Syncope and falls due to timolol eye drops

Case 1

A 73 year old man was referred by his general practitioner because he had been unconscious for half an hour the previous day. His medical history consisted of a myocardial infarction, glaucoma, and insulin dependent diabetes mellitus. During the past few years, he had experienced four spells of dizziness with severe perspiration. These spells had been ascribed to hypoglycaemia, although low blood glucose values had never been detected. His medication consisted of insulin, acenocoumarol, alfuzosin, and timolol eye drops (0.5%, twice daily in both eyes). During his last dizzy spell, his blood glucose concentration had been 8 mmol/l. According to his wife, the patient had not experienced a convulsion, tongue biting, or urinary incontinence.

At referral to our clinic, the patient was alert and feeling well. Blood pressure was 142/90 mm Hg, with a regular pulse rate of 48 beats/min. There was no evidence of orthostatic hypotension. Further physical examination, including neurological examination, showed no abnormalities. Glycated haemoglobin (HbA_1c) was slightly increased—8.2% (reference range 4-6%); the glucose day curve showed values of 4.6-17.4 (3.5-11) mmol/l, with no hypoglycaemia. Electrocardiography showed sinus bradycardia of 41 beats/min, and 24 hour Holter monitoring showed …