March 21, 1996
BST Update
FDA approved Monsanto Company's recombinant bovine somatotropin (rbST) product, Posilac®, in November 1993 after a comprehensive review of the product's safety and efficacy, including human food safety. Posilac® is the only rbST product approved for increasing milk production in dairy cattle. The product has been commercially available since February 4, 1994.
In a March 14, 1995 FDA TALK PAPER, the Agency stated that during the first year of commercial use of Posilac®, a total of 806 reports of adverse effects were reported to Monsanto and submitted to FDA. A CVM UPDATE issued on October 12, 1995, included information on 509 reports of adverse effects reported from February 1 to August 25, 1995.
The following is an update on the adverse experiences to Posilac® reported to FDA from August 26, 1995 through February 3, 1996. During this period, FDA received 144 adverse experience reports (See table below.) It is important to note that a report of an adverse effect in relation to a drug does not itself establish that the effect was caused by the drug. FDA believes that 83 of the 144 reports were possibly associated with the use of Posilac®, and that the other 61 reports were not related to treatment with Posilac®. Also, all of the reported clinical manifestations are known to occur in dairy cattle not supplemented with Posilac®.
Of the 83 reports possibly related to the use of Posilac®, 18 included reproductive disorders, 10 involved digestive disorders, 23 included mastitis, 19 included injection site reactions, 12 included swelling of the udder or abnormal milk, 9 included foot or leg problems, and 17 involved increased somatic cell counts. In some cases, a single report contained multiple conditions.
The number and severity of the reported conditions raise no new animal health concerns about the safety of Posilac®. There is no indication that the drug is any less effective than labeled. In addition, FDA and State regulatory officials have found no indication of a change in the incidence of violative drug residues in milk associated with the commercial use of Posilac®.
Based on the these reports of adverse reactions to Posilac®, FDA finds no cause for concern. However, it is important for dairy farmers to continue to report all adverse reactions associated with the use of rbST. They may report such reactions to Monsanto, to FDA through their veterinarian, or directly to FDA's Center for Veterinary Medicine. CVM accepts collect calls during working hours, and an answering machine is available to record after-hours calls. The telephone numbers are (301) 594-1751 for collect calls during working hours, and (301) 594-0797 to leave a message on evenings and weekends.
SUMMARY OF ADVERSE REACTION REPORTS ON POSILAC®
August 26, 1995 through February 3, 1996
The following table summarizes the important clinical manifestations (CM) from the 83 adverse experience reports possibly related to the use of Posilac® from August 26, 1995 through February 3, 1996.
This summary is intended only as a general reference to the type of reactions that veterinarians and dairy farmers have voluntarily reported to the manufacturer or FDA. Therefore, the summary is not by itself a basis for determining drug association for a particular sign, safety or efficacy of the drug, or determining the frequency or incidence rate of a clinical manifestation. Each of the reports may contain one or more CMs, and as a result the number of CMs exceeds the number of reports. All of the reported clinical manifestations are known to occur in dairy cattle not supplemented with Posilac®.
Clinical Manifestation Number of Reports Estimated Number
(CM) with the CM of Cows Reported
with the CM
Mastitis (clinical) 23 416
Increased Somatic Cell Counts in Milk 17 446
Other Udder Abnormalities* 12 289
Reproductive Disorders** 18 381
Cardiovascular Disorders 1 1
Digestive Disorders*** 10 171
Foot or Leg Problems 9 110
Injection Site Reactions 19 349
Cattle Deaths**** 2 4
* Includes udder swelling, udder edema, or abnormal milk.
** Includes decreased fertility, abortions, premature births, and
retained placentas.
*** Includes anorexia, weight loss, and other digestive tract signs.
**** The most commonly reported CM for all dairy cattle drug products is death.
This includes cows that were euthanized or slaughtered due to an illness,
such as chronic mastitis.
Issued by:
FDA, Center for Veterinary Medicine,
Communications Staff, HFV-12
7519 Standish Place, Rockville, MD 20855
Telephone: (240) 276-9300 FAX: (240) 276-9115
Internet Web Site: http://www.fda.gov/cvm
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