High doses of steroids should be used with caution in patients receiving paralytic agents for prolonged periods. The antimalarial drug chloroquine is often used by rheumatologists for the treatment of various collagen vascular diseases. It can cause macular and corneal degeneration, peripheral neuropathy, and myopathy. After long-term use, colchicine causes a vacuolar myopathy and an axonal neuropathy, often in patients who are between 50 and 70 years of age and who have gout and a mild, chronic renal insufficiency. Symptoms include proximal muscle weakness, elevation of the serum CK level, distal sensory involvement, and areflexia.
Symptoms resolve four to six weeks after discontinuance of the drug.
Lowering the dose of the drug reverses the myopathy. The serum CK level is normal, and the EMG not informative. Preceded by muscle edema and tenderness, the acute myopathy presents as rhabdomyolysis and myoglobinuria and is painful. It can recur if the patient resumes drinking. This myopathy is painless, is not accompanied by muscle swelling, and is quickly reversible.