They were structurally similar to cytisine in many ways, sharing the location of a nitrogen atom in a particular place on a pair of bicycle-like carbon rings.

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So Coe moved a nitrogen atom, too, and suddenly had a series of compounds to test that did exactly what Pfizer had wanted a drug to do.

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He found a 17-year-old paper written by University of Maryland researcher Paul Mazzochi that mentioned how moving a nitrogen atom in a morphine molecule caused its morphinelike properties to disappear--and also made it poisonous, just like nicotine.

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