A Simple Method for Determination of Levels of Amethopterin in Blood and Urine.

Abstract

A simple disc technic was devised for determining concns. of amethopterin in blood and urine. This test has an accuracy which compares favorably with similar assay methods for antibiotics. Amethopterin appeared in the blood and urine in detectable amts. 15-30 min. after the ingestion of a 5 mg. dose on a fasting stomach by 2 normal individuals, and 30 to 60 min. after ingestion at the same dose by 4 normal non-fasting individuals. In some of the 6 it was still detectable at 6 hrs., but in none after 24 hrs. Six normal adults excreted 40-57% of the ingested dose in the urine within 24 hrs. In one patient little difference in serum levels or total excretion could be demonstrated whether the drug was given by the oral or intramusc, route. In a patient with impaired renal function, higher initial serum levels were obtained and detectable amts. were present in the blood serum 48 hrs. after ingestion.