heparin

heparin

(hep' ah rin)

heparin sodium injection

Hepalean (CAN), Heparin Leo (CAN)

heparin sodium and 0.9% sodium chloride

heparin sodium lock flush solution

Hepalean-Lok (CAN), Heparin Lock Flush, Hep-Lock, Hep-Lock U/P

Pregnancy Category C

Drug class

Anticoagulant

Therapeutic actions

Heparin inactivates factor XA, therefore inhibiting thrombus and clot formation by blocking the conversion of prothrombin to thrombin and fibrinogen to fibrin, the final steps in the clotting process. Heparin also inhibits the activation of factor XIII, thrombin-induced activation of factors V and VIII.

Indications

·        Prevention and treatment of venous thrombosis and pulmonary embolism

·        Treatment of atrial fibrillation with embolization

·        Diagnosis and treatment of DIC

·        Prevention of clotting in blood samples and heparin lock sets and during dialysis procedures

·        Unlabeled uses: Adjunct in therapy of coronary occlusion with acute MI, prevention of left ventricular thrombi and CVA post-MI, prevention of cerebral thrombosis in the evolving stroke

Contraindications and cautions

·        Contraindicated with hypersensitivity to heparin; severe thrombocytopenia; uncontrolled bleeding; any patient who cannot be monitored regularly with blood coagulation tests; labor and immediate postpartum period; women older than 60 yr are at high risk for hemorrhaging.

·        Use cautiously with pregnancy; women older than 60 yr are at high risk for hemorrhaging; dysbetalipoproteinemia; recent surgery or injury.

Available forms

Injection—1,000, 2,000, 2,500, 5,000, 7,500, 10,000, 12,500, 20,000, 40,000 units/mL; also single-dose and unit-dose forms. Lock flush solution—10, 100 units/mL.

Dosages

Adjust dosage according to coagulation tests. Dosage is adequate when WBCT = 2.5–3 times control—or aPTT = 1.5–3 times control value. The following are guidelines to dosage:

ADULTS

Subcutaneous (deep subcutaneous injection)

·        For general anticoagulation: IV loading dose of 5,000 units and then 10,000–20,000 units subcutaneously followed by 8,000–10,000 units q 8 hr or 15,000–20,000 units q 12 hr.

·        Prophylaxis of postoperative thromboembolism: 5,000 units by deep subcutaneous injection 2 hr before surgery and q 8–12 hr thereafter for 7 days or until patient is fully ambulatory.

IV

·        Intermittent IV: Initial dose of 10,000 units and then 5,000–10,000 units q 4–6 hr.

·        Continuous IV infusion: Loading dose of 5,000 units and then 20,000–40,000 units/day.

·        Surgery of heart and blood vessels for patients undergoing total body perfusion: Not less than 150 units/kg; guideline often used is 300 units/kg for procedures less than 60 min, 400 units/kg for longer procedures.

·        Clot prevention in blood samples: 70–150 units/10–20 mL of whole blood.

·        Heparin lock and extracorporeal dialysis: See manufacturer's instructions.

PEDIATRIC PATIENTS

Initial IV bolus of 50 units/kg and then 100 units/kg IV q 4 hr, or 20,000 units/m² per 24 hr by continuous IV infusion.

Pharmacokinetics

Route	Onset	Peak	Duration
IV	Immediate	Minutes	2–6 hr
SC	20–60 min	2–4 hr	8–12 hr

Metabolism: T_1/2: 30–180 min

Distribution: Does not cross placenta, does not enter breast milk; broken down in liver

Excretion: Urine

IV facts

Continuous infusion: Can be mixed in normal saline, D₅W, Ringer's; mix well; invert bottle numerous times to ensure adequate mixing. Monitor patient closely; infusion pump is recommended.

Single dose: Direct, undiluted IV injection of up to 5,000 units (adult) or 50 units/kg (pediatric), given over 60 seconds.

Monitoring: Blood should be drawn for coagulation testing 30 min before each intermittent IV dose or q 4–6 hr if patient is on continuous infusion pump.

Incompatibilities: Heparin should not be mixed in solution with any other drug unless specifically ordered; direct incompatibilities in solution and at Y-site seen withamikacin, codeine, chlorpromazine, cytarabine, diazepam, dobutamine, doxorubicin, droperidol, ergotamine, erythromycin, gentamicin, haloperidol, hydrocortisone,kanamycin, levorphanol, meperidine, methadone, methicillin, methotrimeprazine, morphine, netilimicin, pentazocine, phenytoin, polymyxin B, promethazine, streptomycin, tetracycline, tobramycin, triflupromazine, vancomycin.

Adverse effects

·        Dermatologic: Loss of hair

·        Hematologic: Hemorrhage; bruising; thrombocytopenia; elevated AST, ALT levels, hyperkalemia

·        Hypersensitivity: Chills, fever, urticaria, asthma

·        Other: Osteoporosis, suppression of renal function (long-term, high-dose therapy)

Interactions

Drug-drug

·        Increased bleeding tendencies with oral anticoagulants, salicylates, penicillins, cephalosporins; low-moleculer-weight heparins

·        Decreased anticoagulation effects if taken concurrently with nitroglycerin

Drug-lab test

·        Increased AST, ALT levels

·        Increased thyroid function tests

·        Altered blood gas analyses, especially levels of carbon dioxide, bicarbonate concentration, and base excess

Drug-alternative therapy

·        Increased risk of bleeding if combined with chamomile, garlic, ginger, ginkgo, and ginseng therapy; high-dose vitamin E

Nursing considerations

Assessment

·        History: Recent surgery or injury; sensitivity to heparin; hyperlipidemia; pregnancy

·        Physical: Peripheral perfusion, R, stool guaiac test, PTT or other tests of blood coagulation, platelet count, renal function tests

Interventions

·        Adjust dose according to coagulation test results performed just before injection (30 min before each intermittent dose or q 4–6 hr if continuous IV dose). Therapeutic range aPTT: 1.5–2.5 times control.

·        Always check compatabilities with other IV solutions.

·        Use heparin lock needle to avoid repeated injections.

·        Give deep subcutaneous injections; do not give heparin by IM injection.

·        Do not give IM injections to patients on heparin therapy (heparin predisposes to hematoma formation).

·        WARNING: Apply pressure to all injection sites after needle is withdrawn; inspect injection sites for signs of hematoma; do not massage injection sites.

·        Mix well when adding heparin to IV infusion.

·        Do not add heparin to infusion lines of other drugs, and do not piggyback other drugs into heparin line. If this must be done, ensure drug compatibility.

·        Provide for safety measures (electric razor, soft toothbrush) to prevent injury from bleeding.

·        Check for signs of bleeding; monitor blood tests.

·        Alert all health care providers of heparin use.

·        WARNING: Have protamine sulfate (heparin antidote) readily available in case of overdose; each mg neutralizes 100 units of heparin.

·        WARNING: Treatment of overdose: Protamine sulfate (1% solution). Each mg of protamine neutralizes 100 USP heparin units. Give very slowly IV over 10 min, not to exceed 50 mg. Establish dose based on blood coagulation studies.

Teaching points

·        This drug must be given by a parenteral route (cannot be taken orally).

·        Frequent blood tests are necessary to determine blood clotting time is within the correct range.

·        Be careful to avoid injury: Use an electric razor, avoid contact sports and other activities that might lead to injury.

·        You may experience loss of hair.

·        Report nose bleed, bleeding of the gums, unusual bruising, black or tarry stools, cloudy or dark urine, abdominal or lower back pain, severe headache.

Adverse effects in Italic are most common; those in Bold are life-threatening.