Drug reference

Clonidine

Central alpha-2 adrenergic agonist · Antihypertensive

Also known as Clonidine hydrochloride

START

Hypertension 0.1 mg PO BID, titrate; never stop abruptly (taper)

TYPICAL MAX

~2.4 mg/day (HTN); ADHD ER 0.4 mg/day

STOP IF

Severe bradycardia/AV block, profound sedation; if stopping, TAPER over days to weeks

WATCH

BP/HR, sedation, strict counselling against abrupt discontinuation (rebound HTN), renal function

CDSCO approvedSchedule HATC C02AC01

Dose laddermg/d

Renal dose adjustmenteGFR mL/min/1.73m²

KDIGO 2024 + manufacturer label

Pharmacokineticsplasma · t hours

ONSET: 45min · BP onset
PEAK: 3h · Cmax
t½: 14h · plasma t½
DURATION: 12h · effect (IR)

EXCRETION

~50% renal unchanged; rest hepatic metabolites

route + CYP

INTERACTIONS

12 major

incl. contraindicated

PREGNANCY

Use only if clearly needed — limited data; neonatal effects/withdrawal possible

FDA category + note

Top interactionssee all 12 →

Alpha Adrenergic BlockerContraindicatedTextbookKDT 7e · p571
Beta Adrenergic BlockerContraindicatedTextbookKDT 7e · p571
AcebutololSevereDatabaseDDInter
AmitriptylineSevereDatabaseDDInter

Available in India

20 branded formulations. Look up specific brands in the Drugs workspace.

Mechanism

Stimulates central alpha-2 (and imidazoline) receptors reducing sympathetic outflow → lowered BP/heart rate; also dampens noradrenergic withdrawal, has analgesic/sedative effects and reduces ADHD hyperarousal.

Indications

Hypertension (incl. hypertensive urgency adjunct)ADHD (extended-release)Opioid/alcohol/nicotine withdrawal symptom controlTourette syndrome; menopausal flushing; adjunct in chronic/neuropathic pain (epidural)

Dosing

Adult: Hypertension: 0.1 mg PO BID, titrate (usual 0.2–0.6 mg/day; max ~2.4 mg/day). Patch weekly. ADHD ER 0.1 mg nocte titrated. Withdrawal: 0.1–0.3 mg q6–8 h tapered.
Pediatric: ADHD ER per weight/age (specialist).
Renal adjustment: Reduce dose / titrate cautiously (renally eliminated; accumulation).
Hepatic adjustment: No specific adjustment.
Geriatric: Lower dose; sedation/hypotension/falls.
Max dose: ~2.4 mg/day (hypertension); ADHD ER 0.4 mg/day

Pharmacokinetics

Onset

Oral 0.5–1 h

Peak effect

2–4 h

Duration

~6–24 h (formulation-dependent; patch 7 days)

Half-life

~12–16 h (longer in renal impairment)

Bioavailability

~75–95%

Protein binding

~20–40%

Metabolism

Hepatic (~50%); ~50% excreted unchanged renally

Excretion

Renal (~40–60% unchanged)

Contraindications

Severe bradyarrhythmia (sick sinus, 2nd/3rd degree AV block)
Hypersensitivity to clonidine
Caution: cerebrovascular/coronary disease, abrupt withdrawal (rebound hypertension)

Side effects

Common

Dry mouthSedation/drowsinessDizziness/orthostatic hypotensionBradycardiaConstipation

Serious

Rebound hypertensive crisis on abrupt withdrawal
Severe bradycardia/AV block
Profound CNS depression (overdose, esp. children)
Sinus bradycardia/sinus arrest

Pregnancy & lactation

Pregnancy

Use only if clearly needed — limited data; neonatal effects/withdrawal possible

Lactation

Excreted in milk; monitor infant (sedation, BP) — caution

Drug interactions

Alpha Adrenergic Blocker

Contraindicated

Textbook

Reduced efficacy of clonidine.

Avoid combination.

Source: KDT 7e · p571

Beta Adrenergic Blocker

Contraindicated

Textbook

Reduced efficacy of clonidine.

Avoid combination.

Source: KDT 7e · p571

Acebutolol

Severe

Database

Drug interaction classified as: synergy

Source: DDInter

Amitriptyline

Severe

Database

Tricyclic antidepressants may inhibit the antihypertensive effect of clonidine.

Monitor blood pressure and adjust clonidine dose if needed.

Source: DDInter

Amoxapine

Severe

Database

Tricyclic antidepressants may inhibit the antihypertensive effect of clonidine.

Monitor blood pressure and adjust clonidine dose if needed.

Source: DDInter

Atenolol

Severe

Database

Drug interaction classified as: synergy.

Source: DDInter

Betaxolol

Severe

Database

Drug interaction classified as: synergy

Source: DDInter

Bisoprolol

Severe

Database

Beta-blocker masks clonidine withdrawal rebound hypertension; abrupt discontinuation of either can cause hypertensive crisis.

Withdraw bisoprolol first over 1-2 weeks, then taper clonidine.

Source: Kimi deep-research + Cla

Carteolol

Severe

Database

Drug interaction classified as: synergy

Source: DDInter

Carvedilol

Severe

Database

Increased risk of severe bradycardia and hypotension. Risk of rebound hypertension if clonidine is abruptly withdrawn.

Avoid abrupt withdrawal of clonidine. If clonidine needs to be discontinued, gradually reduce its dose over several days while monitoring blood pressure. Monitor heart rate and blood pressure closely during co-administration.

Source: DDInter

Clomipramine

Severe

Database

Tricyclic antidepressants may inhibit the antihypertensive effect of clonidine.

Monitor blood pressure and adjust clonidine dose if needed.

Source: DDInter

Beta Blockers

Severe

Database

Severe rebound hypertension if clonidine stopped while on beta-blocker; additive bradycardia

Withdraw beta-blocker first; taper clonidine slowly; never abrupt stop