In the U.S.—

In Canada—

• Antibacterial, antimycobacterial

Rifabutin (rif-a-BUE-tin) is used to help prevent Mycobacterium avium complex (MAC) disease from causing disease throughout the body in patients with advanced human immunodeficiency virus (HIV) infection. MAC is an infection caused by two similar bacteria, Mycobacterium avium and Mycobacterium intracellulare. Mycobacterium avium is more common in patients with HIV infection. MAC also may occur in other patients whose immune system is not working properly. Symptoms of MAC in people with acquired immunodeficiency syndrome (AIDS) include fever, night sweats, chills, weight loss, and weakness. Rifabutin will not work for colds, flu, or most other infections.

Rifabutin is available only with your doctor's prescription, in the following dosage form:

Oral
• Capsules (U.S. and Canada)

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 rifabutin, the following should be considered:

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

Pregnancy—Rifabutin has not been studied in pregnant women. However, studies in animals have shown that rifabutin causes birth defects. Before you take this medicine, make sure your doctor knows if you are pregnant or if you may become pregnant.

Breast-feeding—It is not known whether rifabutin passes into the breast milk. However, if your baby does not have the AIDS virus, there is a chance that you could pass the virus to your baby by breast-feeding. Talk to your doctor first if you are thinking about breast-feeding your baby.

Children—Studies on this medicine have only been done in adult patients, and there is no specific information comparing use of rifabutin in children with use in other age groups. However, studies are being done to determine the best dose for children.

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. Although there is no specific information comparing use of rifabutin in the elderly with use in other age groups, this medicine is not expected to cause different side effects or problems in older people than it does in younger adults.

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 rifabutin, it is especially important that your health care professional know if you are taking any of the following:

• Amprenavir (e.g. Agenerase) or
• Delavirdine (e.g., Rescriptor) or
• Efavirenz (e.g., Sustiva) or
• Indinavir (e.g., Crixivan) or
• Nelfinavir (e.g., Viracept) or
• Nevirapine (e.g., Viramune) or
• Ritonavir (e.g., Norvir) or
• Saquinavir (e.g., Fortovase, Invirase) or
• Zidovudine (e.g., AZT, Retrovir)—Use of rifabutin with these medicines may lower the amount of these medicines in the blood

• Oral contraceptives (birth control pills) containing estrogen—Use of rifabutin with these birth control pills may increase the chance of pregnancy occurring

• Kidney disease, mild to severe

Rifabutin may be taken on an empty stomach (either 1 hour before or 2 hours after a meal). However, if this medicine upsets your stomach, you may want to take it with food.

For patients unable to swallow capsules:

• The contents of the capsules may be mixed with applesauce. Be sure to take all the food to get the full dose of medicine.

To help prevent MAC disease, it is very important that you keep taking this medicine for the full time of treatment. You may have to take it every day for many months. It is important that you do not miss any doses.

Dosing—

The dose of rifabutin may 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 rifabutin. If your dose is different, do not change it unless your doctor tells you to do so.

• For oral dosage forms (capsules):
  • For the prevention of Mycobacterium avium complex (MAC):
    • Adults and teenagers—300 milligrams (mg) once a day, or 150 mg two times a day.
    • Children—Use and dose must be determined by your doctor.

Missed dose—

If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses. If this medicine is taken on an irregular schedule, side effects may occur more often and may be more serious than usual. If you have any questions about this, check with your health care professional.

Storage—

To store this medicine:

• Keep out of the reach of 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.

It is very important that your doctor check your progress at regular visits.

Rifabutin will cause your urine, stool, saliva, skin, sputum, sweat, and tears to turn reddish-orange to reddish-brown. This is to be expected while you are taking this medicine. This effect may cause soft contact lenses to become permanently discolored. Standard cleaning solutions may not take out all the discoloration. Therefore, it is best not to wear soft contact lenses while taking this medicine. Hard contact lenses are not discolored by rifabutin. If you have any questions about this, check with your doctor.

Be careful when using a regular toothbrush, dental floss, or toothpick. Your medical doctor, dentist, or nurse may recommend other ways to clean your teeth and gums. Check with your medical doctor before having any dental work done.

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.

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

• More common
  • Diarrhea;  fever;  heartburn;  indigestion;  loss of appetite;  nausea;  skin itching and/or rash 
  
  

• sore throat;  sour stomach;  vomiting  

• Less common
  • Loss of strength or energy;  muscle pain  
  
  

• Rare
  • Black, tarry, stools;  bruising or purple spots on skin;  change in taste;  chills;  cough;  eye pain ;  joint pain;  loss of vision ;  lower back or side pain;  muscle inflammation or pain;  pale skin;  painful or difficult urination;  shortness of breath;  ulcers, sores, or white spots in mouth ;  unusual bleeding or bruising;  unusual tiredness or weakness;  yellow skin 
  
  

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
  • Abdominal pain;  bad, unusual, or unpleasant (after) taste in mouth;  belching;  bloated, full feeling;  change in taste ;  chest pain;  excess air or gas in stomach or intestines;  headache;  passing gas;  rash;  trouble in sleeping 
  
  

This medicine commonly causes reddish-orange to reddish-brown discoloration of urine, stools, saliva, skin, sputum, sweat, and tears. This side effect usually does not need medical attention. However, tears that have been discolored by this medicine may also discolor soft contact lenses (see Precautions While Using This Medicine).

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, rifabutin is used in certain patients with the following medical condition:

• Treatment of tuberculosis in patients with human immunodeficiency virus (HIV) infection

Other than the above information, there is no additional information relating proper use, precautions, or side effects of this use.