BETA BLOCKERS AND QUINIDINE

An isolated report describes a patient taking quinidine who developed marked bradycardia when using timolol eye drops. Other reports describe orthostatic hypotension with quinidine and atenolol or propranolol. Quinidine can raise plasma metoprolol, propranolol, and timolol levels, but the clinical relevance of this is uncertain. Additive QT-prolonging effects likely with sotalol, see drugs that prolong the QT interval.
The general relevance of these case reports is unclear.