Section 12 · Monograph

Selumetinib

Reviewed Nov 2026FDA label

KoselugoMEK1/2 inhibitor

Forms: Cap: 10, 25mg | Granules (capsule for opening)
Dose: NF1 plexiform neurofibromas: 25mg/m² twice daily by body surface area (pediatric 2+; check current label for adult use)
MOA: Inhibits MEK1/2 in the RAS-MAPK pathway

Indications

Neurofibromatosis type 1 (NF1) with symptomatic, inoperable plexiform neurofibromas in pediatric patients 2 years of age and older (US); confirm the current label for adult useFDA-labeled

Selective inhibitor of MEK1/2 in the RAS-MAPK pathway, which is hyperactivated in NF1, shrinking plexiform neurofibromas

25mg/m² orally twice daily (about every 12 hours), based on body surface area and rounded to the nearest achievable 5 or 10mg, up to 50mg per dose
Examples: BSA 0.55-0.69m² 20mg AM and 10mg PM; 0.70-0.89 20mg BID; 0.90-1.09 25mg BID; 1.10-1.29 30mg BID; 1.30-1.49 35mg BID; 1.50-1.69 40mg BID; 1.70-1.89 45mg BID; 1.90 or more 50mg BID
Reduce dose with strong or moderate CYP3A4 or CYP2C19 inhibitors; interrupt or reduce for toxicity; continue until progression or unacceptable toxicity

Swallow capsules whole (granule formulation is available for smaller children); follow current regional food-intake instructions

None listed in the US labeling; in the EU, severe hepatic impairment and hypersensitivity

Strong/moderate CYP3A4 and CYP2C19 inhibitors increase exposure (dose reduction needed); strong inducers reduce exposure
Capsules contain vitamin E: possible additive bleeding risk with anticoagulants or high-dose vitamin E supplements