Anaphylaxis occurring at the end of anaesthesia is due to:

Opioids - In Indian scenario - most common anesthetic agent causing anaphylaxis is opioids and then comes neuro muscular blockers - In world scenario - NMB's and then opioids - Most common non anesthetic drug causing anaphylaxis are antibioticsFirst, the time required to reach a substantial fraction of the ultimate steady-state concentration is very long in the context of intraoperative use. To reach a near steady state more quickly requires a bolus be administered before the infusion is commenced (or increased). Remifentanil perhaps represents a paial exception to this general rule. Also, opioid concentrations will increase for many hours after an infusion is commenced; in other words, concentrations are typically increasing even though the infusion rate may have been the same for hours! That remifentanil achieves a near steady state relatively quickly is ceainly pa of why it has emerged as a popular drug for total intravenous anesthesia (TIVA).