Tuberculosis Treatments and drugs

Friday, September 12, 2008

Until the mid-20th century, people with tuberculosis were routinely cared for in sanitariums — often for years — where the clear, cold air, abundant food and enforced rest were believed to heal the lungs and halt the wasting that's characteristic of the disease. Often, the treatment not only helped cure TB, but also prevented its spread.

Today, medications are the cornerstone of tuberculosis treatment. The therapy is lengthy. Normally, you take antibiotics for six to 12 months to completely destroy the bacteria. The exact drugs and length of treatment depends on your age, overall health, the results of susceptibility tests, and whether you have TB infection or active TB.

Treating TB infection
If tests show that you have TB infection but not active disease, your doctor may recommend preventive drug therapy to destroy dormant bacteria that might become active in the future. In that case, you're likely to receive a daily dose of the TB medication isoniazid (INH). For treatment to be effective, you usually take INH for six to nine months. Long-term use can cause side effects, including the life-threatening liver disease hepatitis. For that reason, your doctor will monitor you closely while you're taking INH. During treatment, avoid using acetaminophen (Tylenol, others) and avoid or limit alcohol use. Both greatly increase your risk of liver damage.

Treating active TB disease
If you're diagnosed with active TB, you're likely to begin taking four medications — isoniazid, rifampin (Rifadin, Rimactane), ethambutol (Myambutol) and pyrazinamide. This regimen may change if susceptibility tests later show some of these drugs to be ineffective. Even so, you'll continue to take several medications. Depending on the severity of your disease and whether there is drug resistance, one or two of the four drugs may be stopped after a few months.

Sometimes the drugs may be combined in a single tablet such as Rifater, which contains isoniazid, rifampin and pyrazinamide. This makes your therapy less complicated while ensuring that you get the different drugs needed to completely destroy TB bacteria.

Another drug that may make treatment easier is rifapentine (Priftin), which is taken just once a week during the last four months of therapy. Sometimes you may be hospitalized for the first two weeks of therapy or until tests show that you're no longer contagious.

Completing treatment is essential
Because TB bacteria grow slowly, treatment for an active infection is lengthy — usually six to 12 months. After a few weeks, you won't be contagious and may start to feel better, but it's essential that you finish the full course of therapy and take the medications exactly as prescribed by your doctor. Stopping treatment too soon or skipping doses can create drug-resistant strains of the disease that are much more dangerous and difficult to treat. Drug-resistant strains that aren't treated can quickly become fatal, especially in people with impaired immune systems.

In an effort to help people stick with their treatment regimen, some doctors and clinics use a program called directly observed therapy short-course (DOTS). In this approach, a nurse or other health care professional administers your medication so that you don't have to remember to take it on your own.

Treatment side effects
Side effects of TB drugs aren't common, but can be serious when they do occur. All TB medications can be highly toxic to your liver. Rifampin can also cause severe flu-like signs and symptoms — fever, chills, muscle pain, nausea and vomiting. When taking these medications, call your doctor immediately if you experience any of the following:

  • Nausea or vomiting
  • Loss of appetite
  • A yellow color to your skin (jaundice)
  • A fever lasting three or more days that has no obvious cause, such as a cold or the flu
  • Tenderness or soreness in your abdomen
  • Blurred vision or colorblindness

Treating drug-resistant TB
Multidrug-resistant TB (MDR-TB) is any strain of TB that can't be treated by the two most powerful TB drugs, isoniazid and rifampin. Extensive drug-resistant TB (XDR-TB) is a newly developed strain of TB that's resistant to the same treatments that MDR-TB is, and additionally XDR-TB is resistant to three or more of the second-line TB drugs.

Both strains develop as a result of partial or incomplete treatment — either because people skip doses or don't finish their entire course of medication or because they're given the wrong treatment regimen. This gives bacteria time to undergo mutations that can resist treatment with first-line TB drugs.

MDR-TB can be treated. But it requires at least two years of therapy with second-line medications that can be highly toxic. Even with treatment, many people with MDR-TB may not survive. And when treatment is successful, people with this form of TB may need surgery to remove areas of persistent infection or repair lung damage.

Treating these resistant forms of TB is far more costly than treating nonresistant TB, making therapy unaffordable in many parts of the world.

Because these resistant infections are spreading and could potentially make all TB incurable, some experts believe that ineffective treatment is ultimately worse than no treatment at all.

Treating people who have HIV/AIDS
Treating people who are co-infected with TB and HIV is a particular challenge. HIV-positive people are especially likely to develop MDR-TB and to rapidly progress from latent to active infection. What's more, the most powerful AIDS drugs — protease inhibitors — interact with rifampin and other drugs used to treat TB, reducing the effectiveness of both types of medications.

To avoid interactions, people living with both HIV and TB may stop taking protease inhibitors while they complete a short course of TB therapy that includes rifampin. Or they may be treated with a TB regimen in which rifampin is replaced with another drug that's less likely to interfere with AIDS medications. In such cases, doctors carefully monitor the response to therapy, and the duration and type of regimen may change over time.

Without treatment, most people living with both HIV and TB will die, often in a matter of months. In such cases, the primary cause of death is TB, not AIDS.

No comments: