Despite the importance of pharmacopeial standards, little is known regarding their effect on drug competition. Such information is of particular relevance given the rising costs of prescription drugs and the focus of policy-makers and other stakeholders on addressing these costs. We examined 982 prescription drugs approved by U.S Food and Drug Administration since 1982 to examine the association between U.S. Pharmacopeia (USP) standards, generic entry and prescription costs. The presence of a USP drug product monograph was not associated with the time to the third generic entrant or with the likelihood of having a generic competitor. However, on average, drugs with USP drug product monographs had approximately fifty percent more generic manufacturers in the U.S. than their counterparts after accounting for factors such as market volume, age, route of administration and vintage. This greater competition was associated with an approximate savings of $6.22 billion in 2016, suggesting that USP drug product monographs may play an important role in promoting pharmaceutical competition and reducing prescription drug costs.