Urinary Excretion of Methaqualone-N-oxide in Man

Abstract

1. Oral administration of therapeutic doses (250 mg) of methaqualone (Melsed) to adult human subjects gives rise to the urinary excretion of methaqualone-N-oxide. This metabolite has been identified by chromatography and mass spectrometry and quantitatively determined by reduction with titanium trichloride to methaqualone which was then determined by g.l.c.

2. The N-oxide accounts for 5–9% of the dose in 24 h.

3. 2-Nitrobenzo-o-toluidide, a possible oxidation product of methaqualone-N-oxide, has not been detected.

4. The urinary excretion of unchanged methaqualone is less than 0.3 % of the dose. The ease with which methaqualone-N-oxide is thermally converted to methaqualone casts doubts on the previously published figures for the urinary excretion of methaqualone.