Despite promising results from preclinical studies and 2 clinical trials, the neuroprotective properties of progesterone did not improve functional outcomes or decrease mortality after traumatic brain injury (TBI) in 2 large, parallel, placebo-controlled phase 3 trials.
Participants in the Progesterone for TBI, Experimental Clinical Treatment (PROTECT III) trial had moderate to severe TBI with a Glasgow Coma Scale score of 4 to 12 on a scale of 3 to 15 (lower scores representing a lower level of consciousness), with most injuries resulting from a motor vehicle accident (Wright DW et al. N Engl J Med. doi:10.1056/NEJMoa1404304 [published online December 25, 2014]).
Slomski A. Progesterone Offers No Benefits in Traumatic Brain Injury. JAMA. 2015;313(8):786. doi:10.1001/jama.2015.236