CompositionHydroxychloroquine (200 mg) SALT INFORMATIONHydroxychloroquine (200 mg) TYPICAL USAGE Rheumatoid arthritis, systemic lupus erythematosus. Prophylaxis and treatment of malaria. SIDE EFFECTS Photosensitivity, tinnitus, myopathy. Psychosis, seizures, leucopenia and rarely aplastic anaemia, hepatitis, GI upsets, dizziness, hypokalaemia, headache, pruritus, urticaria, difficulty in visual accommodation. Loss of hair, bleaching of hair pigment, bluish-black pigmentation of the mucous membranes and skin, photosensitivity, tinnitus, reduced hearing, nerve deafness, neuromyopathy, and myopathy, including cardiomyopathy. DRUG INTERACTION Cimetidine may increase serum levels of hydroxychloroquine. Avoid digoxin and alcohol. Increased risk of ventricular arrhythmias when used with halofantrine. Concurrent use with mefloquine may increase the risk of convulsions. MECHANISM OF ACTION Hydroxychloroquine is a 4-aminoquinoline antimalarial with actions similar to those of chloroquine but is mainly used in the treatment of SLE and rheumatoid arthritis. It interferes with digestive vacuole function within susceptible malarial parasites by increasing pH and interrupting with lysosomal degradation of haemoglobin thus impeding normal cell function of sensitive parasites.