EXCRETION OF DRUGS ACROSS GILL OF DOGFISH SQUALUS ACANTHIAS

1. 1. Eight drugs of widely different chemical and physical types were injected into Squalus acanthias, and their excretion by gill and kidney measured. 2. 2. The most lipid-soluble, non-polar substance, ethyl m-aminobenzoate (MS 222) was rapidly excreted by diffusion across the gill. 3. 3. The most lipid-insoluble, ionized substance, benzolamide (CL 11, 366) was excreted by active renal tubular secretion. 4. 4. In general, the rate of excretion across the gill was a function of lipid solubility. 5. 5. Study of the actual rates of excretion and half-lives of the drugs shows that gill excretion is relatively slow unless lipid solubility is very high 6. 6. Unless tubular secretion occurs the excretion by the kidney is also slow, since glomerular filtration rate is relatively low in this species. 7. 7. Many substances, therefore, are excreted more slowly in S. acanthias than in mammals; a typical example is sulfanilamide. © 1968.