The safety of healthy volunteers in First-in-Man trials - an analysis of studies conducted at the Bayer in-house ward from 2000 to 2005

Objective: The Northwick Park incident has focused the attention on the risk of healthy volunteers participating in Phase First-in-Man (FiM) studies irrespective of biologicals or small molecules being applied. However, only few data on the safety of healthy volunteers receiving small molecules in FiM trials are available. This study reports on the safety of healthy volunteers participating in single dose FiM studies performed with small molecules at the Bayer in-house study ward in Wuppertal from 2000 to 2005. Methods: From 2000 to 2005, 24 FiM dose escalation studies with small molecules were performed. Twenty studies were performed with oral formulations and four studies with intravenous formulations. 1,094 young healthy male subjects were included into the studies. 77 subjects dropped out before receiving any study medication. The remaining 1,017 study participants (mean age 31.8 +/- 6.5 years (range: 18 46 years)) received 1,160 treatments, 792 with active drug and 368 with placebo. Results: In total, 586 adverse events (AE) occurred equaling 0.51 AE/treatment and 0.58 AE/subject. 128 AEs occurred under placebo (0.35/treatment) and 458 under active drug (0.58/treatment). 98.3% of AEs were of mild or moderate intensity. Adverse events with a frequency >2% were headache (17.1%), nasopharyngitis (7.3%), flushing (7.0%), feeling hot (5.5%), nausea (4.1%), nasal congestion (3.9%), dizziness (3.4%), diarrhea (3.24%), Alanine aminotransferase (ALT) increase (2.6%) and orthostatic hypotension (2.4%). In only 5 out of 1,160 treatments (0.4%) a serious adverse event occurred. Two cases of hypotension were related to the mode of action of CNS compounds and judged to be drug-related while the other three events (muscle enzyme elevation (2 x), prolonged orthostatic reaction (1 x) were not drug-related. None of the serious adverse events was medically worrying or required hospitalization. Conclusion: The incidence of adverse events in FiM trials with small molecules in our center between 2000 and 2005 and the severity of AEs is comparable to what has been reported previously for Phase I trials with small molecules [3, 4]. It reflects our experience with FiM trials of more than 25 years in which no medically worrying or hospitalization requiring serious adverse event occurred.