THE DETERMINATION OF d-AMPHETAMINE IN BODY FLUIDS

¹ Research and Development Division, Smith, Kline and French Laboratories, Philadelphia, Penna.

1. The methyl orange method as reported here is satisfactory for the estimation of d-amphetamine down to 1 microgm./5 ml. of dog plasma. The procedure not only produces a negligible blood blank but only three hours are required to make a complete analysis. However, the method is not specific for d-amphetamine.

2. The preliminary application of this method to in vivo studies has produced some interesting and perhaps controversial results. For practical purposes, 5 and 10 mgm. oral doses of d-amphetamine sulfate administered to dogs were not detected in the blood over a five-hour period when the blood was withdrawn at the jugular vein. Similarly, a 10 mgm. intravenous dose could not be detected in the blood. A 40 mgm. oral dose produced a detectable blood level at one hour and a higher blood level at five hours when blood was withdrawn at the jugular vein. After a 10 mgm. intravenous administration into the jugular vein, sample withdrawals at the carotid artery, femoral vein and femoral artery have shown blood levels decreasing from 13 to less than 1 microgm. of d-amphetamine/5 ml. of plasma. A difference in the blood levels at the jugular vein and carotid artery over a twenty-minute period after administration indicates that some tissue of the brain removes d-amphetamine in a rapid manner.

3. The methyl orange method when accompanied by a buffer wash is applicable to urine level determinations of d-amphetamine. These results are in accord with those found by another investigator utilizing a different method.