I can find nothing in the literature available online (e.g.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3255391/ ) that suggests skin contact with penicillin can lead to a severe (or any) allergic reaction. [There seems to be some evidence that contact dermatitis can occur but that's not the same thing].
Further, I doubt that there's enough moisture present in a penicillin tablet (together with the natural oils on your skin) to allow the penicillin to enter your body through your skin.
As a precaution though (and as Retrocop suggests) you could use disposable vinyl gloves. (About £4 per hundred from discount stores or several times that price if you're silly enough to buy them from a pharmacy).
As someone who share his life with four cats, I reckon that the chances of you dying from multiple lacerations (due to the results of trying to get a tablet into a cat) are considerably higher than those of you dying through anaphylaxis ;-)