2009-10-01
In collaboration with the Food and Drug Administration (FDA), and
as a service to our members, ASH will provide information from the FDA
regarding therapies for patients. In sending this information, ASH does not
endorse any product or therapy and does not take any position on the safety or efficacy
of the product or therapy described.
The U.S. Food and Drug
Administration (FDA) released an alert noting a change to the United States
Pharmacopeia (USP) monograph for heparin, effective October 1, 2009. The change
will include a new USP reference standard and test method that is used to
determine the potency of the drug. The manufacturing and testing requirements
under the new monograph will lessen the potential for contamination of heparin
and enhance the production of a high quality drug. However, harmonization
of the standard will result in approximately a 10 percent reduction in the
potency of the heparin marketed in the United States.
The change in heparin potency may have clinical significance in some
situations, such as when heparin is administered as a bolus intravenous dose
and an immediate anticoagulant effect is clinically important. In such
situations health-care providers should consider the change in potency of
heparin when making decisions about what dose to administer. The change in
heparin potency is expected to be less clinically significant when it is
administered subcutaneously due to the low and highly variable bioavailability
of heparin when administered by this route. Health-care providers should
also be aware of the decrease in heparin potency as they monitor the
anticoagulant effect of the drug; more heparin may be required to achieve and
maintain the desired level of anticoagulation in some patients.
Manufacturers will not begin shipping heparin products manufactured and
tested according to the new USP monograph until October 8 or later.
FDA highlighted the following
important information and clinical recommendations that should be considered
during this time of transition:
- There will be simultaneous availability of heparin
manufactured to meet the “old” and “new” USP monograph, with potential
differences in potency. This overlap of products on the market is
necessary to make certain that there is an adequate supply of heparin
available for all patients. Products using the new “USP unit” potency
definition are anticipated to be available on or after October 8. FDA
is working with the manufacturers of heparin to ensure that an appropriate
identifier is placed on heparin made under the new USP monograph. Most
manufacturers will place an “N” next to the lot number.
- Consider the potential potency variation when
administering heparin,
particularly in situations where assurance of aggressive anticoagulation
is essential to treat or prevent life-threatening thromboses. Clinicians
should now consider the potential for up to 10 percent estimated decrease
in heparin activity per “USP unit” when deciding what dose to administer
in such cases.
- The potency change may require more frequent or
intensive aPTT or ACTmonitoring.
- Clinical judgment is essential in determining dose of
heparin. Heparin dosing is always individualized to the
patient-specific situation. The FDA-approved labeling for heparin has not
changed, including the recommended doses. Individualization of
heparin dosing has long been the standard for clinical use of the drug and
FDA reiterates the importance of clinical judgment in heparin dosing.
To view the FDA announcement and more
information regarding the heparin dosing changes visit: http://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm184674.htm.
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