Ropivacaine and dexamethasone: Better to separate than mixing together

Dear Editor, We read the article by Saini et al.,[1] recently published in IJA, with great interest. Our concern in the index study is regarding mixing ropivacaine with dexamethasone together for the block.[1] There is a warning against mixing ropivacaine with dexamethasone because it is physiochemically incompatible.[2–5] Unlike other local anaesthetics (bupivacaine and lignocaine), mixing ropivacaine with a non-particulate steroid like dexamethasone can precipitate the whole mixture.[2–4] Dexamethasone has a pH between 7.0 and 8.5; mixing it with ropivacaine lowers the pH, resulting in precipitation of the mixture.[2] Precipitation of non-compatible admixture may lead to occlusion of arterioles and ischaemia.[2] Albrecht et al.[5] found that there is low-quality evidence regarding the perineural administration of dexamethasone as a local anaesthetic adjunct to increase the duration of analgesia (an average of 2 h) compared to intravenous administration for interscalene brachial plexus block. They strongly suggest that ‘given the limited clinical relevance of this difference, the off-label use of perineural administration, and the risk of drug crystallisation, intravenous dexamethasone administration is recommended’.[5] Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.