Mao Inhibitors
Contraindicated
Database
Excess catecholamine/serotonergic effect
Avoid; separate by ≥2 weeks
Source: Kimi deep-research + Cla
Drug reference
Methyldopa
Centrally-acting alpha-2 adrenergic agonist (antihypertensive) · Antihypertensive
START
250 mg PO 2–3 times daily
TYPICAL MAX
3 g/day
STOP IF
Hepatitis, haemolytic anaemia, or marked depression
WATCH
LFTs and CBC/Coombs at baseline and periodically; BP, mood
CDSCO approvedSchedule HATC C02AB01
KDIGO 2024 + manufacturer label
- ONSET
- 4h · BP effect
- PEAK
- 5h · peak effect
- t½
- 1.7h · t½
- DURATION
- 1d · chronic
EXCRETION
Renal ~70% as drug/metabolites
route + CYP
INTERACTIONS
12 major
incl. contraindicated
PREGNANCY
Preferred antihypertensive in pregnancy — long safety record.
FDA category + note
Top interactionssee all 12 →
- Mao InhibitorsContraindicatedDatabaseKimi deep-research + Cla
- IsocarboxazidSevereDatabaseDDInter
- LeflunomideSevereDatabaseDDInter
- LinezolidSevereDatabaseDDInter
Available in India
6 branded formulations. Look up specific brands in the Drugs workspace.
Mechanism
Converted centrally to alpha-methylnorepinephrine, a potent CNS alpha-2 agonist that reduces sympathetic outflow and peripheral resistance, lowering blood pressure without major reduction in uteroplacental flow.
Indications
Hypertension (notably in pregnancy)Hypertensive disorders of pregnancy (chronic/gestational)
Dosing
- Adult
- 250 mg PO 2–3 times daily; titrate every ≥2 days; usual 500 mg–2 g/day in 2–4 divided doses.
- Pediatric
- 10 mg/kg/day in 2–4 divided doses; titrate to max 65 mg/kg/day.
- Renal adjustment
- Renally excreted — extend dosing interval / reduce dose in impairment.
- Hepatic adjustment
- Contraindicated in active hepatic disease; monitor LFTs.
- Geriatric
- Start low; sedation and orthostatic hypotension risk.
- Max dose
- 3 g/day
Pharmacokinetics
Onset
3–6 h (oral); peak BP effect 4–6 h
Peak effect
4–6 h
Duration
12–24 h (single dose); 24–48 h on chronic dosing
Half-life
~1.7 h (longer in renal impairment)
Bioavailability
~25–50% (variable)
Protein binding
Low (<20%)
Metabolism
Conjugation; CNS decarboxylation to active metabolite
Excretion
Renal (~70% as drug/metabolites)
Contraindications
- Active hepatic disease / prior methyldopa-associated hepatitis
- Concurrent MAO inhibitors
- Phaeochromocytoma
- Hypersensitivity; previous methyldopa haemolytic anaemia
Side effects
Common
Sedation/drowsinessDry mouthHeadacheDizzinessFluid retention
Serious
- Drug-induced hepatitis/hepatic necrosis
- Coombs-positive haemolytic anaemia
- Depression
- Bradycardia/myocarditis (rare)
Pregnancy & lactation
Pregnancy
Preferred antihypertensive in pregnancy — long safety record.
Lactation
Compatible with breastfeeding (low milk levels).
Drug interactions
Isocarboxazid
Severe
Database
Clinical effect not specified
Source: DDInter
Leflunomide
Severe
Database
Clinical effect not specified
Source: DDInter
Linezolid
Severe
Database
Clinical effect not specified
Source: DDInter
Lomitapide
Severe
Database
Clinical effect not specified
Source: DDInter
Methylene Blue
Severe
Database
Clinical effect not specified
Source: DDInter
Mipomersen
Severe
Database
Clinical effect not specified
Source: DDInter
Ozanimod
Severe
Database
Clinical effect not specified
Source: DDInter
Pexidartinib
Severe
Database
Clinical effect not specified
Source: DDInter
Phenelzine
Severe
Database
Clinical effect not specified
Source: DDInter
Procarbazine
Severe
Database
Clinical effect not specified
Source: DDInter
Rasagiline
Severe
Database
Clinical effect not specified
Source: DDInter
Related guidelines
Hypertensive disorders of pregnancy
FOGSI · Obstetrics & Gynaecology · 2019
Hypertensive disorders of pregnancy
ACOG · Obstetrics & Gynaecology · 2020
Hypertension in adults
ICMR · Cardiology · 2019
Gestational diabetes mellitus
FOGSI · Obstetrics & Gynaecology · 2023
Hypertension in adults
WHO · Cardiology · 2021
Ask House about Methyldopa
Continue into a citation-backed clinical answer with the drug context already attached.
Sources: KD Tripathi 7e, Goodman & Gilman 14e, Harrison 22e, BNF·Verified: 2026-05-20 · House clinical team·Cockpit curated: 2026-05-20