Curare Phase-Out Decried

Casey D. Blitt, MD

To the Editor

I write this letter to express my disappointment and discouragement because it appears that d-tubocurarine will no longer be available to the anesthesia practitioner. Having finished my residency in 1970, I have been practicing anesthesia for a substantial length of time. Many practitioners who utilize succinylcholine in adults routinely “pretreat” with a small dose of a nondepolarizing neuromuscular blocker prior to administering the succinylcholine. In theory, the rationale for such “pretreatment” is to mitigate, minimize, eliminate, or otherwise modify some of the undesirable side effects of succinylcholine such as fasciculations, postoperative myalgia, increases in intragastric and/or intraocular pressure, and rises in serum potassium.

Although the literature is not crystal clear regarding this issue, it is clear to many practitioners (myself included) that the best nondepolarizer for such “pretreatment” is d-tubocurarine. The other nondepolarizing neuromuscular blockers such as cisatracurium, pancuronium, vecuronium, and rocuronium may be used in such a “pretreatment” strategy. D-tubocurarine clearly is able to consistently modify the effects of succinylcholine without producing any significant effects from the nondepolarizer itself. The therapeutic window of other nondepolarizers is much narrower than that of d-tubocurarine, and, therefore, the practitioner runs the risk of either the “pretreatment” not working or the patient being symptomatic from nondepolarizing neuromuscular blockade. Additionally, the cost of nondepolarizers other than d-tubocurarine is significantly greater than d-tubocurarine.

Why pharmaceutical manufacturers have ceased to produce d-tubocurarine is unknown to me at this time. In my opinion, the drug is clearly a valuable part of our neuromuscular blockade armamentarium, particularly in adult patients who require a rapid sequence induction/intubation. It is my opinion that there is a significant concern regarding patient safety, as practitioners may not feel comfortable utilizing succinylcholine without nondepolarizing pretreatment, and, therefore, would opt to utilize other neuromuscular blockers for a rapid sequence induction/intubation that are not as efficacious as succinylcholine in this situation. Additionally, d-tubocurarine has a long record of safety in facilitating the diagnosis of myasthenia gravis.

I would hope that one or more of the manufacturers of d-tubocurarine will reconsider their decision to eliminate this product from the market. I feel that the lack of d-tubocurarine does a tremendous disservice to anesthesia practitioners regardless of vintage.

Casey D. Blitt, MD
Director of Education, Peer Review, Quality Assurance, and Risk Management
Old Pueblo Anesthesiologists
Tucson, Arizona