Drugs

Chloroquine : Uses, Dosage, Side Effects, Interactions, & Contraindications

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.

Inhibiting polymerization of heme

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.

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