The intravenous LD50 of cefuroxime sodium for mice is 10.4 g/kg. The maximum dosage administered in other acute toxicity tests is well tolerated by mice (10 g/kg, subcutaneous), by rats (4 g/kg, intravenous, 5 g/kg, subcutaneous) and by cats, dogs and monkeys (2 g/kg, intramuscularly). However, when cefuroxime sodium is administered subcutaneously (s.c.) or intramuscularly (i.m.) for 3 months to rats (100, 300 or 900 mg/kg/day) followed by a recovery period, and also for 6 months to rats and dogs (50, 150 or 450 mg/kg/day) and for 1 month to monkeys (150 or 450 mg/kg/day), there are no serious toxic effects in all tests. In rats large doses cause some increase in urine volume and electrolyte excretion, and slightly aggravates an age related nephropathy. Administration to rats intravenously (i.v.) for 1 month of up to 400 mg/kg/day has no toxic effects. In reproduction studies on mice and rabbits there are no adverse effects on fertility, organogenesis or the rearing of young[1].