After a bit brainstorming I first had the idea of a caterpillar, from which I played with the word: caterpillar >> pillarcater >> pillarcat. The idea of consuming pills was already before too, so more or less, "pill" in caterpillar and the name pillarcat was a coincidence, after which I decided not just to turn the caterpillar into a cat, but rather a "caterpillar" with cat head and pill tail.