Platelet Reducing Agent (Specialist Drug) Pregnancy: Not recommended during pregnancy — there are no adequate data in pregnant women and animal studies have shown reproductive toxicity; the potential risk for humans is unknown. Women of child-bearing potential should use adequate birth-control measures during treatment. Breast-feeding should be discontinued during treatment.

Anagrelide

Brand names: Xagrid

Anagrelide is an oral platelet-lowering agent used to reduce a raised platelet count in essential thrombocythaemia and other myeloproliferative disorders at risk of thrombosis or bleeding.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: 1 mg per day (starting dose), given as 0.5 mg per dose

Route: Oral — capsules must be swallowed whole; do not crush or dilute the contents in a liquid

Frequency: Twice daily (two divided doses of 0.5 mg). Maintain the starting dose for at least one week, then titrate individually.

Max: Dose increments must not exceed 0.5 mg/day in any one week, and the recommended maximum single dose should not exceed 2.5 mg. Doses of 10 mg/day have been used during clinical development.

INITIATION: treatment should be started by a clinician experienced in the management of essential thrombocythaemia. TITRATION TARGET: after one week the dose may be titrated on an individual basis to the lowest effective dose needed to reduce and/or maintain the platelet count below 600 x 10^9/L, ideally between 150 and 400 x 10^9/L. A fall in platelet count is typically seen within 14 to 21 days of starting, and most patients achieve and maintain an adequate response at 1 to 3 mg/day. MONITORING: if the starting dose is above 1 mg/day, check platelet counts every two days during the first week and at least weekly thereafter until a stable maintenance dose is reached; the effects of treatment must be monitored regularly. ELDERLY: no different starting regimen or titration step is warranted; about 50% of patients in development were over 60 years and no age-specific dose alterations were required, although this age group had twice the incidence of serious (mainly cardiac) adverse events. HEPATIC: patients with moderate or severe hepatic impairment should NOT be treated with anagrelide; assess risks and benefits before treating mild impairment (limited pharmacokinetic data). PAEDIATRIC (UK SPC): safety and efficacy in children have not been established and experience is very limited — anagrelide should be used with caution in this group and NO RECOMMENDATION ON A POSOLOGY CAN BE MADE. Cytoreductive therapy is typically considered only in high-risk paediatric patients; treatment should only be initiated when there are signs of disease progression or thrombosis, platelet targets are set individually by the treating physician, and discontinuation should be considered if there is no satisfactory response after approximately 3 months. For cross-reference only, the US prescribing information states that safety and effectiveness have been established in paediatric patients 7 years of age and older (no data below 7 years) and gives a paediatric starting dosage of 0.5 mg daily — this is US labelling, is not per kilogram, and must be verified before any paediatric use.

Dose adjustments

Renal

Contraindicated in moderate or severe renal impairment (creatinine clearance less than 50 mL/min). Pharmacokinetic data in renal impairment are limited; the potential risks and benefits should be assessed before treatment is commenced.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Hypersensitivity to anagrelide or to any of the excipients
Patients with moderate or severe hepatic impairment
Patients with moderate or severe renal impairment (creatinine clearance less than 50 mL/min)

Side effects

Headache (approximately 14%)
Palpitations (approximately 9%)
Fluid retention (approximately 6%)
Nausea (approximately 6%)
Diarrhoea (5%)
These reactions are expected from the pharmacology of anagrelide (PDE III inhibition); gradual dose titration may help diminish them

Interactions

Drugs that prolong the QT interval — avoid use of anagrelide in patients taking QT-prolonging medicines (including but not limited to chloroquine, clarithromycin, haloperidol, methadone, moxifloxacin, amiodarone, disopyramide, procainamide and pimozide) (US labelling)
Other PDE3 inhibitors and inotropes (for example cilostazol, milrinone) — anagrelide is a PDE3 inhibitor; avoid products with similar properties because of exacerbation of inotropic effects (US labelling)
Aspirin and other drugs that increase bleeding risk — co-administration with aspirin produced greater ex vivo anti-platelet aggregation effects than aspirin alone, with an increased risk of bleeding (US labelling)
NOTE: the fetched UK SPC extract did not include section 4.5 — these entries come from the US prescribing information and should be checked against the UK SPC.

Clinical monograph

How it works

It selectively inhibits megakaryocyte maturation and proliferation, reducing platelet production; it also has phosphodiesterase III inhibitory and vasodilator activity.

Prescribing in practice

Its positive inotropic and vasodilator effects can cause palpitations, tachycardia and fluid retention, so it is used with caution and cardiovascular assessment in those with known or suspected heart disease.
Dose is titrated against the platelet count under specialist haematology supervision to the lowest level that maintains control.
Headache, diarrhoea and fluid retention are common early adverse effects that often settle with continued treatment.

Monitoring

Monitor the full blood count regularly during titration and maintenance, with baseline and periodic cardiac assessment as clinically indicated.

Counselling the patient

Report palpitations, breathlessness, chest pain or ankle swelling promptly.
Do not stop suddenly without advice, as the platelet count can rebound.

Evidence & guidelines

Use is supported by haematology guidance and the SPC as a cytoreductive option in high-risk essential thrombocythaemia, particularly where hydroxycarbamide is unsuitable.

Reference: NICE TA228 (Anagrelide for essential thrombocythaemia, 2010); PT-1 trial (NEJM 2005); BSH Guidelines on ET (2010 updated); Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways