Drug reference

Amiodarone

Class III antiarrhythmic (multichannel) · Arrhythmia management

Also known as Amiodarone hydrochloride

START

Oral load 200 mg TID 1 wk → BID 1 wk → 200 mg/day; IV 150 mg/10 min then infusion; arrest 300 mg IV

TYPICAL MAX

~400 mg/day chronic maintenance; IV ≤2.2 g/24 h

STOP IF

Pulmonary toxicity, significant hepatotoxicity, severe brady/heart block, optic neuropathy

WATCH

Baseline + 6-monthly TFTs/LFTs, annual CXR/PFTs + eye exam, ECG/QT, drug interactions (CYP/P-gp)

CDSCO approvedSchedule HATC C01BD01

Dose laddermg/d

Renal dose adjustmenteGFR mL/min/1.73m²

KDIGO 2024 + manufacturer label

Pharmacokineticsplasma · t hours

ONSET: 4h · oral absorption (effect over weeks)
PEAK: 5h · Cmax
t½: 8.3w · terminal t½ (~58 days)
DURATION: 1d · once-daily maintenance

EXCRETION

Hepatic CYP3A4; biliary/faecal, negligible renal

route + CYP

INTERACTIONS

12 major

incl. contraindicated

PREGNANCY

Avoid — fetal hypothyroidism/goitre, neurodevelopmental risk; only for life-threatening maternal arrhythmia

FDA category + note

Top interactionssee all 12 →

AmisulprideContraindicatedDatabaseDDInter
DomperidoneContraindicatedDatabaseKimi deep-research + Cla
SparfloxacinContraindicatedDatabaseDDInter
NirmatrelvirContraindicatedDatabaseKimi deep-research + Cla

Available in India

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

Mechanism

Prolongs action-potential duration/refractoriness via K+ channel blockade, with additional Na+ and Ca2+ channel and non-competitive alpha/beta blockade; broad antiarrhythmic activity. Iodine-rich, highly lipophilic, very long-acting.

Indications

Life-threatening recurrent ventricular arrhythmias (VT/VF)Atrial fibrillation/flutter (rhythm control, incl. structural heart disease)Pulseless VT/VF in cardiac arrest (ACLS)

Dosing

Adult: Oral load 200 mg TID ×1 week → 200 mg BID ×1 week → 200 mg/day maintenance (range 100–400 mg/day). IV: 150 mg over 10 min then 1 mg/min ×6 h then 0.5 mg/min; cardiac arrest 300 mg IV bolus.
Pediatric: 5 mg/kg IV load (specialist).
Renal adjustment: No adjustment (hepatic/biliary clearance).
Hepatic adjustment: Monitor LFTs; reduce/withhold if significant hepatotoxicity.
Geriatric: Lower maintenance; heightened toxicity/thyroid risk.
Max dose: Maintenance usually ≤400 mg/day chronic; IV ≤2.2 g/24 h

Pharmacokinetics

Onset

IV minutes (some effects); oral days–weeks (loading needed)

Peak effect

Oral 3–7 h Cmax; full antiarrhythmic weeks

Duration

Weeks after discontinuation (huge tissue stores)

Half-life

~58 days (range 15–142 days)

Bioavailability

~35–65% (variable)

Protein binding

>96%

Metabolism

Hepatic CYP3A4/2C8 → active desethylamiodarone; strong CYP/P-gp inhibitor

Excretion

Biliary/faecal (negligible renal)

Contraindications

Severe sinus-node dysfunction / 2nd–3rd degree AV block without pacemaker
Marked sinus bradycardia/cardiogenic shock
Iodine hypersensitivity; thyroid dysfunction (relative)
Pregnancy (fetal thyroid/neuro harm)

Side effects

Common

Photosensitivity / slate-grey skin discolorationCorneal microdeposits (usually asymptomatic)GI upset, tremor, ataxiaThyroid dysfunction (hypo- or hyper-)Raised transaminases

Serious

Pulmonary toxicity/fibrosis (potentially fatal)
Hepatotoxicity (incl. fulminant)
Pro-arrhythmia/torsades; severe bradycardia/heart block
Amiodarone-induced thyrotoxicosis/hypothyroidism
Optic neuropathy/neuritis; peripheral neuropathy

Pregnancy & lactation

Pregnancy

Avoid — fetal hypothyroidism/goitre, neurodevelopmental risk; only for life-threatening maternal arrhythmia

Lactation

Contraindicated — significant excretion in milk, infant thyroid risk

Drug interactions

Amisulpride

Contraindicated

Database

Increased risk of Torsades de Pointes (TdP) and other ventricular arrhythmias

Concomitant use is contraindicated. Avoid combination.

Source: DDInter

Domperidone

Contraindicated

Database

Additive QT prolongation; high risk of torsades de pointes

Avoid combination; if unavoidable, monitor QTc closely

Source: Kimi deep-research + Cla

Sparfloxacin

Contraindicated

Database

Increased risk of Torsades de Pointes (TdP), ventricular arrhythmias, and sudden cardiac death.

Avoid concomitant use. If no alternative exists and co-administration is absolutely necessary, continuous ECG monitoring and electrolyte correction are mandatory, but generally not recommended.

Source: DDInter

Nirmatrelvir

Contraindicated

Database

Increased antiarrhythmic levels

Contraindicated; choose alternative COVID therapy

Source: Kimi deep-research + Cla

Abarelix

Severe

Database

Drug interaction classified as: synergy

Source: DDInter