Hepatotoxic drugs are all EXCEPT:
Methotrexate (Mtx): It is one of the oldest and highly efficacious antineoplastic drugs; inhibits dihydrofolate reductase (DHFRase)-blocking the conversion of dihydrofolic acid (DHFA) to tetrahydrofolic acid (THFA) which is an essential coenzyme required for one carbon transfer reactions in de novo purine synthesis and amino acid interconversions. It exes major toxicity on bone marrow-low doses given repeatedly cause megaloblastic anaemia, but high doses produce pancytopenia. Desquamation and bleeding may occur in g.i.t. Nodulosis, oral ulceration and g.i. upset are major side effects of low dose Mtx regimen with prolonged therapy, dose dependent progressive liver damage leading to cirrhosis occurs in some patients (this is not seen with sho courses used in cancer) . Incidence of chest infection is increased.Mtx is contraindicated in pregnancy,brest feeding, liver disease, active infection ,leucopenia and peptic ulcer. INH:It is well tolerated by most patients. Peripheral neuritis and a variety of neurological manifestations (paresthesias, numbness, mental disturbances, rarely convulsions) are the most impoant dose-dependent toxic effects. These are due to interference with utilization of pyridoxine and its increased excretion in urine.Hepatitis, a major adverse effect of iNH, is rare in children, but more common in older people and in alcoholics. It is due to dose-related damage to liver cells and is reversible on stopping the drug. Other side effects are rashes, fever, acne and ahralgia. Cycloserine (Cys):The CNS toxicity of Cys is high-sleepiness, headache, tremor and psychosis; convulsions may be prevented by pyridoxine 100 mg/ day.Fall in BP has been noted. Ethionamide:Anorexia, nausea, vomiting and abdominal upset are common, especially in Indian patients. Though the recommended dose of Etm is 1 g/day, more than 0.5 g is generally not tolerated. Other side effects are aches and pains, rashes, hepatitis, peripheral or optic neuritis, mental disturbances and impotence. It is seldom used; only in case of resistance to better tolerated drugs. ESSENTIALS OF MEDICAL PHARMACOLOGY K.D.TRIPATHI SIXTH EDITION PAGE NO:203,741,743,744
Methotrexate
Isoniazid
Cycloserine
Ethionamide
Chemotherapy