Chloroquine Phosphate (3 brand names, 1 dosage form, 1 route)
Available dosage forms: TABLET.
Routes of administration: ORAL.
Brand Names
- ARALEN
- ARALEN PHOSPHATE W/ PRIMAQUINE PHOSPHATE
- CHLOROQUINE PHOSPHATE
Indications and Usage
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 is widespread in P. falciparum, and is reported in P.vivax(see WARNINGS). Concomitant therapy with an 8-aminoquinoline drug is necessary for treatment of the hypnozoite liver stage forms of P.vivaxand P.ovale(see DOSAGE AND ADMINISTRATION).
Dosage and Administration
The dosage of chloroquine phosphate is often expressed in terms of equivalent chloroquine base. Each 500 mg tablet of Chloroquine phosphate contains the equivalent of 300 mg chloroquine base. In infants and children the dosage is preferably calculated by body weight. Prophylaxis against chloroquine-sensitive Plasmodiumspecies 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. However, failing this in adults, an initial double (loading) dose of 1 g (= 600 mg base), or in children 10 mg base/kg may be taken in two divided doses, six hours apart. The suppressive therapy should be continued for eight weeks after leaving the endemic area. Treatment of uncomplicated malaria due to chloroquine-sensitive Plasmodiumspecies Adults:An initial dose of 1 g salt (= 600 mg base) followed by an additional 500 mg (= 300 mg base) after six to eight hours and a single dose of 500 mg (= 300 mg base) on each of two consecutive days. This represents a total dose of 2.5 g chloroquine phosphate or 1.5 g base in three days. Infants and Children:In infants and children, the recommended dose is 10 mg base/kg followed by 5 mg based/kg at 6, 24 and 36 hours (total dose 25 mg based/kg). The pediatric dose should never exceed the adult dose regardless of weight. The dosage for adults of low body weight and for infants and children should be determined as follows: First dose: 10 mg base per kg (but not exceeding a single dose of 600 mg base). Second dose: (6 hours after first dose) 5 mg base per kg (but not exceeding a single dose of 300 mg base). Third dose: (24 hours after first dose) 5 mg base per kg. F
Contraindications
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 is contraindicated in patients with known hypersensitivity to 4- aminoquinoline compounds.
Adverse Reactions
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 (see WARNINGS). Visual disturbances (blurring of vision and difficulty of focusing or accommodation); nyctalopia; scotomatous vision with field defects of paracentral, pericentral ring types, and typically temporal scotomas (e.g., difficulty in reading with words tending to disappear, seeing half an object, misty vision, and fog before the eyes) have been reported. Reversible corneal opacities have also been reported. Immune system disorders:Urticaria, anaphylactic reaction including angioedema. Ear and labyrinth disorders:Nerve type deafness; tinnitus, reduced hearing in patients with preexisting auditory damage. Musculoskeletal and connective tissue-disorders:Sensorimotor disorders, skeletal muscle myopathy or neuromyopathy leading to progressive weakness and atrophy of proximal muscle groups, depression of tendon reflexes and abnormal nerve conduction. Gastrointestinal disorders:Hepatitis, increased liver enzymes, anorexia, nausea, vomiting, diarrhea, abdominal cramps. Skin and subcutaneous tissue disorders: Erythema multiforme, Stevens-Johnson syndrome, toxic epidermal necrolysis, exfoliative dermatitis. Pleomorphic skin eruptions, skin and mucosal pigmentary changes; lichen planus-like eruptions, pruritus,; drug rash with eosinophilia and systemic symptoms (DRESS syndrome); photosensitivity and hair loss and bleaching of h
Overdosage
Signs and Symptoms:Chloroquine is very rapidly and completely absorbed after ingestion. Toxic doses of chloroquine can be fatal. As little as 1 g may be fatal in children. Toxic symptoms can occur within minutes. The symptoms of overdosage may include nausea, vomiting, headache, drowsiness, visual disturbances, cardiovascular collapse, convulsions, hypokalemia, rhythm and conduction disorders including QT prolongation, torsades de pointes, ventricular tachycardia and ventricular fibrillation, followed by sudden potentially fatal respiratory and cardiac arrest. Immediate medical attention is required, as these effects may appear shortly after the overdose. Cases of extrapyramidal disorders have also been reported in the context of chloroquine overdose (see WARNINGS and ADVERSE REACTIONS). Treatment:Treatment is symptomatic and must be prompt with immediate evacuation of the stomach by emesis or gastric lavage followed by treatment with activated charcoal. Chloroquine overdose is a life- threatening emergency and should be managed with cardio-respiratory and hemodynamic support, monitoring of potassium along with management of arrhythmias and convulsions, as necessary. A patient who survives the acute phase and is asymptomatic should be closely observed until all clinical features of toxicity resolve.