Anagrelide Hydrochloride (Page 3 of 5)

6.2 Postmarketing Experience

The following adverse reactions have been identified during post-marketing use of anagrelide. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure. Cases of torsades de pointes, interstitial lung diseases (including allergic alveolitis, eosinophilic pneumonia and interstitial pneumonitis) [see Warnings and Precautions (5)] , tubulointerstitial nephritis and clinically significant hepatotoxicity (including symptomatic ALT and AST elevations and elevations greater than three times the ULN) have been reported.

Other adverse events in pediatric patients reported in spontaneous reports and literature reviews include anemia, cutaneous photosensitivity and elevated leukocyte count.

7 DRUG INTERACTIONS

7.1 Drugs that Prolong QT

Do not use anagrelide in patients taking medications that may prolong QT interval (including, but not limited to, chloroquine, clarithromycin, haloperidol, methadone, moxifloxacin, amiodarone, disopyramide, procainamide and pimozide) [see Warnings and Precautions (5.1) and Clinical Pharmacology (12.2)].

7.2 PDE3 Inhibitors

Anagrelide is a phosphodiesterase 3 (PDE3) inhibitor. The effects of drug products with similar properties such as inotropes and other PDE3 inhibitors (e.g., cilostazol, milrinone) should be avoided [see Warnings and Precautions (5.1) and Clinical Pharmacology (12.2)].

7.3 Aspirin and Drugs that Increase Bleeding Risk

Co-administration of single-dose or repeat-dose anagrelide and aspirin showed greater ex vivo anti-platelet aggregation effects than administration of aspirin alone [see Clinical Pharmacology (12.3)]. Results from an observational study in patients with essential thrombocythemia suggest the rate of major hemorrhagic events (MHEs) in patients treated with anagrelide is higher than in those subjects treated with another cytoreductive treatment. The majority of the major hemorrhagic events occurred in patients who were also receiving concomitant anti-aggregatory treatment (primarily, aspirin). Therefore, the potential risks of the concomitant use of anagrelide with aspirin should be assessed, particularly in patients with a high risk profile for hemorrhage, before treatment is initiated [see Warnings and Precautions (5.2)].

Monitor patients for bleeding, particularly those receiving concomitant therapy with other drugs known to cause bleeding (e.g., anticoagulants, PDE3 inhibitors, NSAIDs, antiplatelet agents, selective serotonin reuptake inhibitors).

7.4 CYP450 Interactions

CYP1A2 inhibitors: Anagrelide and its active metabolite are primarily metabolized by CYP1A2. Drugs that inhibit CYP1A2 (e.g., fluvoxamine, ciprofloxacin) could increase the exposure of anagrelide. Monitor patients for cardiovascular events and titrate doses accordingly when CYP1A2 inhibitors are co-administered.

CYP1A2 inducers: CYP1A2 inducers could decrease the exposure of anagrelide. Patients taking concomitant CYP1A2 inducers (e.g., omeprazole) may need to have their dose titrated to compensate for the decrease in anagrelide exposure.

CYP1A2 substrates: Anagrelide demonstrates limited inhibitory activity towards CYP1A2 in vitro and may alter the exposure of concomitant CYP1A2 substrates (e.g. theophylline, fluvoxamine, ondansetron).

8 USE IN SPECIFIC POPULATIONS

8.1 Pregnancy

Teratogenic Effects

Pregnancy Category C

Risk Summary

There are no adequate and well-controlled studies with anagrelide in pregnant women. In animal embryo-fetal studies, delayed development (delayed skeletal ossification and reduced body weight) was observed in rats administered anagrelide hydrochloride during organogenesis at doses substantially higher than the maximum clinical dose of 10 mg/day. Anagrelide should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

Animal Data

Anagrelide hydrochloride was administered orally to pregnant rats and rabbits during the period of organogenesis at doses up to 900 mg/kg/day in rats and up to 20 mg/kg/day in rabbits (875 and 39 times, respectively, the maximum clinical dose of 10 mg/day based on body surface area). In rats, developmental delays were observed including reductions in fetal weight at 300 and 900 mg/kg/day and delays in skeletal ossification at doses of 100 mg/kg/day and higher. The dose of 100 mg/kg/day (600 mg/m2 /day) in rats is approximately 97 times the maximum clinical dose based on body surface area. No adverse embryo-fetal effects were detected in rabbits at the highest dose of 20 mg/kg/day (39 times the maximal clinical dose based on body surface area).

In a pre- and post-natal study conducted in female rats, anagrelide hydrochloride at oral doses of 60 mg/kg/day (58 times the maximum clinical dose based on body surface area) or higher produced delay or blockage of parturition, deaths of non-delivering pregnant dams and their fully developed fetuses, and increased mortality in the pups born.

In a placental transfer study, a single oral dose of [14 C]-anagrelide hydrochloride was administered to pregnant rats on gestation Day 17. Drug-related radioactivity was detected in maternal and fetal tissue.

8.3 Nursing Mothers

Risk Summary

It is not known whether anagrelide is excreted in human milk. Anagrelide or its metabolites have been detected in the milk of lactating rats. Because many drugs are excreted into human milk and because of the potential for serious adverse reaction in nursing infants from anagrelide, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.

Data

In a rat milk secretion study, a single oral dose of [14 C]-anagrelide hydrochloride was administered to lactating female rats on postnatal Day 10. Drug-related radioactivity was detected in the maternal milk and blood.

8.4 Pediatric Use

Experience with anagrelide in pediatric patients was based on an open label safety and PK/PD study conducted in 18 pediatric patients aged 7 to 16 years with thrombocythemia secondary to ET [see Dosage and Administration (2.1), Clinical Pharmacology (12.3) and Clinical Studies (14)].

There were no apparent trends or differences in the types of adverse events observed between the pediatric patients compared with those of the adult patients [see Adverse Reactions (6.1)].

8.5 Geriatric Use

Of the 942 subjects in clinical studies of anagrelide, 42.1% were 65 years and over, while 14.9% were 75 years and over. No overall differences in safety or effectiveness were observed between these subjects and younger subjects, and other reported clinical experience has not identified differences in response between the elderly and younger patients, but greater sensitivity of some older individuals cannot be ruled out.

8.6 Hepatic Impairment

Hepatic metabolism is the major route of anagrelide clearance. Exposure to anagrelide is increased 8-fold in patients with moderate hepatic impairment [see Clinical Pharmacology (12.3)] and dose reduction is required [see Dosage and Administration (2.3)]. Use of anagrelide in patients with severe hepatic impairment has not been studied. The potential risks and benefits of anagrelide therapy in a patient with mild and moderate hepatic impairment should be assessed before treatment is commenced. Assess hepatic function before and during anagrelide treatment [see Warnings and Precautions (5.1)].

10 OVERDOSAGE

At higher than recommended doses, this medicine has been shown to cause hypotension. There have been postmarketing case reports of intentional overdose with anagrelide hydrochloride. Reported symptoms include sinus tachycardia and vomiting. Symptoms resolved with supportive management. Platelet reduction from anagrelide therapy is dose-related; therefore, thrombocytopenia, which can potentially cause bleeding, is expected from overdosage.

In case of overdosage, close clinical supervision of the patient is required; this especially includes monitoring of the platelet count for thrombocytopenia. Dosage should be stopped, as appropriate, until the platelet count returns to within the normal range.

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