How is cyclosporine microemulsion used in the treatment of rheumatic diseases?
- • Available formulations: 25- and 100-mg capsule; oral solution 100 mg/mL; IV solution 50 mg/mL.
- • Dosage: 2.5 to 4 mg/kg ideal body weight for most rheumatic diseases. Start low in divided doses, and increase 0.5 mg/kg per day every 4 to 8 weeks.
- • Cost (200 mg/day): $450 to $500/month.
- • Follow-up: monitor creatinine and blood pressure every 2 weeks for 3 months, then monthly; periodic CBC, liver function tests, magnesium, potassium, uric acid, and lipid levels.
- • Precautions: concurrent use of nonsteroidal antiinflammatory drugs, aminoglycosides, and angiotensin-converting enzyme (ACE) inhibitors may contribute to renal insufficiency. Erythromycin/clarithromycin, azole antifungals, diltiazem/verapamil, and other CYP3A4 inhibitors increase cyclosporine levels causing toxicity. Cyclosporine is stopped if creatinine increases 30% over baseline even if still in normal range. Cyclosporine can increase toxicity of statins (myopathy), colchicine (neuromyopathy), digoxin, and potassium-sparing diuretics (hyperkalemia). Do not use colchicine in patients on cyclosporine.
Cyclosporine is a potent immunomodulating agent that works by inhibition of T-cell activation (primarily T helper cells). It does so by binding to a cytoplasmic protein (immunophilin) called cyclophilin, which in turn binds to calcineurin. This blocks the interaction of calcineurin with calmodulin, which is necessary to dephosphorylate nuclear factor of activated T cells (NF-AT)—a transcription factor needed to activate T-cell activation genes such as interleukin (IL)-2.
