SIDE-EFFECTS AND SPECIAL PRECAUTIONS:
Side-effects associated with rifampicin:
Some patients may experience a cutaneous syndrome which presents 2 to 3 hours after a daily or intermittent dose i.e. facial flushing, itching, rash, eye irritation.
A 12 hour "flu" syndrome, usually occurring after 3 to 6 months of intermittent treatment and usually with doses of 20 mg/kg or more, may present as fever, chills, bone pain and malaise.
Gastrointestinal effects include nausea, vomiting, anorexia, diarrhoea and epigastric distress, which may be alleviated by administration with food.
There have been reports of pseudomembranous colitis.
Hepatitis and the prodromal symptoms of hepatitis may occur (nausea, vomiting, unusual tiredness/fatigue).
Rifampicin can cause thrombocytopenia and purpura usually with intermittent regimens. Other haematological adverse effects include eosinophilia, leucopenia and haemolytic anaemia.
Nervous system effects include headache, drowsiness, dizziness, ataxia, numbness, visual disturbances and muscular weakness.
Alterations in kidney function and renal failure have occurred.
Rifampicin may cause orange-red discoloration of urine and other body fluids.
Menstrual disturbances have been reported.
Side-effects associated with isoniazid:
Elevated liver enzymes associated with clinical signs of hepatitis such as nausea, vomiting or fatigue may indicate hepatic damage. The incidence of liver damage is highest in patients over 35 years of age, those who are slow acetylators and those who consume alcohol on a daily basis. Gastrointestinal effects (nausea, vomiting, pellagra) and hypersensitivity reactions (skin eruptions including erythema multiforme, fever, lymphadenopathy, vasculitis) may occur.
Haematological effects have been reported (sideroblastic anaemia, agranulocytosis, haemolytic anaemia, thrombocytopenia, neutropenia, eosinophiliaand less frequently, aplastic anaemia).
Neurological effects include psychotic reactions and convulsions.
Other effects: hyperglycaemia, metabolic acidosis, lupus-like syndrome, rheumatoid syndrome, urinary retention and gynaecomastia.
Optic neuritis has also been reported.
Peripheral neuropathy has also been associated with isoniazid administration. Pyridoxine supplementation prevents the development of peripheral neuritis, as well as most other nervous system dysfunctions.
Side-effects associated with pyrazinamide:
The most serious side-effect is hepatotoxicity and its frequency appears to be dose-related. Hyperuricaemia commonly occurs, occasionally accompanied by arthralgia and may lead to attacks of gout. Photosensitivity and skin rash have been reported less frequently. Other side-effects that have been reported are anorexia, nausea and vomiting, malaise, fever, sideroblastic anaemia and dysu