Therapy | Usual adult oral dose | Common adverse effects | Cautions/monitoring |
Pyridostigmine | 60–360 mg/day in 3–6 divided doses (up to 450 mg, rarely) | Diarrhoea, abdominal cramps, nausea, increased salivation, bladder or bowel urgency | Asthma, recent myocardial infarction, bradycardias |
Corticosteroids | For generalised myasthenia gravis 10 mg on alternate days increasing by 10 mg every week up to 1.5 mg/kg (maximum 100 mg) or until symptoms and signs resolve; for ocular myasthenia 5 mg on alternate days increasing by 5 mg every week up to 0.75 mg/kg (maximum 60 mg) on alternate days or until clinical remission, whichever is earlier. | Short term: sleep disturbance, mood changes, acne, weight gain, blurred vision, dyspepsia. Long term: peptic ulceration, osteoporosis, proximal myopathy, fluid retention, weight gain, diabetes mellitus, hypertension and increased susceptibility to infections | Periodic bone density scans (add bisphosphonates, vitamin D and calcium for bone protection, and proton pump inhibitors for gastric protection) (Bisphosphonates may be avoided prior to and during pregnancy) |
3,4 diaminopyridine | 10 mg four times/day increasing to a maximum of 20 mg 4–5 times/day depending on response | Peri-oral and distal paraesthesia (common), insomnia, gastrointestinal disturbances (high doses occasionally cause seizures) | Used only under specialist prescription |
Azathioprine | Usually started at 25 mg/day gradually increasing by 25–50 mg every week up to 2.5 mg/kg daily (requires up to 12 months for therapeutic effect) | Nausea, vomiting, bone marrow suppression and liver dysfunction, warts. Long term risk of non-melanoma skin cancer. | Regular monitoring of full blood count and liver function (weekly for first 2 months and 3 monthly if blood results are stable). TPMT assay if available. |
Mycophenolate mofetil | 1 g twice daily | Dyspepsia and bone marrow suppression. | Regular monitoring of blood pressure, full blood count, creatinine and liver function. (weekly for first month, fortnightly for next 2 months and monthly thereafter). |
Ciclosporin | Start at 25 mg twice daily increased by 50 mg every 3 days. Typically 2.5 mg/kg/day | Nausea, vomiting, excess body hair, hypertension and renal dysfunction. | Monitor renal function and blood pressure. Some centres monitor blood levels. |
Tacrolimus | 50 μg/kg/day (trough level to be maintained at 5–10 ng/ml) | Nausea, vomiting, hypertension, bone marrow suppression, glucose intolerance, renal and hepatic dysfunction. | Regular monitoring of full blood count, blood pressure, renal and liver function. Blood tacrolimus levels to be monitored regularly to adjust the dose. |
Methotrexate | 7.5 mg/week titrated up to a maximum of 20 mg/week as per response and adverse effects | Nausea, vomiting, mouth ulcers, bone marrow suppression, respiratory and hepatic complications | Chest x ray prior to starting treatment. Regular monitoring of full blood count and liver function (weekly for first 2 months and then 3 monthly). Add folic acid 5 mg weekly to prevent bone marrow suppression and gastrointestinal adverse effects |
Cyclophosphamide | 1–3 mg/kg/day | Nausea, vomiting, diarrhoea, fatigue, cystitis, haematuria, bone marrow suppression | Regular monitoring of full blood count, liver function and urine dipstick for haematuria (weekly for first month, fortnightly for next 2 months and monthly thereafter). |
TPMT, thiopurine methyltransferase.