Pyrazinamide

Pyrazinamide may reduce the contraceptive effects of oestrogens.

Pyrazinamide should be avoided 3 days before and after oral typhoid vaccination since it may inactivate the vaccine.

Pyrazinamide antagonizes the effect of uricosuric agents such as probenecid and sulfinpyrazone.

There have been no well-controlled studies in pregnant women. Pyrazinamide should only be used if the potential benefit justifies the risk to the foetus.

Pyrazinamide is contra-indicated in breast-feeding mothers. If its use is deemed essential, the patient should stop breast-feeding.

There are no data to suggest that pyrazinamide affects the ability to drive or use machines.

A hepatic reaction is the most common side effect of pyrazinamide and may occur at any time during therapy. This varies from a symptomless abnormality of hepatic cell function, detectable only by laboratory tests, through a mild syndrome of fever, anorexia, malaise, liver tenderness, hepatomegaly and spleenomegaly, to more serious reactions such as clinical jaundice, and rare cases of hepatic failure and death.

Other side effects-active gout, sideroblastic anaemia, arthralgias, anorexia, nausea and vomiting, flushing, dysuria, malaise, fever, rash, hypersensitivity reactions such as urticaria and pruritus, aggravation of peptic ulcer and occasionally photosensitivity.