New Drugs and Devices From 2011 – 2012 That Might Change Your Practice

Joe Lex, MD


Western J Emerg Med. 2013;14(6):619-628. 

In This Article

Anascorp® (Centruroides Immune F(Ab')2 [Equine])

Scorpions are predatory arthropods in the class Arachnida. They have 8 legs and are easily recognized by the pair of grasping claws and the narrow, segmented tail, often carried in a characteristic forward curve over the back, ending with a venomous stinger. They range in size from 9 mm to 21 cm and are widely distributed over all continents, except Antarctica. There are 1,752 described species of scorpions, with 13 families recognized. Scorpions are known to fluoresce when exposed to certain wavelengths of ultraviolet light, such as that produced by a black light, due to the presence of fluorescent chemicals in the cuticle.

Scorpion venom has a fearful reputation, and about 25 species are known to have venom capable of killing a human being.

Anascorp® is an antivenin indicated for treatment of scorpion envenomations, but only if symptoms develop, such as loss of muscle control, roving or abnormal eye movements, slurred speech, respiratory distress, difficulty with swallowing, excessive secretions or any symptoms that may increase risk for aspiration or compromised airway. It is available in the U.S. in some hospitals in Arizona and Nevada, where the dangerous bark scorpion is found.

Centruroides immune F(ab')2 equine has a mechanism of action similar to that of other available antivenin products. It is composed of F(ab')2 fragments specific to the toxic venom of Centruroides scorpions. These fragments target, bind, and neutralize the toxic venom. This promotes elimination and redistribution of the toxin from body tissues.

Centruroides immune F(ab')2 equine is dosed by the whole number of vials until symptoms are resolved. The approved dosage is t3 vials as soon as possible after symptoms are observed, but an additional vial may be administered every 30 to 60 minutes if symptoms remain. Pharmacokinetic properties are shown in Table 6.

The 6 clinical trials of Centruroides immune F(ab')2 equine show resolution of clinically important signs of envenomation when compared to placebo/supportive care. Only one controlled trial of Centruroides immune F(ab')2 equine has been conducted consisting of 15 pediatric patients that presented for treatment within 5 hours of scorpion envenomation. This trial demonstrated a significant reduction of blood venom levels and full resolution of clinical symptoms by 4 hours post dose versus supportive care with midazolam.

As per the manufacturer, the shelf life of the product is 2 years. The average number of vials required to complete treatment is 3.59. Average treatment cost is $7,820.40 for 3 vials and $10,427.20 for 4 vials.