Generic Medicine Info
Indications and Dosage
Benign prostatic hyperplasia
Adult: Initially, 1 mg at bedtime, may be increased gradually at intervals of 1-2 weeks according to patient's response. Maintenance: 5-10 mg once daily.

Adult: As monotherapy or in combination with other antihypertensive agents (e.g. diuretics, β-blockers): Initially, 1 mg at bedtime, may be increased gradually at weekly intervals according to patient's response. Maintenance: 2-10 mg once daily. Max: 20 mg daily.
May be taken with or without food.
History of micturition syncope.
Special Precautions
Patient with heart failure, pulmonary oedema due to mitral or aortic valve stenosis. Patient undergoing cataract surgery. Concomitant use with other antihypertensive agents (e.g. verapamil). Hepatic impairment. Elderly. Pregnancy and lactation.
Adverse Reactions
Significant: Postural hypotension, syncope (particularly during the initial treatment); intraoperative floppy iris syndrome (during cataract surgery). Rarely, priapism.
Blood and lymphatic system disorders: Thrombocytopenia.
Cardiac disorders: Palpitations, tachycardia, arrhythmia, atrial fibrillation.
Ear and labyrinth disorders: Vertigo, tinnitus.
Eye disorders: Blurred vision, amblyopia, visual impairment, conjunctivitis.
Gastrointestinal disorders: Nausea, vomiting, diarrhoea, constipation, abdominal pain, dry mouth, flatulence, dyspepsia.
General disorders and administration site conditions: Asthenia, pyrexia, chest pain.
Immune system disorders: Rarely, allergic reactions (including anaphylaxis).
Investigations: Increased weight; decreased haematocrit, Hb, WBC count, total protein and blood albumin.
Metabolism and nutrition disorders: Peripheral oedema, facial oedema.
Musculoskeletal and connective tissue disorders: Pain in extremities, back pain, neck pain, shoulder pain, arthralgia, myalgia, gout, arthritis, joint disorders.
Nervous system disorders: Dizziness, somnolence, headache, paraesthesia.
Psychiatric disorders: Depression, nervousness, anxiety, insomnia.
Renal and urinary disorders: UTI, urinary incontinence (primarily in postmenopausal women), urinary frequency.
Reproductive system and breast disorders: Erectile dysfunction, decreased libido.
Respiratory, thoracic and mediastinal disorders: Rhinitis, nasal congestion, sinusitis, cough, bronchitis, pharyngitis, dyspnoea, flu symptoms, cold symptoms, epistaxis.
Skin and subcutaneous tissue disorders: Hyperhidrosis, rash, pruritus.
Vascular disorders: Vasodilation.
Patient Counseling Information
This drug may cause dizziness and drowsiness, if affected, do not drive or operate machinery.
Monitoring Parameters
Monitor blood pressure (standing and sitting or supine position), particularly 2-4 hours after the initial dose and thereafter. Observe for dizziness, palpitations, somnolence, and impotence during initiation of therapy and regularly. In patients with benign prostatic hyperplasia (BPH): Rule out the presence of prostate carcinoma before initiating therapy; monitor the International Prostate Symptom Score (at baseline and 4-12 weeks after initiation of treatment) and urinalysis (at baseline).
Symptom: Acute hypotension. Management: Supportive treatment. Prioritise CV support. Keep the patient in a supine position to restore blood pressure and normalise heart rate; if inadequate, may give volume expanders to treat shock first and then administer vasopressors if necessary. Monitor renal function.
Drug Interactions
Increased incidence of dizziness or other dizziness-related adverse events with ACE inhibitors (e.g. captopril) and diuretics. May increase the risk of hypotension with other antihypertensive agents (e.g. verapamil) and phosphodiesterase-5 inhibitors (e.g. sildenafil, tadalafil).
Food Interaction
Delayed time to peak plasma concentration with food.
Mechanism of Action: Terazosin is an α1-adrenoceptor antagonist. It decreases blood pressure by reducing the total peripheral vascular resistance through competitive inhibition of the postsynaptic α1-adrenoceptors. Additionally, the blockade of these receptors in the bladder neck and prostate produces smooth muscle relaxation, thus reducing bladder outlet obstruction.
Onset: Antihypertensive effect: Within 15 minutes.
Duration: Antihypertensive effect: 24 hours.
Absorption: Rapidly and almost completely absorbed from the gastrointestinal tract. Delayed time to peak plasma concentration with food by approx 40 minutes. Bioavailability: Approx 90%. Time to peak plasma concentration: Approx 1 hour.
Distribution: Plasma protein binding: Approx 90-94%.
Metabolism: Metabolised in the liver via demethylation and conjugation; undergoes minimal first-pass metabolism.
Excretion: Via urine (approx 40%, approx 10% as unchanged drug); faeces (approx 60%, approx 20% as unchanged drug). Elimination half-life: Approx 8-13 hours.
Chemical Structure

Chemical Structure Image

Source: National Center for Biotechnology Information. PubChem Compound Summary for CID 5401, Terazosin. https://pubchem.ncbi.nlm.nih.gov/compound/Terazosin. Accessed May 26, 2022.

Store between 20-25°C. Protect from light and moisture. Storage recommendations may vary among individual products. Refer to specific product guidelines.
MIMS Class
Drugs for Bladder & Prostate Disorders / Other Antihypertensives
ATC Classification
G04CA03 - terazosin ; Belongs to the class of alpha-adrenoreceptor antagonists. Used in the treatment of benign prostatic hypertrophy.
Anon. Terazosin. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 08/03/2022.

Apotex NZ Ltd. Apo-Terazosin (1 mg, 2 mg and 5 mg Tablets) data sheet 28 November 2018. Medsafe. http://www.medsafe.govt.nz. Accessed 08/03/2022.

Buckingham R (ed). Terazosin Hydrochloride. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 08/03/2022.

Hytrin (Abbott Laboratories [M] Sdn Bhd). National Pharmaceutical Regulatory Agency - Ministry of Health Malaysia. https://www.npra.gov.my. Accessed 08/03/2022.

Hytrin 2 mg Tablets (Amdipharm UK Limited). MHRA. https://products.mhra.gov.uk. Accessed 08/03/2022.

Joint Formulary Committee. Terazosin. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 08/03/2022.

Terazosin 5 mg Tablets (Teva UK Limited). MHRA. https://products.mhra.gov.uk. Accessed 13/05/2022.

Terazosin Capsule (RedPharm Drug, Inc.). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 08/03/2022.

Disclaimer: This information is independently developed by MIMS based on Terazosin from various references and is provided for your reference only. Therapeutic uses, prescribing information and product availability may vary between countries. Please refer to MIMS Product Monographs for specific and locally approved prescribing information. Although great effort has been made to ensure content accuracy, MIMS shall not be held responsible or liable for any claims or damages arising from the use or misuse of the information contained herein, its contents or omissions, or otherwise. Copyright © 2024 MIMS. All rights reserved. Powered by MIMS.com
  • Ralsin
Register or sign in to continue
Asia's one-stop resource for medical news, clinical reference and education
Already a member? Sign in
Register or sign in to continue
Asia's one-stop resource for medical news, clinical reference and education
Already a member? Sign in