[Use of markers for compliance control during long-term therapy].

The compliance of 9 patients in taking an antihypertensive therapy was studied by labelling the active substance with riboflavin. The results shows that with a relatively small amount of label it is possible to control the intake of preparations. This is a suitable method for the clinical routine and it allows the direct determination of the elimination of the riboflavin in the urine two hours after the intake of the drug. It is proposed that this method should be used obligatorily in all studies of new drugs for the assessment of their action in the oral long-term therapy. For the daily routine it offers a suitable method for the control of cases where an initial clinical efficiency is followed by therapeutic failures in long-term treatment.