Antidote Scarcity Stirs Concern as Season for Snakebites Starts

At the dawn of a new snake season, hospitals are facing a temporary shortage of antivenin, used to treat the swollen, blackened legs of hikers who are bitten by rattlers that have slithered out of their winter hibernation.

The nation’s longtime sole supplier of the antidote sent warnings to poison control centers across the country this week, saying that it expects to be sold out until July.

A sister company that makes a similar product for the veterinary market also released a shortage announcement. Southland veterinarians are scrambling to find antivenin for dogs and horses that get bitten by rattlesnakes. Some vets are even exploring foreign products.

“We’re in the same situation as the shortage for human antivenin,” said Debbie Houk, who works for an Irvine-based firm that distributes animal medications. “The company that supplies it to us is really rationing it out, and anything they have will go to humans first. We haven’t been able to get it.”

Fortunately for people, a new serum has just hit the market and can be procured within 24 hours, but it is two-thirds more expensive. As of last week, only six California hospitals--but none in Los Angeles, Orange or Ventura counties--had ordered the new medicine.

About 8,000 people in the United States are bitten by venomous snakes annually, according to the U.S. Food and Drug Administration. California Poison Control received 371 reports of snakebites last year. Area hospitals report a wide range in the incidence of cases annually, from half a dozen at UCLA Medical Center to 50 at Antelope Valley Hospital in Lancaster.

“The shortage [of the serum] is not just a problem in Southern California . . . it’s a nationwide problem,” said Dr. Rick Geller, medical director for California Poison Control. “There’s probably enough to get through the season; it’s just maldistributed. Nobody knows where all the antivenin is . . . [because] there’s no central registry.”

Generally, the farther south a rattlesnake is found in California, the more potent its venom and the more serum is needed to treat a bite, experts say. To treat a single bite, a patient is likely to need 20 to 50 vials of the antidote.

About 130 toxins are released during a bite, often causing excessive bleeding, cardiac problems and tissue and nerve damage. In extreme cases, an untreated bite can cause loss of a limb or death, experts say.

The Western rattlesnake--the most common in California--is found in woodlands, scrubby areas, desert or grasslands. Experts say the reptiles emerge from hibernation as the weather warms, usually in early spring--hence the term “snake season,” said Kent Beaman, herpetologist at the Natural History Museum of Los Angeles County.

Agoura Hills resident Joanne MacCallum stopped hiking during rattlesnake season six years ago after she was bitten. She was shopping at a plant nursery when a snake crawled out from under some vines and sank its fangs into her sandaled foot.

It felt as though she had stepped on a nail. Her foot and leg ballooned with fluid like a giant blister. By the time she told someone to call 911, her breathing was constricted and she had a strong metallic taste in her mouth.

Emergency room doctors treated her with Antivenin, which is also a brand name for the product.

“I was in intensive care for four days,” the interior decorator said. “Then I had an allergic reaction--hives--to the antidote.”

Medical literature and experts report a high incidence of allergic reactions to Antivenin.

Since 1954, Wyeth-Ayerst of Pennsylvania has manufactured Antivenin, a serum made from the blood of horses. In September, production was halted after the FDA found what the agency called quality control problems.

In October, Protherics PLC received FDA approval for its sheep-derived serum, CroFab. The product, which became available in December, is touted as being cheaper per treatment and having a lower occurrence of allergic reactions.

In drug trials, researchers reported using less CroFab per treatment than with Antivenin. However, in actual cases, physicians reported needing to use more CroFab than in the trials, said Jude McNally, assistant director of Arizona Poison Control. Wyeth’s product costs about $469 per vial; CroFab is about $775.

As of last week, Loma Linda University Medical Center, UC San Diego Medical Center, San Gorgonio Memorial Hospital in Banning, Palomar Medical Center in Escondido, Pomerado Hospital in Poway and Grossmont Hospital in La Mesa were the only California hospitals to have ordered CroFab, Protherics said.

In the meantime, Wyeth said it expects to have a limited supply of its serum available in July on an emergency basis only and will stop production of Antivenin entirely by the end of the year. Spokesman Doug Petkus said the decision was “based on a review of manufacturing capacity and human/resource issues,” not economic concerns.

A few hospitals around the state have reported an antivenin shortage. California Poison Control began alerting health care providers this week about the availability of CroFab.

Protherics has enough CroFab to distribute to a hospital within a day, said Dan McKerracher, spokesman for the British firm.

CroFab will cost about $15,000 for an average treatment, up from about $9,000 for a similar dose of Antivenin.

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Times staff writers Thuy-Doan Le, Tina Dirmann and Mai Tran contributed to this story.