Theophylline Extended Release vs. Immediate Release Compounded

A very common question we are getting is how do we dose Theophylline compounded (immediate-release)? The manufactured Theophylline tablets that have now been discontinued were all extended release given every 12 hours. Now that all Theophylline must be compounded, thereby making it “immediate-release” instead of “extended-release”, the question is should we dose it differently. Most vets we work with are keeping the immediate release compounded version at the same frequency as the extended release manufactured product. We suggest starting at the same frequency and monitoring. If you feel that the pet requires more frequent dosing based on symptoms, the latest information on immediate release therapy is from Mark Papich at NC State who recommends the following:
Dogs: 9mg/kg q6-8h PO
Cats: 4mg/kg q8-12h PO
Reference: Saunders Handbook of Veterinary Drugs Small and Large Animal Fourth Edition 2016