More animal drugs for minor uses, minor species

Most drugs receiving MUMS designation are to treat aquatic animals
Published on January 01, 2008
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The Minor Use and Minor Species Animal Health Act has so far played a part in the development process for new drugs to treat fish, shrimp, sheep, and goats—and also some uncommon conditions in dogs.

The MUMS Act became law in 2004, with provisions for the designation and conditional approval of MUMS drugs taking effect immediately. The legislation is similar to the Orphan Drug Act of 1983, which increased availability of drugs for rare human diseases by offering incentives to pharmaceutical companies.

"AVMA heard from our veterinary members that some minor animal species or animals with uncommon conditions really needed pharmaceuticals developed to treat their conditions," said Dr. Elizabeth Curry-Galvin, director of the AVMA Scientific Activities Division. "It became clear that a new law was required to encourage such drug development. AVMA worked hard to advocate for passage of the MUMS bill, and we are still working to ensure practical regulations. It is gratifying to see this legislation bearing fruit in the form of drug products labeled for these previously underserved animals."

In 2007, the Food and Drug Administration issued final rules describing procedures for designating a product as a MUMS drug. Incentives for MUMS drugs include seven years of exclusive marketing rights, as well as eligibility for grants.

The FDA already has designated dozens of products as MUMS drugs, many of which remain in the development process. Sponsors must provide annual reports to show progress toward approval.

Several MUMS drugs received approval between 2005 and 2007, and one product received conditional approval. Conditional approval allows a company to market a drug for up to five years after demonstrating the product's safety and a reasonable expectation of effectiveness, while the company is working to confirm effectiveness and achieve full approval.

"MUMS changes the law for limited-use drugs in the hope that sponsors will be more willing and able to do the work needed to bring safe and effective drugs to the market," said Dr. Bernadette Dunham, director of Minor Use and Minor Species Animal Drug Development at the FDA Center for Veterinary Medicine. "The MUMS legislation is just one more improvement in the drug availability picture called for by the Animal Drug Availability Act."

Dr. Dunham said the Animal Medicinal Drug Use Clarification Act is another law that improved the availability of drugs for animals, by allowing veterinarians to prescribe extralabel uses of animal and human drugs. Nevertheless, Dr. Dunham said, "It is always better to have a drug approved for the species you are treating."

The first six MUMS drugs to receive approval, plus the drug that received conditional approval, were for products to treat fish or sheep. Drugs in development under the MUMS designation target conditions ranging from liver flukes in goats to necrotizing hepatopancreatitis in shrimp. The drugs in development for minor uses in dogs are for treating hyperadrenocorticism caused by adrenocortical tumor and for preventing cisplatin-induced emesis.

Drug approvals under the Minor Use and Minor Species Animal Health Act

Drug Species Target of treatment
Florfenicol Catfish Enteric septicemia associated with Edwardsiella ictaluri
Florfenicol Salmonids Cold-water disease associated with Flavobacterium psychrophilum
(conditional approval)
Catfish Columnaris disease associated with Flavobacterium columnare
Hydrogen peroxide Finfish eggs Saprolegniasis
Hydrogen peroxide Salmonids Bacterial gill disease asociated with Flavobacterium branchiophilum
Hydrogen peroxide Cool-water finfish and channel catfish External columnaris disease associated with Flavobacterium columnare
Moxidectin Sheep Adult and larval stages of various internal parasites

With uncommon conditions in major species, Dr. Dunham said, the FDA has encountered some difficulties in defining "small numbers" of animals and "minor use." Most MUMS drugs to date have targeted aquatic animals, partly because the aquaculture industry has a national coordinator for new animal drug applications.

The MUMS Act also contains a provision applicable to some drugs for nonfood-producing minor species. The provision will create an index of such drugs that companies may market without completing the traditional approval process. In late 2007, the FDA published the final regulations to implement the indexing provision (see following story).

In addition, the MUMS Act provides for Congress to appropriate funding for grants to companies that would defray the costs of safety and effectiveness testing for MUMS drugs. The FDA cannot seek appropriations for the grants until fiscal year 2009.