Heparin

HEPARIN SODIUM

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Pronunciation: HEP-a-rin

Heparin ballicule: receptor binding, kinetics and half-life diagram — Mechanism of action: Heparin ballicule

Heparin mascot mnemonic cartoon — Visual mnemonic: Heparin mascot
**“Help Erin!”**
bananas in bunches → increases serum potassium

What it isAntithrombin activator inhibiting thrombin and factor Xa; anticoagulation.

Why this oneIts short half-life and complete protamine reversal make it the anticoagulant when bleeding risk is high or surgery is near.

What limits itRequires aPTT or anti-Xa monitoring. Heparin-induced thrombocytopenia demands platelet monitoring and immediate cessation.

Heparin molecular structure (skeletal formula) — Molecular structure: Heparin

Heparin prescription history

Animated chart of estimated U.S. prescriptions per year, Antithrombotics (1914–2026). Heparin enters in 1939 (estimated).

FDA-approved for

thrombosis prophylaxis and treatment

Principal riskHIT requires platelet monitoring; short half-life, protamine-reversible

Classes and tags

Clinical profile

Therapeutic safety burden3 / 4

Overdose danger3 / 4

Weight-gain liability0 / 4

Sedation liability0 / 4

QT / Torsades0 / 4

Direct muscarinic antagonism0 / 4

Embryofetal risk1 / 4

Legacy pregnancy categoryUnknown / historical label unavailable

Defining liabilityHemorrhage, including fatal bleeding, and heparin-induced thrombocytopenia with or without thrombosis (monitor platelets); fatal errors from confusing vial strengths; preservative-free product in neonates and infants.

FDA label

Read the full label on DailyMed ↗

NO BOXED WARNINGS

FDA dosing	Population	Start	Target
Therapeutic anticoagulation — deep SC	Adults	5,000 units IV, then 10,000-20,000 units SC	8,000-10,000 units q8h or 15,000-20,000 units q12h SC
Therapeutic anticoagulation — intermittent IV	Adults	10,000 units IV	5,000-10,000 units q4-6h IV
Therapeutic anticoagulation — IV infusion	Adults	5,000 units IV bolus	20,000-40,000 units/24 h continuous infusion
Low-dose prophylaxis of postoperative thromboembolism	Adults	5,000 units SC 2 h pre-op	5,000 units q8-12h SC x7 days or until ambulatory
Cardiovascular (open-heart) surgery	Adults	≥150 units/kg IV initial	300 units/kg (<60 min) or 400 units/kg (>60 min)
Extracorporeal dialysis	Adults	25-30 units/kg	1,500-2,000 units/hr infusion

Renal Undefined

Hepatic Undefined

Adjust dose to aPTT 1.5-2× normal (or clotting time 2.5-3× control); monitor platelet counts

Instructions

Confirm correct vial strength before use (fatal medication errors with mix-ups)
Give by IV injection, IV infusion, or deep SC (intrafat); do NOT give IM (hematoma risk)
Use preservative-free heparin in neonates/infants and, if available, in pregnancy/lactation
When converting to warfarin, continue full heparin until INR therapeutic, then stop without tapering

Available strengths

inj 50, 100, 1000, 4000, 5000, 10000, 20000 units/mL

Contraindications

History of heparin-induced thrombocytopenia (HIT) / HIT with thrombosis (HITT)
Known hypersensitivity to heparin or pork products (anaphylactoid reactions)
Uncontrolled active bleeding (except when due to DIC)
Severe thrombocytopenia
Inability to perform coagulation monitoring at appropriate intervals (full-dose heparin)

Cautions

Hemorrhage — can be fatal; use caution in conditions with increased bleeding risk
HIT and HITT — monitor platelets; discontinue if count <100,000 or new thrombosis
Fatal medication errors from vial strength confusion
Benzyl alcohol toxicity (gasping syndrome) in neonates/infants
Hyperkalemia (aldosterone suppression)
Heparin resistance in fever, thrombosis, infection, malignancy

Adverse reactions

Hemorrhage
Thrombocytopenia; HIT/HITT
Injection-site irritation, hematoma, skin necrosis
Hypersensitivity reactions (chills, fever, urticaria, anaphylactoid)
Elevated AST/ALT
Osteoporosis with long-term high-dose use

Pregnancy No evidence of increased fetal risk in humans; use preservative-free formulation when possible

Lactation Not likely excreted in milk (large molecule) and not orally absorbed; use preservative-free formulation

Cost

Heparin (HEPARIN SODIUM)

Strength		#/mo	CostPlus
50 units/mL	inj	per unit	not offered
100 units/mL	inj	per unit	not offered
1000 units/mL	inj	per unit	not offered
4000 units/mL	inj	per unit	not offered
5000 units/mL	inj	per unit	not offered
10000 units/mL	inj	per unit	not offered
20000 units/mL	inj	per unit	not offered

NADAC is a voluntary CMS survey of what retail community pharmacies pay for the drugs they stock. Heparin is administered under clinical supervision and dispensed outside retail pharmacies, so it rarely appears on surveyed invoices.

Generic entryBy 2023

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Memory aids: interaction avatars

no kinetic interactions

Open Heparin in the interactive console ↗

Self-check

Does protamine fully reverse heparin?
Yes.
What action is required when HIT is identified?
Stop heparin immediately.