Effects of food on pharmacokinetics of immediate release oral formulations of aspirin, dipyrone, paracetamol and NSAIDs – a systematic review

AIMS It is common to advise that analgesics, and especially non-steroidal anti-inflammatory drugs (NSAIDs), be taken with food to reduce unwanted gastrointestinal adverse effects. The efficacy of single dose analgesics depends on producing high, early, plasma concentrations; food may interfere with this. This review sought evidence from single dose pharmacokinetic studies on the extent and timing of peak plasma concentrations of analgesic drugs in the fed and fasting states. METHODS A systematic review of comparisons of oral analgesics in fed and fasting states published to October 2014 reporting kinetic parameters of bioavailability, time to maximum plasma concentration (tmax ), and its extent (Cmax ) was conducted. Delayed-release formulations were not included. RESULTS Bioavailability was not different between fasted and fed states. Food typically delayed absorption for all drugs where the fasting tmax was less than 4 h. For the common analgesics (aspirin, diclofenac, ibuprofen, paracetamol) fed tmax was 1.30 to 2.80 times longer than fasted tmax . Cmax was typically reduced, with greater reduction seen with more rapid absorption (fed Cmax only 44-85% of the fasted Cmax for aspirin, diclofenac, ibuprofen and paracetamol). CONCLUSION There is evidence that high, early plasma concentrations produces better early pain relief, better overall pain relief, longer lasting pain relief and lower rates of remedication. Taking analgesics with food may make them less effective, resulting in greater population exposure. It may be time to rethink research priorities and advice to professionals, patients and the public.