Innohep

INNOHEP- tinzaparin sodium injection
Celgene Corporation

For Subcutaneous (SC) Use Only

SPINAL/EPIDURAL HEMATOMAS

When neuraxial anesthesia (epidural/spinal anesthesia) or spinal puncture is employed, patients anticoagulated or scheduled to be anticoagulated with low molecular weight heparins or heparinoids for prevention of thromboembolic complications are at risk of developing an epidural or spinal hematoma which can result in long-term or permanent paralysis.

The risk of these events is increased by the use of indwelling epidural catheters for administration of analgesia or by the concomitant use of drugs affecting hemostasis such as non-steroidal anti-inflammatory drugs (NSAIDs), platelet inhibitors, or other anticoagulants. The risk also appears to be increased by traumatic or repeated epidural or spinal puncture.

Patients should be frequently monitored for signs and symptoms of neurological impairment. If neurological compromise is noted, urgent treatment is necessary.

The physician should consider the potential benefit versus risk before neuraxial intervention in patients anticoagulated or to be anticoagulated for thromboprophylaxis (see also WARNINGS, Hemorrhage, and PRECAUTIONS, Drug Interactions).

DESCRIPTION

INNOHEP® is a sterile solution, containing tinzaparin sodium, a low molecular weight heparin. It is available in a multiple dose 2 mL vial.

Each 2 mL vial contains 20,000 anti-Factor Xa IU (anti-Xa) of tinzaparin sodium per mL, for a total of 40,000 IU, and 3.1 mg/mL sodium metabisulfite as a stabilizer. The vial contains 10 mg/mL benzyl alcohol as a preservative. Sodium hydroxide may be added to achieve a pH range of 5.0 to 7.5.

Table 1 Composition of 20,000 anti-Xa IU/mL INNOHEP® (tinzaparin sodium injection)
Component Quantity per mL

1 Corresponding to 3.4 mg/mL sodium bisulfite

Tinzaparin sodium 20,000 anti-Xa IU
Benzyl alcohol, USP 10 mg
Sodium metabisulfite, USP 3.106 mg1
Sodium hydroxide, USP as necessary
Water for Injection, USP q.s. to 1 mL

Tinzaparin sodium is the sodium salt of a low molecular weight heparin obtained by controlled enzymatic depolymerization of heparin from porcine intestinal mucosa using heparinase from Flavobacterium heparinum. The majority of the components have a 2-O-sulpho-4-enepyranosuronic acid structure at the non-reducing end and a 2-N,6-O-disulpho-D-glucosamine structure at the reducing end of the chain.

Potency is determined by means of a biological assay and interpreted by the first International Low Molecular Weight Heparin Standard as units of anti-factor Xa (anti-Xa) activity per milligram. The mean tinzaparin sodium anti-factor Xa activity is approximately 100 IU per milligram. The average molecular weight ranges between 5,500 and 7,500 daltons. The molecular weight distribution is:

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Structural Formula

CLINICAL PHARMACOLOGY

Tinzaparin sodium is a low molecular weight heparin with antithrombotic properties. Tinzaparin sodium inhibits reactions that lead to the clotting of blood including the formation of fibrin clots, both in vitro and in vivo. It acts as a potent co-inhibitor of several activated coagulation factors, especially Factors Xa and IIa (thrombin). The primary inhibitory activity is mediated through the plasma protease inhibitor, antithrombin.

Bleeding time is usually unaffected by tinzaparin sodium. Activated partial thromboplastin time (aPTT) is prolonged by therapeutic doses of tinzaparin sodium used in the treatment of deep vein thrombosis (DVT). Prothrombin time (PT) may be slightly prolonged with tinzaparin sodium treatment but usually remains within the normal range. Neither aPTT nor PT can be used for therapeutic monitoring of tinzaparin sodium.

Neither unfractionated heparin nor tinzaparin sodium have intrinsic fibrinolytic activity; therefore, they do not lyse existing clots. Tinzaparin sodium induces release of tissue factor pathway inhibitor, which may contribute to the antithrombotic effect. Heparin is also known to have a variety of actions that are independent of its anticoagulant effects. These include interactions with endothelial cell growth factors, inhibition of smooth muscle cell proliferation, activation of lipoprotein lipase, suppression of aldosterone secretion, and induction of platelet aggregation.

Pharmacokinetics/Pharmacodynamics

Anti-Xa and anti-IIa activities are the primary biomarkers for assessing tinzaparin sodium exposure because plasma concentrations of low molecular weight heparins cannot be measured directly. Because of analytical assay limitations, anti-Xa activity is the more widely used biomarker. The measurements of anti-Xa and anti-IIa activities in plasma serve as surrogates for the concentrations of molecules which contain the high-affinity binding site for antithrombin (anti-Xa and anti-IIa activities). Monitoring patients based on anti-Xa activity is generally not advised. The data are provided in Figure 1 and Table 2. below.

Studies with tinzaparin sodium in healthy volunteers and patients have been conducted with both fixed- and weight-adjusted dose administration. Recommended therapy with tinzaparin sodium is based on weight-adjusted dosing (see DOSAGE AND ADMINISTRATION).

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Figure 1. Mean and Standard Deviation of Anti-Xa Activity Following SC Administration of a Single 4,500 IU* dose and Once Daily Multiple SC Dose of 175 IU/kg Tinzaparin Sodium to Healthy Volunteers

Table 2 Summary of Pharmacokinetic Parameters (Mean and Standard Deviation) Based on Anti-Xa Activity Following Single and Once Daily Multiple Dose SC Administration of Tinzaparin Sodium to Healthy Volunteers
Parameter (Units) Single Dose (N=23) Multiple Dose (N=14)
4,500 IU* Day 1 (175 IU/kg) Day 5 (175 IU/kg)

*Dosing based on single dose of 4,500 IU. Mean dose administered was 64.3 IU/kg.

Cmax (IU/mL) 0.25 (0.05) 0.87 (0.15) 0.93 (0.15)
Tmax (hr) 3.7 (0.9) 4.4 (0.7) 4.6 (1.0)
AUC0‑∞ (IU*hr/mL) 2.0 (0.5) 9.0 (1.1) 9.7 (1.4)
Half-life (hr) 3.4 (1.7) 3.3 (0.8) 3.5 (0.6)

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