Schedule H

Oral

• Tablets: 1 mg, 2 mg, 5 mg

INDICATIONS + DOSING — FOR CLINICIAN USE ONLY

Primary Indications (Approved / Standard in India)

1. Benign Prostatic Hyperplasia (BPH)

Parameter Recommendation

Starting dose: 1 mg once daily at bedtime

Titration: Increase by doubling dose every 1–2 weeks (1 mg → 2 mg → 5 mg → 10 mg) based on symptom response and tolerability

Usual maintenance dose: 5–10 mg once daily

Maximum dose: 20 mg/day (rarely required; use under specialist supervision)

Clinical notes:

• Always initiate at bedtime to minimise first-dose hypotension

• Symptomatic improvement typically assessed using IPSS (International Prostate Symptom Score)

• Relieves dynamic obstruction via smooth muscle relaxation of prostate and bladder neck

• Does not reduce prostate volume or alter disease progression

• If treatment interrupted for several days, re-initiate at 1 mg dose

1. Hypertension

Parameter Recommendation

Starting dose: 1 mg once daily at bedtime

Titration: Increase gradually every 1–2 weeks (1 mg → 2 mg → 5 mg → 10 mg) based on BP response

Usual maintenance dose: 2–10 mg once daily

Maximum dose: 20 mg/day (rarely needed)

Clinical notes:

• Not recommended as first-line antihypertensive agent (ALLHAT evidence: increased cardiovascular events vs diuretics)

• Useful as add-on therapy when other agents insufficient

• Particularly beneficial in hypertensive males with concurrent BPH

• Correct volume depletion before initiation

• Monitor BP carefully during titration phase

Secondary Indications — Adults (Off-label)

Indication Dose Duration Notes

Ureteric stone expulsion (Medical Expulsive Therapy) (OFF-LABEL) Starting dose: 2 mg once daily; Usual dose: 2–5 mg once daily Up to 4–6 weeks or until stone passage Specialist only (Urology). Evidence: Meta-analyses supporting alpha-blockers for distal ureteric stones; commonly used in Indian urology practice

PTSD-associated nightmares (OFF-LABEL) Starting dose: 1 mg at bedtime; Titration: increase by 1–2 mg weekly; Usual dose: 2–10 mg at bedtime Continue if benefit observed; reassess every 4–8 weeks Specialist only (Psychiatry). Evidence: Limited data compared to prazosin; used selectively in Indian specialist practice

PAEDIATRIC DOSING (Specialist Only)

Primary Indications (Approved / Standard in India)

Not approved for routine paediatric use in India.

Secondary Indications — Paediatrics (Off-label)

Indication Age Dose Notes

Ureteric stone expulsion (Medical Expulsive Therapy) (OFF-LABEL) ≥6 years 0.05–0.1 mg/kg once daily (maximum 5 mg/day) Specialist only (Paediatric Urology/Nephrology). Duration: up to 4 weeks. Evidence: Small studies; Indian tertiary care experience

Refractory Hypertension (OFF-LABEL) ≥6 years Starting dose: 0.02–0.05 mg/kg once daily; Titration: every 1–2 weeks; Maximum: 0.4 mg/kg/day or 5 mg/day (whichever lower) Specialist only (Paediatric Nephrology/Cardiology). Evidence: Limited data; extrapolated from adult use

Safety monitoring:

• Blood pressure (supine and standing) before each dose escalation

• Monitor for dizziness, syncope, orthostatic symptoms

• First-dose precaution: administer at bedtime with patient lying down

Minimum age statement: Not recommended below 6 years of age for any indication. Use only under specialist supervision in tertiary care settings.

• Known hypersensitivity to terazosin or other quinazoline derivatives (prazosin, doxazosin)

• History of syncope due to alpha-blocker therapy

• Concurrent administration with other alpha-1 blockers (duplication of mechanism)

• First-dose phenomenon — marked hypotension or syncope, especially within 30–90 minutes of first dose; initiate at bedtime

• History of orthostatic hypotension or recurrent postural symptoms

• Volume depletion or concurrent diuretic therapy

• Elderly patients — heightened risk of falls and orthostatic hypotension

• Heart failure — not recommended as first-line; may worsen outcomes

• Planned cataract surgery — risk of Intraoperative Floppy Iris Syndrome (IFIS); inform ophthalmologist

• Driving or operating machinery — advise caution until individual response is known

• Concurrent use with PDE-5 inhibitors — stagger dosing by at least 4 hours

• Avoid abrupt withdrawal after prolonged therapy

• Re-initiate at 1 mg if therapy interrupted for more than a few days

Parameter Information

Overall safety: Limited human data; animal studies do not indicate direct teratogenicity

Risk category: Not formally classified in India; avoid unless clearly necessary

Preferred alternatives: Labetalol, methyldopa, nifedipine (established safety in gestational hypertension)

When may be used: Only when standard agents are contraindicated and potential benefit justifies risk; specialist supervision mandatory

What to monitor: Maternal BP (supine and standing), fetal growth, signs of placental hypoperfusion

Parameter Information

Compatible with breastfeeding: Unknown; likely excreted in breast milk; use with caution

Drug levels in milk: Not well quantified; presumed low based on physicochemical properties

Preferred alternatives: No safer alpha-blocker established; consider alternative antihypertensive classes if indicated for hypertension

What to monitor in infant: Feeding adequacy, excessive sedation, lethargy, weight gain, signs of hypotension

Parameter Recommendation

Starting dose: 1 mg once daily at bedtime (never skip low-dose initiation)

Titration: Slower than standard — increase no more frequently than every 2 weeks

Extra risks: Postural hypotension, syncope, falls with fractures, confusion, nocturnal falls (especially with nocturia from BPH)

Special considerations: Review concurrent medications (diuretics, other antihypertensives, psychotropics); ensure adequate hydration; advise slow positional changes; avoid nighttime waking activities if possible

Interacting Drug Effect Recommendation

PDE-5 inhibitors (sildenafil, tadalafil, vardenafil) Severe additive hypotension Avoid co-administration within 4 hours; ensure terazosin dosing is stable before introducing PDE-5 inhibitor at lowest dose

Other alpha-1 blockers (prazosin, doxazosin, tamsulosin, alfuzosin) Duplication of alpha-blockade; profound hypotension Avoid combination

Potent antihypertensives (nitrates, hydralazine) Marked additive BP lowering Avoid concurrent initiation; use with careful dose adjustment and BP monitoring

Strong CYP3A4 inhibitors (ketoconazole, itraconazole, ritonavir) May increase terazosin exposure Monitor for enhanced hypotensive effects

Interacting Drug Effect Recommendation

Beta-blockers Additive hypotensive effect Can be used together; monitor BP especially during initiation

Diuretics Enhanced hypotensive effect; increased orthostatic risk May need to reduce or temporarily hold diuretic during terazosin initiation

Calcium channel blockers Additive vasodilation Monitor BP closely

NSAIDs May blunt antihypertensive response Monitor BP; consider paracetamol as alternative analgesic

Alcohol Potentiates orthostatic hypotension Counsel to avoid alcohol, especially during initiation phase

Tricyclic antidepressants Additive hypotensive effect Monitor BP; counsel patient on orthostatic precautions

Rifampicin May reduce terazosin levels (enzyme induction) Monitor BP; dose adjustment may be needed

• Dizziness and light-headedness (most common)

• Headache

• Asthenia and fatigue

• Postural hypotension

• Nasal congestion/rhinitis

• Peripheral oedema

• Somnolence

• Palpitations

• Nausea

Adverse Effect Clinical Action

First-dose syncope Have patient lie down immediately; assess volume status; if occurs, restart at lower dose with strict bedtime dosing once stable

Severe hypotension IV fluids; rarely vasopressors; hospitalise if unresponsive to supportive measures

Intraoperative Floppy Iris Syndrome (IFIS) Not reversible on discontinuation; must document alpha-blocker history and inform ophthalmologist before any cataract surgery

Priapism (rare) Urological emergency; immediate discontinuation; may require urological intervention

Angioedema (rare) Discontinue immediately; manage airway; supportive care

Phase Parameters

Baseline Blood pressure (sitting and standing), heart rate, renal function, hepatic function, IPSS score (if used for BPH), ECG if significant cardiac history

After initiation/dose change BP within 2–6 hours of first dose or any dose increment; repeat for first 3–5 days of new dose level; assess for orthostatic symptoms

Long-term BP at each visit, orthostatic tolerance, symptom scores (IPSS for BPH), signs of fluid retention, renal function if on concurrent diuretics

• Hytrin (Abbott)

• Olyster (Sun Pharma)

• Terazosin (generic — multiple manufacturers)

Note: Limited brand availability compared to other alpha-blockers. No significant FDCs relevant to clinical use.

Strength Approximate Price (per 10 tablets)

• NLEM status: Not listed under NLEM 2022

• NPPA control: Not under price control

• Government supply: Limited availability; generics available at lower prices

• Private retail: Widely available

1. Always start at bedtime: First-dose hypotension is a class effect — never skip the 1 mg starting dose regardless of final target.

1. Re-titrate after interruption: If terazosin is stopped for more than a few days, restart from 1 mg to avoid hypotensive episodes.

1. ALLHAT lesson: Avoid terazosin as first-line monotherapy for hypertension — reserve as add-on or for hypertensive males with concurrent BPH.

1. IFIS warning: Even if discontinued months before surgery, terazosin can cause intraoperative floppy iris syndrome — always document alpha-blocker history before ophthalmic referral.

1. Dual benefit in men: Terazosin addresses both BPH symptoms and BP control with single daily dosing — useful in older hypertensive males with LUTS.

1. Stone expulsion: Increasingly used off-label for medical expulsive therapy in distal ureteric stones — evidence comparable to tamsulosin.

terazosin; alpha-blocker; BPH; LUTS; hypertension; ureteric-stone; first-dose-syncope; elderly-caution; IFIS; renal-safe; Schedule-H

RxIndia v0.4 — 09 Jan 2025

• CDSCO-approved product inserts

• Indian Pharmacopoeia

• NFI 2021

• API Textbook of Medicine, 12th edition

• AIIMS Drug Formulary

• Indian Urology Association Guidelines (for BPH and stone management)

• ICMR Guidelines on Non-Communicable Diseases

• Goodman & Gilman's The Pharmacological Basis of Therapeutics

• Meta-analyses on medical expulsive therapy (for off-label stone indication)