Caffeine has been variously reported to increase, decrease, andhave no effect on absorption of paracetamol.
Clinical evidence,mechanism, importance and management
Caffeine citrate 120mg increased AUC of a single 500mg dose of paracetamol in 10 healthy subjects by 29%, increased maximum plasma levels by 15 % and decreased total body clearance by 32%. The decrease in time to maximum level and increase in absorption rate did not reach statistical significance (See reference number 1). However, in another study, although caffeine slightly increased rate of absorption of paracetamol, it had no effect on extent of absorption (See reference number 2). Moreover,a third study states that caffeine decreased plasma paracetamol levels and AUC and increased paracetamol elimination in healthy men (See reference number 3). Caffeine is commonly included in paracetamol preparations as an analgesic adjuvant. Its potential benefit and mechanisms behind its possible effects remain unclear.
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