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Tinzaparin

Pronunciation

(tin ZA pa rin)

Index Terms

  • Tinzaparin Sodium

Pharmacologic Category

  • Anticoagulant
  • Anticoagulant, Low Molecular Weight Heparin

Pharmacology

Tinzaparin is a low molecular weight heparin (average molecular weight ranges between 5,500 and 7,500 daltons, distributed as <2,000 daltons [<10%], 2,000 to 8,000 daltons [60% to 72%], and >8,000 daltons [22% to 36%]) that binds antithrombin III, enhancing the inhibition of several clotting factors, particularly factor Xa. Tinzaparin anti-Xa activity (70 to 120 units/mg) is greater than anti-IIa activity (~55 units/mg) and it has a higher ratio of antifactor Xa to antifactor IIa activity compared to unfractionated heparin. Low molecular weight heparins have a small effect on the activated partial thromboplastin time.

Absorption

Slow; absorption half-life ~3 hours after subcutaneous administration

Distribution

4 L

Metabolism

Does not undergo hepatic metabolism

Excretion

Urine

Time to Peak

4 to 6 hours

Duration of Action

Detectable anti-Xa activity persists for 24 hours

Half-Life Elimination

82 minutes; prolonged in renal impairment

Use: Labeled Indications

Note: Not available in the US

Anticoagulation in extracorporeal circuit during hemodialysis: Prevention of clotting in indwelling intravenous lines and extracorporeal circuit during hemodialysis (in patients without high bleeding risk)

Deep vein thrombosis/pulmonary embolus (treatment): Treatment of deep vein thrombosis (DVT) and/or pulmonary embolism (PE)

Postoperative thromboprophylaxis: Prevention of venous thromboembolism (VTE) following orthopedic surgery or following general surgery in patients at high risk of VTE; prevention of clotting in indwelling intravenous lines and extracorporeal circuit during hemodialysis (in patients without high bleeding risk)

Contraindications

Hypersensitivity to tinzaparin sodium, heparin or other low molecular weight heparins (LMWH), or any component of the formulation; active bleeding from a local lesion such as an acute ulcer (eg, gastric, duodenal) or ulcerating carcinoma; history of confirmed or suspected immunologically-mediated heparin-induced thrombocytopenia (HIT) or positive in vitro platelet-aggregation test in the presence of tinzaparin; acute or subacute septic endocarditis; generalized hemorrhage tendency and other conditions involving increased risks of hemorrhage (eg, severe hepatic insufficiency, imminent abortion); hemophilia or major blood clotting disorders; acute cerebral insult or hemorrhagic cerebrovascular accidents without systemic emboli; uncontrolled severe hypertension; diabetic or hemorrhagic retinopathy; injury or surgery involving the brain, spinal cord, eyes or ears; spinal/epidural anesthesia in patients requiring treatment dosages of tinzaparin; use of multi-dose vials containing benzyl alcohol in children <3years of age, premature infants, and neonates

Note: Use of tinzaparin in patients with current HIT or HIT with thrombosis is not recommended and considered contraindicated due to high cross-reactivity to heparin-platelet factor-4 antibody (Guyatt [ACCP] 2012; Warkentin 1999).

Dosing: Adult

Note: 1 mg of tinzaparin equals 70 to 120 units of anti-Xa activity

DVT and/or PE treatment: SubQ: 175 anti-Xa units/kg once daily. The 2012 Chest guidelines recommend starting warfarin on the first or second treatment day and continuing tinzaparin until INR is ≥2 for at least 24 hours (usually 5 to 7 days) (Guyatt 2012). Body weight dosing using prefilled syringes may also be considered. Refer to manufacturer labeling for detailed dosing recommendations.

Obesity: Use actual body weight to calculate dose; dose capping is not recommended (Nutescu 2009).

Postoperative thromboprophylaxis: SubQ:

Obesity: Note: In morbidly obese patients (BMI ≥40 kg/m2), increasing the prophylactic dose by 30% may be appropriate for some indications (Nutescu 2009).

Hip replacement surgery: Note: The American College of Chest Physicians recommends initiation of LMWH ≥12 hours preoperatively or ≥12 hours postoperatively; extended duration up to 35 days suggested (Guyatt 2012).

Preoperative regimen: 50 anti-Xa units/kg given 2 hours preoperatively followed by 50 anti-Xa units/kg once daily for 7 to 10 days

Postoperative regimen: 75 anti-Xa units/kg once daily, with initial dose given postoperatively and continued for 7 to 10 days

Knee replacement surgery: 75 anti-Xa units/kg once daily, with initial dose given postoperatively and continued for 7 to 10 days. Note: The American College of Chest Physicians recommends initiation of LMWH ≥12 hours preoperatively or ≥12 hours postoperatively; extended duration of up to 35 days suggested (Guyatt 2012). Body weight dosing using prefilled syringes may also be considered. Refer to manufacturer labeling for detailed dosing recommendations.

General surgery: 3500 anti-Xa units once daily, with initial dose given 2 hours prior to surgery and then continued postoperatively for 7 to 10 days

Anticoagulant in extracorporeal circuit during hemodialysis (recommendations apply to stable patients with chronic renal failure): IV:

Dialysis session ≤4 hours (no hemorrhage risk): Initial bolus (via arterial side of circuit or IV): 4500 anti-Xa units at beginning of dialysis; typically achieves plasma concentrations of 0.5 to 1 anti-Xa units/mL; may give larger bolus for dialysis sessions >4 hours. For subsequent dialysis sessions, may adjust dose as necessary in increments of 500 anti-Xa units based on previous outcome.

Dialysis session ≤4 hours (hemorrhage risk): Initial bolus (IV only): 2,250 anti-Xa units at beginning of dialysis (do not add to dialysis circuit). A smaller second IV dose may be administered during dialysis sessions >4 hours. For subsequent dialysis sessions, adjust dose as necessary to achieve plasma concentrations of 0.2 to 0.4 anti-Xa units/mL.

Dosing: Geriatric

Refer to adult dosing. Increased sensitivity to tinzaparin in elderly patients may be possible due to a decline in renal function. Avoid use in patients >70 years of age with renal impairment (Leizorovicz 2011).

Dosing: Pediatric

Note: 1 mg of tinzaparin equals 70 to 120 units of anti-Xa activity

DVT and/or PE treatment (off-label dose) (Monagle 2012): SubQ: Infants, Children, and Adolescents: Note: May initiate a vitamin K antagonist on day 1 of tinzaparin therapy; discontinue tinzaparin on day 6 or later if INR is not >2.

Birth to 2 months: 275 anti-Xa units/kg once daily

2 to 12 months: 250 anti-Xa units/kg once daily

1 to 5 years: 240 anti-Xa units/kg once daily

5 to 10 years: 200 anti-Xa units/kg once daily

10 to 16 years: 175 anti-Xa units/kg once daily

Dosing: Renal Impairment

CrCl ≥30 mL/minute: There are no dosage adjustments provided in the manufacturer’s labeling; however, primarily undergoes renal elimination and clearance is decreased in renal impairment; use with caution.

CrCl <30 mL/minute: There are no specific dosage adjustments provided in the manufacturer’s labeling; however, it is recommended that a dose reduction be considered; use with caution.

Dosing: Hepatic Impairment

There are no dosage adjustments provided in the manufacturer’s labeling. Does not undergo hepatic metabolism; however, has been associated with transient increases in transaminase levels; use with caution.

Dosing: Obesity

A pharmacokinetic study confirmed that weight-based dosing (single doses of 75 or 175 units/kg) using actual body weight in heavy/obese patients between 100 and 165 kg led to achievement of similar anti-Xa activity levels compared to normal-weight patients (Hainer 2002). However, there is limited clinical experience in patients with a BMI >40 kg/m2. Also refer to indication-specific dosing for obesity-related information (may not be available for all indications).

Administration

SubQ: Patient should be lying down or sitting. Administer by deep SubQ injection into the lower abdomen (avoiding navel area), outer thigh, lower back, or upper arm. Injection site should be varied daily. To minimize bruising, do not rub the injection site.

IV: During hemodialysis, may be administered IV (patients with high or low hemorrhage risk) or added to the dialyzer circuit (patients with low hemorrhage risk).

Storage

Store at 15°C to 25°C (59°F to 77°F).

Drug Interactions

5-ASA Derivatives: May enhance the adverse/toxic effect of Heparin (Low Molecular Weight). Specifically, the risk for bleeding/bruising may be increased. Monitor therapy

ACE Inhibitors: Heparin (Low Molecular Weight) may enhance the hyperkalemic effect of ACE Inhibitors. Monitor therapy

Agents with Antiplatelet Properties (e.g., P2Y12 inhibitors, NSAIDs, SSRIs, etc.): May enhance the anticoagulant effect of Anticoagulants. Monitor therapy

Aliskiren: Heparin (Low Molecular Weight) may enhance the hyperkalemic effect of Aliskiren. Monitor therapy

Angiotensin II Receptor Blockers: Heparin (Low Molecular Weight) may enhance the hyperkalemic effect of Angiotensin II Receptor Blockers. Monitor therapy

Antithrombin: May enhance the anticoagulant effect of Heparin (Low Molecular Weight). Monitor therapy

Apixaban: May enhance the anticoagulant effect of Anticoagulants. Refer to separate drug interaction content and to full drug monograph content regarding use of apixaban with vitamin K antagonists (eg, warfarin, acenocoumarol) during anticoagulant transition and bridging periods. Avoid combination

Canagliflozin: Heparin (Low Molecular Weight) may enhance the hyperkalemic effect of Canagliflozin. Monitor therapy

Collagenase (Systemic): Anticoagulants may enhance the adverse/toxic effect of Collagenase (Systemic). Specifically, the risk of injection site bruising and/or bleeding may be increased. Monitor therapy

Dabigatran Etexilate: May enhance the anticoagulant effect of Anticoagulants. Refer to separate drug interaction content and to full drug monograph content regarding use of dabigatran etexilate with vitamin K antagonists (eg, warfarin, acenocoumarol) during anticoagulant transition and bridging periods. Avoid combination

Dasatinib: May enhance the anticoagulant effect of Anticoagulants. Monitor therapy

Deferasirox: Anticoagulants may enhance the adverse/toxic effect of Deferasirox. Specifically, the risk for GI ulceration/irritation or GI bleeding may be increased. Monitor therapy

Deoxycholic Acid: Anticoagulants may enhance the adverse/toxic effect of Deoxycholic Acid. Specifically, the risk for bleeding or bruising in the treatment area may be increased. Monitor therapy

Desirudin: Anticoagulants may enhance the anticoagulant effect of Desirudin. Consider therapy modification

Edoxaban: May enhance the anticoagulant effect of Anticoagulants. Refer to separate drug interaction content and to full drug monograph content regarding use of edoxaban with vitamin K antagonists (eg, warfarin, acenocoumarol) during anticoagulant transition and bridging periods. Management: Some limited combined use may be indicated during periods of transition from one anticoagulant to another. See the full edoxaban drug monograph for specific recommendations on switching anticoagulant treatment. Avoid combination

Eplerenone: Heparin (Low Molecular Weight) may enhance the hyperkalemic effect of Eplerenone. Monitor therapy

Estrogen Derivatives: May diminish the anticoagulant effect of Anticoagulants. More specifically, the potential prothrombotic effects of some estrogens and progestin-estrogen combinations may counteract anticoagulant effects. Management: Carefully weigh the prospective benefits of estrogens against the potential increased risk of procoagulant effects and thromboembolism. Use is considered contraindicated under some circumstances. Refer to related guidelines for specific recommendations. Exceptions: Tibolone. Consider therapy modification

Factor X (Human): Anticoagulants (Inhibitors of Factor Xa) may diminish the therapeutic effect of Factor X (Human). Monitor therapy

Hemin: May enhance the anticoagulant effect of Anticoagulants. Avoid combination

Herbs (Anticoagulant/Antiplatelet Properties) (eg, Alfalfa, Anise, Bilberry): May enhance the adverse/toxic effect of Anticoagulants. Bleeding may occur. Consider therapy modification

Ibritumomab: Anticoagulants may enhance the adverse/toxic effect of Ibritumomab. Both agents may contribute to an increased risk of bleeding. Monitor therapy

Ibrutinib: May enhance the adverse/toxic effect of Anticoagulants. Monitor therapy

Limaprost: May enhance the adverse/toxic effect of Anticoagulants. The risk for bleeding may be increased. Monitor therapy

Nintedanib: Anticoagulants may enhance the adverse/toxic effect of Nintedanib. Specifically, the risk for bleeding may be increased. Monitor therapy

Nonsteroidal Anti-Inflammatory Agents: May enhance the anticoagulant effect of Anticoagulants. Monitor therapy

Obinutuzumab: Anticoagulants may enhance the adverse/toxic effect of Obinutuzumab. Specifically, the risk of serious bleeding-related events may be increased. Monitor therapy

Omacetaxine: Anticoagulants may enhance the adverse/toxic effect of Omacetaxine. Specifically, the risk for bleeding-related events may be increased. Management: Avoid concurrent use of anticoagulants with omacetaxine in patients with a platelet count of less than 50,000/uL. Avoid combination

Omega-3 Fatty Acids: May enhance the anticoagulant effect of Anticoagulants. Monitor therapy

Palifermin: Heparin (Low Molecular Weight) may increase the serum concentration of Palifermin. Monitor therapy

Pentosan Polysulfate Sodium: May enhance the anticoagulant effect of Anticoagulants. Monitor therapy

Pentoxifylline: May enhance the anticoagulant effect of Heparin (Low Molecular Weight). Monitor therapy

Potassium Salts: Heparin (Low Molecular Weight) may enhance the hyperkalemic effect of Potassium Salts. Monitor therapy

Potassium-Sparing Diuretics: Heparin (Low Molecular Weight) may enhance the hyperkalemic effect of Potassium-Sparing Diuretics. Management: Monitor serum potassium concentrations closely. The spironolactone Canadian product monograph lists its combination with heparin or low molecular weight heparins as contraindicated. Monitor therapy

Progestins: May diminish the therapeutic effect of Anticoagulants. More specifically, the potential prothrombotic effects of some progestins and progestin-estrogen combinations may counteract anticoagulant effects. Management: Carefully weigh the prospective benefits of progestins against the potential increased risk of procoagulant effects and thromboembolism. Use is considered contraindicated under some circumstances. Refer to related guidelines for specific recommendations. Consider therapy modification

Prostacyclin Analogues: May enhance the adverse/toxic effect of Anticoagulants. Specifically, the antiplatelet effects of these agents may lead to an increased risk of bleeding with the combination. Monitor therapy

Rivaroxaban: Anticoagulants may enhance the anticoagulant effect of Rivaroxaban. Refer to separate drug interaction content and to full drug monograph content regarding use of rivaroxaban with vitamin K antagonists (eg, warfarin, acenocoumarol) during anticoagulant transition and bridging periods. Avoid combination

Salicylates: May enhance the anticoagulant effect of Anticoagulants. Monitor therapy

Sugammadex: May enhance the anticoagulant effect of Anticoagulants. Monitor therapy

Thrombolytic Agents: May enhance the anticoagulant effect of Anticoagulants. Management: See full drug monograph for guidelines for the use of alteplase for acute ischemic stroke during treatment with oral anticoagulants. Monitor therapy

Tibolone: May enhance the anticoagulant effect of Anticoagulants. Monitor therapy

Tipranavir: May enhance the anticoagulant effect of Anticoagulants. Monitor therapy

Tositumomab and Iodine I 131 Tositumomab: Anticoagulants may enhance the adverse/toxic effect of Tositumomab and Iodine I 131 Tositumomab. Specifically, the risk of bleeding-related adverse effects may be increased. Monitor therapy

Urokinase: May enhance the anticoagulant effect of Anticoagulants. Avoid combination

Vitamin E (Systemic): May enhance the anticoagulant effect of Anticoagulants. Monitor therapy

Vitamin K Antagonists (eg, warfarin): Anticoagulants may enhance the anticoagulant effect of Vitamin K Antagonists. Monitor therapy

Vorapaxar: May enhance the adverse/toxic effect of Anticoagulants. More specifically, this combination is expected to increase the risk of bleeding. Avoid combination

Adverse Reactions

As with all anticoagulants, bleeding is the major adverse effect of tinzaparin. Hemorrhage may occur at virtually any site. Risk is dependent on multiple variables. Note: Incidence not always reported.

>10%:

Hepatic: ALT increased (≤13%)

Local: Injection site hematoma

1% to 10%:

Cardiovascular: Chest pain (2%), angina pectoris (≥1%), arrhythmia (≥1%), coronary thrombosis/MI (≥1%), dependent edema (≥1%), thromboembolism (≥1%)

Central nervous system: Fever (2%), headache (2%), pain (2%)

Dermatologic: Bullous eruption (≥1%), erythematous rash (≥1%), maculopapular rash (≥1%), skin necrosis (≥1%)

Gastrointestinal: Nausea (2%), abdominal pain (1%), constipation (1%), diarrhea (1%), vomiting (1%)

Genitourinary: Urinary tract infection (4%)

Hematologic: Bleeding events (major events including intracranial, retroperitoneal, or bleeding into a major prosthetic joint: ≤3%; hemorrhage site not specified (2%); other bleeding events reported at an incidence of ≥1% include anorectal bleeding, GI hemorrhage, hemarthrosis, hematemesis, hematuria, hemopericardium, injection site bleeding, melena, purpura, intra-abdominal bleeding, vaginal bleeding, wound hemorrhage), granulocytopenia (≥1%), thrombocytopenia (≥1%)

Hepatic: AST increased (9%)

Local: Injection site cellulitis (≥1%)

Neuromuscular & skeletal: Back pain (2%)

Respiratory: Epistaxis (2%), dyspnea (1%)

Miscellaneous: Allergic reaction (≥1%), neoplasm (≥1%)

<1% (Limited to important or life-threatening): Agranulocytosis, angioedema, anaphylactoid reaction, GGT increased, hemoptysis, hypoaldosteronism, hyperkalemia, LDH increased, lipase increased, metabolic acidosis, ocular hemorrhage, osteopenia, osteoporosis, priapism, pruritus, rash, spinal epidural hematoma, Stevens-Johnson syndrome, thrombocytosis, toxic epidermal necrolysis, urticaria

Warnings/Precautions

Concerns related to adverse effects:

• Bleeding: Monitor patient closely for signs or symptoms of bleeding, which may occur at any site. Certain patients are at increased risk of bleeding. Risk factors include bacterial endocarditis; congenital or acquired bleeding disorders; active ulcerative or angiodysplastic GI diseases; severe uncontrolled hypertension; history of hemorrhagic stroke; or use shortly after brain, spinal, or ophthalmology surgery; those concomitantly treated with drugs that increase the risk of bleeding (eg, antiplatelet agents, anticoagulants); recent GI bleeding; thrombocytopenia or platelet defects; severe liver disease; hypertensive or diabetic retinopathy; or in patients undergoing invasive procedures. Withhold or discontinue for minor bleeding. Protamine infusion may be necessary for serious bleeding (consult Protamine monograph for dosing recommendations).

• Hyperkalemia: Monitor for hyperkalemia. Heparin can cause hyperkalemia by suppressing aldosterone production; similar reactions could occur with LMWHs. Most commonly occurs in patients with risk factors for the development of hyperkalemia (eg, diabetes, renal dysfunction, preexisting metabolic acidosis, concomitant use of potassium-sparing diuretics or potassium supplements, long-term use of tinzaparin, and hematoma in body tissues).

• Thrombocytopenia: Cases of thrombocytopenia including thrombocytopenia with thrombosis have occurred. Use with caution in patients with history of thrombocytopenia (drug-induced or congenital) or platelet defects; monitor platelet count closely. Use is contraindicated in patients with history of confirmed or suspected heparin-induced thrombocytopenia (HIT) or positive in vitro test for antiplatelet antibodies in the presence of tinzaparin. Discontinue therapy and consider alternative treatment if platelets are <100,000/mm3 and/or thrombosis develops.

• Thrombocytosis: Asymptomatic thrombocytosis has been observed with use, particularly in patients undergoing orthopedic surgery or with concurrent inflammatory process; discontinue use with increased platelet counts and evaluate the risks/necessity of further therapy.

Disease-related concerns:

• GI ulceration: Use with caution in patients with history of GI ulcer.

• Hepatic impairment: Use with caution in hepatic impairment; associated with transient, dose-dependent increases in AST/ALT which typically resolve within 2 to 4 weeks of therapy discontinuation.

• Prosthetic heart valves: Prosthetic valve thrombosis has been reported in patients receiving thromboprophylaxis therapy with LMWHs. Pregnant women may be at increased risk.

• Renal impairment: Use with caution in renal impairment; clearance is decreased in patients with CrCl ≤50 mL/minute; consider dosage reduction in patients with CrCl <30 mL/minute.

Concurrent drug therapy issues:

•Drug-drug interactions: Potentially significant interactions may exist, requiring dose or frequency adjustment, additional monitoring, and/or selection of alternative therapy. Consult drug interactions database for more detailed information.

Special populations:

• Elderly: Use with caution due to increased bleeding risks. Avoid use in patients >70 years of age with renal impairment. In a trial terminated early, an increase in all-cause mortality has been observed in patients ≥70 years (mean age: >82 years) with CrCl ≤60 mL/minute treated with tinzaparin compared to unfractionated heparin for acute DVT and/or PE (Leizorovicz 2011).

• Extreme body weights: Use with caution in patients <45 kg or >120 kg; limited experience in these patients. Individualized clinical and laboratory monitoring are recommended.

Dosage form specific issues:

• Benzyl alcohol and derivatives: Some dosage forms may contain benzyl alcohol and should not be used in pregnant women. In neonates, large amounts of benzyl alcohol (≥99 mg/kg/day) have been associated with a potentially fatal toxicity (“gasping syndrome”); the “gasping syndrome” consists of metabolic acidosis, respiratory distress, gasping respirations, CNS dysfunction (including convulsions, intracranial hemorrhage), hypotension, and cardiovascular collapse (AAP ["Inactive" 1997]; CDC 1982); some data suggests that benzoate displaces bilirubin from protein binding sites (Ahlfors, 2001); avoid or use dosage forms containing benzyl alcohol with caution in neonates. See manufacturer’s labeling.

• Porcine intestinal mucosa: This product is derived from porcine intestinal mucosa and should not be used in patients allergic to pork products.

• Sodium metabisulfite: Some dosage forms contain sodium metabisulfite which may cause allergic-type reactions, including anaphylactic symptoms and life-threatening asthmatic episodes in susceptible people; this is observed more frequently in asthmatics.

Other warnings/precautions:

• Administration: For subcutaneous use only (except in hemodialysis patients); do not administer IM and avoid IM administration of other medications due to the risk of hematoma formation.

• Conversion to other products: Not to be used interchangeably (unit for unit) with heparin or any other low molecular weight heparins.

• Neuraxial anesthesia: Spinal or epidural hematomas, including subsequent paralysis, may occur with recent or anticipated neuraxial anesthesia (epidural or spinal) or spinal puncture in patients anticoagulated with LMWH or heparinoids. Consider risk versus benefit prior to spinal procedures; risk is increased by the use of concomitant agents which may alter hemostasis, the use of indwelling epidural catheters for analgesia, a history of spinal deformity or spinal surgery, as well as traumatic or repeated epidural or spinal punctures. Optimal timing between neuraxial procedures and tinzaparin administration is not known. Delay placement or removal of catheter for at least 12 hours after administration of the last prophylactic dose and at least 24 hours after the last treatment dose of tinzaparin; consider doubling these times in patients with creatinine clearance <30 mL/minute. Risk of neuraxial hematoma may still exist since antifactor Xa levels are still detectable at these time points. Consider holding the next tinzaparin dose for 24 hours if the spinal puncture caused trauma Patient should be observed closely for bleeding and signs and symptoms of neurological impairment if therapy is administered during or immediately following diagnostic lumbar puncture, epidural anesthesia, or spinal anesthesia. If neurological compromise is noted, urgent treatment is necessary. If spinal hematoma is suspected, diagnose and treat immediately; spinal cord decompression may be considered although it may not prevent or reverse neurological sequelae.

Monitoring Parameters

CBC with platelet count (at baseline then periodically throughout therapy); renal function (use Cockcroft-Gault formula); hepatic function; potassium (baseline and regularly thereafter in patients at risk for hyperkalemia); stool for occult blood. Routine monitoring of anti-Xa levels is generally not recommended; however, anti-Xa levels may be beneficial in certain patients (eg, children, obese patients, patients with severe renal insufficiency receiving therapeutic doses, and possibly pregnant women receiving therapeutic doses) (Guyatt 2012). Peak anti-Xa levels are measured 4 to6 hours after administration. Monitoring of PT and/or aPTT is not of clinical benefit.

Pregnancy Considerations

Use is contraindicated in conditions involving increased risks of hemorrhage, including women with imminent abortion.

Tinzaparin does not cross the human placenta; increased risks of fetal bleeding or teratogenic effects have not been reported (Bates 2012). Low molecular weight heparin (LMWH) is recommended over unfractionated heparin for the treatment of acute venous thromboembolism (VTE) in pregnant women. LMWH is also recommended over unfractionated heparin for VTE prophylaxis in pregnant women with certain risk factors. LMWH should be discontinued prior to induction of labor or a planned cesarean delivery. For women undergoing cesarean section and who have additional risk factors for developing VTE, the prophylactic use of LMWH may be considered (Bates 2012). When choosing therapy, fetal outcomes (ie, pregnancy loss, malformations), maternal outcomes (ie, VTE, hemorrhage), burden of therapy, and maternal preference should be considered (Bates 2012).

Multiple-dose vials contain benzyl alcohol (avoid use in pregnant women due to association with gasping syndrome in premature infants); use of preservative-free formulation is recommended.

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