Chloroquine Phosphate 500mg Tablets
It is used to treat or prevent malaria. It is used to treat a type of bowel infection.It may be given to you for other reasons. Talk with the doctor.
Drug Class
Antimalarial; Antirheumatic
Pharmacologic Class
4-aminoquinoline
Pregnancy Category
Category D
FDA Approved
Jan 1970
DEA Schedule
Not Controlled
Overview
What is this medicine?
Chloroquine is a medication used to prevent and treat malaria, a serious disease caused by parasites. It is also used to treat certain autoimmune conditions like rheumatoid arthritis and lupus, where it helps reduce inflammation and pain.
How to Use This Medicine
Taking Your Medication
To use this medication correctly, follow your doctor's instructions and read all the information provided. You can take this medication with or without food. If it causes stomach upset, taking it with food may help. Continue taking the medication as directed by your doctor or healthcare provider, even if you start feeling well.
It's essential to avoid taking antacids or kaolin within 4 hours of taking this medication.
Storing and Disposing of Your Medication
Store this medication at room temperature in a dry place, avoiding the bathroom. Keep all medications in a safe location, out of the reach of children and pets. When disposing of unused or expired medications, do not flush them down the toilet or pour them down the drain unless instructed to do so. Instead, consult your pharmacist for guidance on the best disposal method. You may also want to explore local drug take-back programs.
Missing a Dose
If you miss a dose, take it as soon as you remember. However, if it's close to the time for your next scheduled dose, skip the missed dose and resume your regular dosing schedule. Do not take two doses at the same time or take extra doses to make up for the missed one.
To use this medication correctly, follow your doctor's instructions and read all the information provided. You can take this medication with or without food. If it causes stomach upset, taking it with food may help. Continue taking the medication as directed by your doctor or healthcare provider, even if you start feeling well.
It's essential to avoid taking antacids or kaolin within 4 hours of taking this medication.
Storing and Disposing of Your Medication
Store this medication at room temperature in a dry place, avoiding the bathroom. Keep all medications in a safe location, out of the reach of children and pets. When disposing of unused or expired medications, do not flush them down the toilet or pour them down the drain unless instructed to do so. Instead, consult your pharmacist for guidance on the best disposal method. You may also want to explore local drug take-back programs.
Missing a Dose
If you miss a dose, take it as soon as you remember. However, if it's close to the time for your next scheduled dose, skip the missed dose and resume your regular dosing schedule. Do not take two doses at the same time or take extra doses to make up for the missed one.
Lifestyle & Tips
- Take with food or milk to reduce stomach upset.
- Do not take antacids (like Maalox or Tums) within 4 hours of taking chloroquine, as they can reduce its absorption.
- For malaria prophylaxis, take exactly as directed, starting before travel and continuing for 4 weeks after leaving the malaria area.
- Avoid excessive sun exposure, as chloroquine can increase sensitivity to sunlight.
- Report any vision changes immediately to your doctor.
Available Forms & Alternatives
Available Strengths:
Dosing & Administration
Adult Dosing
Standard Dose:
Varies by indication. For malaria prophylaxis: 500 mg (300 mg base) orally once weekly. For acute malaria treatment: Initial 1000 mg (600 mg base) orally, followed by 500 mg (300 mg base) 6-8 hours later, then 500 mg (300 mg base) daily for 2 days (total 2500 mg phosphate / 1500 mg base over 3 days). For rheumatoid arthritis/lupus: 250-500 mg (150-300 mg base) orally daily.
Dose Range:
250 - 1000 mg
Condition-Specific Dosing:
Malaria Prophylaxis:
500 mg (300 mg base) once weekly, starting 1-2 weeks before exposure and continuing for 4 weeks after leaving endemic area.
Acute Malaria Treatment:
Initial 1000 mg (600 mg base), then 500 mg (300 mg base) at 6-8 hours, then 500 mg (300 mg base) daily for 2 days.
Extraintestinal Amebiasis:
1000 mg (600 mg base) daily for 2 days, then 500 mg (300 mg base) daily for 2-3 weeks.
Rheumatoid Arthritis/Systemic Lupus Erythematosus:
250-500 mg (150-300 mg base) daily; maximum 2.5 mg/kg/day (base).
Pediatric Dosing
Neonatal:
Not established (use with extreme caution, if at all, due to toxicity risk).
Infant:
Malaria prophylaxis: 5 mg base/kg (max 300 mg base) orally once weekly. Acute malaria treatment: Initial 10 mg base/kg (max 600 mg base), then 5 mg base/kg (max 300 mg base) at 6-8 hours, then 5 mg base/kg (max 300 mg base) daily for 2 days (total 25 mg base/kg over 3 days).
Child:
Malaria prophylaxis: 5 mg base/kg (max 300 mg base) orally once weekly. Acute malaria treatment: Initial 10 mg base/kg (max 600 mg base), then 5 mg base/kg (max 300 mg base) at 6-8 hours, then 5 mg base/kg (max 300 mg base) daily for 2 days (total 25 mg base/kg over 3 days).
Adolescent:
Malaria prophylaxis: 5 mg base/kg (max 300 mg base) orally once weekly. Acute malaria treatment: Initial 10 mg base/kg (max 600 mg base), then 5 mg base/kg (max 300 mg base) at 6-8 hours, then 5 mg base/kg (max 300 mg base) daily for 2 days (total 25 mg base/kg over 3 days).
Dose Adjustments
Renal Impairment:
Mild:
No specific adjustment recommended, but monitor for increased side effects.
Moderate:
Consider dose reduction (e.g., 50% reduction for CrCl < 50 mL/min) or extended dosing interval, especially for long-term use.
Severe:
Significant dose reduction (e.g., 50-75% reduction for CrCl < 10 mL/min) or extended dosing interval is necessary. Avoid if possible for non-life-threatening indications.
Dialysis:
Chloroquine is not significantly removed by hemodialysis. Follow severe renal impairment guidelines. Monitor closely for toxicity.
Hepatic Impairment:
Mild:
No specific adjustment recommended.
Moderate:
Use with caution; consider dose reduction or extended dosing interval, especially for long-term use, due to hepatic metabolism.
Severe:
Use with extreme caution; significant dose reduction may be necessary. Avoid if possible for non-life-threatening indications.
Pharmacology
Mechanism of Action
Chloroquine is a 4-aminoquinoline that acts as an antimalarial by concentrating in the parasite's food vacuole, inhibiting the polymerization of heme into hemozoin. This leads to the accumulation of toxic heme, which disrupts parasite metabolism and ultimately causes parasite death. It also has immunomodulatory effects, inhibiting lysosomal activity, prostaglandin synthesis, and cytokine production, which contributes to its anti-inflammatory properties in conditions like rheumatoid arthritis and lupus.
Pharmacokinetics
Absorption:
Bioavailability:
Approximately 89%
Tmax:
3-5 hours (for parent drug)
FoodEffect:
Food may slightly delay absorption but does not significantly affect bioavailability; taking with food may reduce GI upset.
Distribution:
Vd:
Extremely large (100-1000 L/kg), indicating extensive tissue binding and accumulation.
ProteinBinding:
Approximately 55%
CnssPenetration:
Limited but present; concentrations in CSF are about 10-30% of plasma levels.
Elimination:
HalfLife:
Terminal elimination half-life is highly variable and prolonged, ranging from 3-5 days to 1-2 months (due to slow release from tissues).
Clearance:
Highly variable, dependent on renal and hepatic function.
ExcretionRoute:
Primarily renal (approximately 50% unchanged drug), with some biliary excretion.
Unchanged:
Approximately 50%
Pharmacodynamics
OnsetOfAction:
Antimalarial: Within hours to days. Anti-inflammatory: Weeks to months (for full therapeutic effect in RA/SLE).
PeakEffect:
Antimalarial: Within 24-48 hours. Anti-inflammatory: 3-6 months.
DurationOfAction:
Antimalarial: Due to long half-life, effects persist for weeks after discontinuation. Anti-inflammatory: Effects persist as long as drug is taken.
Safety & Warnings
Side Effects
Urgent Side Effects: Seek Medical Help Immediately
Although rare, this medication can cause severe and potentially life-threatening side effects. If you experience any of the following symptoms, contact your doctor or seek medical attention right away:
Signs of an allergic reaction: rash, hives, itching, red, swollen, blistered, or peeling skin (with or without fever), wheezing, tightness in the chest or throat, trouble breathing, swallowing, or talking, unusual hoarseness, or swelling of the mouth, face, lips, tongue, or throat
Signs of liver problems: dark urine, tiredness, decreased appetite, upset stomach or stomach pain, light-colored stools, vomiting, or yellow skin or eyes
Signs of low blood sugar: dizziness, headache, feeling sleepy, feeling weak, shaking, fast heartbeat, confusion, hunger, or sweating
Trouble controlling body movements or restlessness
Seizures
Mood changes or changes in behavior
Trouble sleeping
Feeling confused
Hallucinations (seeing or hearing things that are not there)
Changes in hearing or ringing in the ears
Muscle pain or weakness
Burning, numbness, or tingling sensations that are not normal
Fever, chills, or sore throat; unexplained bruising or bleeding; or feeling very tired or weak
Severe skin reactions (Stevens-Johnson syndrome/toxic epidermal necrolysis): red, swollen, blistered, or peeling skin (with or without fever); red or irritated eyes; or sores in the mouth, throat, nose, or eyes
Heart problems: fast or abnormal heartbeat, severe dizziness or fainting, or shortness of breath, significant weight gain, or swelling in the arms or legs
Other Possible Side Effects
Like all medications, this drug can cause side effects. While many people may not experience any side effects or only minor ones, it's essential to discuss any concerns with your doctor. If you experience any of the following side effects, contact your doctor or seek medical attention if they bother you or do not go away:
Stomach pain or cramps
Decreased appetite
Diarrhea, upset stomach, or vomiting
Headache
Changes in skin color
Changes in hair color
Hair loss
Reporting Side Effects
This list is not exhaustive, and you may experience other side effects. If you have questions or concerns about side effects, contact your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Although rare, this medication can cause severe and potentially life-threatening side effects. If you experience any of the following symptoms, contact your doctor or seek medical attention right away:
Signs of an allergic reaction: rash, hives, itching, red, swollen, blistered, or peeling skin (with or without fever), wheezing, tightness in the chest or throat, trouble breathing, swallowing, or talking, unusual hoarseness, or swelling of the mouth, face, lips, tongue, or throat
Signs of liver problems: dark urine, tiredness, decreased appetite, upset stomach or stomach pain, light-colored stools, vomiting, or yellow skin or eyes
Signs of low blood sugar: dizziness, headache, feeling sleepy, feeling weak, shaking, fast heartbeat, confusion, hunger, or sweating
Trouble controlling body movements or restlessness
Seizures
Mood changes or changes in behavior
Trouble sleeping
Feeling confused
Hallucinations (seeing or hearing things that are not there)
Changes in hearing or ringing in the ears
Muscle pain or weakness
Burning, numbness, or tingling sensations that are not normal
Fever, chills, or sore throat; unexplained bruising or bleeding; or feeling very tired or weak
Severe skin reactions (Stevens-Johnson syndrome/toxic epidermal necrolysis): red, swollen, blistered, or peeling skin (with or without fever); red or irritated eyes; or sores in the mouth, throat, nose, or eyes
Heart problems: fast or abnormal heartbeat, severe dizziness or fainting, or shortness of breath, significant weight gain, or swelling in the arms or legs
Other Possible Side Effects
Like all medications, this drug can cause side effects. While many people may not experience any side effects or only minor ones, it's essential to discuss any concerns with your doctor. If you experience any of the following side effects, contact your doctor or seek medical attention if they bother you or do not go away:
Stomach pain or cramps
Decreased appetite
Diarrhea, upset stomach, or vomiting
Headache
Changes in skin color
Changes in hair color
Hair loss
Reporting Side Effects
This list is not exhaustive, and you may experience other side effects. If you have questions or concerns about side effects, contact your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Seek Immediate Medical Attention If You Experience:
- Any changes in vision (blurred vision, difficulty reading, halos around lights, dark spots, loss of side vision)
- Muscle weakness or difficulty walking
- Ringing in the ears or hearing loss
- Severe dizziness or lightheadedness
- Unusual bleeding or bruising
- Fever, sore throat, or other signs of infection
- Severe skin rash or peeling skin
- Seizures
- Irregular heartbeat or palpitations
- Signs of low blood sugar (shakiness, sweating, confusion, extreme hunger)
Before Using This Medicine
Before Taking This Medication: Important Information to Share with Your Doctor
It is essential to inform your doctor about the following:
Any allergies you have, including allergies to this medication, its components, or other substances, such as foods or drugs. Be sure to describe the allergic reaction and its symptoms.
Any history of eye changes or vision problems.
Certain health conditions, including porphyria or psoriasis.
If you are currently taking cimetidine or tamoxifen, as these medications may interact with this drug.
Please note that this is not an exhaustive list of potential interactions. To ensure your safety, it is crucial to disclose all of your:
Prescription and over-the-counter (OTC) medications
Natural products
Vitamins
Health problems
Your doctor and pharmacist need this information to determine whether it is safe for you to take this medication with your existing health conditions and medications. Never start, stop, or adjust the dosage of any medication without first consulting your doctor.
It is essential to inform your doctor about the following:
Any allergies you have, including allergies to this medication, its components, or other substances, such as foods or drugs. Be sure to describe the allergic reaction and its symptoms.
Any history of eye changes or vision problems.
Certain health conditions, including porphyria or psoriasis.
If you are currently taking cimetidine or tamoxifen, as these medications may interact with this drug.
Please note that this is not an exhaustive list of potential interactions. To ensure your safety, it is crucial to disclose all of your:
Prescription and over-the-counter (OTC) medications
Natural products
Vitamins
Health problems
Your doctor and pharmacist need this information to determine whether it is safe for you to take this medication with your existing health conditions and medications. Never start, stop, or adjust the dosage of any medication without first consulting your doctor.
Precautions & Cautions
Important Warnings and Cautions
When taking this medication, it is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, about your treatment.
Severe Eye Problems
This medication can cause a severe eye problem, potentially leading to permanent vision loss. The risk is higher if you have pre-existing eye or kidney problems, take high doses, use the medication for more than 5 years, or take certain other medications like tamoxifen. If you experience any changes in your vision, such as blurred or foggy vision, difficulty focusing or reading, or trouble seeing in low light, contact your doctor immediately. Additionally, seek medical attention right away if you lose part of your vision, see dark spots, or have a limited field of vision. Regular eye exams, as recommended by your doctor, are crucial to monitor your eye health.
Low G6PD Levels
If you have low levels of the enzyme G6PD, you may be at risk of developing anemia. This condition is more common in individuals of African, South Asian, Middle Eastern, and Mediterranean descent. Your doctor may recommend regular blood tests to monitor your condition.
Long-Term Use and Blood Work
If you are taking this medication for an extended period, your doctor may recommend regular blood tests to monitor your health. It is also essential to discuss your alcohol consumption with your doctor, as it may interact with the medication.
Interactions with Other Medications
When taking other medications, they may need to be taken at a different time than this medication. Consult your doctor or pharmacist to determine the best schedule for your medications.
Sun Sensitivity
This medication can increase your risk of sunburn. Take precautions when spending time outdoors, and inform your doctor if you experience excessive sunburn.
Low Blood Sugar
This medication can cause low blood sugar, which can be life-threatening in severe cases. Monitor your blood sugar levels as directed by your doctor and seek medical attention if you experience any symptoms.
Severe and Potentially Deadly Reaction
In rare cases, this medication can cause a severe and potentially deadly reaction, characterized by fever, rash, swollen glands, and problems with organs such as the liver, kidney, blood, heart, muscles, joints, or lungs. If you have any concerns or questions, discuss them with your doctor.
Cancer Risk
This medication may increase the risk of certain types of cancer. Discuss the benefits and risks with your doctor.
Accidental Exposure and Age-Related Risks
Keep this medication out of reach of children, as accidental exposure can be fatal. If a child ingests this medication, seek medical help immediately. Additionally, if you are 65 or older, use this medication with caution, as you may be more susceptible to side effects.
Pregnancy and Breastfeeding
If you are pregnant, plan to become pregnant, or are breastfeeding, discuss the benefits and risks of this medication with your doctor.
Malaria Prevention
When using this medication to prevent malaria, it is essential to take additional precautions, including:
Using screens and bed netting
Applying insect repellent (10% to 35% DEET) and permethrin spray on clothing and nets
Avoiding spraying insect repellents on children
Reducing outdoor activities during evening and nighttime hours
If you experience a fever while in or after leaving a malaria-infested area, contact your doctor immediately. If you are pregnant and traveling to a malaria-infested area, discuss the risks with your doctor before taking this medication.
When taking this medication, it is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, about your treatment.
Severe Eye Problems
This medication can cause a severe eye problem, potentially leading to permanent vision loss. The risk is higher if you have pre-existing eye or kidney problems, take high doses, use the medication for more than 5 years, or take certain other medications like tamoxifen. If you experience any changes in your vision, such as blurred or foggy vision, difficulty focusing or reading, or trouble seeing in low light, contact your doctor immediately. Additionally, seek medical attention right away if you lose part of your vision, see dark spots, or have a limited field of vision. Regular eye exams, as recommended by your doctor, are crucial to monitor your eye health.
Low G6PD Levels
If you have low levels of the enzyme G6PD, you may be at risk of developing anemia. This condition is more common in individuals of African, South Asian, Middle Eastern, and Mediterranean descent. Your doctor may recommend regular blood tests to monitor your condition.
Long-Term Use and Blood Work
If you are taking this medication for an extended period, your doctor may recommend regular blood tests to monitor your health. It is also essential to discuss your alcohol consumption with your doctor, as it may interact with the medication.
Interactions with Other Medications
When taking other medications, they may need to be taken at a different time than this medication. Consult your doctor or pharmacist to determine the best schedule for your medications.
Sun Sensitivity
This medication can increase your risk of sunburn. Take precautions when spending time outdoors, and inform your doctor if you experience excessive sunburn.
Low Blood Sugar
This medication can cause low blood sugar, which can be life-threatening in severe cases. Monitor your blood sugar levels as directed by your doctor and seek medical attention if you experience any symptoms.
Severe and Potentially Deadly Reaction
In rare cases, this medication can cause a severe and potentially deadly reaction, characterized by fever, rash, swollen glands, and problems with organs such as the liver, kidney, blood, heart, muscles, joints, or lungs. If you have any concerns or questions, discuss them with your doctor.
Cancer Risk
This medication may increase the risk of certain types of cancer. Discuss the benefits and risks with your doctor.
Accidental Exposure and Age-Related Risks
Keep this medication out of reach of children, as accidental exposure can be fatal. If a child ingests this medication, seek medical help immediately. Additionally, if you are 65 or older, use this medication with caution, as you may be more susceptible to side effects.
Pregnancy and Breastfeeding
If you are pregnant, plan to become pregnant, or are breastfeeding, discuss the benefits and risks of this medication with your doctor.
Malaria Prevention
When using this medication to prevent malaria, it is essential to take additional precautions, including:
Using screens and bed netting
Applying insect repellent (10% to 35% DEET) and permethrin spray on clothing and nets
Avoiding spraying insect repellents on children
Reducing outdoor activities during evening and nighttime hours
If you experience a fever while in or after leaving a malaria-infested area, contact your doctor immediately. If you are pregnant and traveling to a malaria-infested area, discuss the risks with your doctor before taking this medication.
Overdose Information
Overdose Symptoms:
- Headache
- Drowsiness
- Visual disturbances (transient blindness, blurred vision)
- Cardiovascular collapse (hypotension, shock)
- Cardiac arrhythmias (QT prolongation, Torsades de Pointes, ventricular fibrillation)
- Seizures
- Respiratory depression
- Coma
- Cardiac arrest (can occur rapidly)
What to Do:
Seek immediate emergency medical attention. Call 911 or your local emergency number. For poison control, call 1-800-222-1222. Overdose is extremely dangerous and can be rapidly fatal. Treatment involves immediate gastric lavage, activated charcoal, and supportive care including respiratory and cardiovascular support, vasopressors, and antiarrhythmics.
Drug Interactions
Contraindicated Interactions
- Mefloquine (increased risk of seizures and ECG abnormalities)
- Amiodarone (increased risk of cardiac arrhythmias and QT prolongation)
Major Interactions
- QT-prolonging drugs (e.g., antiarrhythmics, antipsychotics, macrolides, fluoroquinolones) - increased risk of torsades de pointes.
- Antacids (aluminum- or magnesium-containing) and Kaolin - decreased chloroquine absorption (separate administration by at least 4 hours).
- Cyclosporine - increased cyclosporine plasma concentrations (monitor cyclosporine levels).
- Digoxin - increased digoxin serum levels (monitor digoxin levels).
- Cimetidine - inhibits chloroquine metabolism, leading to increased chloroquine plasma concentrations and toxicity.
- Praziquantel - decreased praziquantel plasma concentrations (may reduce efficacy).
Moderate Interactions
- Ampicillin - decreased ampicillin absorption (separate administration).
- Neostigmine, Pyridostigmine - chloroquine may antagonize the effects of anticholinesterases.
- Hepatotoxic drugs - increased risk of liver injury.
- Myelosuppressive drugs - increased risk of bone marrow suppression.
Minor Interactions
- Not specifically identified as minor, but general caution with drugs affecting renal or hepatic function.
Monitoring
Baseline Monitoring
Ophthalmologic examination (visual acuity, fundoscopy, visual fields, color vision)
Rationale: To establish baseline and detect pre-existing retinopathy, as chloroquine can cause irreversible retinal damage.
Timing: Prior to initiation of therapy, especially for long-term use.
Complete Blood Count (CBC) with differential
Rationale: To assess for baseline hematologic abnormalities, as chloroquine can cause bone marrow suppression (rare).
Timing: Prior to initiation of therapy.
Liver Function Tests (LFTs)
Rationale: To assess baseline hepatic function, as chloroquine is metabolized by the liver and can rarely cause hepatotoxicity.
Timing: Prior to initiation of therapy.
Electrocardiogram (ECG)
Rationale: To assess for baseline cardiac abnormalities, especially QT interval, given the risk of cardiotoxicity and QT prolongation.
Timing: Prior to initiation of therapy, particularly in patients with pre-existing cardiac disease or on other QT-prolonging drugs.
Routine Monitoring
Ophthalmologic examination (visual acuity, fundoscopy, visual fields, color vision)
Frequency: Annually after 5 years of continuous therapy or sooner if high risk (e.g., cumulative dose > 1000g, renal impairment, concomitant tamoxifen, age > 60).
Target: Normal findings; no signs of retinopathy.
Action Threshold: Discontinue drug and refer to ophthalmologist immediately if any signs of retinopathy (e.g., visual field defects, pigmentary changes) are detected.
Complete Blood Count (CBC) with differential
Frequency: Periodically (e.g., every 3-6 months) for long-term therapy.
Target: Within normal limits.
Action Threshold: Discontinue drug if significant bone marrow suppression (e.g., neutropenia, thrombocytopenia) occurs.
Liver Function Tests (LFTs)
Frequency: Periodically (e.g., every 3-6 months) for long-term therapy.
Target: Within normal limits.
Action Threshold: Discontinue drug if significant elevation in liver enzymes occurs.
ECG (QTc interval)
Frequency: Periodically, especially in patients with cardiac risk factors or on concomitant QT-prolonging drugs.
Target: QTc < 450 ms (men), < 470 ms (women).
Action Threshold: Discontinue drug if QTc prolongation > 500 ms or increase of > 60 ms from baseline occurs, or if symptomatic arrhythmias develop.
Symptom Monitoring
- Visual disturbances (blurred vision, difficulty reading, halos, dark spots, loss of peripheral vision)
- Muscle weakness or atrophy
- Hearing loss or tinnitus
- Gastrointestinal upset (nausea, vomiting, diarrhea, abdominal cramps)
- Skin rash, itching, or pigmentation changes
- Headache, dizziness, nervousness, insomnia
- Signs of cardiac dysfunction (palpitations, chest pain, shortness of breath, fainting)
- Signs of hypoglycemia (sweating, tremor, confusion, hunger)
Special Patient Groups
Pregnancy
Category D. Chloroquine crosses the placenta. While generally considered safe for malaria prophylaxis and treatment during pregnancy due to the high risk of malaria to both mother and fetus, its use for other indications (e.g., RA/SLE) should be carefully weighed against potential risks. Congenital defects have been reported but a causal link is not definitively established.
Trimester-Specific Risks:
First Trimester:
Potential for fetal exposure; use only if clearly needed and benefits outweigh risks.
Second Trimester:
Generally considered safer for malaria treatment/prophylaxis if indicated.
Third Trimester:
Generally considered safer for malaria treatment/prophylaxis if indicated.
Lactation
Chloroquine is excreted into breast milk in small amounts. The amount transferred is generally considered too low to provide effective malaria prophylaxis to the infant. However, it is generally considered compatible with breastfeeding for mothers taking it for malaria prophylaxis or treatment, as the benefits of breastfeeding often outweigh the minimal risk to the infant. Monitor infant for adverse effects (e.g., GI upset, rash).
Infant Risk:
Low risk at standard doses for malaria prophylaxis/treatment. Higher doses or long-term use for other indications may warrant more caution. Not sufficient for infant malaria prophylaxis.
Pediatric Use
Dosing is weight-based. Children are particularly susceptible to chloroquine toxicity, especially in overdose, which can be rapidly fatal. Store medication securely out of reach of children. Careful dose calculation and administration are crucial.
Geriatric Use
Use with caution in elderly patients due to potential age-related decreases in renal and hepatic function, which can lead to increased plasma concentrations and higher risk of toxicity (e.g., retinopathy, cardiotoxicity). Lower doses or extended dosing intervals may be necessary. Monitor closely for adverse effects.
Clinical Information
Clinical Pearls
- Chloroquine phosphate 500 mg contains 300 mg of chloroquine base. Dosing is often expressed in terms of chloroquine base.
- Long half-life (weeks to months) due to extensive tissue binding and slow release; this leads to prolonged drug exposure and accumulation with chronic use.
- Risk of irreversible retinopathy is a major concern with long-term use, especially at cumulative doses exceeding 1000g or daily doses > 2.5 mg/kg (base). Regular ophthalmologic monitoring is critical.
- Cardiotoxicity (QT prolongation, cardiomyopathy) is a serious, though less common, adverse effect. ECG monitoring is advised, especially in patients with pre-existing cardiac conditions or on other QT-prolonging drugs.
- Acute overdose is extremely dangerous and can be rapidly fatal due to cardiovascular collapse and respiratory arrest. Immediate medical intervention is required.
- Take with food or milk to minimize gastrointestinal upset.
Alternative Therapies
- For Malaria: Mefloquine, Atovaquone/Proguanil, Doxycycline, Primaquine, Tafenoquine, Artemisinin-based combination therapies (ACTs).
- For Rheumatoid Arthritis/Systemic Lupus Erythematosus: Methotrexate, Sulfasalazine, Leflunomide, Biologic DMARDs (e.g., TNF inhibitors), Corticosteroids, NSAIDs.
Cost & Coverage
Average Cost:
Varies widely, typically $10-$50 per 30 tablets
Generic Available:
Yes
Insurance Coverage:
Tier 1 or 2 (Generic)
General Drug Facts
If your symptoms or health issues persist or worsen, it is essential to contact your doctor for further guidance. To ensure safe and effective treatment, never share your medication with others or take someone else's medication. Some medications may come with an additional patient information leaflet, so it's a good idea to check with your pharmacist for more information. If you have any questions or concerns about your medication, don't hesitate to reach out to your doctor, nurse, pharmacist, or other healthcare provider. In the event of a suspected overdose, immediately call your local poison control center or seek emergency medical attention. When seeking help, be prepared to provide details about the medication taken, the amount, and the time it happened.