Shire Pharmaceuticals Ireland Limited

Drug interactions: effects of anagrelide on other substances

·               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 PDE III. The effects of medicinal products with similar properties such as the inotropes milrinone, enoximone, amrinone, olprinone and cilostazol may be exacerbated by anagrelide.

·               In vivo interaction studies in humans have demonstrated that anagrelide does not affect the pharmacokinetic properties of digoxin or warfarin.

·               At the doses recommended for use in the treatment of essential thrombocythaemia, anagrelide may theoretically potentiate the effects of other medicinal products that inhibit or modify platelet function e.g. acetylsalicylic acid.

·               A clinical interaction study performed in healthy subjects showed that co-administration of repeat-dose anagrelide 1 mg once daily and acetylsalicylic acid 75 mg once daily may enhance the anti-platelet aggregation effects of each drug compared with administration of acetylsalicylic acid alone. In some ET patients concomitantly treated by acetylsalicylic acid and anagrelide, major haemorrhages occurred. Therefore, due to the lack of data in ET patients, the potential risks of the concomitant use of anagrelide with acetylsalicylic acid should be assessed, particularly in patients with a high risk profile for haemorrhage before treatment is initiated.

·               Anagrelide may cause intestinal disturbance in some patients and compromise the absorption of hormonal oral contraceptives.

Food interactions

·               Food delays the absorption of anagrelide, but does not significantly alter systemic exposure.

·The effects of food on bioavailability are not considered clinically relevant to the use of anagrelide.

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