Heparin Sodium

Monitoring Coagulation - Ensure regular monitoring of activated partial thromboplastin time (APTT) or activated clotting time (ACT) to assess anticoagulation status. Maintain APTT at 1.5 to 2 times the control value for therapeutic anticoagulation.  ACT goals depend on the procedure.

Drug interactions - Digoxin, tetracyclines, and nitroglycerin may reduce heparin's anticoagulant effect.

Hyperkalemia - heparin inhibits aldosterone synthesis; monitor potassium in renally impaired, diabetic, or acidotic patients and those on potassium-sparing drugs.

Altered protein binding - Heparin can alter protein binding, creating a greater free-fraction of highly protein-bound drugs (ie. ceftriaxone, fentanyl, midazolam).

Bleeding Risks - Be cautious of increased bleeding risks, particularly in procedures with significant blood loss. Anticoagulants, thrombolytics, and platelet inhibitors such as aspirin, NSAIDs, glycoprotein IIb/IIIa inhibitors, and dextran all increase bleeding risk when combined with heparin. Have emergency measures and reversal agents (e.g., protamine sulfate) ready for heparin reversal if excessive bleeding occurs.

Reversal Agent Protocol - Protamine sulfate is the antidote for heparin; administer 1 mg of protamine per 90–115 units of heparin to neutralize its effect. Prepare for potential side effects of protamine, including hypotension and anaphylactoid reactions.

Older adults (≥60 years) - equivalent doses may yield higher plasma concentrations due to age-related clearance changes; slower elimination prolongs aPTT — use lower doses and monitor closely.

Platelet Count - Confirm platelet counts preoperatively to assess for thrombocytopenia and as a baseline to detect heparin-induced thrombocytopenia (HIT).

Neonates and Infants - Use preservative-free formulations of this drug in neonates and infants. The benzyl alcohol preservative is associated with gasping syndrome, seizures, and cardiovascular collapse in preterm/low-birth-weight infants.

Pre-procedure discontinuation - IV heparin should be stopped at least 6 hours before neuraxial or interventional pain procedures; may resume minimum 2 hours post-procedure, or 24 hours if significant bleeding occurred.

OB - heparin does not cross the placenta and is not teratogenic; both UFH and LMWH are safe for fetal exposure throughout pregnancy. Parturients should transition to IV UFH near term; discontinue 4–6 hours before anticipated labor or neuraxial anesthesia to minimize bleeding risk. cesarean section with anticoagulation reversal is preferred

Concentration verification is critical - heparin is available in multiple concentrations (1,000–20,000 units/mL for injectables; 1–100 units/mL for lock flushes); NEVER use high-concentration vials for catheter flushes — fatal pediatric errors have occurred.

SQ administration - typically for thromboembolism prophylaxis. Common dose is 5000 units every 8-12 hours

Absolute - Severe thrombocytopenia or uncontrollable active bleeding (except DIC).  History of heparin-induced thrombocytopenia (HIT). Platelet count ≤100,000/mm³, Inability to perform required monitoring.

Relative - Recent CNS, eye, or spinal surgery, severe hypertension, subacute bacterial endocarditis, hemophilia or vascular purpura, GI ulcerative lesions, hereditary antithrombin III deficiency (dose adjustment required)

Caution - Age ≥60 (especially women — increased bleeding risk, lower doses recommended), hepatic or renal impairment, pregnancy, concurrent antiplatelet or anticoagulant therapy, diabetic patients on potassium-affecting medications.

*Use Actual Body Weight (ABW)

Percutaneous Stent Interventions

Initial Bolus Dose: 5,000–10,000 units or 60–100 U/kg.

Target ACT Goal: 300–350 seconds.

Rationale: Optimizes anticoagulation and minimizes thrombus formation during stent placement.

Open Vascular Surgeries (e.g., Carotid Endarterectomies):

Initial Bolus Dose: 100 U/kg.

Target ACT Goal: >200 seconds.

Rationale: Higher doses reduce the risk of cerebral ischemic events during procedures involving cross-clamping.

Peripheral Vascular Interventions:

Initial Bolus Dose: <60 U/kg.

Target ACT Goal: <250 seconds.

Rationale: Aimed at reducing bleeding complications and transfusion rates during interventions.

18 units/kg/hr continuous infusion; titrate per aPTT nomogram (target aPTT 1.5–2× control)

Not recommended — associated with hematoma formation, pain, and erratic absorption

Binds AT III, inducing conformational change that markedly enhances inactivation of thrombin (IIa) and factor Xa; also inhibits IXa, XIa, XIIa. By inactivating thrombin, heparin blocks conversion of fibrinogen to fibrin.

Prolongs clotting time (aPTT, ACT, PT); does not affect bleeding time; does not lyse existing clots; also binds plasma proteins, endothelial cells, and macrophages.

Hepatic (primary)

Protamine sulfate (1 mg neutralizes 100 units of heparin) is the reversal. dose calculated based on time elapsed since last heparin dose. Maximum 50 mg per administration.administered via slow IV infusion. Caution: may cause severe hypotension or anaphylactoid reactions. Neutralization is typically within ~5 minutes of IV administration. Effect is relatively short; re-heparinization (rebound) can occur after protamine wears off, particularly after large heparin doses or following CPB.