Chloroquine Phosphate

WARNINGS Chloroquine-Resistant Malaria Chloroquine phosphate tablets are not effective against chloroquine-or hydroxychloroquine-resistant strains of Plasmodium species (see CLINICAL PHARMACOLOGY , Microbiology ). 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. Treatment of Exo-Erythocytic Forms of Malaria Chloroquine does not treat the hypnozoite liver stage forms of Plasmodium and will therefore not prevent relapses of malaria due to P. vivax or P. ovale . Additional treatment with an anti-malarial agent active against these forms, such as an 8-aminoquinoline, is required for the treatment of infections with P. vivax and P. ovale . Cardiac Effects including Cardiomyopathy and QT prolongation Fatal and life-threatening cardiotoxicity, including cardiomyopathy and arrhythmias, have been reported with the use of chloroquine (see ADVERSE REACTIONS and OVERDOSAGE ). In multiple cases, endomyocardial biopsy showed association of the cardiomyopathy with phospholipidosis in the absence of inflammation, infiltration or necrosis. Patients may present with ventricular hypertrophy and conduction disorders. ECG findings include atrioventircular, right or left bundle branch block. Chronic toxicity should be considered when conduction disorders (bundle branch block/ atrio-ventricular heart block) are diagnosed. QT interval proongation, torsades de pointes, and ventricular arrhythmias have been reported with the use of chloroquine. The risk is greater if chloroquine is administered at high doses. Chloroquine should be used with caution in patients with cardiac disease,a history of ventricular arrhythmias, uncorrected hypokalemia and/or hypomagnesemia, or bradycardia (< 50bpm), and during concomitant administration with QT interval prolonging agents due to potential for QT interval prolongation (see WARNINGS , PRECAUTIONS , Drug Interactions, ADVERSE REACTIONS and OVERDOSAGE ) Monitor for signs and symptoms of cardiotoxicity is suspected or demonstrated by tissue biopsy. Skeletal Muscle Myopathy and Neuropathy Skeletal muscle myopathy and neuropathy leading to progressive weakness and atrophy of proximal muscle groups, and abnormal nerve conduction, have been reported. Muscle and nerve biopsies have shown associated phospholipidosis. Assess muscle strength and deep tendon reflexes periodically in patients on long-term therapy with chloroquine. Discontinue chloroquine if muscle or nerve toxicity is suspected or demonstrated by tissue biopsy. Hypoglycemia Chloroquine has been shown to cause severe hypoglycemia including loss of consciousness that could be life-threatening in patients treated with or without antidiabetic medications (see PRECAUTIONS , Drug Interactions). Patients treated with chloroquine phosphate tablets should be warned about the risk of hypoglycemia and the associated clinical signs and symptoms. Patients presenting with clinical symptoms suggestive of hypoglycemia during treatment with chloroquine should have their blood glucose level checked and treatment reviewed as necessary. Retinopathy 1 Irreversible retinal damage has been observed in some patients who had received chloroquine. Significant risk factors for retinal damage include daily doses of chloroquine phosphate greater than 2.3 mg/kg of actual body weight, durations of use greater than five years, subnormal glomerular filtration, use of some concomitant drug products such as tamoxifen citrate (see PRECAUTIONS ), and concurrent macular disease. A baseline ophthalmological examination should be performed within the first year of starting chloroquine phosphate tablets. The baseline exam should include: best corrected distance visual acuity (BCVA), an automated threshold visual field (VF) of the central 10 degrees (with retesting if an abnormality is noted), and spectral domain optical coherence tomography (SD-OCT). For individuals with significant risk factors (daily dose of chloroquine phosphate greater than 2.3 mg/kg of actual body weight, subnormal glomerular filtration, use of tamoxifen citrate or concurrent macular disease) monitoring should include annual examinations which include BCVA, VF and SDOCT. For individuals without significant risk factors, annual exams (including BCVA, VF and SD-OCT) can usually be deferred until five years of treatment. In individuals of Asian descent, retinal toxicity may first be noticed outside the macula. In patients of Asian descent, it is recommended that visual field testing be performed in the central 24 degrees instead of the central 10 degrees. It is recommended that chloroquine be discontinued if ocular toxicity is suspected and the patient should be closely observed given that retinal changes (and visual disturbances) may progress even after cessation of therapy. Central Nervous System Effects Acute extrapyramidal disorders may occur with chloroquine (see PRECAUTIONS , ADVERSE REACTIONS and OVERDOSAGE ). These adverse reactions usually resolve after treatment discontinuation and/or symptomatic treatment. Renal Toxicity Proteinuria with or without a moderate reduction in glomerular filteration rate have been reported with the use of chloroquine. Renal biopsy showed phospholipidosis without immune deposits, inflammation, and/or increased cellularity. Physcians should consider phospholipidosis as a possible cause of renal injury in patients with underlying connective tissue disorders who are receiving chloroquine. Discontinue chloroquine if renal toxicity is suspected or demonstrated by tissue biopsy. Pediatric Accidental Ingestion A number of fatalities have been reported following the accidental ingestion of chloroquine, sometimes in relatively small doses (0.75 g or 1 g chloroquine phosphate in one 3-year-old child). Patients should be strongly warned to keep chloroquine phosphate tablets out of the reach of children because they are especially sensitive to the 4-aminoquinoline compounds (see OVERDOSAGE and ADVERSE REACTIONS ). Worsening of Psoriasis and Porphyria Use of chloroquine phosphate tablets in patients with psoriasis may precipitate a severe attack of psoriasis. When used in patients with porphyria the condition may be exacerbated. Chloroquine phosphate tablets should not be used in these conditions unless the benefit to the patient outweighs the potential risks. Potential Carcinogenic Risk Experimental data showed a potential risk of inducing gene mutations. There is insufficient evidence regarding the carcinogenecity of chloroquine in experimental animals (see PRECAUTIONS , Carcinogenesis, Mutagenesis, Impairment of Fertility). In humans, there are insufficient data to rule out an increased risk of cancer in patients receiving long-term treatment. Usage in Pregnancy In animal studies, embryo-fetal developmental toxicity was shown at doses ranging from 250 to 1500 mg/kg body weight; approximately 3 to 16 times the maximum recommended therapeutic dose based on a body surface area comparison (see PRECAUTIONS , Animal Pharmacology and/or Animal Toxicology). Preclinical data showed a potential risk of genotoxicity in some test systems ( PRECAUTIONS , Carcinogenesis, Mutagenesis, Impairment of Fertility). In humans, at recommended doses for prophylaxis and treatment of malaria, observational studies as well as a meta-analysis, including a small number of prospective studies with chloroquine exposure during pregnancy, have shown no increase in the rate of birth defects or spontaneous abortions. The individual benefit-risk balance should be reviewed before prescribing chloroquine in pregnant women.