Papers of the Week

The neurotransmitter Substance P, and its neurokinin-1 receptor (NK-1R) are involved in the regulation of many pathophysiological processes including emesis, inflammation and nociceptive processing. This review provides a brief summary of the anti-inflammatory and analgesic properties of experimental NK-1R antagonists followed by a systematic review and meta-analysis on maropitant, the only NK-1R antagonist with a label indication for emesis in veterinary patients. There is very limited evidence based information on the putative clinical utilisation of maropitant for pain and inflammation. The aim of this systematic review and meta-analysis was to evaluate published reports on anti-inflammatory, analgesic and anaesthesia-sparing effects of maropitant. Medline, Pubmed, Science direct and Web of Science were searched to identify all published studies on maropitant, followed by a meta-analysis. Fourteen studies with 128 animals receiving maropitant and 127 controls met the inclusion criteria. Overall, maropitant had a significant inhalation anaesthetic-sparing effect (SMD -0.92, 95% CI -1.30, -0.54; P < 0.00001). However, treatment with maropitant had no effect on pain (SMD 0.06, 95% CI -0.37, 0.48; P = 0.80), or leukocyte cell infiltration in different inflammatory conditions (SMD -0.60, 95% CI -1.31, 0.11; P = 0.10). Based on all eligible studies for this review, it can be deduced that maropitant significantly reduced the minimum alveolar concentrations for isoflurane and sevoflurane for many different surgical procedures but it had no clearly proven effect on inflammation and pain.