Biological effects of furosemide in relation to its disposition in rabbits

Pharmacokinetics and toxicity testing

The pharmacokinetic basis for the design of toxicity tests is discussed with reference to the absorption and clearance of drugs. The absorption and clearance of a wide range of drugs by laboratory animals and man has been examined and reviewed to provide a firm basis against which new drugs can be compared. Some pitfalls in either the empirical approach to toxicology or the incorrect interpretation of kinetic data are highlighted. An approach is outlined for the rational application of animal pharmacokinetic data in the assessment of the safety in man of a new therapeutic agent.

BTS 39542, a dihydrophthalazin-1-ylacetic acid with high efficacy diuretic activity

1 BTS 39542, a novel dihydrophthalazin-1-ylacetic acid, has high efficacy diuretic activity in mice, rats, rabbits and dogs. It is twice as potent as frusemide in mice and dogs, ten times as potent in rats and twenty times as potent in rabbits. 2 BTS 39542, like frusemide, exerts its major effects in the loop of Henle and increases renal blood flow but does not affect glomerular filtration rate in dogs. 3 The ratio of the excretion of the major cations (sodium plus potassium) to that of the major anion (chloride) after either BTS 39542 or frusemide varied with species. In rats and rabbits the ratio was approximately unity but in mice and dogs the ratio consistently exceeded unity. 4 A method for evaluating diuretics based on potency and relative potassium excretion is described.