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DR. ANNE Z. MURPHY RESPONDS

Thank you for your interest in the article about my research in Neurology Today. In response to your comment — “The most egregious is her statement, ‘A dose of morphine that barely touches the pain in a female is above the lethal dose for males’ — the preceding sentence states “… in a persistent pain model in rats.” I was in no way inferring that opioids are unsafe in women and I apologize for any confusion that may have arisen.

The author of the story was referring to our data demonstrating that administration of morphine directly into the periaqueductal gray of cycling female Sprague-Dawley rats (dose range: 12–20 μg/0.5 μl), had no effect on thermal hyperalgesia induced by persistent inflammation; by contrast, these doses were lethal in the majority of male rats tested (Wang, X. and A.Z. Murphy). Morphine injection into the periaqueductal gray produces a sexually dimorphic response in a model of persistent inflammatory pain (Soc Neurosci Abstr 2005). Similar results were noted when we administered morphine systemically (Am J Physiol Regul Integr Comp Physiol. 2006;291;R300-306. E-pub 2006 Feb. 23).

Anne Z. Murphy, PhD

Georgia State University, Atlanta, GA