I was thinking about the hypospray McCoy gave Kirk to ‘adjust for the difference in oxygen levels and other environmental conditions.’

From the time I first watched the episode as a young child, I reasoned that there had to have been something more in the hypospray. Even in Earth-like conditions and gravity, Kirk wouldn’t last a minute against a Vulcan engaged by Pon Farr. McCoy wouldn’t have hesitated to add in a combat serum if he thought it would give Kirk a chance to survive.

(This was validated by the discussion of who and how someone could fight Vorik in Voyager before B’Elanna decided to take him on herself.)