When a patient presents with dizziness, falls, or orthostatic symptoms, antihypertensives and diuretics often get the blame first. However, many non–blood pressure medications can lower blood pressure through a variety of mechanisms. Failing to recognize these culprits can lead to unnecessary dose reductions of essential cardiovascular therapies while the true cause goes unnoticed. Let’s review several commonly prescribed medications that cause hypotension.
Antipsychotics
Many antipsychotics, particularly agents like quetiapine, clozapine, and risperidone, have alpha-1 adrenergic blocking activity. This can lead to orthostatic hypotension, especially during initiation or titration. Monitoring blood pressure and counseling patients about slow positional changes is essential. Recall that clozapine actually has a boxed warning for this concern (one of five).
Levodopa (Sinemet)
Used in Parkinson’s disease, levodopa increases dopamine levels but can also impair autonomic regulation and cause vasodilation. Orthostatic hypotension is common in Parkinson’s disease itself, and levodopa may exacerbate this issue. It is ideal to avoid giving carbidopa/levodopa too close to each other as this may exacerbate the hypotensive effect. Paying attention to dosing and timing is important as a patient ages and the disease progresses.
Sildenafil and Other PDE-5 Inhibitors
Phosphodiesterase-5 inhibitors like sildenafil increase nitric oxide–mediated vasodilation. While generally well tolerated, they can lower systemic blood pressure, particularly when combined with nitrates or alpha-blockers. These are really important drug interactions to remember when studying for board exams.
Tamsulosin and Other Alpha-Blockers for BPH
Tamsulosin is used for benign prostatic hyperplasia and works by blocking alpha-1 receptors in the prostate and bladder neck. However, alpha-1 receptors are also located in the peripheral vasculature. Blockade can lead to vasodilation and orthostatic hypotension, particularly when therapy is initiated or doses are increased. Bedtime dosing and slow position changes can help reduce symptoms.
Tricyclic Antidepressants
Similar to antipsychotics, TCA agents such as amitriptyline have significant alpha-1 blocking activity. Orthostatic hypotension is a well-known adverse effect and can be dose-dependent. These agents also carry anticholinergic effects, which further complicate management in older adults.
Trazodone
Trazodone is frequently used off-label for insomnia at low doses. It has alpha-1 blocking properties, which can cause vasodilation and orthostatic hypotension. As dosages escalate, this side effect becomes more prominent.This effect is especially important in elderly patients and those at high risk for falls.
What other medications that cause hypotension do you worry about?
0 Comments