[jrumbut]

It should be "script" I believe, short for "prescription".

Scrip is a word, but its meaning is different and it's close to archaic.

[waqf]

Interesting, why do you perceive that "scrip" cannot be short for "prescription" whereas "script" can be?

FWIW, Wiktionary lists both: https://en.wiktionary.org/wiki/scrip#Etymology_4

[WalterGR]

People in medicine use "scrip" to mean "prescription" when speaking to others in the field.