Active TB is treated using a combination of drugs (antibiotics). As with HIV, in which a combination of three antiretroviral drugs is used to help prevent resistance and keep viral load undetectable, tuberculosis is usually treated with a combination of four drugs to maintain control over the infection.
Some people are infected with strains of Mycobacterium tuberculosis that are resistant to one or more of the drugs commonly used to treat tuberculosis. This problem is becoming more and more common in some areas of the United States, including heavily populated cities like New York. As a result, testing the bacteria for drug resistance as a part of diagnosing TB is recommended.
Unfortunately, both a confirmed diagnosis and drug-resistance testing take a long time. "Growing out" Mycobacterium tuberculosis in test tubes can take more than a week, and drug-resistance testing can take as long as a month. Thus, treatment is often started if key signs and symptoms are present (e.g., positive PPD, abnormal chest X-ray, etc.). In cases where it is suspected that a person has been exposed to drug-resistant TB, their provider should consult about treatment with local public health authorities as well as an expert on multi-drug-resistant TB.
For the first two months of therapy, a combination of four drugs are usually prescribed, all of which are taken by mouth:
Isoniazid (Nydrazid): One of the most effective antibiotics used to control TB. It can cause liver problems and tingling/numbness of the hands and/or feet (peripheral neuropathy). It is usually taken with a second drug, pyridoxine, to help prevent peripheral neuropathy.
Rifampin (Rifadin): Another powerful antibiotic needed to manage TB. It can cause nausea, vomiting, diarrhea, rash, liver problems, red-orange discoloration of body fluids (e.g., urine), along with a decrease in white blood cells and platelets. Rifampin can be a problem for some HIV-positive people. This is because it interacts with many of the medications used to treat HIV. It is not recommended that people stop their antiretroviral (ARV) medications in order to treat their TB. Instead, your doctor will probably need to change the dose of either the rifampin or the anti-HIV medications to make sure that you are being treated correctly without the risk of additional side effects. If rifampin cannot be used, an alternative drug—rifabutin—will be prescribed.
Pyrazinamide: The dose of this drug depends on the body weight of the person being treated. Its side effects are similar to those of rifampin.
Ethambutol (Myambutol) or streptomycin: Like pyrazinamide, the dose of these two drugs depends on the body weight of the person being treated. Ethambutol can cause vision problems and can cause hearing problems.
To help make these drugs easier to take, some of them have been combined into single pills. For example, if you take isoniazid and rifampin, your doctor can write a prescription for Rifamate, a capsule that contains both drugs. Two Rifamate capsules are taken twice a day, almost always in combination with other antibiotics. If your doctor has recommended a combination of isoniazid, rifampin, and pyrazinamide, you may be able to take Rifater, a tablet that contains all three drugs. Depending on how much you weigh, you will need to take four, five, or six Rifater tablets once a day, always on an empty stomach.
If a drug-resistant strain of Mycobacterium tuberculosis is present—either suspected by a doctor (i.e., direct exposure to someone known to have a drug-resistant strain of the bacteria) or confirmed by testing—additional drugs are often added to this combination. Additional drugs include: capreomycin (Capastat Sulfate), kanamycin (Kantrex), amikacin (Amikin), ethionamide (Trecator-Sc), ciprofloxacin (Cipro), ofloxacin (Floxin), lomefloxacin (Maxaquin), clofazimine (Lamprene), cycloserine (Seromycin), and/or aminosalicylic acid (Paser). These drugs can also be used as a substitute for other anti-TB drugs that cause side effects.
Treatment guidelines published by the National Institutes of Health (NIH), Centers for Disease Control (CDC) and the Infectious Disease Society of America (IDSA) recommend that all HIV-positive people being treated for active TB should report to a clinic to receive their medications under observation, DOT, to guard against the potential for the development of drug resistance.
Here are the three ways tuberculosis can be treated using these drugs:
Standard course of therapy:
This is the most common method used to treat TB, especially for HIV-positive people. For the first eight weeks of treatment, the four drugs listed above are used ever day. After two months of therapy have been completed, isoniazid and rifabutin are continued for an additional 16 weeks (four months). These drugs can be taken either every day or two to three times a week. If you have less that 100 CD4 cells, experts recommend taking rifabutin every day or three times a week (but not two times a week). You will probably have to go to a clinic—or have a trained medical professional watch you take your medication—every time you take your isoniazid and rifabutin during this period, especially if you are only taking them two or three times a week.
First alternative course of therapy:
For the first two weeks of treatment, the four drugs listed above are used every day. After two weeks of daily treatment have been completed, the same four drugs are taken two times a week for an additional eight weeks. After a total of eight weeks of four-drug treatment have been completed, isoniazid and rifabutin are continued for an additional 16 weeks (four months).
These drugs can be taken either two or three times a week. Like the standard course of therapy, you will probably have to go to a clinic—or have a trained medical professional watch you take your medication—every time you take your medication.
Second alternative course of therapy:
For six months, the four drugs listed above are used three times a week. The dose of each drug will remain the same for the entire six months and you will need to take all four drugs until therapy is officially completed. Like the standard course of therapy, you will probably have to go to a clinic—or have a trained medical professional watch you take your medication—every time you take your medication.
It is very important that you take your medications exactly as your doctor tells you to and that you continue taking them until your doctor tells you that it is time to stop. This is necessary to prevent the bacteria from becoming resistant to the drugs. If the bacteria becomes resistant to these drugs, the TB may return and may be more difficult to treat. There are a number of potential side effects of tuberculosis treatment including stomach problems, rash, hepatitis and neuropathy. Because the recommended treatments for TB are the most effective and generally the least toxic, it is recommended that your doctor consult with a TB specialist in the event of a serious side effect and verify that it is the TB medication causing the side effect before stopping or switching TB treatment.
The Centers for Disease Control (CDC) in Atlanta published treatment guidelines for TB that make recommendations for dose changes when using rifampin with HIV medications. The guidelines may be found here. In general, the most recent guidelines recommend that people taking ARV treatment along with TB treatment should avoid using protease inhibitors whenever possible. For people who are not currently taking either ARV or TB medications, some doctors would recommend starting TB medications first followed by ARV medications a few weeks or months later, depending on their CD4 count and overall health.
Although relatively rare, some people experience a "flare" of TB symptoms within the first few months after starting ARV treatment. This is called immune reconstitution inflammatory syndrome, or IRIS. This most commonly happens when a person starts ARV treatment with a CD4 count of 200 or less, and when starting ARV treatment within the first two months after starting TB treatment. If your TB treatment has been successful, but you suddenly begin eperiencing TB symptoms, such as fevers, breathing problems and swollen lymph nodes, within the first few weeks after starting ARV treatment you should tell your doctor right away. It is important that your TB doctor and HIV doctor consult carefully to determine whether you are experiencing IRIS or the possibility that your TB medications are no longer working.
Can pregnant women take TB treatment?
It is recommended that HIV-positive pregnant women receive the same TB treatment as non-pregnant adults. Rifampin, however, can cause a bleeding disorder in babies born to women who took TB treatment during pregnancy. To guard against this disorder, babies born to pregnant women on TB treatment should receive a single 10 mg dose of vitamin K.
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