systemic absorption, and can precipitate severe bronchospasm in asthmatics. It also masks hypoglycaemia awareness in diabetics on insulin, making uncontrolled diabetes on insulin a relative concern, but asthma is the absolute contraindication. Calcium channel antihypertensives and prior cataract surgery pose no problem.

Reference: Katzung Basic and Clinical Pharmacology, 15th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.