I seriously doubt Esplin wanted his host drugged for even a small amount of time.
Alloran was probably locked ball-and-chain style. Something for his tail. Something probably around his neck so Esplin could enter and exit his head easily.
Esplin probably had his own personal Yeerk Pool on his Blade Ship. It was also probably isolated in it's own room where he could have guards placed on the outside to look in. If Alloran would try to escape, Dracon Beams.
