ria.
Side-effects associated with ethambutol:
Retrobulbar neuritis with a reduction in visual acuity, constriction of visual field, central or peripheral scotoma, and green-red colour blindness may occur, affecting one or both eyes. The degree of visual impairment appears to depend on the dose and duration of therapy. Retinal haemorrhage has occurred less frequently. Renal clearance of urate may be reduced and acute gout has been precipitated. Hypersensitivity reactions include skin rash, pruritis, leucopenia, fever and joint pains. Gastrointestinal disturbances include metallic taste, nausea, vomiting, anorexia and abdominal pain. Other adverse effects: Confusion, disorientation, hallucinations, headache, dizziness, malaise, jaundice or transient liver dysfunction, peripheral neuritis.
SPECIAL PRECAUTIONS:
In the following cases, treatment with Rifafour e-275 tablets should be stopped immediately and the patient eva luated: jaundice, rash and fever, elevated liver enzymes associated with the clinical signs of hepatitis, visual impairment. If liver damage is confirmed, the medicine should not be recommenced.
Treatment should be discontinued permanently should thrombocytopenia, purpura, shock or renal failure occur. Periodic eye examinations during treatment is suggested.
INTERACTIONS:
Rifampicin:
Concurrent use of alcohol, acetaminophen, isoniazid and other hepatotoxic medication may increase the incidence of rifampicin-induced hepatotoxicity. The effectiveness of oestrogen-containing oral preparations is reduced. Rifampicin accelerates the metabolism of certain medicines by inducing microsomal enzymes. Medicines that are affected include: atorvaquone, azathioprine, chloramphenicol, cimetidine, clofibrate, corticosteroids, coumarin anticoagulants, cyclosporin, dapsone, diazepam and other benzodiazepines, doxycycline, azole antifungals (ketoconazole, itraconazole, fluconazole), haloperidol, hexobarbitone, methadone, oral hypoglycaemic agents, phenytoin, quinine, sulphasalazine, thyroxine, theophylline, zidovudine, beta-blockers, digitoxin, digoxin, antiarrhythmic agents (e.g. disopyramide, verapamil) and calcium channel blockers.
Isoniazid:
Chronic use of isoniazid may decrease the plasma clearance and prolong the duration of action of alfentanil, coumarin anticoagulants, benzodiazepines, carbamazepine, phenytoin, ethosuximide, chlorzoxazone, and theophylline. Appropriate adjustment of the anticonvulsant dose may be required. Concurrent use of paracetamol, alcohol, rifampicin and other hepatotoxic medication, may increase the potential for isoniazid-induced hepatotoxicity.
Aluminium-containing antacids may delay absorption and decrease serum concentrations of isoniazid. Ingestion of certain types of cheese e.g. Swiss or Cheshire, or fish e.g. tuna, may result in itching of the skin, rapid or pounding heart, chills or headache. Glucocorticoid corticosteroids may increase hepatic metabolism and/or excretion of isoniazid.
Concurrent use of cycloserine, disulfiram and other neurotoxic medicines may increase the potential for CNS toxicity. Isoniazid may increase the formation of potentially nephrotoxic inorganic fluoride metabolites when used concurrently with enflurane. Interactions with ketoconazole and miconazole have been reported. False positive reactions with copper sulphate urine glucose tests may occur.
Pyraz |
