Low Molecular Weight Heparin (LMWH) is a class of anticoagulants with predictable pharmacokinetics and high bioavailability, used to prevent and treat venous thromboembolism, pulmonary embolism, and acute coronary syndromes with simplified subcutaneous administration and reduced monitoring requirements.
Mechanism of Action:
- LMWHs are anticoagulants acting by inhibition of the final common pathway of the coagulation cascade. The final common pathway is the conversion of fibrinogen into fibrin by the activity of thrombin. LMWH inhibits coagulation by activating antithrombin III. Antithrombin III binds to and inhibits factor Xa; Xa inactivation means that prothrombin is not activated to thrombin, thereby not converting fibrinogen into fibrin for the formation of a clot.
- Secondary effects mediated by impairing adhesion and aggregation of platelets.
Indications:
- Prevention of VTE.
- Treatment of VTE and acute coronary syndrome/ MI.
- Prevention of clotting in extracorporeal circuits.
- DVT prophylaxis in medium and high-risk groups (surgical, orthopaedic, and medical patients)
- Treatment of venous thromboembolism in pregnancy
Cautions & Contraindications:
- Heparin Sensitivity
- Hemophilia and other bleeding disorders.
- Severe hypertension.
- Severe hepatic or renal disease
- In patients undergoing surgery on brain, eye or spinal cord.
- Trauma
- Peptic ulcer disease
- Recent cerebral hemorrhage
- Severe hypertension
| Dalteparin |
| Availability: Injection, Solution: 2,500 units/0.2 mL, 5,000 units/0.2 mL, 7,500 units/0.3 mL, 10,000 units/mL, 12,500 units/0.5 mL, 15,000 units/0.6 mL, 18,000 units/0.72 mL |
| Administration/handling: SQ • Visually inspect for particulate matter or discoloration. • Subcutaneously insert needle into abdomen, outer thigh, or upper arm region and inject solution. • Do not inject into areas of active skin disease or injury such as sunburns, rashes, inflammation, or infection. Rotate injection sites. |
| Non-Orthopedic Surgery: SQ: Adults, elderly: 5,000 units 12 hrs before surgery (or evening before), then 5,000 units once daily. Continue until fully ambulatory and VTE risk has diminished. |
| Total Hip Surgery: SQ: Adults, elderly: 5,000 units once daily (initial dose 12 or more hrs pre-operative or 12 or more hrs postoperative once hemostasis achieved) for 10–14 days up to 35 days. |
| Unstable Angina, Non–Q-Wave MI: SQ: Adults, elderly: 120 units/kg q12h for up to 5–8 days (maximum: 10,000 units/dose) given with aspirin. Discontinue Dalteparin once clinically stable. |
| Venous Thromboembolism (Cancer Pts): SQ: Adults, elderly: Initially (1 mo), 200 units/kg (maximum: 18,000 units) daily for 30 days. Maintenance (2–6 mos): 150 units/kg once daily (maximum: 18,000 units). If platelet count 50,000–100,000 cells/mm3, reduce dose by 2,500 units until platelet count recovers to 100,000 cells/mm3 or more. If platelet count less than 50,000 cells/ mm3, discontinue until platelet count recovers to more than 50,000 cells/mm3. |
| Prevention of DVT, Acutely Ill Pt, Immobile Pt SQ: Adults, elderly: 5,000 units once daily. Continue for length of hospital stay or until pt is fully ambulatory and VTE risk has diminished. Treatment, Symptomatic VTE (Children) SQ: Children 8 yrs and older, adolescents: 100 units/kg/dose q12h. Children 2 yrs to younger than 8 yrs: 125 units/kg/dose q12h. Infants to children younger than 2 yrs: 150 units/kg/ dose q12h. |
| Enoxaparin |
| Availability: Injection Solution: 30 mg/0.3 mL, 40 mg/0.4 mL, 60 mg/0.6 mL, 80 mg/0.8 mL, 100 mg/mL, 120 mg/0.8 mL, 150 mg/mL in prefilled syringes. |
| Administration/handling: Do not mix with other injections, infusions. Do not give IM. |
| SQ Preparation: Visually inspect for particulate matter or discoloration. Solution should appear clear, colorless to pale yellow in color. Do not use if solution is cloudy, discolored, or if visible particles are observed. Administration • Flick syringe so that the air bubble rises toward the plunger. • Insert needle subcutaneously into abdomen or outer thigh and inject solution (including air bubble). • Do not inject into areas of active skin disease or injury such as sunburns, skin rashes, inflammation, skin infections, or active psoriasis. • Rotate injection sites. Storage: Store at room temperature |
| Prevention of Deep Vein Thrombosis (DVT) After Hip and Knee Surgery: SC: Adults, elderly: Knee surgery: 30 mg twice daily, generally for 10 days or up to 35 days, with initial dose given 12 hrs or more pre-operatively or 12 hrs or more postoperatively once hemostasis achieved. Hip surgery: (Once daily): An initial dose of 40 mg, given 12 hrs or more preoperatively or 12 hrs or more postoperatively once hemostasis achieved. Following hip surgery, recommend continuing 40 mg once daily for at least 10 days or up to 35 days post-op. (Twice daily): 30 mg q12h with initial dose, 12 hrs or more pre-operatively or 12 hrs or more postoperatively once hemostasis achieved and q12h for at least 10 days or up to 35 days. |
| Prevention of DVT After Non-Orthopedic Surgery SQ: Adults, elderly: 40 mg/day for 7–10 days, with initial dose given 2 hrs before abdominal surgery or approximately 12 hrs before other surgeries. Prevention of DVT After Bariatric Surgery: BMI 50 kg/m2 or less: 40 mg q12h. BMI greater than 50 kg/m2: 60 mg q12h. Prevention of Long-Term DVT in Nonsurgical Acute Illness: SC: Adults, elderly: 40 mg once daily; continue until risk of DVT has diminished (usually 6–11 days). Prevention of Ischemic Complications of Unstable Angina, Non–Q-Wave MI (with oral aspirin therapy): SC: Adults, elderly: 1 mg/kg q12h (with oral aspirin). STEMI: SC: Adults younger than 75 yrs: 30 mg IV once plus 1 mg/kg q12h (maximum: 100 mg first 2 doses only). Adults 75 yrs or older: 0.75 mg/kg (maximum: 75 mg first 2 doses only) q12h. Acute DVT SC: Adults, elderly: (inpatient): 1 mg/kg q12h or 1.5 mg/kg once daily. (outpatient): 1 mg/kg q12h. Usual Pediatric Dosage SC: Children 2 months and older: 0.5 mg/ kg q12h (prophylaxis); 1 mg/kg q12h (treatment). Neonates, infants younger than 2 months: 0.75/mg/kg/dose q12h (prophylaxis); 1.5 mg/kg/dose q12h (treatment). |
| Tinzaparin |
| Availability: Multi-dose vial 10,000 anti-Xa IU/mL 20,000 anti-Xa IU/mL Pre-filled syringe with safety needle device 2,500 anti-Xa IU/0.25 mL 3,500 anti-Xa IU/0.35 mL 4,500 anti-Xa IU/0.45 mL 8,000 anti-Xa IU/0.4 mL 10,000 anti-Xa IU/0.5 mL 12,000 anti-Xa IU/0.6 mL 14,000 anti-Xa IU/0.7 mL 16,000 anti-Xa IU/0.8 mL 18,000 anti-Xa IU/0.9 mL |
| Administration and handling: Tinzaparin is administered by SC injection. It must not be administered by intramuscular or intravenous injection. Administration should be alternated between the left and right anterolateral and left and right posterolateral abdominal wall. The injection site should be varied daily. The whole length of the needle should be introduced into a skin fold held between the thumb and forefinger; the skin fold should be held throughout the injection. To minimize bruising, do not rub the injection site after completion of the injection. |
| DVT & PE : the recommended dose is 175IU anti-Xa/kg subcutaneously once daily for at least 6 days and until the patient is adequately anticoagulated with warfarin. |
| Thromboprophylaxis inpatients with moderate risk of thrombosis ( general surgery) : On the day of operation 3500IU anti Xa SC – 2hours before surgery and post operatively OD- 3500IU anti Xa for 7-10 days. |
| Thromboprophylaxis in patients with high risk of thrombosis ( e.g., total hip replacement) : on the day of operation 4500IU anti Xa – SC – 12hours before surgery Or 50IU anti Xa/kg SC- 2hours before surgery and then OD until the patient has been mobilized. |
| Short-term hemodialysis ( less than 4 hours): a bolus dose of 2000-2500IU anti Xa into the arterial side of the dialyzer ( or intravenously) at the beginning of dialysis. |
| Long – term hemodialysis (more than 4 hours): a bolus dose of 2500IU anti Xa into the arterial side of the dialyzer (or intravenously) at the beginning of dialysis, followed by an infusion of 750 IU anti Xa/hour. |
Side – Effects:
- Bleeding
- Heparin – Induced thrombocytopenia
- Hypersensitivity reaction
- Osteoporosis (long- term use)
- Spontaneous fractures
- Hypoaldosteronism
Metabolism and Half- life:
- Metabolized by heparinase in the liver and reticuloendothelial cells.
- Metabolites are excreted in the urine. T ½ is 2- 4 Hrs. (prolonged in renal or hepatic failure)
Drug Interactions:
- Increased risk of bleeding with NSAISs (Including aspirin), warfarin, clopidogrel, and dipyridamole.
- Nitrate infusion reduces efficacy of LMWH.
NURSING CONSIDERATIONS
Baseline assessment
- Obtain baseline coagulation studies, CBC, esp. platelet count.
- Determine baseline B/P. Screen for risk factors.
- Question medical history as listed in Precautions.
- Ensure that pt has not received spinal anesthesia, spinal procedures.
- Assess for active bleeding.
- Assess pt’s willingness to self-inject medication.
Intervention/evaluation
- Periodically monitor CBC, platelet count, stool for occult blood (no need for daily monitoring in pts with normal presurgical coagulation parameters). A decrease in the platelet counts of more than 50% from baseline may indicate heparin-induced thrombocytopenia.
- Assess for any sign of bleeding (bleeding at surgical site, hematuria, blood in stool, bleeding from gums, petechiae, bruising/bleeding at injection sites). Ensure active hemostasis of puncture site following PCI.
- Monitor for DVT (extremity pain, swelling, redness), pulmonary embolism (chest pain, dyspnea, hypoxia, tachycardia).
Patient/family teaching
- Usual length of therapy is 5–10 days.
- Report bleeding(bloody urine, stool; nosebleeds; increased menstrual bleeding), bruising, dizziness, light-headedness, rash, itching, fever, swelling, breathing difficulty. If bleeding occurs, it may take longer to stop bleeding.
- Teach proper injection technique. Rotate injection sites daily.
- Suddenly stopping therapy may increase the risk of blood clots or stroke.
- Excessive bruising at injection site may be lessened by ice massage before injection.
- Monitor for symptoms of blood clots in the leg (extremity pain, swelling, redness) or blood clots in the lungs (chest pain, difficulty breathing, shortness of breath, fast heart rate).
- Immediately report signs of stroke (confusion, headache, numbness, one-sided weakness, trouble speaking, loss of vision).
- Minor blunt force trauma to the head, chest, or abdomen can be life-threatening.
- Do not take aspirin, herbal supplements, OTC nonsteroidal anti-inflammatories without consulting physician(may increase risk of bleeding).
- Consult physician before any surgery/dental work.
- Use electric razor, soft toothbrush to prevent bleeding.
Important Points:
- Maximum plasma levels after subcutaneous injection are achieved more rapidly and bioavailability is improved.
- Shorter Half- life (approximately half that of unfractionated heparin)
- Predictable response reduces the need for monitoring (monitored by measurement of anti- factor Xa activity instead of APTT in patients at increased risk of bleeding). As effective as unfractionated heparin in the prevention and treatment of venous thromboembolism and associated with fewer bleeding complications.
- Osteoporosis may occur in long- term use (usually >6 months)
REFERENCES
- Robert Kizior, Keith Hodgson, Saunders Nursing Drug handbook,1st edition 2024, Elsevier Publications. ISBN-9780443116070
- McGraw Hill- Drug Handbook, Seventh Edition, 2013, McGraw Hill Education Publications,9780071799430.
- April Hazard, Cynthia Sanoski, Davi’s Drug Guide for Nurses -Sixteenth Edition 2019, FA Davis Company Publications,9780803669451.
- Jones and Bartlet, Pharmacology for Nurses, Second Edition, 2020, Jones and Bartlet Learning Publications, ISBN 9781284141986.
- Nursebro.com, Search – Nursebro
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