MPR provides concise and up-to-date drug information for healthcare professionals. Prescribing Reference, Inc. (PRI) is a sub ... sidiary of Haymarket Media Group of London, England. Established in 1984, PRI's goal was to provide healthcare professionals in the United States with a version of Monthly Index of Medical Specialties® (MIMS), the United Kingdom's leading monthly drug reference. This reference would be concise, compact, easy-to-use and updated frequently. In June of 1985, PRI launched Monthly Prescribing Reference® (MPR), its first and main publication. MPR is distributed on a controlled basis to primary care physicians throughout the U.S. read more