Halothane Atracurium

Plotz J, Schreiber W. Vergleichende Untersuchung von Atracurium und Alcuronium zur Intubation alterer Patienten in Halothannarkose. [Comparative study of atracurium and alcuronium for the intubation of older patients in halothane anesthesia.] Anaesthesist 1984 33(11) 548-51. 

From animal experiments (8) it seems hkely that drug interactions with atracurium will be similar to those for other non-depolarizing neuromuscular blocking agents. Laudanosine has been reported to increase the MAC for halothane in animals (61). 

In man, potentiation and prolongation of the action of atracurium by halothane (62-64) have been reported, as has potentiation after 30 minutes of isoflurane anesthesia (65). Whether the dose of atracurium should be reduced from that used during balanced anesthesia by 20, 30, or 50% when patients are anesthetized with inhalational anesthetics can only be decided in the case of an individual patient if neuromuscular monitoring is available, since many other variables, such as the tissue concentrations of the volatile anesthetic and the response of the individual patient to the neuromuscular blocking drug, will influence the overall blocking effect. 

Stirt JA, Murray AL, Katz RL, Schehl DL, Lee C. Atracurium during halothane anesthesia in humans. Anesth Analg 1983 62(2) 207-10. 

Muscle relaxants may also contribute to anesthesia. Pancuronium 0.1 mg/kg has been reported to lower the MAC for halothane by 25% (135). It was conjectured that this could be due to a central effect or peripheral effect, through reduction of afferent input from muscle spindles to the reticular activating system. Recently, however, a similar though not identical study (SEDA-15, 124) (136) failed to confirm that pancuronium, vecuronium, or atracurium lowers the MAC for halothane. 

Fahey MR, Sessler Dl, Cannon JE, Brady K, Stoen R, Miller RD. Atracurium, vecuronium, and pancuroninm do not alter the minimum alveolar concentration of halothane in humans. Anesthesiology 1989 71(l) 53-6. 

The dosage of the neuromuscular blocker may need to be adjusted according to the anaesthetic in use. For example, the dosage of atracurium can be reduced by 25 to 30% if, instead of balanced anaesthesia (with thiopental, fentanyl and nitrous oxide/oxygen)," enflurane is used, and by up to 50% if isoflurane or desflurane are used. Another study recommended reduced doses of neuromuscular blockers such as atracurium and tubocurarine in children undergoing anaesthesia with enflurane or isoflurane. In one study, enflurane and isoflurane reduced the vecuronium infusion rate requirements by as much as 70%, when compared with fentanyl anaesthesia. Another study demonstrated that although halothane and isoflurane could both increase the neuromuscular potency of vecuronium, only isoflurane prolonged the recovery from neuromuscular blockade. ... 

---