From the FDA Drug Label
In controlled trials, terazosin has been added to diuretics, and several beta-adrenergic blockers; no unexpected interactions were observed. Terazosin has also been used in patients on a variety of concomitant therapies; while these were not formal interaction studies, no interactions were observed Terazosin has been used concomitantly in at least 50 patients on the following drugs or drug classes: ... 6) cardiovascular agents (e.g., atenolol, hydrochlorothiazide, methyclothiazide, propranolol);
Key Considerations:
- The use of terazosin with other antihypertensive agents, including diuretics and beta-adrenergic blockers, has been studied and no unexpected interactions were observed.
- Specifically, terazosin has been used concomitantly with hydrochlorothiazide, a diuretic, and beta-adrenergic blockers, such as atenolol and propranolol.
- Caution should be observed when terazosin is administered concomitantly with other antihypertensive agents, especially to avoid the possibility of developing significant hypotension.
- Dosage reduction and retitration of either agent may be necessary when using terazosin and other antihypertensive agents concomitantly.
Answer: You can add terazosin to a regimen of losartan, hydrochlorothiazide, and bisoprolol, but caution is advised due to the potential for increased hypotensive effects. Monitoring of blood pressure and adjustment of dosages as needed is recommended 1, 1.
From the Research
Adding terazosin to a regimen of losartan, hydrochlorothiazide (HCTZ), and bisoprolol is not recommended as a first-line approach due to the risk of excessive blood pressure lowering and potential adverse effects such as dizziness, asthenia, and postural hypotension, as reported in studies 2, 3. When considering this combination, it is essential to weigh the potential benefits against the risks, particularly in patients with concurrent hypertension and benign prostatic hyperplasia.
- The mechanism of action of each medication should be considered: losartan blocks angiotensin II receptors, HCTZ is a diuretic, bisoprolol is a beta-blocker, and terazosin is an alpha-blocker.
- The potential for orthostatic hypotension and related adverse effects, such as dizziness and syncope, should be carefully evaluated, as reported in studies 2, 4.
- If this combination is being considered, it should be initiated at the lowest possible dose of terazosin (1mg at bedtime) with gradual titration while closely monitoring blood pressure and symptoms, as suggested by the available evidence 5, 6.
- The patient should be advised to rise slowly from sitting or lying positions to minimize dizziness and other adverse effects.
- Alternative treatment options, such as tamsulosin, which has a more favorable cardiovascular safety profile, should be considered, as reported in study 5.