From the Guidelines
Terazosin carries several important risks that patients should be aware of before starting treatment, particularly orthostatic hypotension, which can be minimized by taking the initial dose at bedtime and starting with a low dose (1mg) before gradually increasing, as recommended by the 2017 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA guideline for the prevention, detection, evaluation, and management of high blood pressure in adults 1. The most significant risk is orthostatic hypotension, which can cause dizziness, lightheadedness, or fainting when standing up quickly, particularly after the first dose or when increasing the dosage. Other common side effects include:
- Headache
- Drowsiness
- Weakness
- Nasal congestion
- Peripheral edema Some patients may experience sexual dysfunction, including decreased libido or retrograde ejaculation. Terazosin can interact with other blood pressure medications, PDE-5 inhibitors like sildenafil, and certain antidepressants, potentially causing dangerous drops in blood pressure. The medication works by blocking alpha-1 adrenergic receptors, causing blood vessel relaxation and smooth muscle relaxation in the prostate and bladder neck, which explains both its therapeutic effects and side effect profile. Patients with a history of heart disease, liver problems, or kidney disease should use terazosin with caution and inform their healthcare provider about all medications they're taking to avoid harmful interactions, as noted in the 2018 guideline for the prevention, detection, evaluation, and management of high blood pressure in adults 1. It is essential to weigh the benefits and risks of terazosin, considering the patient's individual circumstances, including the presence of benign prostatic hyperplasia (BPH) and other comorbidities, as discussed in the AUA guideline on management of BPH 1.
From the FDA Drug Label
ADVERSE REACTIONS Benign Prostatic Hyperplasia The incidence of treatment-emergent adverse events has been ascertained from clinical trials conducted worldwide. Asthenia, postural hypotension, dizziness, somnolence, nasal congestion/rhinitis, and impotence were the only events that were significantly (p </= 0. 05) more common in patients receiving terazosin than in patients receiving placebo. An analysis of the incidence rate of hypotensive adverse events (see PRECAUTIONS) adjusted for the length of drug treatment has shown that the risk of the events is greatest during the initial seven days of treatment, but continues at all time intervals. Table 1 Adverse Reactions During Placebo-controlled Trials Benign Prostatic Hyperplasia Body System Terazosin (N = 636) Placebo (N = 360) BODY AS A WHOLE †Asthenia 7.4%* 3.3% CARDIOVASCULAR SYSTEM Postural Hypotension 3.9%* 0. 8% Syncope 0.6% 0.0% NERVOUS SYSTEM Dizziness 9.1%* 4.2% Somnolence 3.6%* 1.9%
The risks of terazosin include:
- Postural hypotension (3.9% of patients)
- Dizziness (9.1% of patients)
- Somnolence (3.6% of patients)
- Asthenia (7.4% of patients)
- Syncope (0.6% of patients)
- Impotence (1.6% of patients) These adverse events are significantly more common in patients receiving terazosin than in patients receiving placebo 2.
From the Research
Risk of Terazosin
The risk of terazosin is associated with several adverse events, including:
- Dizziness: reported in 19% of patients in a study published in 3
- Asthenia: reported in 6% of patients in a study published in 3
- Postural hypotension: reported in 6% of patients in a study published in 3
- Syncope: reported in 1% of patients in a study published in 3
- Headache and nasal congestion: reported as common side effects in a study published in 4
Cardiovascular Risks
The cardiovascular risks associated with terazosin include:
- Orthostatic hypotension: reported in 4 patients out of 163 in a study published in 5
- First-dose syncope: reported as a rare occurrence in a study published in 4
- Reduction in blood pressure: reported in several studies, including 6, 4, and 7
Safety in Patients with Hypertension
Terazosin can be safely used in patients with hypertension, including those taking concurrent antihypertensive medications, as reported in studies published in 6 and 7.
- The addition of terazosin to an existing antihypertensive regimen was found to lower mean systolic blood pressure by 6.7 mm Hg in treated patients in a study published in 7
- The incidence of blood pressure-related side effects in patients on terazosin was found to be comparable between untreated and treated patients in a study published in 7
Efficacy and Safety in Patients with Symptomatic BPH
Terazosin has been found to be effective and safe in treating patients with symptomatic benign prostatic hyperplasia (BPH), as reported in studies published in 3, 6, and 5.