Suxamethonium Rocuronium

Rocuronium is a desacetoxy analogue of vecuronium which is stable in solution and formulated as an aqueous ready-to-use solution. It was deliberately designed as a low-potency relaxant in an attempt to develop a non-depolarising agent which would have a fast onset of action, closer to that of suxamethonium. The basis for this development was the observation that potency and the speed of onset... 

In 113 patients undergoing general anesthesia, intravenous midazolam 15 mg slowed recovery of the twitch height after vecuronium and atracurium compared with diazepam. The recovery index was not altered (162). However, in another study in 20 patients, midazolam 0.3 mg/kg did not affect the duration of blockade, recovery time, intensity of fasciculations, or adequacy of relaxation for tracheal intubation produced by suxamethonium 1 mg/kg, nor the duration of blockade and adequacy of relaxation for tracheal intubation produced by pancuronium 0.025 mg/kg in incremental doses until 99% depression of muscle-twitch tension was obtained (161). Furthermore, in 60 patients undergoing maintenance anesthesia randomly assigned to one of six regimens (etomidate, fentanyl, midazolam, propofol, thiopental plus nitrous oxide, or isoflurane plus nitrous oxide), midazolam did not alter rocuronium dosage requirements (165). 

There are several reports of pain during injection of rocuronium (5,6). Eight of 10 patients complained of severe pain, one complained of moderate pain, and another reported an unpleasant sensation (5). This suggests that rocuronium will almost invariably cause pain. The mechanism of this phenomenon is not clear, but there appear to be some similarities to propofol injection pain. Several authors have suggested that rocuronium should not be given to awake patients (5,6). On the other hand, small doses of rocuronium have been used, with some success, to prevent fasciculations and myalgia after suxamethonium (7-10). With regard to the severity of injection pain, rocuronium pretreatment in awake patients does not seem advisable. 

The matemofetal transfer or rocuronium, as indicated by a fetaFmatemal plasma concentration ratio of 0.16, is between that of vecuronium and pancuronium (32). When rocuronium was used for cesarean section, no adverse effects on the fetus were observed (32). With regard to the duration of rocuronium-induced paralysis and the relatively high incidence of failed intubations in obstetric patients, however, it was agreed that rocuronium should be considered for rapid-sequence intubation for cesarean section only if suxamethonium is contraindicated (33-35). 

Findlay GP, Spittal MJ. Rocuronium pretreatment reduces suxamethonium-induced myalgia comparison with vecuronium. Br J Anaesth 1996 76(4) 526-9. 

Rocuronium has an intemiediate duration of action of about 30 minutes hut with a rapid onset of action (1-2 minutes) comparable to that of suxamethonium (1-1,5 minute.s). It is reported to have no cardiovascu lar effects. 

The inhalational anaesthetics increase the effects of the neuromuscular blockers to differing extents, but nitrous oxide appears not to interact significantly. Ketamine has been reported to potentiate the effects of atracurium. Propofol does not appear to interact with mivacurium or vecuronium. Xenon is reported not to interact with mivacurium or rocuronium, and has less effect than sevoflurane on vecuronium neuromuscular blockade. Bradycardia has been seen in patients given vecuronium with eto-midate or thiopental. Propofol can cause serious bradycardia if it is given with suxamethonium (succinylcholine) without adequate antimuscarinic premedication, and asystole has been seen when fentanyl, propofol and suxamethonium were given sequentially. 

The duration of paralysis due to suxamethonium was reduced in one study by 20% when diazepam (150 micrograms/kg) was also given and the recovery time was shortened. Diazepam also slightly reduced the time to 25% and 75% recovery of twitch height in patients given vecuronium by about 15% (not statistically significant). In animals, diazepam increased the mean dose of rocuronium required by 13%, but this was not statistically significant. ... 

A study of 16 patients who had been taking various beta blockers (propranolol 5, atenolol 5, metoprolol 2, bisoprolol 2, oxprenolol 1, celiprolol 1) for longer than one month found no difference in the onset and duration of action of rocuronium, when compared with a control group. Similarly, intra-operative esmolol did not affect the onset and recovery time from suxamethonium (succinylcholine) blockade in patients with normal plasma cholinesterase (pseudocholinesterase) activity, but see also (b) above. 

An isoiated case report describes potentiation of tubocurarine and pancuronium by orai verapamii. However, long-term oral nifedipine did not aiter vecuronium or atracurium effects, and iong-term therapy with various caicium-channel blockers did not interact with rocuronium. Caicium-channei blockers do not increase the piasma potassium rise due to suxamethonium (succi-nyichoiine). 

One report suggests that recovery from the neuromuscular blocking effects of suxamethonium (succinyichoiine) is prolonged by ci-metidine, but this may possibiy have been due to the presence of metociopramide. Four other reports say that no interaction occurs between suxamethonium and either cimetidine, famotidine or ranitidine. Cimetidine, but not ranitidine, has been reported to increase the effects of vecuronium. Cimetidine does not aiter the effects of atracurium or rocuronium and ranitidine does not aiter the effects of atracurium. 

Robertson EN, Driessen JJ, Booij LHDJ. Suxamethonium administraticei prolongs the duration of action of subsequent rocuronium. EurJAnaes iesiol (2004) 21, 734-7. 

Systematic reviews The place of suxamethonium in pediatric practice has been reviewed It has significant adverse effects, some of which can be life-threatening. This is particularly relevant in pediatric anesthesia, because the spectrum of childhood diseases may expose susceptible individuals to an increased chance of adverse events compared with adults. The authors suggested that the rapidity of onset and offset of suxamethonium encourages its use by practitioners with only occasional experience of pediatric anesthesia. Rocuronium has a similar onset of action at a dose of 1.2 mg/kg, but sugammadex (a reversal agent specific to rocuronium) does not have a product licence for immediate reversal of neuromuscular blockade in children. 

Systematic reviews Because of its fast onset of action, rocuronium is a potential alternative to suxamethonium for rapid-sequence intubation in patients with an increased risk of aspiration. Four relevant studies considering the use of suxamethonium and rocuronium in emergency departments were selected from an evidence search and a structured review performed [11 ]. For the outcomes of clinically acceptable intubation conditions and time to onset, the two agents were not statistically significantly different. Suxamethonium seems to produce conditions that have higher satisfaction scores. The authors concluded that suxamethonium remains the drug of choice for emergency department rapid-sequence induction, unless there is a contraindication. 

This is a shghtly different conclusion from that reached in a Cochrane review of rocuronium versus suxamethonium for rapid-sequence intubation, which was that suxamethonium creates excellent intubation conditions more rehably than rocuronium [12 ]. However, the abihty of sugammadex to reverse deep neuromuscular blockade under rocuronium may alter the benefit to harm balance in comparison with suxamethonium. 

Comparative studies The impact of rocuronium versus succinylcholine neuromuscular blocking drug choice for laparoscopic pyloromyotomy was studied retrospectively in 246 infant patients and it was concluded that despite the potential side effects of suxamethonium, this agent remains the best choice of neuromuscular blocking drug [1. ... 

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