The rapid detection of metronidazole in urine.

When metronidazole (Flagyl) is prescribed for trichomoniasis or lambliasis, it is unusual for the treatment not to be followed-up; however, it is possible that the patient does not take the drug, and the doctor may wonder whether the drug is being properly absorbed. It is also thought that metronidazole decreases the desire for alcohol in alcoholics. Here the co-operation of the patient may be doubtful and the question of whether or not he is taking the drug arises much more often. It appears, therefore, that it would be of value to establish whether metronidazole has been ingested and if it has been absorbed. A well-equipped laboratory can easily study the presence of metronidazole in blood or in urine but this cannot be carried out in an ordinary clinic. In the absence of a rapid blood test, the simple and quick detection of metronidazole in urine is of practical interest. A similar problem arose 20 years ago concerning sulphonamides and prostitutes. We had to examine prostitutes periodically for gonorrhoea, and quite often before this weekly examination, they took sulphonamides in order to "have a good specimen". Of course, they emphatically denied this when asked. We tioted, at this time, a paper by Vanhaecke (1944) which stated that a yellow colouration was produced when newspaper, previously acidified, was dipped into the urine of patients taking sulphonamides. There was diazotization between certain components of the paper and the NH2 group of the sulphonamide. We often used this method with known prostitutes and were able to convince them that they were trying to deceive us. Our colleague, Dubost (1944) showed that the principal reactive component in the paper was furfurol, or lignin, and that a similar reaction could