Adverse Effects of Pyrazinamide
The primary adverse effects of pyrazinamide include hepatotoxicity, hyperuricemia with arthralgias, gastrointestinal upset, and rash, with hepatitis being the most clinically significant concern requiring monitoring at weeks 2,4, and 8 of therapy. 1
Major Adverse Effects
Hepatotoxicity
- Hepatitis is the most serious adverse effect of pyrazinamide, occurring at variable rates depending on the drug combination used 1
- Clinical hepatitis rates increase when pyrazinamide is combined with other hepatotoxic agents, particularly isoniazid and rifampin 1
- Liver function tests should be obtained at baseline and monitored clinically at weeks 2,4, and 8 when pyrazinamide is included in the regimen 1
- The risk may be increased in patients with underlying liver disease or those with heavy alcohol consumption 1
Hyperuricemia and Arthralgias
- Pyrazinamide commonly causes asymptomatic hyperuricemia due to interference with renal uric acid excretion 1
- Symptomatic gout is rare, and hyperuricemia should only be treated if the patient develops symptoms 1
- Arthralgias can occur independent of elevated uric acid levels 1
Gastrointestinal Effects
- Gastrointestinal upset including nausea and abdominal distress are common 1
- These effects are generally mild and manageable 1
Dermatologic Reactions
- Rash can occur as a hypersensitivity reaction 1
- Skin reactions are typically mild but require monitoring 1
Special Populations and Precautions
Pregnancy
- Pyrazinamide should be avoided in pregnancy according to U.S. guidelines 1
- The combination product Rifater® (containing pyrazinamide) should not be used in pregnant women for this reason 1
Diabetes Management
- Pyrazinamide may make glucose control more difficult in persons with diabetes, requiring closer monitoring of blood glucose levels 1
Renal Disease
- Dose adjustments are necessary in patients with renal insufficiency 1
- The combination product Rifater® should not be used in renal disease because of the need for pyrazinamide dose adjustment 1
Hepatic Disease
- Pyrazinamide should be used with extreme caution in patients with underlying hepatic disease 1
- In patients with pre-existing liver disease, it is advisable to use single-drug formulations initially until safety can be established 1
Monitoring Requirements
Clinical monitoring is mandatory at weeks 2,4, and 8 when pyrazinamide is given 1
- Baseline liver function tests should be obtained in selected high-risk cases 1
- Repeat liver function tests if symptoms of hepatitis develop (fatigue, nausea, dark urine, jaundice) 1
- Monitor for signs of arthralgias or gout 1
- Assess glucose control in diabetic patients 1
Common Pitfall
The most critical pitfall is continuing pyrazinamide despite symptoms of hepatitis, which can lead to severe or fatal hepatotoxicity 1. Any patient developing symptoms suggestive of hepatitis should have immediate liver function testing and the drug should be discontinued if clinically indicated.