THERAPEUTICS

Brands

• Imuran, Azasan, Azamun, Imurel

Generic?

• Yes

Class

• Immunosuppressant

Commonly Prescribed for

(FDA approved in bold)

• Prophylaxis of organ rejection in patients with allogenic renal transplants

• Reducing signs and symptoms of rheumatoid arthritis

• Myasthenia gravis (MG) (monotherapy or adjunctive)

• Lambert-Eaton myasthenia syndrome

• Inflammatory myopathies: polymyositis (PM) and dermatomyositis (DM)

• Multiple sclerosis (MS)

• Neuromyelitis optica

• Crohn's disease, ulcerative colitis

• Lupus nephritis

How the Drug Works

• Azathioprine, a derivative of 6-mercaptopurine, inhibits the synthesis of purine. This interferes with DNA and RNA synthesis as well as repair and replication of T and B leukocytes

• The mechanism of action in autoimmune diseases is unclear, but it appears to suppress cellular cytotoxicity and blunt hypersensitivity reactions

How Long Until It Works

• At least 3 months. Full effect may occur after 1–2 years

If It Works

• MG: improves strength and muscle fatigue. Often used as an adjunctive to corticosteroids or acute treatment such as immune globulin or plasma exchange. Taper corticosteroids if clinical symptoms Improve

• PM/DM: may allow improvement in strength and discontinuation or reduced dose of corticosteroids. (Corticosteroids are usually tapered first.) Taper slowly over 6 months if clinical remission occurs

• MS: may reduce relapses and new lesions on MRI

If It Doesn't Work

• MG: effectiveness may not occur until 1 year. For patients with severe disability, consider more rapid-acting treatments, such as IV immune globulin

• DM/PM: question the diagnosis (inclusionbody myositis, hypothyroidism, muscular dystrophy), rule out corticosteroid-induced myopathy, and evaluate for undiagnosed malignancy (especially in DM). Change to methotrexate

• MS: if clearly not helpful, change to another agent

Best Augmenting Combos for Partial Response or Treatment-Resistance

• MG: usually combined with corticosteroids or other treatments in MG. Most patients also use symptomatic medication, such as pyridostigmine