chloroquine phosphate (redirected from 4-aminoquinolone derivative)

chlo·ro·quine phosphate (klôr-kwn, -kwn)

n.

An antimalarial drug also used in the treatment of hepatic amebiasis and certain skin diseases.

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chloroquine phosphate

Pharmacologic class: 4-aminoquinolone derivative

Therapeutic class: Antimalarial, amebicide

Pregnancy risk category C

FDA Boxed Warning

• Drug is indicated for treating malaria and extraintestinal amebiasis.
• Before prescribing, clinician should be familiar with complete package insert contents.

Action

Unknown. Antimalarial action may occur through inhibition of protein synthesis and alteration of DNA in susceptible parasites.

Availability

Tablets: 250 mg (150-mg base), 500 mg (300-mg base)

⊘Indications and dosages

➣ Uncomplicated acute malarial attacks

Adults: Initially, 1 g (600-mg base) P.O., then an additional 500 mg (300-mg base) P.O. 6 hours later and a single dose of 500 mg (300-mg base) P.O. on second and third days. Or initially, 160- to 200-mg base I.M., repeated in 6 hours (800-mg base maximum dosage during first 24 hours); continue for 3 days until total dosage of 1.5-g base has been given. Switch to oral therapy as soon as possible.

Children: Initially, 10 mg (base)/kg P.O., then 5 mg (base)/kg 6 hours, 24 hours, and 36 hours later; don't exceed recommended adult dosage. Or initially, 5 mg (base)/kg I.M. repeated 6 hours later, 18 hours after second dose, and then 24 hours after third dose; don't exceed recommended adult dosage.

➣ Malaria prophylaxis

Adults: 500 mg (300-mg base) P.O. weekly 1 to 2 weeks before visiting endemic area and continued for 4 weeks after leaving area. If therapy starts after malaria exposure, initial dosage is 600-mg base P.O. in two divided doses given 6 hours apart.

Children: 5 mg (base)/kg P.O. weekly for 1 to 2 weeks before visiting endemic area and continued for 4 weeks after leaving area, to a maximum dosage of 300 mg weekly. If treatment starts after exposure, 10 mg (base)/kg P.O. in two divided doses 6 hours apart and continued for 8 weeks after leaving area.

➣ Extraintestinal amebiasis

Adults: Initially, 1 g (600-mg base) P.O. daily for 2 days, then 500 mg (300-mg base) daily for 2 to 3 weeks. When oral therapy isn't tolerated, give 160- to 200-mg base I.M. daily for 10 to 12 days; switch to oral therapy as soon as possible.

Children: 10 mg (base)/kg P.O. once daily for 2 to 3 weeks, to a maximum dosage of 300 mg (base) daily

Off-label uses

• Lupus erythematosus
• Rheumatoid arthritis

Contraindications

• Hypersensitivity to drug
• Retinal and visual field changes
• Porphyria

Precautions

Use cautiously in:
• severe GI, neurologic, or blood disorders; hepatic impairment; G6PD deficiency; neurologic disease; eczema; alcoholism
• pregnant patients
• children.

Administration

• For obese patient, determine weight-based dosages from lean body weight. (Drug is stored in body tissues and eliminated slowly.)

Route	Onset	Peak	Duration
P.O.	Unknown	1-3 hr	Unknown

Adverse reactions

CNS: mild and transient headache, personality changes, dizziness, vertigo neuropathy, seizures

CV: hypotension, ECG changes

EENT: blurred vision, difficulty focusing, reversible corneal changes, irreversible retinal damage leading to vision loss, scotomas, ototoxicity, tinnitus, nerve deafness

GI: nausea, vomiting, diarrhea, abdominal pain, stomatitis, anorexia

Hematologic: agranulocytosis, aplastic anemia, hemolytic anemia, thrombocytopenia

Skin: lichen planus eruptions, skin and mucosal pigmentation changes, pruritus, pleomorphic skin eruptions

Interactions

Drug-drug. Aluminum and magnesium salts, kaolin: decreased GI absorption of chloroquine

Ampicillin: reduced ampicillin bioavailability

Cimetidine: decreased hepatic metabolism of chloroquine

Cyclosporine: sudden increase in cyclosporine blood level

Drug-diagnostic tests. Granulocytes, hemoglobin, platelets: decreased values

Drug-behaviors. Sun exposure: exacerbation of drug-induced dermatoses

Patient monitoring

• Monitor hepatic enzyme levels in patients with hepatic disease.
• Assess creatinine levels in patients with renal insufficiency or failure.
• In long-term therapy (as for lupus or rheumatoid arthritis), be aware that desired effects may be delayed for up to 6 months.
• Be aware that drug is secreted in breast milk but not in sufficient amounts to prevent malaria in infant.

Patient teaching

• Tell patient to take drug with food at evenly spaced intervals.
☞ Instruct patient to immediately report blurred vision or hearing changes.
• In areas where malaria is endemic, advise pregnant patient to consult prescriber about taking drug.
• Inform patient on long-term therapy that beneficial effects may take up to 6 months.
• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs, tests, and behaviors mentioned above.