Medication Summary
Be prepared to support the patient's cardiovascular and respiratory systems after a Mojave rattlesnake or similar envenomation.
Antivenins
Class Summary
These agents neutralize toxins from snakebites caused by North American pit vipers.
Crotalidae polyvalent immune FAB (ovine) (CroFab)
It is indicated for envenomation by North American pit vipers (eg, cottonmouths/water moccasins, copperheads, rattlesnakes) in adults and children.
Crotalidae immune FAB (equine) (Anavip)
Crotalidae immune FAB (equine) contains venom-specific F(ab’)2; fragments of immunoglobulin G (IgG) that bind and neutralize venom toxins, thereby facilitating redistribution away from target tissues and elimination from the body. It is indicated for envenomation caused by North American pit vipers, including rattlesnakes, copperheads, and cottonmouths (water moccasins).
Immunizations
Class Summary
Patients should be immunized against tetanus.
Diphtheria-tetanus toxoid (dT)
Diphtheria-tetanus toxoid is used to induce active immunity against tetanus in selected patients. The immunizing agent of choice for most adults and children older than 7 years are tetanus and diphtheria toxoids. It is necessary to administer booster doses to maintain tetanus immunity throughout life.
Pregnant patients should receive only tetanus toxoid, not a diphtheria antigen–containing product. In children and adults, one may administer into the deltoid or midlateral thigh muscles. In infants, the preferred site of administration is the mid thigh laterally.
Antibiotics
Class Summary
Prophylactic antibiotics are probably not indicated routinely, although they are widely prescribed. Common etiologic bacteria suspected in snakebite wound infections include Pseudomonas aeruginosa species, Enterobacteriaceae species, Clostridium species, and Staphylococcus epidermidis. For infected wounds, empiric therapy may include ciprofloxacin (contraindicated in pediatric patients and pregnant women) as a single agent or a combination of ceftriaxone plus amoxicillin-clavulanate, pending wound culture and sensitivity results. Retained foreign bodies (eg, fang, other tooth) are a common cause of wound infection.
Ceftriaxone (Rocephin)
Ceftriaxone is a third-generation cephalosporin with broad-spectrum gram-negative activity. It has lower efficacy against gram-positive organisms and higher efficacy against resistant organisms. Ceftriaxone arrests bacterial growth by binding to one or more penicillin-binding proteins.
Analgesics
Class Summary
Pain control is essential to quality patient care. It ensures patient comfort and promotes pulmonary toilet. Most analgesics have sedating properties, which are beneficial for patients with painful skin lesions. Use opiates with caution in unintubated patients because Mojave rattlesnake envenomation may cause respiratory difficulties.
Morphine (Astramorph, Duramorph, MS Contin)
Morphine is the drug of choice for narcotic analgesia because of its reliable and predictable effects, safety profile, and ease of reversibility with naloxone. Morphine sulfate administered intravenously may be dosed in a number of ways and is commonly titrated until the desired effect is obtained
Antihistamines
Class Summary
These agents are used to treat minor allergic reactions and anaphylaxis to antivenom or venom. Diphenhydramine may be used to pretreat patients with prior documentation of minor allergic reactions. Antihistamines are used for premedication to antivenom administration to reduce acute adverse reactions (not for direct treatment of snakebite).
Diphenhydramine (Benadryl)
Diphenhydramine is used for symptomatic relief of allergic symptoms caused by histamine released in response to allergens.
-
Mojave rattlesnake (Crotalus scutulatus). Note the diamond pattern fades into bands along the caudal third of the back and the white tail rings are wider than the black. Photo by Sean Bush, MD.
-
This is the typical appearance of a southern California Mojave rattlesnake bite site. Photo by Sean Bush, MD.
-
Mojave rattlesnake (Crotalus scutulatus). Photo by Sean Bush, MD.
-
A red diamond rattlesnake (Crotalus ruber). The postocular light stripe extends above the angle of the mouth in Mojave rattlesnakes. Photo by Sean Bush, MD.
-
This is a juvenile Mojave rattlesnake (postmortem). Note that the diamondback pattern fades into bands along the latter part of the snake's dorsum. Photo by Sean Bush, MD.
-
A western diamondback rattlesnake (Crotalus atrox). Photo by Sean Bush, MD.
