Chloroquine toxicity

At low doses, chloroquine causes gastrointestinal irritation, skin rash, and headaches. High doses may cause severe skin lesions, peripheral neuropathies, myocardial depression, retinal damage, auditory impairment,pruritis and toxic psychosis.Discoloration of the nail beds and mucous membranes may be seen on chronic administration. Chloroquine should be used cautiously in patients with hepatic dysfunction or severe gastrointestinal problems and in patients with neurologic or blood disorders. Chloroquine can cause electrocardiographic (ECG) changes, because it has a quinidine-like effect. It may also exacerbate dermatitis produced by gold or phenylbutazone therapy. [Note: Patients with psoriasis or porphyria should not be treated with chloroquine, because an acute attack may be provoked.]