THE HEALTHY VOLUNTEER IN CLINICAL-PHARMACOLOGY - PERSONALITY AND MOTIVATION

The aim of the present study was to quantify the personality structure and motivation of medical students, who are often the most readily av ailable source of healthy volunteers, since it has long been known tha t the pharmacodynamics and pharmacokinetics of drugs can be substantia lly modified by predominant personality traits (e.g. neuroticism, extr aversion). Over the course of 4 years, a total of 337 subjects (165 ma les, 172 females) out of the 496 medical students asked, participated in the study after appropriate instruction. Students were tested using the Motivation Q-Sort method which, by means of questions (''question naire sort''), investigates whether a subject tends to react in a succ ess-motivated (SM) or a failure-motivated (FM) mode. The variable meas ured is the so-called net hope (NH), where NH > 1.6 corresponds to SM and NH < -0.3 corresponds to FM. We also used the Freiburg Personality Inventory (FPI) as a suitable method of determining personality struc ture. The predominant traits of interest found were nervousness (FPI 1 ), extraversion (FPI E), and neuroticism (FPI N). In the first series of tests (primary selection), motivation only was determined in 337 vo lunteers. The range was fairly broad, with NH values from 4.32 (highly SM) to -3.09 (highly FM). In the second series of tests, about 60 SM and 60 FM subjects were selected. The Motivation Q-Sort method was rep eated with students placed under more difficult conditions, and the FP I was also performed. This procedure showed that (1) the NH values wer e comparatively stable under varied conditions and (2) in part marked correlations existed between motivation and personality: SM subjects t ended to be extravert, emotionally stable and not nervous, whereas FM volunteers tended to be introvert, emotionally unstable and nervous.