Mark: The decongestant drug Zokaz was discontinued by its manufacturer because long-term studies revealed that it increased the risk of heart attack  Qualzan, another decongestant, works by essentially the same physiological mechanism as Zokaz  So Qualzan probably also increases the risk of heart attack  Kathy: The decongestive effects of the two drugs do stem from the same physiological mechanism
But since they are different chemically, the two drugs probably have different side effects
arguing against a conclusion by raising questions about the validity of scientific studies cited in support of that conclusion