Bonnie,

A cats digestion is approximately 5 hours. However, in your case it may be
longer or shorter depending on the medication and the effects the medication
has on the cats metabolism. If it has a mild case of Pancreatitis, your vet
may recommend putting her on a 24-hour fast, followed by a week of small,
bland meals (That is prob what you are doing now). After that, it should be
okay.  In more serious cases, your cat will need to be hospitalized, put on
a fast, and given intravenous fluids and injections of antibiotics. It all
depends on the cat.