pharmacopeia
GET
/api/v1/drug/doxazosin
2D structure
[4-(4-amino-6,7-dimethoxyquinazolin-2-yl)piperazin-1-yl]-(2,3-dihydro-1,4-benzodioxin-3-yl)methanone
SMILES COC1=C(C=C2C(=C1)C(=NC(=N2)N3CCN(CC3)C(=O)C4COC5=CC=CC=C5O4)N)OC
InChIKey RUZYUOTYCVRMRZ-UHFFFAOYSA-N

Mechanism of action

Sourced from openFDA

Mechanism-of-action classes: Adrenergic alpha-Antagonists; Adrenergic alpha1-Antagonists.

Indications

Sourced from openFDA
  • Doxazosin tablets are an alpha 1 adrenergic antagonist indicated for: • Signs and symptoms of Benign Prostatic Hyperplasia (BPH) • Treatment of HypertensionTreatment of Hypertension 1.1 Benign Prostatic Hyperplasia (BPH) Doxazosin tablets are indicated for the treatment of the signs and symptoms of BPH. 1.2 Hypertension Doxazosin tablets are indicated for the treatment of hypertension, to lower blood pressure.ICD-10: I10, N40.0

Contraindications

Sourced from openFDA
  • The use of doxazosin tablets is contraindicated in patients with a hypersensitivity to doxazosin, other quinazolines (e.g., prazosin, terazosin), or any of its components. • Hypersensitivity to doxazosin, other quinazolines, or any other ingredient in doxazosin tablets.contraindicated

Dosage & administration

Sourced from openFDA

• For the treatment of BPH: Initiate therapy at 1 mg once daily. Dose may be titrated at 1 to 2 week intervals, up to 8 mg once daily.( 2.2 ) • For the treatment hypertension: Initiate therapy at 1 mg once daily. Dose may be titrated as needed, up to 16 mg once daily. ( 2.3 ) 2.1 Dosing Information Following the initial dose and with each dose increase of doxazosin tablets, monitor blood pressure for at least 6 hours following administration. If doxazosin tablets administration is discontinued for several days, therapy should be restarted using the initial dosing regimen. 2.2 Benign Prostatic Hyperplasia The recommended initial dosage of doxazosin tablets is 1 mg given once daily either in the morning or evening. Depending on the individual patient’s urodynamics and BPH symptomatology, the dose may be titrated at 1 to 2 week intervals to 2 mg, and thereafter to 4 mg and 8 mg once daily. The maximum recommended dose for BPH is 8 mg once daily. Routinely monitor blood pressure in these patients. 2.3 Hypertension The initial dosage of doxazosin tablets is 1 mg given once daily. Daily dosage may be doubled up 16 mg once daily, as needed, to achieve the desired reduction in blood pressure.

Warnings & precautions

Sourced from openFDA

• Postural hypotension with or without syncope may occur. ( 5.1 ) • Risk of Intraoperative Floppy Iris Syndrome during cataract surgery. ( 5.2 ) • Screen for the presence of prostate cancer prior to treatment for BPH and at regular intervals afterwards. ( 5.3 ) 5.1 Postural Hypotension Postural hypotension with or without symptoms (e.g., dizziness) may develop within a few hours following administration of doxazosin tablets. However, infrequently, symptomatic postural hypotension has also been reported later than a few hours after dosing. As with other alpha-blockers, there is a potential for syncope, especially after the initial dose or after an increase in dosage strength. Advise patient how to avoid symptoms resulting from postural hypotension and what measures to take should they develop. Concomitant administration of doxazosin tablets with a PDE-5 inhibitor can result in additive blood pressure lowering effects and symptomatic hypotension. 5.2 Cataract Surgery Intraoperative Floppy Iris Syndrome (IFIS) has been observed during cataract surgery in some patients on or previously treated with alpha 1 blockers. This variant of small pupil syndrome is characterized by the combination of a flaccid iris that billows in response to intraoperative irrigation currents, progressive intraoperative miosis despite preoperative dilation with standard mydriatic drugs, and potential prolapse of the iris toward the phacoemulsification incisions.

Adverse reactions

Sourced from openFDA

The most commonly reported adverse reactions from clinical trials are Fatigue, malaise, hypotension, and dizziness. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Apotex Corp at 1-800-706-5575 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. Benign Prostatic Hyperplasia (BPH) The incidence of adverse events has been ascertained from worldwide clinical trials in 965 BPH patients. The incidence rates presented below (Table 2) are based on combined data from seven placebo-controlled trials involving once-daily administration of doxazosin tablets in doses of 1 to 16 mg in hypertensives and 0.5 to 8 mg in normotensives. Adverse reactions occurring more than 1% more frequently in BPH patients treated with doxazosin tablets vs placebo are summarized in Table 1. Table 1.

Use in specific populations

Sourced from openFDA

• Hepatic Impairment: Monitor for hypotension. ( 8.6 , 12.3 ) 8.1 Pregnancy Risk Summary The limited available data with doxazosin tablets in pregnant women are not sufficient to inform a drug-associated risk for major birth defects and miscarriage. However, untreated hypertension during pregnancy can result in increased maternal risks [ see Clinical Considerations ]. In animal reproduction studies, no adverse developmental effects were observed when doxazosin was orally administered to pregnant rabbits and rats during the period of organogenesis at doses of up to 41 and 20 mg/kg, respectively (exposures in rabbits and rats were 10 and 4 times, respectively, the human AUC exposures with a 12 mg/day therapeutic dose). A dosage regimen of 82 mg/kg/day in the rabbit was associated with reduced fetal survival [ see Data ]. The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2 to 4% and 15 to 20%, respectively.

Overdosage

Sourced from openFDA

Experience with doxazosin overdosage is limited. Two adolescents, who each intentionally ingested 40 mg doxazosin tablets with diclofenac or acetaminophen, were treated with gastric lavage with activated charcoal and made full recoveries. A two-year-old child who accidently ingested 4 mg doxazosin tablets were treated with gastric lavage and remained normotensive during the five-hour emergency room observation period. A six-month-old child accidentally received a crushed 1 mg tablet of doxazosin and was reported to have been drowsy. A 32-year-old female with chronic renal failure, epilepsy, and depression intentionally ingested 60 mg doxazosin (blood level = 0.9 mcg/mL; normal values in hypertensives = 0.02 mcg/mL); death was attributed to a grand mal seizure resulting from hypotension. A 39-year-old female who ingested 70 mg doxazosin tablets, alcohol, and Dalmane ® (flurazepam) developed hypotension which responded to fluid therapy. The oral LD 50 of doxazosin is greater than 1,000 mg/kg in mice and rats. The most likely manifestation of overdosage would be hypotension, for which the usual treatment would be intravenous infusion of fluid.

Approval history

Sourced from openFDA
  • Nov 2, 1990NDANDA019668Viatris
  • Oct 18, 2000ANDAANDA075646Chartwell Rx
  • Oct 18, 2000ANDAANDA075536Teva
  • Oct 18, 2000ANDAANDA075580Apotex
  • Oct 19, 2000ANDAANDA075509Aurobindo Pharma Usa
  • Feb 22, 2005NDANDA021269Viatris
  • Jun 11, 2014ANDAANDA202824Accord Hlthcare
  • Jul 7, 2017ANDAANDA208719Zydus Pharms

FAERS reports

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Reference statistics only. FAERS reports are voluntarily submitted and are not incidence rates, safety signals, or causal evidence. Counts reflect reporting volume — how often a reaction was reported, not how often it occurs. For decision-grade use, consult openFDA and the FAERS Public Dashboard directly.
35,435 total reports matchedLatest report Share = reports listing the reaction ÷ total matched reports. Rows can sum to >100% because a single report often lists multiple reactions.
  1. 1Dyspnoea1,9575.5%
  2. 2Dizziness1,7054.8%
  3. 3Fatigue1,6994.8%
  4. 4Diarrhoea1,6454.6%
  5. 5Drug Ineffective1,5864.5%
  6. 6Nausea1,4614.1%
  7. 7Hypotension1,2973.7%
  8. 8Asthenia1,2613.6%
  9. 9Acute Kidney Injury1,2443.5%
  10. 10Headache1,2173.4%
  11. 11Hypertension1,1403.2%
  12. 12Drug Interaction1,1083.1%
  13. 13Vomiting1,0503.0%
  14. 14Fall1,0102.9%
  15. 15Malaise9922.8%

Literature

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Recent PubMed references pinned to Doxazosin as a MeSH major topic. Citations link to pubmed.ncbi.nlm.nih.gov.

Clinical trials

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The 10 most recently updated of 73 ClinicalTrials.gov registrations naming Doxazosin as an intervention. Registration is not evidence of efficacy or safety — reference crosswalk only.

Structural analogs

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Ranked by 2D fingerprint (Tanimoto) similarity over PubChem structures. Structural proximity only — not a claim of therapeutic equivalence.

Frequently asked questions

How does Doxazosin work?
Mechanism-of-action classes: Adrenergic alpha-Antagonists; Adrenergic alpha1-Antagonists.
What is Doxazosin used for?
According to FDA labeling, Doxazosin carries indications including: Doxazosin tablets are an alpha 1 adrenergic antagonist indicated for: • Signs and symptoms of Benign Prostatic Hyperplasia (BPH) • Treatment of HypertensionTreatment of Hypertension 1.1 Benign Prostatic Hyperplasia (BPH) Doxazosin tablets are indicated for the treatment of the signs and symptoms of BPH. 1.2 Hypertension Doxazosin tablets are indicated for the treatment of hypertension, to lower blood pressure.. This is a reference summary of labeled uses, not medical advice or a treatment recommendation.
What class of drug is Doxazosin?
Doxazosin is classified as Alpha-adrenoreceptor antagonists, alpha-Adrenergic Blocker, Adrenergic alpha-Antagonists, Adrenergic alpha1-Antagonists, Arterial Vasodilation, Decreased Bladder Sphincter Tone, Decreased Blood Pressure, Venous Vasodilation.
What are the brand names for Doxazosin?
Doxazosin is marketed under brand names including Cardura.
What are the contraindications for Doxazosin?
Doxazosin labeling lists contraindications including: The use of doxazosin tablets is contraindicated in patients with a hypersensitivity to doxazosin, other quinazolines (e.g., prazosin, terazosin), or any of its components. • Hypersensitivity to doxazosin, other quinazolines, or any other ingredient in doxazosin tablets.. Always consult the full prescribing information and a clinician.
Note. Data for doxazosin is illustrative MVP content compiled from public sources. pharmacopeia is for educational and informational use only and is not a substitute for professional medical advice.

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