Paracetamol: the potential therapeutic pathways defining its clinical use

The non-narcotic analgesic paracetamol is used as both an antipyretic and an analgesic. For mild-to-moderate pain, paracetamol is utilized; however, because it has no anti-inflammatory effect, it is not as effective as non-steroidal anti-inflammatory medicines (NSAIDs) as to reduce pain. Even while paracetamol is widely used and safe, its exact mechanism is still unknown. It has been shown that in addition to the well-established cyclooxygenase (COX) pathways, paracetamol and its metabolites can also modify other signaling pain pathways. The COX enzyme is inhibited by paracetamol either directly or indirectly through the activation of cannabinoid receptors (CB1R and CB2R) and transient receptor potential cation channel subfamily member 1 (TRPV1) by its metabolite N-arachidonoylphenolamine (AM404). Furthermore, paracetamol increases serotonin release, decreases serotonin metabolism, or blocks serotonin reuptake to boost serotonin levels in the brain. A small number of animal studies have suggested that COX-3, a brain-expressed COX-1 variation, may have a therapeutic role in the way paracetamol works. However, the COX-3 pathway alone cannot account for paracetamol's potent analgesic, antinociceptive, and antipyretic properties. The possible molecular routes of paracetamol with regard to its clinical applications are therefore revised in this review.