Chloroquine

Chloroquine phosphate tablets are indicated for the: Treatment of uncomplicated malaria due to susceptible strains of P. falciparum, P.malariae, P. ovale, and P.vivax. Prophylaxis of malaria in geographic areas where resistance to chloroquine is not present. Treatment of extraintestinal amebiasis. Chloroquine phosphate tablets do not prevent relapses in patients with vivax or ovale malaria because it is not effective against exoerythrocytic forms of the parasites. Limitations of Use in Malaria: Do not use chloroquine phosphate tablets for the treatment of complicated malaria (high-grade parasitemia and/or complications e.g., cerebral malaria or acute renal failure). Do not use chloroquine phosphate tablets for malaria prophylaxis in areas where chloroquine resistance occurs, Resistance to chloroquine phosphate tablets are widespread in P. falciparum, and is reported in P.vivax.

Chloroquine, a 4-aminoquinoline, is an anti-protozoal agent. The precise mechanism by which chloroquine exhibits activity is not known. Chloroquine, may exert its effect against Plasmodium species by concentrating in the acid vesicles of the parasite and by inhibiting polymerization of heme. It can also inhibit certain enzymes by its interaction with DNA. Activity in Vitro and in Clinical Infections: Chloroquine is active against the erythrocytic forms of susceptible strains of Plasmodium falciparum, Plasmodium malariae, Plasmodium ovale, and Plasmodium vivax. Chloroquine is not active against the gametocytes and the exoerythrocytic forms including the hypnozoite stage ( P. vivax and P. ovale ) of the Plasmodium parasites. In vitro studies with Chloroquine demonstrated that it is active against the trophozoites of Entamoeba histolytica.

The dosage of chloroquine phosphate is often expressed in terms of equivalent chloroquine base. Each 500 mg tablet of chloroquine phosphate tablet contains the equivalent of 300 mg chloroquine base. In infants and children the dosage is preferably calculated by body weight. Prophylaxis against chloroquine-sensitive Plasmodium species Adult Dose: The dosage for prophylaxis is 500 mg (= 300 mg base) administered once per week on exactly the same day of each week. Pediatric Dose: The dosage for prophylaxis is 5 mg calculated as base, per kg of body weight, administered once per week on exactly the same day of each week. The pediatric dose should never exceed the adult dose regardless of weight. If circumstances permit, suppressive therapy should begin two weeks prior to exposure.

Use of chloroquine phosphate tablets for indications other than acute malaria is contraindicated in the presence of retinal or visual field changes of any etiology. Use of chloroquine phosphate tablets are contraindicated in patients with known hypersensitivity to 4-aminoquinoline compounds.

Chloroquine-Resistant Malaria Chloroquine phosphate tablets are not effective against chloroquine-or hydroxychloroquine-resistant strains of Plasmodium species. Chloroquine resistance is widespread in P. falciparum and is reported in P. vivax. Before using chloroquine for prophylaxis, it should be ascertained whether chloroquine is appropriate for use in the region to be visited by the traveler. Information regarding the geographic areas where resistance to chloroquine occurs, is available at the Centers for Disease Control and Prevention (www.cdc.gov\malaria). Patients infected with a resistant strain of plasmodia as shown by the fact that normally adequate doses have failed to prevent or cure clinical malaria or parasitemia should be treated with another form of antimalarial therapy.

The following adverse reactions have been identified during post-approval use of chloroquine or other 4-aminoqunoline compounds. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure. Ocular disorders: Maculopathy and macular degeneration have been reported and may be irreversible. Irreversible retinopathy with retinal pigmentation changes (bull’s eye appearance) and visual field defects (paracentral scotomas) in patients receiving long-term or high-dosage 4-aminoquinoline therapy have been reported.

Store at 20-25°C (68-77°F). Protect from light and moisture.