Chloroquine : Therapeutic uses, Clinical uses, Indications, Dosage, Side Effects, Warnings, Interactions, Precautions, Contraindications & Brand names
Chloroquine phosphate is a quinoline drug, useful in preventing or treating the malaria.
Dose : 250-500 mg [16.6 mg salt = 10 mg chloroquine base]
Route : Oral
Onset of action : ?
Plasma half-life : 3-5 days
Duration of action : N/A
Bioavailability : ~89%
Plasma protein binding : 55%
Metabolism : Hepatic (Main metabolite- desethylchloroquine)
Pregnancy risk category : N/A
Chemical formula : C18H26ClN3
IUPAC name : (RS)-N’-(7-chloroquinolin-4-yl)-N,N-diethyl-pentane-1,4-diamine
Trade name : Aralen, Chloroquine FNA, Resochin, Dawaquin, and Lariago
Therapeutic uses : Chloroquine phosphate has following usage :
- Used to prevent & treat the uncomplicated malaria due to susceptible strains.
- Used to treat extraintestinal amebiasis.
- Off Label Uses: Coronavirus Disease 2019 (COVID-19), Porphyria cutanea tarda, Autoimmune diseases such as discoid lupus erythematosus, & Glioblastoma (Orphan).
Mechanism of action
Malaria
- Chloroquine interfere with heme detoxification.
Chloroquine, a weak base, concentrates in the highly acidic digestive vacuoles of susceptible Plasmodium, where it binds to heme and disrupts its sequestration.
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Inhibiting polymerization of heme
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Failure to inactivate heme or even enhanced toxicity of drug-heme complexes is thought to kill the parasites via oxidative damage to membranes, digestive proteases, or other critical biomolecules.
Autoimmune diseases
- Exact mechanism unknown but may include inhibition of phospholipase A2 and platelet aggregation, membrane stabilization, effects on the immune system, and antioxidant activity.
Coronavirus Disease 2019 (COVID-19)
- Hampers low PH dependant steps of viral replication.
Side effects : Chloroquine is safe when taken in proper doses and for recommended total durations. Commonly observed side effects are as following:
Common
- GI upset such as nausea, vomiting, loss of appetite, diarrhea, abdominal cramps,
- Dizziness, or headache,
- Urticaria, Pruritus.
Uncommon
- Blurring of vision, diplopia,
- Confusion, convulsions,
- Lichenoid skin eruptions, bleaching of hair,
- Widening of the QRS interval (QTc prolongation), T-wave abnormalities,
- Hemolysis and blood dyscrasias particularly in G6PD,
- Discoloration of nail beds & mucous membranes,
- Retinopathy (dose-dependent),
- Ototoxicity,
- Toxic myopathy,
- Cardiopathy,
- Peripheral neuropathy.
Acute chloroquine toxicity: Chloroquine acute toxicity is encountered most frequently when therapeutic or high doses are administered too rapidly because its safety margin is narrow and a single dose of 30 mg/kg may be fatal.
- Toxic manifestations: Cardiovascular effects (include hypotension, vasodilation, suppressed myocardial function, cardiac arrhythmias, and eventual cardiac arrest), CNS effects (include confusion, convulsions, & coma).
- Treament: Prompt treatment with mechanical ventilation, epinephrine, and diazepam.
Patients receiving long-term, high-dose therapy should undergo ophthalmological and neurological evaluations every 3-6 months.
Drug Interactions : Chloroquine may interact with following drugs :
- Antacids × Chloroquine: May reduce absorption of chloroquine.
- Mefloquine × Chloroquine: Increased risk for QTc-prolongation & seizures, lack of added benefit.
- QT-prolonging agents × Chloroquine: Enhancing the QTc-prolonging effect of QT-prolonging agents (Highest Risk).
- Digoxin × Chloroquine: Increases the serum concentration of digoxin.
- Cyclosporine × Chloroquine: Increases the serum concentration of digoxin.
- Antidiabetic agents × Chloroquine: May enhance the hypoglycemic effect of Hypoglycemia-Associated Agents.
- Rabies vaccine × Chloroquine: Attenuates the efficacy of vaccine when administered at the same time.
- Cholera vaccine × Chloroquine: Attenuates the efficacy of vaccine when administered at the same time.
- Antiepileptics × Chloroquine: Activity of antiepileptic drugs might be impaired.
- Penicillamine × Chloroquine:
- Retinal toxic agents (Tamoxifen) × Chloroquine: Increased risk of retinal toxicity.
Precautions
Before using this medication, tell your doctor or pharmacist
- If you are allergic to it; or if you have any other allergies.
- Your medical history, especially of G6PD deficiency, eye problems, ear problems, kidney disease, liver disease, regular alcohol use/abuse, skin problems such as psoriasis, blood disorders such as porphyria, seizures, myasthenia gravis.
Cautions
- Chloroquine should be used cautiously if at all in the presence of advanced liver disease or severe GI, neurological, or blood disorders.
- In individuals with decreased renal function, dosage should be adjusted to avoid elevated plasma concentrations.
- Chloroquine is not recommended for treating individuals who have epilepsy or myasthenia gravis.
- Concomitant use of gold or phenylbutazone with Chloroquine, in the treatment of rheumatoid arthritis, should be avoided because of the tendency of all three agents to produce dermatitis.
Contraindications
- Known hypersensitivity to hydroxychloroquine, 4-aminoquinoline derivatives, or any component of the formulation.
- Retinal or visual field changes due to any etiology (when used for indications other than acute malaria).
- Exfoliative skin conditions such as psoriasis.
- Porphyria.
For detailed query or in case of uncertainty, Always consult your doctor or pharmacist.
