Nondepolarizing neuromuscular blockers

Nondepolarizing neuromuscular blockers may be useful in severe, refractory cases... 

Halothane exerts a pronounced hypotensive effect, to which a negative inotropic effect contributes. Enflurane and isoflurane cause less circulatory depression. Halothane sensitizes the myocardium to catecholamines (caution serious tachyarrhythmias or ventricular fibrillation may accompany use of catecholamines as antihypotensives or toco-lytics). This effect is much less pronounced with enflurane and isoflurane. Unlike halothane, enflurane and isoflurane have a muscle-relaxant effect that is additive with that of nondepolarizing neuromuscular blockers. 

Drugs that may be affected by aminoglycosides include depolarizing and nondepolarizing neuromuscular blockers and polypeptide antibiotics. 

Pancuronium (Pavulon) [Nondepolarizing neuromuscular Blocker/Para lytic] WARNING Use restricted to experienced personnel Uses Induce paralysis to facilitate ET intubation (RSI) Action Competitive antagonist of acetylcholine Dose Adults Peds. 0.04-0.1 mg/kg IV Maim 0.01 mg/kg q45-60min (onset w/in 1 min duration 30-60 min) Caution [C/-] Cardiac monitor, BP monitor, intubation supplies and ventilator required Contra Use w/ caution in... 

Various preventive measures have been recommended, but none is effective in all cases. One rehable method is the injection of a small non-paralysing dose of a nondepolarizing neuromuscular blocker 2-3 minutes before the injection of suxamethonium (53-57) in preventing fasciculations, but the patient must be carefully observed, since an unexpected degree of paralysis occasionally ensues (SEDA-6,130). 

Blitt CD, Carlson GL, Rolling GD, Hameroff SR, Otto CW. A comparative evaluation of pretreatment with nondepolarizing neuromuscular blockers prior to the administration of succinylcholine. Anesthesiology 1981 55(6) 687-9. 

Meyers EF, Krupin T, Johnson M, Zink H. Failure of nondepolarizing neuromuscular blockers to inhibit succi-nylcholine-induced increased intraocular pressure, a controlled study. Anesthesiology 1978 48(2) 149-51. 

There are two types of neuromuscular blocking drugs used during surgery nondepolarizing neuromuscular blockers and depolarizing neuromuscular blockers. 

Rocuronium bromide is a nondepolarizing neuromuscular blocker that binds competitively to cholinergic receptors on motor end plate to antagonize action of acetylcholine, resulting in block of neuromuscular transmission. It is indicated as an adjunct to general anesthesia for inpatients and outpatients to facilitate both rapid sequence and routine... 

Identify the major nondepolarizing neuromuscular blockers and one depolarizing neuromuscular blocker compare their pharmacokinetics. 

Table 27-2. Comparison of a typical nondepolarizing neuromuscular blocker (tubocurarine) and a depolarizing blocker (sucdnylcholine). ...

Nondepolarizing neuromuscular blockers Renal elimination, long duration Tubocurarine Pancuronium... 

Some of the new fa/s-quaternary ammonium agents produced depolarization of the postjunctional membrane at the neuromuscular junction before causing blockade other compounds, such as tubocurarine, did not produce this depolarization. Thus, the structural features of the remainder of the molecule determined whether the nicotinic antagonist was a depolarizing or a nondepolarizing neuromuscular blocker. 

The prototype of this class is cl-tubocurarine. It is administered intravenously and has a relatively long duration of action. Only approximately 1% of a dose is demethylated in the liver, and it is excreted primarily as unchanged drug in the urine and bile. d-Tubocurarine preparations contain bisulfites and, thus, may potentiate allergic reactions in patients virith bisultate allergy. It is the most potent inducer of histamine release of all the nondepolarizing neuromuscular blockers. 

The client is undergoing electroconvulsive therapy (ECT) for major depression and is receiving tubocurarine, a nondepolarizing neuromuscular blocker. Wbicb data would warrant immediate intervention by tbe nurse ... 

Immediately check the rectal or tympanic temperature and cool the patient rapidly (see p 22) if the temperature is above 40°C (104°F). The most rapid and reliably effective method of temperature control is neuromuscular paralysis with pancuronium, 0.1 mg/kg IV (p 472) or another nondepolarizing neuromuscular blocker. Caution If paralysis is used, the patient must be intubated and ventilated in addition, monitor the electroencephalogram (EEG) for continued brain seizure activity because peripheral muscular hyperactivity is no longer visible. 

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