Vaccines, Blood & Biologics

Extension of Expiration Date for Black Widow Spider Antivenin Packaged Lot H019984 until July 8, 2014 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.  The expiration for the sterile diluent lot 0671078 in packaged lot H019984 is March 31, 2014. DO NOT USE EXPIRED DILUENT.  Antivenin lot 0672105 may be used until its expiration date of July 8, 2014. 

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: 03/27/2015
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