Anagrelide should be used with caution in patients with known or suspected heart disease, and only if the potential benefits of therapy outweigh the potential risks. Because of the positive inotropic effects and side-effects of anagrelide, a pre-treatment cardiovascular examination is recommended along with careful monitoring during treatment. In humans, therapeutic doses of anagrelide may cause cardiovascular effects, including vasodilation, tachycardia, palpitations, and congestive heart failure.
Exposure to anagrelide is increased 8-fold in patients with moderate hepatic impairment (see CLINICAL PHARMACOLOGY). 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 impairment of hepatic function should be assessed before treatment is commenced. In patients with moderate hepatic impairment, dose reduction is required and patients should be carefully monitored for cardiovascular effects (see DOSAGE AND ADMINISTRATION for specific dosing recommendations).
Anagrelide therapy requires close clinical supervision of the patient. While the platelet count is being lowered (usually during the first two weeks of treatment), blood counts (hemoglobin, white blood cells), liver function (SGOT, SGPT) and renal function (serum creatinine, BUN) should be monitored.
In 9 subjects receiving a single 5 mg dose of anagrelide, standing blood pressure fell an average of 22/15 mm Hg, usually accompanied by dizziness. Only minimal changes in blood pressure were observed following a dose of 2 mg.
Cessation of AGRYLIN® Treatment
In general, interruption of anagrelide treatment is followed by an increase in platelet count. After sudden stoppage of anagrelide therapy, the increase in platelet count can be observed within four days.
Limited PK and/or PD studies investigating possible interactions between anagrelide and other medicinal products have been conducted. In vivo interaction studies in humans have demonstrated that digoxin and warfarin do not affect the PK properties of anagrelide, nor does anagrelide affect the PK properties of digoxin or warfarin.
Although additional drug interaction studies have not been conducted, the most common medications used concomitantly with anagrelide in clinical trials were aspirin, acetaminophen, furosemide, iron, ranitidine, hydroxyurea, and allopurinol. There is no clinical evidence to suggest that anagrelide interacts with any of these compounds.
An in vivo interaction study in humans demonstrated that a single 1mg dose of anagrelide administered concomitantly with a single 900 mg dose of aspirin was generally well tolerated. There was no effect on bleeding time, PT or aPTT. No clinically relevant pharmacokinetic interactions between anagrelide and acetylsalicylic acid were observed. In that same study, aspirin alone produced a marked inhibition in platelet aggregation ex vivo. Anagrelide alone had no effect on platelet aggregation, but did slightly enhance the inhibition of platelet aggregation by aspirin.
Anagrelide is metabolized at least in part by CYP1A2. It is known that CYP1A2 is inhibited by several medicinal products, including fluvoxamine, and such medicinal products could theoretically adversely influence the clearance of anagrelide. Anagrelide demonstrates some limited inhibitory activity towards CYP1A2 which may present a theoretical potential for interaction with other co-administered medicinal products sharing that clearance mechanism e.g. theophylline.
Anagrelide is an inhibitor of cyclic AMP PDE III. The effects of medicinal products with similar properties such as inotropes milrinone, enoximone, amrinone, olprinone and cilostazol may be exacerbated by anagrelide.
There is a single case report which suggests that sucralfate may interfere with anagrelide absorption.
Food has no clinically significant effect on the bioavailability of anagrelide.
Carcinogenesis, Mutagenesis, Impairment of Fertility
No long-term studies in animals have been performed to evaluate carcinogenic potential of anagrelide hydrochloride. Anagrelide hydrochloride was not genotoxic in the Ames test, the mouse lymphoma cell (L5178Y, TK+/-) forward mutation test, the human lymphocyte chromosome aberration test, or the mouse micronucleus test. Anagrelide hydrochloride at oral doses up to 240 mg/kg/day (1,440 mg/m2/day, 195 times the recommended maximum human dose based on body surface area) was found to have no effect on fertility and reproductive performance of male rats. However, in female rats, at oral doses of 60 mg/kg/day (360 mg/m2/day, 49 times the recommended maximum human dose based on body surface area) or higher, it disrupted implantation when administered in early pregnancy and retarded or blocked parturition when administered in late pregnancy.
Pregnancy Category C.
Teratology studies have been performed in pregnant rats at oral doses up to 900 mg/kg/day (5,400 mg/m2/day, 730 times the recommended maximum human dose based on body surface area) and in pregnant rabbits at oral doses up to 20 mg/kg/day (240 mg/m2/day, 32 times the recommended maximum human dose based on body surface area) and have revealed no evidence of impaired fertility or harm to the fetus due to anagrelide hydrochloride.
A fertility and reproductive performance study performed in female rats revealed that anagrelide hydrochloride at oral doses of 60 mg/kg/day (360 mg/m2/day, 49 times the recommended maximum human dose based on body surface area) or higher disrupted implantation and exerted adverse effect on embryo/fetal survival.
A perinatal and postnatal study performed in female rats revealed that anagrelide hydrochloride at oral doses of 60 mg/kg/day (360 mg/m2/day, 49 times the recommended maximum human dose based on body surface area) or higher produced delay or blockage of parturition, deaths of nondelivering pregnant dams and their fully developed fetuses, and increased mortality in the pups born.
Five women became pregnant while on anagrelide treatment at doses of 1 to 4 mg/day. Treatment was stopped as soon as it was realized that they were pregnant. All delivered normal, healthy babies. There are no adequate and well-controlled studies in pregnant women. Anagrelide hydrochloride should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.
Anagrelide is not recommended in women who are or may become pregnant. If this drug is used during pregnancy, or if the patient becomes pregnant while taking this drug, the patient should be apprised of the potential harm to the fetus. Women of child-bearing potential should be instructed that they must not be pregnant and that they should use contraception while taking anagrelide. Anagrelide may cause fetal harm when administered to a pregnant woman.
It is not known whether this drug is excreted in human milk. Because many drugs are excreted in human milk and because of the potential for serious adverse reaction in nursing infants from anagrelide hydrochloride, 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.
Myeloproliferative disorders are uncommon in pediatric patients and limited data are available in this population. An open label safety and PK/PD study (see CLINICAL PHARMACOLOGY) was conducted in 17 pediatric patients 7-14 years of age (8 patients 7-11 years of age and 9 patients 11-14 years of age, mean age of 11 years; 8 males and 9 females) with thrombocythemia secondary to ET as compared to 18 adult patients (mean age of 63 years, 9 males and 9 females). Prior to entry on to the study, 16 of 17 pediatric patients and 13 of 18 adult patients had received anagrelide treatment for an average of 2 years. The median starting total daily dose, determined by retrospective chart review, for pediatric and adult ET patients who had received anagrelide prior to study entry was 1mg for each of the three age groups (7-11 and 11-14 year old patients and adults). The starting dose for 6 anagrelide-naive patients at study entry was 0.5 mg once daily. At study completion, the median total daily maintenance doses were similar across age groups, median of 1.75 mg for patients of 7-11 years of age, 2 mg in patients 11-14 years of age, and 1.5 mg for adults.
The study evaluated the pharmacokinetic (PK) and pharmacodynamic (PD) profile of anagrelide, including platelet counts (see CLINICAL PHARMACOLOGY).
The frequency of adverse events observed in pediatric patients was similar to adult patients. The most common adverse events observed in pediatric patients were fever, epistaxis, headache, and fatigue during a 3-months treatment of anagrelide in the study. Adverse events that had been reported in these pediatric patients prior to the study and were considered to be related to anagrelide treatment based on retrospective review were palpitation, headache, nausea, vomiting, abdominal pain, back pain, anorexia, fatigue, and muscle cramps. Episodes of increased pulse rate and decreased systolic or diastolic blood pressure beyond the normal ranges in the absence of clinical symptoms were observed in some patients. Reported AEs were consistent with the known pharmacological profile of anagrelide and the underlying disease. 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. No overall difference in dosing and safety were observed between pediatric and adult patients.
In another open-label study, anagrelide had been used successfully in 12 pediatric patients (age range 6.8 to 17.4 years; 6 male and 6 female), including 8 patients with ET, 2 patients with CML, 1 patient with PV, and 1 patient with OMPD. Patients were started on therapy with 0.5 mg qid up to a maximum daily dose of 10 mg. The median duration of treatment was 18.1 months with a range of 3.1 to 92 months. Three patients received treatment for greater than three years. Other adverse events reported in spontaneous reports and literature reviews include anemia, cutaneous photosensitivity and elevated leukocyte count.
Of the total number of subjects in clinical studies of AGRYLIN ®, 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.