A nurse is caring for a client who has a new diagnosis of primary open-angle glaucoma and a prescription for timolol ophthalmic drops. For which of the following adverse effects should the nurse monitor the client?

Choice A rationale Timolol is a nonselective beta-adrenergic antagonist applied topically to reduce intraocular pressure. Although administered in the eye, significant systemic absorption can occur via the nasolacrimal duct. Once in the systemic circulation, it blocks beta-1 receptors in the myocardium. This action decreases the heart rate, potentially leading to symptomatic bradycardia. Nurses must monitor pulse rates, as normal resting heart rates typically range from 60 to 100 beats per minute. Choice B rationale Anemia involves a decrease in the total amount of red blood cells or hemoglobin in the blood, often measured by hemoglobin levels which normally range from 12 to 18 g/dL depending on gender. Timolol does not interfere with erythropoiesis in the bone marrow or cause hemolysis of existing erythrocytes. There is no established physiological mechanism linking topical beta-blocker use to a reduction in red cell mass or hemoglobin concentration in patients. Choice C rationale Hypertension is defined by persistent blood pressure elevations, typically above 130/80 mmHg. Beta-blockers like timolol generally cause vasodilation or reduced cardiac output, which would lower blood pressure rather than raise it. Systemic absorption of timolol is more likely to cause hypotension due to decreased cardiac contractility and heart rate. Therefore, monitoring for hypertension is not clinically indicated for a patient starting this specific ophthalmic medication for open-angle glaucoma. Choice D rationale Seizures are caused by abnormal, excessive electrical activity in the brain. Timolol is a beta-adrenoceptor blocker and does not significantly lower the seizure threshold or irritate cortical neurons. While some medications can cross the blood-brain barrier and cause central nervous system irritability, timolol's primary systemic risks are cardiovascular and respiratory, such as bronchospasm. Monitoring for seizure activity is unnecessary as it is not a documented adverse effect of this drug.