Letter to the Editor
The review of envenomation treatment, in this case black widow spider bites, by Leon Gussow, MD, was very interesting, and the risk of anaphylaxis versus the potential benefit of antivenin was well stated, and is an important consideration. (“Unusual — and Fatal — Cases from the Latest National Poison Data System Report,” EMN 2012;34:10; http://bit.ly/IY7ooB.) One point that I thought should also be addressed is the narcotic analgesic used. Many narcotics are associated with the release of histamine, including Dilaudid, but fentanyl is not. It seems reasonable to consider using fentanyl for narcotic analgesia in cases where anaphylaxis is or might be present.
The contribution of any histamine release associated with Dilaudid and its contribution to the anaphylaxis seems small, if at all, but as a practice I use only fentanyl in cases where there is the potential for anaphylaxis to avoid possible histamine release, the consequent allergic manifestations, and the venodilation that accompanies it.
Paul Janson, MD
Dr. Gussow responds: You bring up a very interesting point. This question has not been studied to my knowledge, and I'm not aware of any case reports where a bad outcome following black widow spider bite was associated with specific opiates. As I mentioned in the article, the two fatal cases of anaphylaxis following administration of black widow spider antivenin involved atopic or asthmatic patients; one inappropriately received IV push instead of infusion and the other clearly did not have adequate treatment with opiates and benzodiazepines before antivenin was given. I carefully consider the risk-and-benefit calculation before administering antivenin, and administer it if indicated according to guidelines would have a far greater effect on prognosis than the specific opiate used for pain control.