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Authoritative Clinical Reference
Schedule H
Oral
INDICATIONS + DOSING — FOR CLINICIAN USE ONLY
Primary Indications (Approved / Standard in India)
Essential Hypertension
⚠️ OBSOLETE IN CURRENT INDIAN PRACTICE
Drug withdrawn from Indian market due to poor tolerability and availability of safer, more effective alternatives. Information retained for academic and historical reference only.
Historical Dosing (Academic Reference Only):
Parameter Recommendation
Starting dose 10 mg orally once daily (after meals)
Titration Increase by 10–25 mg every 5–7 days based on standing blood pressure
Usual maintenance dose 25–50 mg once daily
Maximum dose 100 mg/day
Clinical notes Full antihypertensive effect may take 1–2 weeks; concurrent diuretic often required to prevent fluid retention; administer in morning to minimize nocturnal hypotension
Secondary Indications — Adults (Off-label)
Not applicable — No documented off-label use in current Indian practice.
PAEDIATRIC DOSING (Specialist Only)
Primary Indications (Approved / Standard in India)
Not applicable — No approved paediatric indications.
Secondary Indications — Paediatrics (Off-label)
Not applicable — No documented paediatric use.
Not recommended in any age group — drug not available in India and lacks paediatric safety/efficacy data.
| eGFR (ml/min/1.73m²) | Recommendation |
|---|---|
| eGFR (ml/min/1.73m²) | Recommendation |
| eGFR (ml/min/1.73m²) | Recommendation |
| eGFR (ml/min/1.73m²) | Recommendation |
Dialysis Contraindicated
| Hepatic Impairment | Recommendation |
|---|---|
| Mild impairment | Use with caution; may increase orthostatic hypotension risk |
| Moderate impairment | Avoid if possible; no formal dosing data available |
| Severe impairment | Contraindicated — unpredictable metabolism and high adverse event risk |
Parameter Recommendation
Risk category Not formally classified; limited human data
Safety statement Not recommended — potential for fetal hypotension and growth restriction
Preferred alternatives Labetalol, methyldopa, nifedipine (as per Indian obstetric practice)
When may be used Not recommended under any circumstance; safer alternatives available
Monitoring If inadvertent exposure: fetal growth monitoring, Doppler studies
Parameter Recommendation
Breastfeeding compatibility Not recommended
Expected drug levels in milk Low (limited data)
Preferred alternatives Labetalol, nifedipine, methyldopa
Infant monitoring If exposure occurs: monitor for lethargy, poor feeding, hypotension
Parameter Recommendation
Starting dose 5–10 mg once daily (if ever used)
Titration Very slow — every 7–14 days
Extra risks High risk of orthostatic hypotension, syncope, falls with fractures, cognitive impairment from cerebral hypoperfusion
Recommendation Avoid use in elderly — not appropriate for geriatric hypertension management
Interacting Drug/Class Effect Recommendation
MAO inhibitors Prevents noradrenaline metabolism leading to hypertensive crisis Contraindicated; allow 14-day washout
Tricyclic antidepressants (amitriptyline, imipramine) Block neuronal uptake of guanethidine → complete loss of efficacy Avoid combination; guanethidine becomes ineffective
Sympathomimetics (ephedrine, phenylephrine, pseudoephedrine) Antagonise hypotensive effect; may cause paradoxical hypertension Avoid concurrent use
Reserpine Additive catecholamine depletion → severe hypotension and bradycardia Avoid combination
Interacting Drug/Class Effect Recommendation
Diuretics Enhanced hypotensive effect Monitor orthostatic BP; reduce guanethidine dose if needed
Beta-blockers Additive bradycardia and hypotension Use with caution; close monitoring required
Alcohol Potentiates orthostatic hypotension Advise avoidance or minimal intake
Antipsychotics (phenothiazines) Additive hypotensive effects; partial antagonism of guanethidine Monitor BP closely
Levodopa Additive hypotension Monitor for symptomatic hypotension
Adverse Effect Action Required
Syncope or severe orthostatic hypotension Discontinue; supportive care; consider IV fluids
Falls with injury (fractures, head trauma) Discontinue; orthopaedic/neurological evaluation as needed
Rebound hypertension on abrupt withdrawal Gradual tapering if discontinuing after chronic use
Angina or myocardial ischaemia (from hypotension) Discontinue; cardiology evaluation
Severe bradycardia Discontinue; supportive management
Baseline:
After initiation/dose change:
Long-term:
NOT AVAILABLE in India — All formulations withdrawn from market.
Formerly available as:
Not applicable — No commercially available products in India.
guanethidine; antihypertensive; adrenergic neuron blocker; sympatholytic; obsolete therapy; not available India; orthostatic hypotension; historical reference; withdrawn drug
RxIndia v1.0 — 24 Apr 2025
This platform is designed strictly for healthcare professionals. Data provided is synthesized from authoritative pharmacological sources and clinical registries. Do not use for consumer medical decisions. Always verify critical dosing and contraindications with official institutional protocols and peer-reviewed journals.
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