Adding to my own comment, this also helps explain the true sample size as it was much larger than 10. The reason being that each participant received:
1x dose placebo
1x dose low active drug
1x dose med active drug
1x dose high active drug
Each dose was administered over a 7 day period with 1 week washout periods. 10 participants x4 doses = 40, essentially 4x groups of 10.
