Vaccines, Blood & Biologics

Extension of Expiration Date for Black Widow Spider Antivenin Packaged Lot H019984 until January 3, 2015 And Instructions for Diluent Use

Important Notification

This is to provide you with important information regarding Antivenin (Latrodectus mactans) (Equine), commonly referred to as Black Widow Spider Antivenin (BWSA).  Black Widow Spider Antivenin is indicated for patients with symptoms due to bites by the Black Widow spider. This product is manufactured by Merck and Company, Inc.  Due to limited supplies, Merck currently ships BWSA only for patients with symptomatic bites, within 24 hours of notification (see Merck contact information, below).  

Packaged Lot H019984 has a labeled expiration date of March 31, 2014. The packaged lot contains a) Antivenin (BWSA) lot 0672105; b) sterile diluent (water for injection), and c) horse serum for sensitivity testing. 

FDA has extended the expiration date of Antivenin lot 0672105, contained in Packaged Lot H019984.  This extension is based upon FDA evaluation of stability data, which has determined that the Antivenin will maintain stability and potency through January 3, 2015.  Since Antivenin lot 0672105 has a new expiration date, you may maintain the entire Black Widow Spider Antivenin Packaged Lot H019984 in your inventory and keep it available for use until January 3, 2015.

This expiration extension does not apply to the sterile diluent.  The expiration for the sterile diluent lot 0671078 in packaged lot H019984 was March 31, 2014.  DO NOT USE EXPIRED DILUENT.  

Instructions for diluent use

Do not use the expired diluent packaged with BWSA.  Instead, reconstitute the BWSA with 2.5 mL of Sterile Water for Injection.   Then proceed to follow the package insert instructions under DOSAGE AND ADMINISTRATION. 

To urgently obtain BWSA for patients with confirmed symptomatic bites, you should call the Merck National Service Center Call Line at 1-800- 672-6372.  

Contact FDA

(800) 835-4709
(240) 402-8010
Consumer Affairs Branch (CBER)

Division of Communication and Consumer Affairs

Office of Communication, Outreach and Development

Food and Drug Administration

10903 New Hampshire Avenue

Building 71 Room 3103

Silver Spring, MD 20993-0002

Page Last Updated: 03/18/2015
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