The compatibility of oxytocin and tranexamic acid injection products when mixed for co-administration by infusion for the treatment of postpartum haemorrhage: An in vitro investigation.

Abstract

To investigate the compatibility of oxytocin and tranexamic acid injection products when mixed for the purpose of co-administration by intravenous infusion. Compatibility testing. Hospitals taking part in a multicentre postpartum haemorrhage treatment (E-MOTIVE) trial in Kenya, Nigeria, Tanzania and South Africa. Oxytocin and tranexamic acid products. The compatibility of two sentinel products of oxytocin injection and tranexamic acid injection in 200-mL infusion bags of both 0.9% w/v saline and Ringer's lactate solution was assessed. We analysed all tranexamic acid-oxytocin combinations, and each evaluation was conducted for up to 3 h. Subsequently, the compatibility of multiple tranexamic acid products with reference oxytocin products when mixed in 0.9% w/v saline over a period of 1 h was investigated. Concentration of oxytocin over time after mixing with tranexamic acid products. We found significant interaction between certain oxytocin and tranexamic acid products after mixing them in vitro and observing for 1 h. The interaction substantially impacted oxytocin content leading to reduction in concentration (14.8%-29.0%) immediately on mixing (t = 0 min). In some combinations, the concentration continued to decline throughout the stability assessment period. Oxytocin loss was observed in 7 out of 22 (32%) of combinations tested. In a clinical setting, mixing certain oxytocin and tranexamic acid products before administration may result in an underdosing of oxytocin, compromising care in an emergency life-threatening situation. The mixing of oxytocin and tranexamic acid injection products for co-administration with intravenous infusion fluids should be avoided until the exact nature of the observed interaction and its implications are understood.