[Infrequent systemic drug interaction: repeated syncope caused by combined treatment with timolol-containing eye drops and lercanidipine tablet].

The control and planning of the treatment of hypertensive patients need specific attention. As regards concomitant diseases and treatments, glaucoma and the use of eye drops should be taken into consideration. The ingredients of the administered eye drops get through the nasolacrimal canal and can be absorbed by the nasal mucosa. Because of the lack of enterohepatic 'first pass' effect, they can act systemically - like after intravenous administration. This way they can cause systemic side effects. The authors present a case of a patient, too, who was examined and medically checked regularly for years with negative results because of repeated syncope. It became clear only at the Hypertension Centre that the timolol-containing combined eye drops caused the symptoms. The authors draw attention to the fact that in the case of systemic side effects which can be connected to beta-blocking agents (blood pressure fall, bradycardia, breathing disturbance, depression), the role of the eye drops should be taken into consideration. At the same time, the possibility of the systemic drug interactions should not be forgotten either. The interaction with dihydropyridine-type calcium-channel blockers can be of great importance. In these cases, after consultation with an ophthalmologist, the glaucoma treatment with eye drops containing beta-blockers should be modified. Orv Hetil. 2019; 160(8): 309-313.