Chloroquine Phosphate

Adults: Doses are usually expressed in terms of chloroquine base. As a general guide, chloroquine base 300 mg is roughly equivalent to chloroquine phosphate 500 mg. For treating an acute attack of malaria: Adults and children are given a total of 25 mg of chloroquine base per kg body weight spread over 3 days. This can be done in different ways. One approach is 10 mg per kg first, followed 6 to 8 hours later by 5 mg per kg, then 5 mg per kg daily for the next 2 days. Another approach is 10 mg per kg daily for the first 2 days, then 5 mg per kg on the 3rd day. Adult doses are sometimes given as fixed amounts rather than by body weight: 600 mg first, followed 6 to 8 hours later by 300 mg, then 300 mg daily for the next 2 days. For malaria prophylaxis: Adults take an oral dose equal to 300 mg of chloroquine base every 7 days, starting about one week before exposure, continuing throughout exposure, and for at least 4 weeks afterward. Children are usually given a weekly oral dose of 5 mg per kg body weight. For hepatic amoebiasis: Adults take 600 mg of base daily for 2 days, then 300 mg of base daily for at least 2 to 3 weeks. This is usually combined with an effective intestinal amoebicide. For discoid and systemic lupus erythematosus: The suggested oral dose is 150 mg of base daily, reduced gradually once symptoms are under control. For rheumatoid arthritis: Adults take 150 mg of base daily, and some clinicians recommend limiting treatment to 10 months of each year. Children are given 3 mg per kg body weight of base daily. For managing photoallergic reactions: Adults take 150 to 300 mg of base daily during periods of intense light exposure. Children are given 3 mg per kg body weight. For porphyria cutanea tarda: When chloroquine was first used for this condition, at doses of 150 mg to 600 mg of base per day for 4 to 7 days, it caused severe, life threatening toxic hepatitis. Using a low dose of 75 mg of base 2 to 3 times per week for 6 to 18 months can avoid this effect and lead to remission.