Methylergonovine
Methylergonovine is only found in individuals that have used or taken this drug. It is a homolog of ergonovine containing one more CH2 group (Merck Index, 11th ed). Methylergonovine acts directly on the smooth muscle of the uterus and increases the tone, rate, and amplitude of rhythmic contractions through binding and the resultant antagonism of the dopamine D1 receptor. Thus, it induces a rapid and sustained tetanic uterotonic effect which shortens the third stage of labor and reduces blood loss.