Food typically delayed absorption for all drugs for which the time to Cmax (tmax) during fasting was under 4 h. The degree of delay varied between drugs; for example there was little or no delay in absorption for celecoxib and meloxicam, but an increase of fed tmax over fasted tmax of 250% or more for diclofenac, etoricoxib, and ketoprofen. Ibuprofen, paracetamol and naproxen were intermediate between these extremes.
Food reduced the Cmax for all drugs with a fasting tmax of <2 hours, which includes analgesics typically available without prescription in many parts of the world (aspirin, diclofenac potassium, ibuprofen and paracetamol). For celecoxib, Cmax increased in the fed state, while meloxicam was unaffected.
The authors acknowledge the potential limitations of their review; including only partial coverage of the potentially available data (many bioavailability studies are not published). They say that their findings may provoke companies with unpublished studies to revisit them, with a view to confirming their results. In addition the studies were often of a small size, there was insufficient detail to determine whether the type of meal has any particular consequences, and the findings cannot necessarily be extrapolated to chronic dosing.
Despite the limitations, they say the results are significant and stem from the increasing understanding of the importance of early, high, plasma drug concentrations for pain relief, particularly in the treatment of acute pain. If taking analgesics with food reduces analgesic efficacy then this will increases the likelihood of additional doses or different analgesics being taken. They conclude that it ‘may be time to rethink research priorities and advice to patients and public’.