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Medical Disclaimer: This information is for educational purposes only and is not a substitute for professional medical advice.
Brand Name
Chloroquine Phosphate
Generic Name
Chloroquine Phosphate
Active Ingredient
ChloroquineCategory
Antimalarial [EPC]
Salt Form
Phosphate
Variants
9
Different strengths and dosage forms
| Strength | Form | Route | NDC |
|---|---|---|---|
| 500 mg/1 | TABLET, COATED | ORAL | 68022-0265 |
| 500 mg/1 | TABLET, COATED | ORAL | 23155-850 |
| 500 mg/1 | TABLET, COATED | ORAL | 68022-0264 |
References used for this content
This page is for informational purposes only and does not replace medical advice. Before using any prescription or over-the-counter medication for Chloroquine Phosphate, you must consult a qualified healthcare professional.
| 500 mg/1 | TABLET | ORAL | 64980-178 |
| 500 mg/1 | TABLET | ORAL | 42291-047 |
| 250 mg/1 | TABLET | ORAL | 64980-177 |
| 250 mg/1 | TABLET | ORAL | 0115-2790 |
| 500 mg/1 | TABLET, COATED | ORAL | 62135-717 |
| 500 mg/1 | TABLET | ORAL | 0115-7010 |
Detailed information about Chloroquine Phosphate
Chloroquine is an antimalarial and amebicide medication primarily used to prevent and treat malaria and certain types of liver infections. It belongs to the 4-aminoquinoline class of drugs and has been a cornerstone of infectious disease treatment for decades.
The dosage of Chloroquine varies significantly depending on whether it is being used for prevention or treatment. Healthcare providers typically express doses in terms of Chloroquine Phosphate (the salt).
Chloroquine is approved for use in children, but the dosage must be strictly calculated based on the child's body weight. Extreme caution is required, as children are particularly sensitive to 4-aminoquinoline compounds.
Because a significant portion of Chloroquine is excreted by the kidneys, patients with decreased kidney function (renal impairment) may require a reduction in dosage or an increase in the interval between doses. Your doctor may monitor your creatinine clearance to determine the safest dose.
Chloroquine concentrates in the liver and is partially metabolized there. Patients with liver disease or those taking other hepatotoxic medications should use Chloroquine with caution. Dose adjustments may be necessary to prevent accumulation and toxicity.
Clinical studies have not included sufficient numbers of subjects aged 65 and over to determine if they respond differently than younger subjects. However, because elderly patients are more likely to have decreased renal or hepatic function, dose selection should be cautious, usually starting at the low end of the dosing range.
To ensure the medication works effectively and to minimize discomfort, follow these guidelines:
If you miss a dose of Chloroquine, take it as soon as you remember. However, if it is almost time for your next scheduled dose, skip the missed dose and resume your regular schedule. Do not 'double up' or take two doses at once to make up for a missed one. If you are taking it for prophylaxis and miss a dose, your risk of contracting malaria increases significantly.
An overdose of Chloroquine is a medical emergency and can be rapidly fatal. Symptoms often appear within minutes and may include:
In the event of a suspected overdose, call 911 or your local emergency services immediately. Emergency treatment often involves gastric lavage (stomach pumping), administration of activated charcoal, and intensive supportive care in a hospital setting.
> Important: Follow your healthcare provider's dosing instructions. Do not adjust your dose without medical guidance.
Most patients tolerate Chloroquine well, especially at the lower doses used for malaria prophylaxis. However, some common side effects may occur, particularly during the first few weeks of treatment:
Chloroquine is a powerful medication that requires careful medical supervision. It is not suitable for everyone, and its use must be balanced against the risk of the condition being treated. One of the most critical safety points is that Chloroquine has a very narrow 'therapeutic index,' meaning the difference between a safe dose and a toxic dose is relatively small. This is why strict adherence to the prescribed dosage is essential.
No FDA black box warnings for Chloroquine. However, the absence of a black box warning does not imply the drug is without significant risk. The warnings regarding ocular toxicity and cardiac effects are considered 'Major Warnings' in the official prescribing information.
Certain medications should never be taken with Chloroquine because the risk of a life-threatening interaction is too high. These include:
There are several situations where Chloroquine must NEVER be used because the risks clearly outweigh any possible benefit:
Chloroquine has been used for decades to prevent and treat malaria in pregnant women. According to the CDC and WHO, the risk of the mother contracting malaria (which can cause miscarriage, stillbirth, and maternal death) generally outweighs the potential risks of the medication.
Chloroquine is excreted in human breast milk in small amounts. While the amount of drug the infant receives is generally considered safe, it is important to understand that the amount of Chloroquine in breast milk is NOT
Chloroquine is a lysosomotropic agent, meaning it concentrates in the acidic organelles (lysosomes) of cells. In the malaria parasite (Plasmodium), the drug enters the acidic food vacuole. Because Chloroquine is a weak base, it becomes protonated (gains a hydrogen ion) in the acidic environment, which 'traps' the drug inside the vacuole. Once concentrated, it inhibits the enzyme 'heme polymerase.' This enzyme is responsible for converting toxic ferriprotoporphyrin IX (heme) into non-toxic hemozoin. The resulting accumulation of free heme causes oxidative damage to the parasite's membranes and proteins, leading to cell lysis (bursting) and death.
Common questions about Chloroquine Phosphate
Chloroquine is primarily used for the prevention and treatment of malaria, a serious disease caused by parasites transmitted through mosquito bites. It is effective against specific strains of the Plasmodium parasite that have not developed resistance to the drug. Additionally, it is FDA-approved to treat extraintestinal amebiasis, which is an infection caused by amoebas that spreads to organs like the liver. In some cases, healthcare providers may use it off-label for certain autoimmune conditions, although other medications are now more common for that purpose. It is essential to use Chloroquine only for the specific condition for which it was prescribed by a medical professional.
The most frequently reported side effects of Chloroquine include gastrointestinal issues such as nausea, vomiting, diarrhea, and stomach cramps. Many patients also experience 'chloroquine-induced pruritus,' which is an intense itching sensation, particularly common in individuals of African descent. Other common effects include mild headaches, dizziness, and a temporary blurring of vision. Most of these symptoms are dose-dependent and often subside if the medication is taken with food or once the treatment course is completed. However, any persistent or worsening symptoms should be reported to a healthcare provider immediately.
While there is no absolute ban on alcohol in the Chloroquine prescribing information, it is generally recommended to avoid or strictly limit alcohol consumption during treatment. Alcohol can exacerbate the gastrointestinal side effects of the drug, such as nausea and upset stomach, and may increase the risk of dizziness. Furthermore, both Chloroquine and alcohol are processed by the liver; consuming them together could potentially increase the strain on this organ. To ensure the medication works effectively and to minimize the risk of adverse reactions, it is best to discuss your alcohol intake with your doctor. Maintaining a healthy liver is crucial for the proper metabolism and clearance of this drug.
Chloroquine is generally considered safe for use during pregnancy when prescribed for the prevention or treatment of malaria. The World Health Organization (WHO) and the CDC state that the risks of malaria to the mother and the fetus—which include miscarriage and severe maternal illness—are much greater than the risks of the medication. Clinical data from decades of use have not shown a significant increase in birth defects at the low doses used for malaria prophylaxis. However, high-dose or long-term use for other conditions is usually avoided unless absolutely necessary. Pregnant women should always consult their obstetrician before starting any new medication, including antimalarials.
When used for the treatment of an active malaria infection, Chloroquine begins working almost immediately by attacking the parasites in the bloodstream, but it usually takes 24 to 48 hours for a patient to notice a significant reduction in fever and other symptoms. For malaria prevention (prophylaxis), the drug must be started 1 to 2 weeks before potential exposure to ensure that protective levels of the medication have built up in the tissues. Because Chloroquine has a very long half-life, it stays in the body for several weeks after the final dose. This long-lasting effect is why the medication only needs to be taken once a week for prevention.
If you are taking Chloroquine for malaria prevention, you must not stop taking it just because you have left the area where malaria is present. You must continue the weekly doses for a full four weeks after leaving the region to ensure that any parasites that may have entered your system are completely eliminated. Stopping early increases the risk of developing a 'delayed' malaria attack. If you are taking it for a chronic condition, stopping suddenly will not cause withdrawal symptoms, but it may cause your underlying symptoms to flare up. Always follow the specific duration of treatment prescribed by your healthcare provider to ensure the infection is fully resolved.
If you miss a dose of Chloroquine, you should take it as soon as you remember. If you are taking the medication once a week for malaria prevention and you forget your dose on the scheduled day, take it as soon as possible and then resume your regular weekly schedule on the next planned day. However, if it is almost time for your next dose, skip the missed one entirely. Never take a double dose to make up for a missed one, as this can increase the risk of toxicity and heart rhythm problems. If you miss multiple doses while in a malarious area, contact your healthcare provider for advice on how to proceed.
Weight gain is not a typical or documented side effect of Chloroquine. In fact, some patients may experience slight weight loss due to the gastrointestinal side effects like nausea or a reduced appetite. If you notice significant or rapid weight changes while taking this medication, it is likely due to another factor or an underlying medical condition. Always discuss unexpected changes in your weight with your doctor. They can help determine if the change is related to the medication, your diet, or another health issue that requires attention.
Chloroquine has several significant drug interactions that require careful management. It should not be taken with other drugs that prolong the QT interval, such as certain antipsychotics or heart rhythm medications like amiodarone, due to the risk of serious heart problems. It can also interact with antacids, which reduce its absorption, and medications for diabetes, as it may lower blood sugar levels further. Because Chloroquine stays in the system for a long time, interactions can occur even after you stop taking it. Always provide your healthcare provider with a complete list of all prescription drugs, over-the-counter medicines, and herbal supplements you are using.
Yes, Chloroquine Phosphate is widely available as a generic medication. Generic versions are required by the FDA to have the same active ingredient, strength, dosage form, and route of administration as the brand-name drug. Because it has been on the market since the 1940s, the brand-name versions (such as Aralen) are less commonly used today than the generic equivalents. Generic Chloroquine is typically very affordable and is included on most insurance formularies. When picking up your prescription, ensure the pharmacist explains whether the dose is based on the 'base' or the 'salt' weight to avoid any confusion.
Other drugs with the same active ingredient (Chloroquine)
> Warning: Stop taking Chloroquine and call your doctor immediately if you experience any of these serious symptoms.
The primary concern with long-term Chloroquine use (usually defined as taking the drug for more than 6-12 months or reaching a high cumulative dose) is Chloroquine Retinopathy. The drug accumulates in the pigmented layer of the retina, leading to a 'bull's-eye maculopathy.' Because the early stages of this condition may not have symptoms, regular eye exams with specialized testing (like visual field tests and SD-OCT) are mandatory for anyone on long-term therapy.
Another long-term risk is Cardiomyopathy, a weakening of the heart muscle. This can lead to heart failure and is often associated with specific changes on an EKG. If you are on long-term therapy, your doctor may order periodic heart imaging or EKG monitoring.
As of 2024, Chloroquine does not carry a specific FDA 'Black Box Warning.' However, the FDA has issued several Drug Safety Communications regarding the risks of serious heart rhythm problems and other safety issues when the drug is used outside of its approved indications (such as the historical context of the COVID-19 pandemic).
Report any unusual symptoms to your healthcare provider immediately. Early detection of side effects is the best way to prevent permanent damage.
If you are taking Chloroquine, your healthcare provider will likely require the following tests:
Chloroquine may cause blurred vision or dizziness in some patients. You should not drive, operate heavy machinery, or participate in dangerous activities until you know how this medication affects you. If you notice any changes in your vision, stop these activities and contact your doctor immediately.
While there is no direct 'contraindication' for alcohol, it is generally advised to limit alcohol consumption while taking Chloroquine. Alcohol can increase the risk of liver strain and may worsen the dizziness or gastrointestinal side effects associated with the drug.
For malaria prophylaxis, do not stop taking the medication early. You must continue taking it for the full 4 weeks after leaving the malarious area to ensure all parasites are cleared from your system. For other conditions, do not stop the medication without consulting your doctor, as your symptoms may return. There is no known 'withdrawal syndrome' for Chloroquine, but the underlying disease must be managed.
> Important: Discuss all your medical conditions with your healthcare provider before starting Chloroquine.
Chloroquine does not typically interfere with common laboratory tests like cholesterol or basic metabolic panels. However, it may affect the results of certain specialized tests, such as those for porphyria (urinary porphyrins) or certain neuromuscular diagnostic tests (EMG) if the patient has developed neuromyopathy.
Mechanism of Interactions: Most Chloroquine interactions occur through two pathways: either by competing for the same metabolic enzymes in the liver (CYP450 system) or by having 'additive' effects on the heart's electrical system (pharmacodynamic interaction). For example, taking two drugs that both slow down the heart's electrical recharging phase (QT interval) creates a much higher risk than either drug alone.
> Important: Tell your doctor about ALL medications, supplements, and herbal products you are taking. Even 'natural' products can interact dangerously with Chloroquine.
In these cases, a healthcare provider must perform a careful risk-benefit analysis before prescribing Chloroquine:
Patients who are allergic to Hydroxychloroquine (Plaquenil) are highly likely to be allergic to Chloroquine. There is also a theoretical risk of cross-sensitivity with other quinoline derivatives, such as Quinine or Mefloquine, although this is less common. Always inform your doctor if you have had a reaction to any 'quinine-like' medication in the past.
> Important: Your healthcare provider will evaluate your complete medical history before prescribing Chloroquine. Be honest about all past medical issues, especially those involving your eyes, heart, or liver.
Chloroquine is approved for use in children for both the prevention and treatment of malaria. However, children are extremely susceptible to the toxic effects of 4-aminoquinolines.
Elderly patients (aged 65 and older) may be at higher risk for side effects from Chloroquine.
For patients with a GFR (Glomerular Filtration Rate) less than 10 mL/min, the dose of Chloroquine is often reduced by 50%. The drug is not significantly removed by hemodialysis or peritoneal dialysis, so 'supplemental doses' after a dialysis session are not necessary. Close monitoring for signs of toxicity is required in all patients with stage 4 or 5 chronic kidney disease.
Chloroquine should be used with caution in patients with liver disease. While there are no specific 'Child-Pugh' based dosing charts, clinicians typically monitor liver function tests (LFTs) closely. If LFTs worsen during treatment, the drug may need to be discontinued, as Chloroquine itself can rarely cause hepatotoxicity.
> Important: Special populations require individualized medical assessment. Never share your medication with others, especially children or pregnant women.
| Parameter | Value |
|---|---|
| Bioavailability | 80% to 100% (Rapidly absorbed) |
| Protein Binding | 50% to 70% (Mainly to albumin) |
| Half-life | 30 to 60 days (Terminal phase) |
| Tmax | 1 to 6 hours |
| Metabolism | Hepatic (CYP2C8, CYP3A4, CYP2D6) |
| Excretion | Renal (50% unchanged), Fecal (approx. 10%) |
Chloroquine is classified as a 4-aminoquinoline. It is chemically related to Hydroxychloroquine and Amodiaquine. Within the broader therapeutic area of infectious disease, it is categorized as an Antimalarial and an Amebicide. Unlike Quinine, which is a cinchona alkaloid, Chloroquine is a fully synthetic compound designed to be more effective and less toxic than earlier antimalarial treatments.