Pyrazinamide is a drug that is used in the treatment of tuberculosis, a lung disease that develops as a result of infection with a bacterial species called Mycobacterium tuberculosis. This slow-growing species is resistant to treatment, and an effective course of tuberculosis treatment typically lasts for six to nine months and sometimes even longer. Treatment with this medication in conjunction with other tuberculosis drugs can shorten the treatment time required by several months.
An estimated one-third of the world’s population has been exposed to Mycobacterium tuberculosis; most people, however, do not progress to having an active infection. Symptoms of an active tuberculosis infection include fever, weight loss and chronic coughing that might produce bloody sputum. These symptoms occur because the bacterium colonizes in the lungs and causes chronic infection that the immune system cannot easily overcome. An untreated tuberculosis infection eventually leads to severe necrosis of lung tissue and death as a result of respiratory failure.
Pyrazinamide is a bacteriostatic tuberculosis drug. This means that it does not kill the bacteria but merely slows its rate of growth. For this reason, pyrazinamide alone is not an effective tuberculosis treatment. Instead, this drug must be used in combination with one or more tuberculosis drugs that are bacteriocidal, which means they are capable of killing the bacteria. Pyrazinamide is not completely effective alone, but it often is added to a course of tuberculosis drugs because its ability to slow the rate of bacterial growth means that it shortens the duration of treatment.
This tuberculosis drug works by interfering with the activity of a Mycobacterium tuberculosis enzyme called pyrazinamidase. When the bacteria is exposed to pyrazinamide, the enzyme pyrazinamidase converts the drug into an active form called pyrazinoic acid. The exact way in which pyrazinoic acid reduces the growth rate of the bacteria is unknown; some theories suggest that it might interfere with fatty acid synthesis or disrupt the bacteria’s cell membrane.
Treatment with this medication can cause several side effects. One of the most common is mild joint pain, and other relatively common side effects include vomiting, nausea, loss of appetite, anemia, skin rash and fever. Toxic doses of the drug can cause hepatitis and liver damage.
One of the most useful aspects of this drug is its ability to shorten the duration of treatment required. This is important because a treatment program of long duration and high complexity can reduce patient compliance in completing the course of drugs. Tuberculosis tends to be more common in people who live below the poverty line or are homeless, and compliance is a particularly serious issue. As with traditional antibiotics, failing to complete the prescribed treatment can lead to the development of a drug-resistant strain of bacteria, so it is crucial that treatment regimens for tuberculosis are patient-friendly. Pyrazinamide is an important tool in achieving this aim.