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U.S. Department of Health and Human Services

Animal & Veterinary

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VMAC Endorses Post-Approval Monitoring Program for Posilac®

December 18, 1996

The Veterinary Medicine Advisory Committee (VMAC) met on November 20, 1996 to consider the issue of bovine somatotropin (bST). FDA approved Monsanto Company's Posilac® in November 1993, following an extensive and comprehensive review of the product's safety and efficacy, including human food safety. Posilac® is currently the only recombinant bovine somatotropin product approved for increasing milk production in dairy cattle in the U.S. Prior to approval, the Center for Veterinary Medicine (CVM) determined that use of Posilac® caused a small increase in the incidence of mastitis and an increase in the use of medications for mastitis and other health problems. At a meeting held in March 1993, the VMAC concluded that the increased potential for drug residue in milk could be managed by practices currently in use by the dairy industry.

At the time of commercial introduction of Posilac®, the Monsanto Company initiated a Post-Approval Monitoring Program (PAMP) to determine if mastitis incidence and antibiotic use was manageable under actual use conditions and to determine if label directions were adequate. The key components of the PAMP were:

  1. A proactive system of collecting Adverse Drug Experience Reports,
  2. A program of tracking milk residues by key dairy States before and after the approval of Posilac®,
  3. A 28-herd study to evaluate Posilac® under actual conditions of use.

This PAMP is the most extensive post-approval study ever conducted for any animal product. The herd component involved 28 herds representing 1213 cows in key dairy producing States. The results of this study reflect the general good health of dairy cattle given Posilac® for a single lactation under commercial conditions. Stringent requirements were placed on the participants regarding data collection, recordkeeping, veterinary consultation, daily observations, etc. Throughout the entire program, FDA closely monitored all PAMP activities. Special drug experience reports were submitted to CVM every 90 days, including status reports, units of product sold, etc. FDA conducted on-site inspections of the PAMP components five times during the Program. During these visits investigators reviewed raw data, interviewed clinical investigators, reviewed the firm's Quality Assurance Standard Operating Procedures for the herd study, and reviewed test article storage and inventory. In addition, CVM scientists conducted farm inspections of 10 herds selected from the 28 herds. They interviewed herd managers and veterinarians, reviewed the recordkeeping systems, and observed drug administration and inspected drug storage areas and inventories. No significant problems were found. Data integrity was acceptable, and farm records from data entry to data analysis showed excellent fidelity. CVM concluded from data collected in the PAMP that the effects of the use of Posilac® in this study were in close agreement with the effects observed in the preclearance studies.

Monsanto officials presented information from their State tracking program showing that there have been no changes in the percentage of milk discarded due to violative residues attributable to the use of Posilac®.

The Veterinary Medicine Advisory Committee was asked to consider the following two questions prior to the start of the meeting:

  1. Does the proposed revised labeling for Posilac® provide adequate directions for actual conditions of use?
  2. Do the results of the Post-Approval Monitoring Program adequately address the safety of the milk supply as it relates to the use of Posilac®?

At the end of the meeting each VMAC member affirmatively responded to these questions. The VMAC concluded that the labeling of Posilac® provides adequate directions for actual conditions of use. In addition, the VMAC endorsement of the final results of the PAMP confirms that bST is indeed safe and has no adverse effect on the milk supply.

FDA management also agrees that Monsanto Company's Post-Approval Monitoring Program adequately addressed the safety of the milk supply as related to Posilac®. Recently, Dr. Michael A. Friedman, FDA's Deputy Commissioner for Operations, told the Monsanto Company, "The issues surrounding this highly visible product are in many ways a microcosm of the science and public policy challenges that industry and the Agency face in bringing new products to the market place that offer potential benefits to society...I believe the outstanding quality of your studies and your commitment to working closely with the Agency in meeting your PAMP goals establish a model for successfully dealing with challenging approval issues."


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Issued by: FDA, Center for Veterinary Medicine

Communications Staff, HFV-12

7519 Standish Place

Rockville, MD 20855