Effects Of Large-Dose Methylprednisolone On Pharmacodynamics Of Rocuronium In Septic Rats

Objective To study effects of large-dose methylprednisolone on the pharmacodynamics of rocuronium in different stages of septic rats.Methods Using 3×2 factorial design 48 healthy adult male SD rats were randomly divided into six groups and eight in each group. All rats were treated with two kinds of treatment; and one was the model which it was divided into no model, early septic model and late septic model; another was pretreatment which had two levels as saline and methylprednisolone pretreatment. In no model groups sepsis model was not established; in early septic model groups early sepsis model was established and in late septic model groups late sepsis model was established. In methylprednisolone pretreatment groups rats were injected intravenously by methylprednisolone 190.28 mg/kg and in saline pretreatment groups rats were injected by the same volume of saline intravenously 30 min before rocuronium 3.81 mg/kg injected intravenously. MAP and HR were recorded 30 min before, right at, 30, 60, 240 min after rocuronium administered after each rat anesthetized and onset time (from injection of muscle relaxant to maximum depression of twitch tension of T₄), TOF unresponsive period (duration of muscle relaxant to maximum depression of twitch tension of T₁), apex time (from muscle relaxant to maximum depression of twitch tension to return of twitch tension to 5% of the control T₁ value) and clinical duration time (from injection of muscle relaxant to return of twitch tension to 25% of the control T₁ value) , the time at which T₁ recovers to 10%, 25%, 50%, 75% and 90% of control T₁ value and recovery index (from 25% recovery of the control twitch tension to 75%) , and vivo action time (from injection of muscle relaxant to return of twitch tension to 5% of the control value) and rate of macodynamic index were measured.Results (1) Compared with no model groups, early sepsis model groups HR and MAP increased (P<0.05) and late sepsis model groups MAP reduced (P<0.05). (2) Onset time in late sepsis model groups was significantly prolonged than no model groups (P<0.05). Apex time, TOF unresponsive period and clinical duration time were significantly shorten in early sepsis model groups and late sepsis model groups than those in no model groups (P<0.05) and significantly shorten in late sepsis model groups than those in early sepsis model groups (P<0.05); they reduced in methylprednisolone pretreatment groups than saline pretreatment groups (P<0.05). The time of recovery to 10%, 25%, 50%, 75%, 90% T₁ and recovery index were significantly shorten in early sepsis model groups and late sepsis model groups than those in no model groups (P<0.05) and significantly shorten in late sepsis model groups than those in early sepsis model groups (P<0.05); they reduced in methylprednisolone pretreatment groups than saline pretreatment groups (P<0.05). The vivo action time was significantly shorten in early sepsis model groups and late sepsis model groups than those in no model groups (P<0.05) and significantly shorten in late sepsis model groups than those in early sepsis model groups (P<0.05); there were no significantly differences in rate of macodynamic index including TOF unresponsive period, apex time, clinical duration time, time at which T₁ recovers to 10%, 25%, 50%, 75% and 90% of control T₁ value, recovery index and vivo action time (P>0.05).Conclusion Sepsis attenuates the effects of nondepolarizing neuromuscular blocker rocuronium, relevant to stages of sepsis; large-dose methylprednisolone also attenuates the effects of rocuronium; and there are interactions between sepsis and large-dose methylprednisolone on effects of neuromuscular block of rocuronium.