Doxazosin
Regulatory sources consulted
- AEMPS CIMA Ficha Técnica: 62655 (https://cima.aemps.es/cima/dochtml/ft/62655/FT_62655.html)
- General clinical pharmacology knowledge base
- AEMPS CIMA · nº registro 62655 ↗
- RxNorm rxcui 49276 ↗
Approved indications
- Treatment of essential arterial hypertension (HTN).
- Treatment of clinical symptoms of benign prostatic hyperplasia (BPH).
Contraindications
Absolute
- Hypersensitivity to doxazosin, other quinazolines (e.g., prazosin, terazosin), or to any of the excipients.
- History of orthostatic hypotension.
- Patients with BPH and congestion of the upper urinary tract, chronic urinary tract infection, or bladder stones.
- Severe hepatic impairment.
Clinical warnings
- Major warning · Postural Hypotension/Syncope: Marked hypotension may occur, especially with the first dose ('first-dose effect'). Treatment should be initiated with the lowest dose (1 mg) and the patient should be advised to avoid situations that could result in injury should dizziness or weakness occur. — AEMPS SPC
- Major warning · Intraoperative Floppy Iris Syndrome (IFIS): Has been observed during cataract surgery in some patients on or previously treated with alpha-blockers. Inform the ophthalmologist of current or past use of doxazosin before surgery. — AEMPS SPC
- Priapism: Prolonged erections and priapism have been reported with alpha-blockers, including doxazosin. If priapism is not treated immediately, it can result in penile tissue damage and permanent loss of potency. — AEMPS SPC
Drug interactions
- HighPDE-5 inhibitors (e.g., Sildenafil)G04BE03
Mechanism: Additive vasodilation via alpha-1 blockade and increased cGMP, which can lead to symptomatic hypotension.
Recommendation: Initiate therapy with the lowest dose of either drug. Administer several hours apart. Monitor blood pressure, especially at initiation.
AEMPS SPC
- ModerateStrong CYP3A4 inhibitors (e.g., Clarithromycin, Itraconazole)J01FA09
Mechanism: Inhibition of CYP3A4-mediated metabolism of doxazosin, increasing its plasma concentration and the risk of adverse effects such as hypotension.
Recommendation: Use with caution. Monitor for signs of hypotension. Consider a lower dose of doxazosin if co-administered.
AEMPS SPC
Adverse events
Common (≥1%)
dizziness · headache · hypotension · postural hypotension · palpitations · tachycardia · vertigo · somnolence · rhinitis · asthenia · peripheral edema
Rare but serious
syncope · priapism · leukopenia · thrombocytopenia · hepatitis · cholestasis · myocardial infarction · cerebrovascular accident
Pregnancy and lactation
FDA category: C
Pregnancy: There are no adequate and well-controlled studies in pregnant women. The safety of doxazosin during pregnancy has not been established. It should only be used if the potential benefit justifies the potential risk to the fetus. Lactation: Breast-feeding is not recommended during treatment with doxazosin.