Which drug class may potentially cause first dose syncope and orthostasis?

Peripheral alpha-1 antagonists are known to potentially cause first dose syncope and orthostasis due to their mechanism of action. These medications work by blocking alpha-1 adrenergic receptors, leading to vasodilation and a decrease in blood pressure. When a patient first starts these medications, the sudden drop in blood pressure can overwhelm the body's compensatory mechanisms, leading to lightheadedness, syncope (fainting), or orthostatic hypotension, especially when transitioning from a sitting or lying position to standing.

This characteristic effect is pronounced with the initial doses of peripheral alpha-1 antagonists, which is why they are often recommended to be taken at bedtime, to minimize the risk of syncope during the daytime activities. Monitoring is necessary during the first few doses to ensure the patient does not experience significant hypotension.

Other drug classes mentioned, while they may have side effects, do not typically carry the same risk for first dose syncope in the same manner. For example, calcium channel blockers can cause peripheral edema and, in some cases, bradycardia, but they are not primarily associated with first dose effects. Beta-blockers can lead to reduced heart rate and blood pressure but do not commonly result in orthostatic issues on first