Glucosylceramide synthase inhibitor Pregnancy: eMC 4.6: No adequate data in pregnant women; animal studies have shown reproductive toxicity including dystocia. Miglustat crosses the placenta and should not be used during pregnancy. It is not known whether miglustat is secreted in breast milk - it should not be taken during breast-feeding. Contraceptive measures should be used by women of childbearing potential. Male patients should maintain reliable contraception while taking miglustat and, before seeking to conceive, should stop miglustat and continue reliable contraception for a further 3 months (rat studies show adverse effects on spermatogenesis and sperm parameters, reducing fertility).

Miglustat

Brand names: Zavesca

Miglustat is an oral substrate reduction therapy used in type 1 Gaucher disease (when enzyme replacement is unsuitable) and to treat progressive neurological manifestations in Niemann-Pick disease type C.

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: Type 1 Gaucher disease (adults): 100 mg three times a day (recommended starting dose)

Route: Oral (100 mg hard capsules; may be taken with or without food)

Frequency: Three times a day

eMC SPC 4.2 (Miglustat Dipharma 100 mg hard capsules). Type 1 Gaucher disease, adults: 'The recommended starting dose for the treatment of adult patients with type 1 Gaucher disease is 100 mg three times a day.' Temporary dose reduction to 100 mg once or twice a day may be necessary in some patients because of diarrhoea. Niemann-Pick type C disease, adults and adolescents aged 12 years and above: 200 mg three times a day. Niemann-Pick type C under 12 years is dosed by BODY SURFACE AREA, not by weight: greater than 1.25 m2 - 200 mg three times a day; greater than 0.88 up to 1.25 m2 - 200 mg twice a day; greater than 0.73 up to 0.88 m2 - 100 mg three times a day; greater than 0.47 up to 0.73 m2 - 100 mg twice a day; 0.47 m2 or less - 100 mg once a day; verify against a children's formulary before use. Efficacy in children and adolescents aged 0-17 years with type 1 Gaucher disease has not been established (no data). There is limited experience in Niemann-Pick type C patients under 4 years and no experience in patients over 70 years. Therapy should be directed by physicians knowledgeable in the management of Gaucher disease or Niemann-Pick type C disease. The benefit of treatment should be evaluated on a regular basis. Miglustat has not been evaluated in hepatic impairment.

Dose adjustments

Renal

eMC 4.2: Adjusted creatinine clearance 50-70 ml/min/1.73 m2 - start at 100 mg twice daily in type 1 Gaucher disease, or 200 mg twice daily in Niemann-Pick type C disease (adjusted for body surface area in patients below 12 years). Adjusted creatinine clearance 30-50 ml/min/1.73 m2 - start at 100 mg once daily in type 1 Gaucher disease, or 100 mg twice daily in Niemann-Pick type C disease (adjusted for body surface area in patients below 12 years). Severe renal impairment (creatinine clearance below 30 ml/min/1.73 m2) - use is not recommended.

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 the active substance or to any of the excipients

Side effects

Very common: diarrhoea, flatulence, abdominal pain (gastrointestinal events, mainly diarrhoea, occur in more than 80% of patients)
Very common: weight loss (reported in 55% of patients) and decreased appetite
Very common: tremor - typically an exaggerated physiological tremor of the hands, usually beginning within the first month and often resolving after 1-3 months; dose reduction may help
Common: peripheral neuropathy (the most common serious adverse reaction), ataxia, amnesia, paraesthesia, hypoaesthesia, headache, dizziness
Common: thrombocytopenia; muscle spasms and muscle weakness; fatigue, asthenia, chills and malaise
Common: nausea, vomiting, abdominal distension/discomfort, constipation, dyspepsia; depression, insomnia, decreased libido

Interactions

Co-administration with imiglucerase appeared to increase the clearance of imiglucerase by around 70%, although the result is not conclusive because of the small number of patients and variable imiglucerase doses (US label section 7; eMC 4.5 was not captured in the source bundle)

Clinical monograph

How it works

It inhibits glucosylceramide synthase, reducing the synthesis of glycosphingolipids so that less accumulates within cells when the degrading enzyme is deficient.

Prescribing in practice

Diarrhoea and weight loss are very common and can be limiting, often improved by dietary measures and dose adjustment.
Peripheral neuropathy and tremor have been reported, so neurological function should be assessed before and during treatment.
It may reduce sperm parameters, so men should use reliable contraception during and for a period after treatment.

Monitoring

Monitor body weight, gastrointestinal tolerance, neurological status including for peripheral neuropathy, and platelet counts where relevant.

Counselling the patient

Gastrointestinal upset such as diarrhoea is common and may be eased by adjusting your diet.
Report any numbness, tingling or tremor to your specialist.
Men should use effective contraception during and after treatment as advised.

Evidence & guidelines

Miglustat is an established substrate reduction therapy for type 1 Gaucher disease and for neurological involvement in Niemann-Pick disease type C.

Reference: NICE; SmPC; 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