ARGATROBAN (Page 3 of 6)

7 DRUG INTERACTIONS

7.1 Heparin

If argatroban is to be initiated after cessation of heparin therapy, allow sufficient time for heparin’s effect on the aPTT to decrease prior to initiation of argatroban therapy.

7.2 Oral Anticoagulant Agents

Pharmacokinetic drug-drug interactions between argatroban and warfarin (7.5 mg single oral dose) have not been demonstrated. However, the concomitant use of argatroban and warfarin (5 to 7.5 mg initial oral dose, followed by 2.5 to 6 mg/day orally for 6 to 10 days) results in prolongation of the prothrombin time (PT) and International Normalized Ratio (INR) [see Dosage and Administration (2.5) and Clinical Pharmacology (12.2)].

7.3 Aspirin/Acetaminophen

No drug-drug interactions have been demonstrated between argatroban and concomitantly administered aspirin or acetaminophen [see Clinical Pharmacology (12.3)].

7.4 Thrombolytic Agents

The safety and effectiveness of argatroban with thrombolytic agents have not been established [see Adverse Reactions (6.1)].

7.5 Glycoprotein IIb/IIIa Antagonists

The safety and effectiveness of argatroban with glycoprotein IIb/IIIa antagonists have not been established.

8 USE IN SPECIFIC POPULATIONS

8.1 Pregnancy

Risk Summary

Limited data from published literature and postmarketing reports do not suggest an association between argatroban and adverse fetal developmental outcomes. There are risks to the mother associated with untreated thrombosis in pregnancy and a risk of hemorrhage in the mother and fetus associated with use of anticoagulants (see Clinical Considerations). In animal reproduction studies, there was no evidence of adverse developmental outcomes with intravenous administration of argatroban during organogenesis in rats and rabbits at doses up to 0.3- and 0.2-times, respectively, the maximum recommended human dose (MHRD) (see Data).

The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2%-4% and 15%-20%, respectively.

Clinical Considerations

Disease-Associated Maternal and/or Embryo/Fetal Risk

Pregnancy confers an increased risk for thromboembolism that is higher for women with underlying thromboembolic disease and certain high risk pregnancy conditions. Published data describe that women with a previous history of venous thrombosis are at high risk for recurrence during pregnancy.

Fetal/Neonatal Adverse Reactions

Use of anticoagulants, including argatroban, may increase the risk of bleeding in the fetus and neonate. Monitor neonates for bleeding [see Warnings and Precautions (5.1, 5.3)].

Labor or Delivery

All patients receiving anticoagulants, including pregnant women, are at risk for bleeding. Pregnant women receiving argatroban should be carefully monitored for evidence of excessive bleeding or unexpected changes in coagulation parameters [see Warnings and Precautions (5.1, 5.3)].

Data

Animal Data

Developmental studies performed in rats with argatroban at intravenous doses up to 27 mg/kg/day (0.3 times the maximum recommended human dose, based on body surface area) and in rabbits at intravenous doses up to 10.8 mg/kg/day (0.2 times the maximum recommended human dose, based on body surface area) have revealed no evidence of harm to the fetus.

8.2 Lactation

Risk Summary

There are no data on the presence of argatroban in human milk, or its effects on milk production. Argatroban is present in rat milk. The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for Argatroban and any potential adverse effects on the breastfed infant from Argatroban or from the underlying maternal condition.

8.4 Pediatric Use

Safety and effectiveness have not been established in pediatric patients.

Argatroban was studied among 18 seriously ill pediatric patients who required an alternative to heparin anticoagulation. Most patients were diagnosed with HIT or suspected HIT. Age ranges of patients were <6 months, n = 8; six months to < 8 years, n = 6; 8 to 16 years, n = 4. All patients had serious underlying conditions and were receiving multiple concomitant medications. Thirteen patients received argatroban solely as a continuous infusion (no bolus dose). Dosing was initiated in the majority of these 13 patients at 1 mcg/kg/min. Dosing was titrated as needed to achieve and maintain an aPTT of 1.5 to 3 times the baseline value. Most patients required multiple dose adjustments to maintain anticoagulation parameters within the desired range. During the 30-day study period, thrombotic events occurred during argatroban administration to two patients: and following argatroban discontinuation in three other patients. Major bleeding occurred among two patients: one patient experienced an intracranial hemorrhage after 4 days of argatroban therapy in the setting of sepsis and thrombocytopenia and another patient experienced an intracranial hemorrhage after receiving argatroban for greater than 14 days. The study findings did not establish the safe and effective use of argatroban in pediatric patients and the dosing of 1 mcg/kg/in was not supported by the pharmacokinetic data described below.

Pediatric Pharmacokinetics (PK) and Pharmacodynamics (PD)

PK parameters of argatroban were characterized in population PK/PD analysis model with sparse data from 15 seriously ill pediatric patients. Argatroban clearance in these seriously ill pediatric patients (0.16 L/hr/kg) was 50% lower compared to argatroban clearance in healthy adults (0.31 L/hr/kg). Four pediatric patients with elevated bilirubin (secondary to cardiac complications or hepatic impairment) had, on average, 80% lower clearance (0.03 L/hr/kg) when compared to pediatric patients with normal bilirubin levels.

These PK/PD analysis models based on a goal of aPTT prolongation of 1.5 to 3 times the baseline value and avoidance of an aPTT greater than 100 seconds for seriously ill pediatric patients with HIT/HITTS who require an alternative to heparin suggested the following:

For patients with normal hepatic function, a starting infusion rate of 0.75 mcg/kg/min may have comparable aPTT responses as a starting dose of 2 mcg/kg/min in healthy adults. Additionally, based on an evaluation of aPTT every two hours, increasing the dosage by 0.1 to 0.25 mcg/kg/min could achieve additional aPTT responses.
For patients with hepatic impairment a starting infusion rate of 0.2 mcg/kg/min with increasing dosing by increments of 0.05 mcg/kg/min may have comparable argatroban exposure as expected with adult doses.

The safety and effectiveness of argatroban with the above dosing have not been adequately assessed in pediatric patients and the safety and effectiveness of argatroban is not established in pediatric patients. In addition, the described dosage did not take into account multiple factors that could affect the dosage such as current aPTT, target aPTT, and the clinical status of the patient.

8.5 Geriatric Use

Of the total number of subjects (1340) in clinical studies of argatroban, 35% were 65 and over. In the clinical studies of adult patients with HIT (with or without thrombosis), the effectiveness of argatroban was not affected by age. No trends were observed across age groups for both aPTT and the ACT. The safety analysis did suggest that older patients had increased underlying conditions, which may predispose them to events. The studies were not sized appropriately to detect differences in safety between age groups.

8.6 Hepatic Impairment

Dose reduction and careful titration are required when administering argatroban to patients with hepatic impairment. Reversal of anticoagulant effect may be prolonged in this population [see Dosage and Administration (2.3), Warning and Precautions (5.2), Clinical Pharmacology (12.3)].

10 OVERDOSAGE

Excessive anticoagulation, with or without bleeding, may be controlled by discontinuing argatroban or by decreasing the argatroban dose. In clinical studies, anticoagulation parameters generally returned from therapeutic levels to baseline within 2 to 4 hours after discontinuation of the drug. Reversal of anticoagulant effect may take longer in patients with hepatic impairment.

No specific antidote to argatroban is available; if life-threatening bleeding occurs and excessive plasma levels of argatroban are suspected, discontinue argatroban immediately and measure aPTT and other coagulation parameters. When argatroban was administered as a continuous infusion (2 mcg/kg/min) prior to and during a 4-hour hemodialysis session, approximately 20% of argatroban was cleared through dialysis.

Single intravenous doses of argatroban at 200, 124, 150, and 200 mg/kg were lethal to mice, rats, rabbits, and dogs, respectively. The symptoms of acute toxicity were loss of righting reflex, tremors, clonic convulsions, paralysis of hind limbs, and coma.

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