Chloroquine Phosphate Information
Chloroquine phosphate ()
Chloroquine phosphate ()
Chloroquine phosphate () Description
Chloroquine phosphate () , USP is a 4-aminoquinoline compound for oral administration. It is a white crystalline powder; odorless; has a bitter taste, and is discolored slowly on exposure to light. It is freely soluble in water, practically insoluble in alcohol, in chloroform and in ether.
Chloroquine phosphate () , USP is an antimalarial and amebicidal drug.
Each tablet, for oral administration, contains 250 mg of Chloroquine phosphate () , USP (equivalent to 150 mg base).
Inactive ingredients: colloidal silicon dioxide, corn starch, hypromellose, magnesium stearate, microcrystalline cellulose, polyethylene glycol 400, polyethylene glycol 3350, polysorbate 80, povidone, sodium starch glycolate, talc, and titanium dioxide.
Chemically, it is 7-chloro-4-[[4-(diethylamino)-1-methylbutyl]amino] quinoline phosphate (1:2) and has the following molecular structure:
CHClN.2HPO Molecular Weight: 515.86
Chloroquine phosphate () Clinical Pharmacology
Chloroquine is rapidly and almost completely absorbed from the gastrointestinal tract, and only a small proportion of the administered dose is found in the stools. Approximately 55% of the drug in the plasma is bound to nondiffusible plasma constituents. Excretion of chloroquine is quite slow, but is increased by acidification of the urine. Chloroquine is deposited in the tissues in considerable amounts. In animals, from 200 to 700 times the plasma concentration may be found in the liver, spleen, kidney, and lung; leukocytes also concentrate the drug. The brain and spinal cord, in contrast, contain only 10 to 30 times the amount present in plasma.
Chloroquine undergoes appreciable degradation in the body. The main metabolite is desethylchloroquine, which accounts for one fourth of the total material appearing in the urine; bisdesethylchloroquine, a carboxylic acid derivative, and other metabolic products as yet uncharacterized are found in small amounts. Slightly more than half of the urinary drug products can be accounted for as unchanged chloroquine.
Mechanism of Action: Chloroquine is an antimalarial agent. While the drug can inhibit certain enzymes, its effect is believed to result, at least in part from its interaction with DNA. However, the mechanism of plasmodicidal action of chloroquine is not completely certain.
Activity and : Chloroquine is active against the erythrocytic forms of , and susceptible strains of (but not the gametocytes of ). It is not effective against exoerythrocytic forms of the parasite.
Chloroquine phosphate () Indications And Usage
Chloroquine phosphate () tablets, USP are indicated for the suppressive treatment and for acute attacks of malaria due to , and susceptible strains of The drug is also indicated for the treatment of extraintestinal amebiasis.
Chloroquine phosphate () tablets, USP does not prevent relapses in patients with or malaria because it is not effective against exoerythrocytic forms of the parasite, nor will it prevent or infection when administered as a prophylactic. It is highly effective as a suppressive agent in patients with or malaria, in terminating acute attacks, and significantly lengthening the interval between treatment and relapse. In patients with malaria it abolishes the acute attack and effects complete cure of the infection, unless due to a resistant strain of .
Chloroquine phosphate () Contraindications
Use of this drug is contraindicated in the presence of retinal or visual field changes either attributable to 4-aminoquinoline compounds or to any other etiology, and in patients with known hypersensitivity to 4-aminoquinoline compounds. However, in the treatment of acute attacks of malaria caused by susceptible strains of plasmodia, the physician may elect to use this drug after carefully weighing the possible benefits and risks to the patient.
Chloroquine phosphate () Warnings
It has been found that certain strains of have become resistant to 4- aminoquinoline compounds (including chloroquine and hydroxychloroquine). Chloroquine resistance is widespread and, at present, is particularly prominent in various parts of the world including sub-Saharan Africa, Southeast Asia, the Indian subcontinent, and over large portions of South America, including the Amazon basin.
Before using chloroquine for prophylaxis, it should be ascertained whether chloroquine is appropriate for use in the region to be visited by the traveler. Chloroquine should not be used for treatment of infections acquired in areas of chloroquine resistance or malaria occurring in patients where chloroquine prophylaxis has failed.
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.
Irreversible retinal damage has been observed in some patients who had received long-term or high-dosage 4-aminoquinoline therapy. Retinopathy has been reported to be dose related.
When prolonged therapy with any antimalarial compound is contemplated, initial (base line) and periodic ophthalmologic examinations (including visual acuity, expert slit-lamp, funduscopic, and visual field tests) should be performed.
If there is any indication (past or present) of abnormality in the visual acuity, visual field, or retinal macular areas (such as pigmentary changes, loss of foveal reflex), or any visual symptoms (such as light flashes and streaks) which are not fully explainable by difficulties of accommodation or corneal opacities, the drug should be discontinued immediately and the patient closely observed for possible progression. Retinal changes (and visual disturbances) may progress even after cessation of therapy.
All patients on long-term therapy with this preparation should be questioned and examined periodically, including testing knee and ankle reflexes, to detect any evidence of muscular weakness. If weakness occurs, discontinue the drug.
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 this drug out of the reach of children because they are especially sensitive to the 4-aminoquinoline compounds.
Use of Chloroquine phosphate () in patients with psoriasis may precipitate a severe attack of psoriasis. When used in patients with porphyria the condition may be exacerbated. The drug should not be used in these conditions unless in the judgment of the physician the benefit to the patient outweighs the potential risks.
Chloroquine phosphate () Precautions
Complete blood cell counts should be made periodically if patients are given prolonged therapy. If any severe blood disorder appears which is not attributable to the disease under treatment, discontinuance of the drug should be considered.
The drug should be administered with caution to patients having G-6-PD (glucose-6 phosphate dehydrogenase) deficiency.
Antacids and kaolin: Antacids and kaolin can reduce absorption of chloroquine; an interval of at least 4 hours between intake of these agents and chloroquine should be observed.
Cimetidine: Cimetidine can inhibit the metabolism of chloroquine, increasing its plasma level. Concomitant use of cimetidine should be avoided.
Ampicillin: In a study of healthy volunteers, chloroquine significantly reduced the bioavailability of ampicillin. An interval of at least two hours between intake of this agent and chloroquine should be observed.
Cyclosporine: After introduction of chloroquine (oral form), a sudden increase in serum cyclosporine level has been reported. Therefore, close monitoring of serum cyclosporine level is recommended and, if necessary, chloroquine should be discontinued.
Mefloquine: Co-administration of chloroquine and mefloquine may increase the risk of convulsions.
The blood concentrations of chloroquine and desethylchloroquine (the major metabolite of chloroquine, which also has antimalarial properties) were negatively associated with log antibody titers. Chloroquine taken in the dose recommended for malaria prophylaxis can reduce the antibody response to primary immunization with intradermal human diploid-cell rabies vaccine.
Because of the potential for serious adverse reactions in nursing infants from chloroquine, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the potential clinical benefit of the drug to the mother.
The excretion of chloroquine and the major metabolite, desethylchloroquine, in breast milk was investigated in eleven lactating mothers following a single oral dose of chloroquine (600 mg base). The maximum daily dose of the drug that the infant can receive from breastfeeding was about 0.7% of the maternal start dose of the drug in malaria chemotherapy. Separate chemoprophylaxis for the infant is required. See
Chloroquine phosphate () Overdosage
Convulsions, if present, should be controlled before attempting gastric lavage. If due to cerebral stimulation, cautious administration of an ultra short-acting barbiturate may be tried but, if due to anoxia, it should be corrected by oxygen administration and artificial respiration, monitor ECG. In shock with hypotension, a potent vasopressor should be administered. Replace fluids and electrolytes as needed. Cardiac compressing or pacing may be indicated to sustain the circulation. Because of the importance of supporting respiration, tracheal intubation or tracheostomy, followed by gastric lavage, may also be necessary. Peritoneal dialysis and exchange transfusions have also been suggested to reduce the level of the drug in the blood.
Intervention options can involve: diazepam for life-threatening symptoms, seizures and sedation, epinephrine for treatment of vasodilation and myocardial depression, potassium replacement with close monitoring of serum potassium levels.
A patient who survives the acute phase and is asymptomatic should be closely observed for at least six hours. Fluids may be forced, and sufficient ammonium chloride (8 g daily in divided doses for adults) may be administered for a few days to acidify the urine to help promote urinary excretion in cases of both overdosage or sensitivity.
Chloroquine phosphate () Dosage And Administration
The dosage of Chloroquine phosphate () is often expressed or calculated as the base. Each 250 mg tablet of Chloroquine phosphate () , USP is equivalent to 150 mg base. In infants and children the dosage is preferably calculated on the body 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.
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.
Fourth dose: (36 hours after first dose) 5 mg base per kg.
For radical cure of and malaria concomitant therapy with an 8-aminoquinoline compound is necessary.
See
Chloroquine phosphate () How Supplied
Chloroquine phosphate () tablets, USP 250 mg are white to off-white, round, film-coated tablets, debossed with and on one side and break line on the other side.
NDC 63304-460-03 Bottles of 10
NDC 63304-460-50 Bottles of 50
NDC 63304-460-10 Bottles of 1000
Dispense in a tight, light-resistant container as defined in the USP using a child-resistant closure.
Store at 20 - 25° C (68 - 77° F) [See USP Controlled Room Temperature].
Protect from light and moisture.
You may report side effects to FDA at
Chloroquine phosphate () References
Manufactured for:
Ranbaxy Pharmaceuticals Inc.
Jacksonville, FL 32257 USA
by: Ohm Laboratories Inc.
North Brunswick, NJ 08902 USA
July 2010
