The determination of isoniazid and its metabolites acetylisoniazid, monoacetylhydrazine, diacetylhydrazine, isonicotinic acid and isonicotinylglycine in serum and urine.

1. A solvent system was devised for the extraction of isoniazid and its metabolites acetylisoniazid, monoacetylhydrazine, diacetylhydrazine, isonicotinic acid and isonicotinylglycine from serum and urine. 2. Specific chemical and fluorimetric methods were developed for the determination of the extracted isoniazid and acetylisoniazid, and chemical methods for the determination of monoacetylhydrazine, diacetylhydrazine, isonicotinic acid and isonicotinylglycine. 3. When applied to serum, these methods were capable of measuring concentrations of down to about 0.005mug of isoniazid/ml, 0.05mug of acetylisoniazid/ml, 0.2mug of monoacetylhydrazine/ml, 0.2mug of diacetylhydrazine/ml, 0.02mug of isonicotinic acid/ml and 0.1mug of isonicotinylglycine/ml. 4. In urine, these methods were capable of measuring concentrations of down to about 0.05mug of isoniazid/ml, 0.2mug of acetylisoniazid/ml, 1mug of diacetylhydrazine/ml, 0.1mug of isonicotinic acid/ml and 0.2mug of isonicotinylglycine/ml. 5. The stability of these compounds was studied in serum and urine and a method devised to decrease their decomposition in serum.