Heparin, an anticoagulant, is considered a high-alert medication. It reduces blood’s capacity to clot and prevents dangerous clots from forming in arteries. Although commonly mistaken as a blood thinner, it doesn’t actually thin the blood. Blood clots that have already formed cannot be dissolved by heparin, but they may be prevented from growing and posing more significant health risks.
Certain blood vessel, heart, and lung diseases can be prevented or treated with heparin. Patients who have undergone certain procedures or are bedridden may receive heparin in low dosages to prevent the formation of blood clots.
Generic names: Heparin Sodium
Brand names: Calciparine, Canusal, Hepalean, Heparin Leo, Hep-Lock, Hepsal, Monoparin, Multiparin
Pharmacologic class: Antithrombotic
Therapeutic class: Anticoagulant
Mechanism of action: Heparin prevents the formation of new thrombi and the enlargement of existing clots. It does not dissolve formed clots. Heparin blocks the conversion of clotting factors prothrombin to thrombin and fibrinogen to fibrin.
Indications for use: Prevention and treatment of venous thromboembolism (VTE) and complications associated with atrial fibrillation; anticoagulant for extracorporeal and dialysis procedures; maintain patency of IV devices as an IV flush; prevention of blood clotting during cardiovascular surgery. Off-label uses include unstable angina, prophylaxis of left ventricular thrombi, and stroke after myocardial infarction. Disseminated intravascular coagulation is a dangerous clotting disorder that can be treated with heparin.
Precautions and contraindications:
- Do not use if sensitive to heparin, with bleeding disorders, severe thrombocytopenia, and uncontrolled active bleeding
- Not for use in patients who can’t regularly test for blood coagulation
- Take caution in patients with severe liver or renal disease, bacterial endocarditis, hypertension, brain injury, retinopathy, and ulcer disease
- Carefully use in patients with recent CNS or ophthalmic surgery
- Use cautiously in pregnant and postpartum patients and women older than age 60
Drug Interactions
- Heparin with other anticoagulants (dabigatran, warfarin) and platelet aggregation inhibitors (aspirin, clopidogrel), and thrombolytics (such as tissue plasminogen activator [TPA]) can increase the risk of bleeding
- Antihistamines, digoxin, nicotine, and tetracyclines can decrease the anticoagulant effect of heparin
- Hypoprothrombinemia-inducing cephalosporins (antibiotics causing risk for prolonged bleeding), quinidine, and valproic acid can lead to a risk of blood loss
- Higher risk of bleeding when taking drugs that affect platelet function (such as aspirin, clopidogrel, dextran, nonsteroidal anti-inflammatory drugs (NSAIDs), some penicillins, and thrombolytics)
- Heparin may increase liver enzyme levels
- Cholesterol and triglycerides can have decreased levels
- False-negative may be expected when testing for fibrinogen uptake
- Heparin can cause prolonged prothrombin time
- Bleeding risk may worsen when used with drug-herbs such as chamomile, garlic, ginger, and ginseng
- Increased bleeding risk with smoking
Adverse Effects
- Rhinitis
- Anemia, thrombocytopenia, bleeding, severely prolonged clotting time
- Hepatitis
- Hyperkalemia
- Osteoporosis with long-term use
- Skin irritation, rash, urticaria, hematoma (abnormal blood pooling outside the blood vessel), ulceration, cutaneous or subcutaneous necrosis (tissue death), pruritus, and alopecia
- Fever, pain at the injection site, hypersensitivity reactions, white clot syndrome (heparin-associated thrombocytopenia and thrombosis), anaphylactoid (nonimmunologic anaphylaxis) reactions
Administration Considerations
Available preparations: Solution for flushes, solution for injection
Dosages for adults: Dosage is dependent on use.
- For DVT: 80 units/kg IV bolus (Maximum: 5,000 units), then 18 units/kg/hr adjusted according to aPTT
- For acute coronary syndrome: 60 units/kg IV bolus (maximum 4,000 units), then 12 units/kg/hr (maximum 1,000 units/hr)
- For thromboembolic prophylaxis: 5,000 units subcutaneously every 8–12 hours
- For prevention of blood clotting during cardiovascular surgery: at least 150 units/kg IV depending on the length of surgery
- For line flushing: 10 to 100 units/mL IV as needed
Dosages for children: Dose is dependent on weight.
- For therapeutic anticoagulation: Initially, 50 units/kg by IV drip, then 100 units/kg by IV drip every 4 hours or 20,000 units/m²/24 hours by continuous IV infusion
- For line flushing: 10 to 100 units/mL as needed
Dosages for infants weighing less than 10 kg: Dose is dependent on weight. 10 units as needed.
| Route | Onset | Peak | Duration |
| IV | Immediate | 5-10 minutes | 2-6 hours |
| Subcutaneous | 20-60 minutes | 2-4 hours | 8-12 hours |
Nursing Considerations for Heparin
Related Nursing Diagnoses
Nursing Assessment
- Assess for allergies to anticoagulants.
- Obtain CBC, PT/INR, and aPTT.
- Assess for bleeding risk.
- Obtain a history of recent trauma, head injuries, or surgeries.
- Verify medical history for any spinal anesthesia use or spinal procedures.
- Check peripheral pulses and skin discoloration.
- Assess for excessive bleeding from minor cuts, scratches, and gingival bleeding.
- Observe urine output for hematuria.
Nursing Interventions
- Since heparin is considered a high-alert drug, counter-check with a co-worker before administering.
- Administer subcutaneous injection above the iliac crest or in the abdominal fat layer. Do not inject within 2 inches of the umbilicus or any scar tissue. Withdraw the needle immediately, and apply prolonged pressure at the injection site. Avoid applying heat/cold or massaging the injection site.
- Rotate sites in subcutaneous injection.
- Avoid the IM route for injections due to the risk of hematoma.
- For IV, administer each injection with 1,000 units or a single dose for at least a minute. Depending on the dosage and volume of the infusion solution, administer a continuous infusion for 4 to 24 hours.
- Closely monitor the IV infusion rate, even if infusion pumps are in use.
- Avoid heparin products with benzyl alcohol with premature infants due to the risk of fatal toxic reactions.
- Monitor CBC (particularly hematocrit and platelet count), PTT, PT, and INR.
- Obtain the aPTT 6 hours after the start of treatment or any dosage adjustment (or as per facility policy) until the maintenance dose is determined then, every 24 hours (or as per facility policy) thereafter.
- Monitor aPTT 1-2 times per month for patients on long-term therapy.
- Monitor stool and urine for occult blood.
- Monitor decreased blood pressure, increased pulse rate, complaints of back or abdominal pain, and a severe headache as these are signs of severe bleeding.
- Monitor PT/INR results when bridging to warfarin (coumadin). Concurrent use of warfarin can cause an increase of 10%-20% in PT/INR results.
- Implement bleeding precautions with initial therapy as bleeding may occur.
- Invasive procedures such as lab draws may require prolonged pressure to prevent bleeding.
- Prepare protamine sulfate as an antidote for heparin toxicity.
Patient Teaching Associated with Heparin
- Alert the healthcare provider immediately for allergic reaction symptoms (such as swelling in the face or tongue or difficulty breathing).
- Teach correct injection techniques and stress the necessity of rotating injection sites if the patient will be administering the medication themselves.
- Inform the patient that any symptoms of toxicity, including nosebleeds, blood in the urine, or black stools, should be reported immediately.
- Instruct the patient to report any unusual bleeding or bruising right away.
- Encourage the patient to refrain from contact sports or activities.
- Advise the use of an electric razor to minimize bleeding.
- Teach the patient to use a soft toothbrush to protect the gums from bleeding.
- Explain to the patient that they will have regular blood tests while receiving treatment.
- Emphasize not to take any OTC medication which may alter heparin’s effect without a healthcare provider’s consent.
- Wear or carry identification that informs of anticoagulant therapy.
- If there is a need for a dental procedure, inform the dentist of heparin therapy.
- Encourage limited alcohol intake which can increase the risk of bleeding.
This is not an all-inclusive list of possible drug interactions, adverse effects, precautions, nursing considerations, or patient instructions. Please consult further with a pharmacist for complete information.
References and Sources
- Kizior, R. J., & Hodgson, K. J. (2019). Saunders Nursing Drug Handbook 2019. Elsevier Health Sciences.
- Schull, P. (2013). McGraw-hill nurses drug handbook (7th ed.). McGraw Hill Professional.
