Dose and Dosage:
- The dosage of chloroquine varies depending on the condition being treated and individual factors such as weight and age.
- For malaria prophylaxis, the typical adult dosage is 500 mg once a week, starting 2 weeks before potential exposure and continuing for 4 to 6 weeks after leaving the endemic area.
- For treatment of malaria, the typical adult dosage is an initial dose of 600 mg followed by 300 mg 6 to 8 hours later, then 300 mg daily for 2 consecutive days.
- Dosage adjustments may be necessary in patients with hepatic impairment or renal impairment.
Frequency:
- The frequency of dosing varies depending on the indication. For malaria prophylaxis, it is usually administered once weekly, while for treatment of acute malaria, it may be given in divided doses over several days.
Route of Administration (ROA):
- Chloroquine is typically administered orally in the form of tablets or suspension.
Mechanism of Action (MOA):
- Chloroquine’s mechanism of action involves inhibiting the growth of Plasmodium parasites by interfering with their ability to digest and utilize hemoglobin.
Pharmacokinetics (PK):
- Chloroquine is well absorbed after oral administration and widely distributed in body tissues, including the liver, spleen, kidney, and lung.
- It is extensively metabolized in the liver by CYP450 enzymes, primarily CYP2C8 and CYP3A4, into active metabolites.
- The elimination half-life of chloroquine is approximately 20 to 60 days.
Pharmacodynamics (PD):
- Chloroquine exerts its antimalarial effects by accumulating within the acidic vacuoles of Plasmodium parasites, leading to disruption of their metabolic processes and eventual death.
Pathophysiology:
- Chloroquine’s efficacy against malaria is attributed to its ability to disrupt the metabolism of Plasmodium parasites, particularly within their digestive vacuoles.
Indications:
- Chloroquine is indicated for the prophylaxis and treatment of malaria caused by susceptible strains of Plasmodium parasites.
- It may also be used off-label for conditions such as rheumatoid arthritis and lupus erythematosus.
Contraindications:
- Hypersensitivity to chloroquine or related compounds
- Pre-existing retinopathy
- G6PD deficiency
- Severe hepatic impairment
- Seizure disorders
Drug Interactions:
- Chloroquine may interact with other medications, including antacids, cimetidine, mefloquine, and certain antibiotics and antifungal agents.
- Concomitant use with drugs known to prolong the QT interval or induce arrhythmias should be avoided.
Monitoring and Laboratory Tests:
- Regular monitoring of renal and hepatic function, as well as blood cell counts, may be necessary during long-term therapy with chloroquine.
- Ophthalmologic examination may be recommended for patients receiving prolonged treatment to detect any signs of retinal toxicity.
- Electrocardiogram (ECG) monitoring may be warranted in patients with pre-existing cardiac conditions or those at risk of QT prolongation.
Why is this medication prescribed? Chloroquine is primarily prescribed for the prevention and treatment of malaria caused by susceptible strains of Plasmodium parasites. It may also be used off-label for the treatment of autoimmune conditions such as rheumatoid arthritis and lupus erythematosus.
How should this medicine be used? The dosage and administration of chloroquine depend on the indication being treated, the patient’s age and weight, and other factors. It is typically administered orally in the form of tablets or suspension. For malaria prophylaxis, chloroquine is usually taken once weekly starting 2 weeks before potential exposure and continuing for 4 to 6 weeks after leaving the endemic area. For the treatment of acute malaria, an initial higher dose may be followed by lower maintenance doses over several days. Dosage adjustments may be necessary in patients with hepatic or renal impairment.
Other uses for this medicine Aside from its primary use in preventing and treating malaria, chloroquine has been investigated for its potential efficacy in treating autoimmune conditions such as rheumatoid arthritis and lupus erythematosus.
What special precautions should I follow?
- Patients should inform their healthcare provider about any pre-existing medical conditions, including hepatic impairment, renal impairment, and G6PD deficiency.
- Caution is advised in patients with a history of seizure disorders or psychiatric illness.
- Regular ophthalmologic monitoring is recommended during long-term therapy to detect any signs of retinal toxicity.
What special dietary instructions should I follow? There are no specific dietary restrictions associated with chloroquine therapy. However, patients should maintain a balanced diet and stay well-hydrated, especially in regions where malaria is endemic.
What should I do if I forget a dose? If a dose of chloroquine is missed, it should be taken as soon as remembered. However, if it is almost time for the next dose, the missed dose should be skipped, and the regular dosing schedule resumed. Patients should not double the dose to make up for a missed one.
What side effects can this medication cause? Common side effects of chloroquine may include gastrointestinal upset, headache, dizziness, blurred vision, and skin rash. Less common but more serious side effects may include retinal toxicity, cardiac arrhythmias, and hematologic disorders. Patients should seek medical attention if they experience any adverse effects while taking chloroquine.
What should I know about storage and disposal of this medication? Chloroquine should be stored at room temperature away from moisture and heat. It should be kept out of reach of children and pets. Unused or expired medication should be properly disposed of according to local regulations or guidelines.
In case of emergency/overdose In the event of an overdose or suspected overdose of chloroquine, immediate medical attention should be sought. Overdose symptoms may include severe dizziness, fainting, seizures, or difficulty breathing.