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CroFab® Crotalidae Polyvalent Immune Fab
CroFab® [Crotalidae Polyvalent Immune Fab (Ovine)] is a sterile, nonpyrogenic, purified, lyophilized preparation of ovine Fab (monovalent) immunoglobulin fragments obtained from the blood of healthy sheep flocks immunized with one of the following North American snake venoms: Crotalus atrox (Western Diamondback rattlesnake), Crotalus adamanteus (Eastern Diamondback rattlesnake), Crotalus scutulatus (Mojave rattlesnake), and Agkistrodon piscivorus (Cottonmouth or Water Moccasin). To obtain the final antivenin product, the four different monospecific antivenins are mixed. Each monospecific antivenin is prepared by fractionating the immunoglobulin from the ovine serum, digesting it with papain, and isolating the venom specific Fab fragments on ion exchange and affinity chromatography columns.
CroFab® is standardized by its ability to neutralize the lethal action of each of the four venom immunogens following intravenous injection in mice. The potency of the product will vary from batch to batch; however, a minimum number of mouse LD50 neutralizing units against each of the four venoms is included in every vial of final product, as shown in Table 3.
Table 3 : Minimum Mouse LD50 Neutralizing Units1 for
Each Venom Component
|Venom||Minimum Potency per Vial of CroFab®2|
|Crotalus atrox||≥ 1270|
|Crotalus adamanteus||≥ 420|
|Crotalus scutulatus||≥ 5570|
|Agkistrodon piscivorus||≥ 780|
|1 One neutralizing unit is determined as the
amount of the mixed monospecific Fab proteins necessary to neutralize one LD50 of each of the four venoms, where the LD50 is the amount of venom that would be
lethal in 50% of mice.
2 As of 2008, the potency assay has been optimized for a new strain of mice, which has resulted in changes to the minimum mouse LD50 neutralizing units. These changes do not reflect any change in product potency, but only a different biological response of the mouse strain to the venom.
Each vial of CroFab® contains up to 1 g of total protein and sodium phosphate buffer consisting of dibasic sodium phosphate USP and sodium chloride USP. Thimerosal is used as a preservative in the manufacturing process, and as such, mercury is carried over into the final product at an amount no greater than 30 mcg per vial, which amounts to no more than 0.6 mg of mercury per dose (based on the maximum dose of 18 vials used in clinical studies of CroFab®). The product is intended for intravenous administration after reconstitution with 18 mL of 0.9% Saline.
Last reviewed on RxList: 4/17/2015
This monograph has been modified to include the generic and brand name in many instances.
Additional Crofab Information
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