Sulfaethylthiadiazole IV. Steady State Blood Concentration and Urinary Excretion Data Following Repeated Oral Doses * *Smith Kline & French Laboratories and from Division of Microbiology, Hahnemann School and Hospital, Philadelphia, Pa.

Experimental data are presented illustrating the use of a specific velocity constant for drug disappearance from the blood stream in the determination of dosage regimens. Equations are presented which permit estimation of the limits of steady state blood concentrations in adult human subjects receiving equal doses of sulfaethyl-thiadiazole at regular time intervals following a priming dose. These concepts are illustrated with experimental blood and urine data for subjects receiving fixed doses at one-, four-, and six-hour periods. The importance of these type concepts and data in pharmaceutical product development is discussed.