April 22, 2020: The value of a Medical Toxicology Fellowship I note here. I can still see my teacher and mentor Dr. Matthew J. Ellenhorn almost 40 years ago, during his weekly Medical Toxicology Grand Rounds*, "never add two QTc prolongators together." This point added to many years of study of the effects of multiple similar toxins added to the system at the same time. Similar, though not identical toxins, operating with similar but not identical mechanisms of injury, not only have an addition of their toxic effects, but the physiological injury is usually multiple times that of the individual toxin.

(When I heard of a study that was taking place recently, the first thing I said to my colleague was "Aren't these both QT prolongators?"

(Another analogy that is not well understood, even by so-called experts, is the fact that the toxic effect of two heavy metals with similar but not identical mechanisms of injury, the toxic physiological will be not just an additive, but an exponent/multiple of each individual effect. A similar scenario may apply to the above cases.)

*These recorded Rounds led to the text books: Medical Toxicology: Diagnosis and Treatment of Human Poisoning.