In the U.S.—

In Canada—

• Antihypercalcemic
• antiprotozoal
• antirheumatic, disease-modifying
• lupus erythematosus suppressant
• polymorphous light eruption suppressant
• porphyria cutanea tarda suppressant

Chloroquine ( KLOR-oh-kwin) is a medicine used to prevent and treat malaria, a red blood cell infection transmitted by the bite of a mosquito, and to treat some conditions such as liver disease caused by protozoa (tiny one-celled animals).

Malaria transmission occurs in large areas of Central and South America, Hispaniola, sub-Saharan Africa, the Indian subcontinent, Southeast Asia, the Middle East, and Oceania. Country-specific information on malaria can be obtained from the Centers for Disease Control and Prevention (CDC), or from the CDC's web site at http://www.cdc.gov/travel/yellowbk.

This medicine may be given alone or with one or more other medicines. It may also be used for other conditions as determined by your doctor.

Chloroquine is available only with your doctor's prescription, in the following dosage forms:

Oral
• Tablets (U.S. and Canada)

Parenteral
• Injection (U.S.)

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For chloroquine, the following should be considered:

Allergies—Tell your doctor if you have ever had any unusual or allergic reaction to chloroquine or hydroxychloroquine. Also tell your health care professional if you are allergic to any other substances, such as foods, preservatives, or dyes.

Pregnancy—Unless you are taking chloroquine to treat malaria or liver disease caused by protozoa, use of this medicine is not recommended during pregnancy. In animal studies, chloroquine has been shown to cause damage to the central nervous system (brain and spinal cord) of the fetus, including damage to hearing, sense of balance, bleeding inside the eyes, and other eye problems. However, when given in low doses (once a week) to prevent malaria, this medicine has not been shown to cause birth defects or other problems in humans.

Breast-feeding—Chloroquine passes into breast milk. Chloroquine has not been reported to cause problems in nursing babies. However, babies and children are especially sensitive to the effects of chloroquine. The amount in breast milk is not enough to prevent the infant from getting malaria.

Children—Children are especially sensitive to the effects of chloroquine. This may increase the chance of side effects during treatment. Overdose is especially dangerous in children. Taking as little as 1 tablet (300-mg strength) has resulted in the death of a small child. Children should avoid traveling to areas where there is a chance of getting malaria, unless they can take antimalarial medicines that are more effective than chloroquine.

Older adults—Many medicines have not been studied specifically in older people. Therefore, it may not be known whether they work exactly the same way they do in younger adults or if they cause different side effects or problems in older people. There is no specific information comparing use of chloroquine in the elderly with use in other age groups.

Other medicines—Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking chloroquine, it is especially important that your health care professional know if you are taking the following:

• Mefloquine (e.g., Lariam)—Use of chloroquine with mefloquine may increase the chance of convulsions (seizures)

• Blood disease (severe)—Chloroquine may cause blood disorders

• Eye or vision problems—Chloroquine, especially in high doses, may cause serious side effects affecting the eyes

• Glucose-6-phosphate dehydrogenase (G6PD) deficiency—Chloroquine may cause serious side effects affecting the blood in patients with this deficiency

• Liver disease—May decrease the removal of chloroquine from the blood, increasing the chance of side effects

• Nerve or brain disease (severe), including convulsions (seizures)—Chloroquine may cause muscle weakness and, at high doses, seizures

• Porphyria—Chloroquine may cause episodes of porphyria to occur more frequently

• Psoriasis—Chloroquine may bring on severe attacks of psoriasis

• Stomach or intestinal disease (severe)—Chloroquine may cause stomach or intestinal irritation

Take this medicine with meals or milk to lessen stomach upset, unless otherwise directed by your doctor.

Keep this medicine out of the reach of children. Children are especially sensitive to the effects of chloroquine and overdose is especially dangerous in children. Taking as little as 1 tablet (300-mg strength) has resulted in the death of a small child.

It is very important that you take this medicine only as directed. Do not take more of it, do not take it more often, and do not take it for a longer time than your doctor ordered. To do so may increase the chance of serious side effects.

If you are taking this medicine to help keep you from getting malaria, keep taking it for the full time of treatment. If you already have malaria, you should still keep taking this medicine for the full time of treatment even if you begin to feel better after a few days. This will help to clear up your infection completely. If you stop taking this medicine too soon, your symptoms may return.

Chloroquine works best when you take it on a regular schedule. For example, if you are to take it once a week to prevent malaria, it is best to take it on the same day each week. Or if you are to take two doses a day, one dose may be taken with breakfast and the other with the evening meal. Make sure that you do not miss any doses. If you have any questions about this, check with your health care professional.

For patients taking chloroquine to prevent malaria :

• Your doctor may want you to start taking this medicine 1 to 2 weeks before you travel to an area where there is a chance of getting malaria. This will help you to see how you react to the medicine. Also, it will allow time for your doctor to change to another medicine if you have a reaction to this medicine.
• Also, you should keep taking this medicine while you are in the area and for 4 weeks after you leave the area. No medicine will protect you completely from malaria. However, to protect you as completely as possible, it is important to keep taking this medicine for the full time your doctor ordered. Also, if fever develops during your travels or within 2 months after you leave the area, check with your doctor immediately .

Dosing—

The dose of chloroquine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of chloroquine. If your dose is different, do not change it unless your doctor tells you to do so.

The number of tablets that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are taking chloroquine.

• For oral dosage form (tablets):
  • For prevention of malaria:
    • Adults—500 milligrams (mg) once every seven days.
    • Children—Dose is based on body weight and must be determined by your doctor. The usual dose is 8.3 mg per kilogram (kg) (3.7 mg per pound) of body weight once every seven days.
  • For treatment of malaria:
    • Adults—Start with 1 gram. Then, 500 mg six to eight hours after the first dose, and 500 mg once a day on the second and third days of treatment.
    • Children—Dose is based on body weight and must be determined by your doctor. The usual dose is 41.7 mg per kg (18.9 mg per pound) of body weight divided up over three days. This dose is given as follows: Start with 16.7 mg per kg (7.5 mg per pound) of body weight, then 8.3 mg per kg (3.7 mg per pound) of body weight six hours, twenty-four hours, and forty-eight hours after the first dose.
  • For treatment of liver disease caused by protozoa:
    • Adults—At first, start with 250 mg four times a day for two days. Then 250 mg two times a day for at least two to three weeks.
    • Children—Dose is based on body weight and must be determined by your doctor. The usual dose is 10 mg per kg (4.5 mg per pound) of body weight a day for three weeks.
• For injection dosage form:
  • For treatment of malaria:
    • Adults—200 to 250 mg injected into a muscle. This dose may be repeated in six hours if needed.
    • Children—Dose is based on body weight and must be determined by your doctor. The usual dose is 4.4 mg per kg (2 mg per pound) of body weight injected into a muscle or under the skin. This dose may be repeated in six hours if needed. Chloroquine may also be injected slowly into a vein. If the medicine is given in this way, the dose must be determined by your doctor.
  • For treatment of liver disease caused by protozoa:
    • Adults—200 to 250 mg a day injected into a muscle for ten to twelve days.
    • Children—Dose is based on body weight and must be determined by your doctor. The usual dose is 7.5 mg per kg (3.4 mg per pound) of body weight a day for ten to twelve days.

Missed dose—

If you miss a dose of this medicine and your dosing schedule is:

• One dose every seven days—Take the missed dose as soon as possible. Then go back to your regular dosing schedule.
• One dose a day—Take the missed dose as soon as possible. But if you do not remember until the next day, skip the missed dose and go back to your regular dosing schedule. Do not double doses.
• More than one dose a day—Take it right away if you remember within an hour or so of the missed dose. But if you do not remember until later, skip the missed dose and go back to your regular dosing schedule. Do not double doses.

If you have any questions about this, check with your doctor.

Storage—

To store this medicine:

• Keep out of the reach of children. Overdose of chloroquine is very dangerous in children.
• Store away from heat and direct light.
• Do not store in the bathroom, near the kitchen sink, or in other damp places. Heat or moisture may cause the medicine to break down.
• Do not keep outdated medicine or medicine no longer needed. Be sure that any discarded medicine is out of the reach of children.

If you will be taking this medicine for a long time, it is very important that your doctor check you at regular visits for any blood problems or muscle weakness that may be caused by this medicine. In addition, check with your doctor immediately if blurred vision, difficulty in reading, or any other change in vision occurs during or after treatment. Your doctor may want you to have your eyes checked by an ophthalmologist (eye doctor).

If your symptoms do not improve within a few days or if they become worse, check with your doctor.

Make sure you know how you react to this medicine before you drive, use machines, or do anything else that could be dangerous if you are not able to see well.

Chloroquine may cause blurred vision, difficulty in reading, or other change in vision. It may also cause some people to become lightheaded.

If these reactions are especially bothersome, check with your doctor.

Malaria is spread by mosquitoes. If you are living in, or will be traveling to, an area where there is a chance of getting malaria, the following mosquito-control measures will help to prevent infection:

• Avoid going out between dusk and dawn because it is at these times when mosquitoes most commonly bite.
• If possible, sleep in a screened or air-conditioned room or under mosquito netting, preferably netting coated or soaked with pyrethrum, to avoid being bitten by malaria-carrying mosquitoes.
• Remain in air-conditioned or well-screened rooms to reduce contact with mosquitoes
• Wear long-sleeved shirts or blouses and long trousers to protect your arms and legs, especially from dusk through dawn when mosquitoes are out.
• Apply mosquito repellent, preferably one containing DEET, to uncovered areas of the skin from dusk through dawn when mosquitoes are out.
• Use mosquito coils or sprays to kill mosquitoes in living and sleeping quarters during evening and night-time hours.

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention. When this medicine is used for short periods of time, side effects usually are rare. However, when it is used for a long time and/or in high doses, side effects are more likely to occur and may be serious.

Check with your doctor immediately if any of the following side effects occur:

• Less common
  • Blurred vision;  change in vision;  eye pain;  loss of vision 
  
  

  The above side effects may also occur or get worse after you stop taking this medicine.

• Rare
  • Black, tarry stools;  blood in urine or stools;  convulsions (seizures);  cough or hoarseness;  feeling faint or lightheaded ;  fever or chills;  increased muscle weakness;  lower back or side pain;  mood or other mental changes;  painful or difficult urination;  pinpoint red spots on skin ;  ringing or buzzing in ears or any loss of hearing ;  sore throat;  unusual bleeding or bruising;  unusual tiredness or weakness 
  
  

• Symptoms of overdose
  • Drowsiness;  headache;  increased excitability 
  
  

Other side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. However, check with your doctor if any of the following side effects continue or are bothersome:

• More common
  • Diarrhea;  difficulty in seeing to read ;  headache;  itching (more common in black patients);  loss of appetite;  nausea or vomiting;  stomach cramps or pain 
  
  

• Less common
  • Bleaching of hair or increased hair loss;  blue-black discoloration of skin, fingernails, or inside of mouth;  skin rash 
  
  

Other side effects not listed above may also occur in some patients. If you notice any other effects, check with your doctor.

Once a medicine has been approved for marketing for a certain use, experience may show that it is also useful for other medical problems. Although these uses are not included in product labeling, chloroquine is used in certain patients with the following medical conditions:

• Arthritis in children
• High levels of calcium in the blood associated with sarcoidosis
• Rheumatoid arthritis
• Systemic lupus erythematosus (lupus; SLE)
• Various skin disorders

For patients taking chloroquine for arthritis or lupus :

• This medicine must be taken regularly as ordered by your doctor in order for it to help you. It may take up to several weeks before you begin to feel better. It may take up to 6 months before you feel the full benefit of this medicine.
• If your symptoms of arthritis do not improve within a few weeks or months, or if they become worse, check with your doctor.

Other than the above information, there is no additional information relating to proper use, precautions, or side effects for these uses.