One day, you may find yourself heading for a pharmacy because your veterinarian prescribed a special drug that the pharmacist has to prepare. These medications are called “compounded drugs,” and they serve an important role in veterinary medicine.
Compounded drugs are not necessarily generic drugs. Generic drugs have been tested and approved by the FDA as being the bioequivalent of a brand-name drug. The FDA advises veterinarians that an approved brand or generic drug should be used before considering a compounded medication.
With cats, a common reason to compound a drug is its route of administration. Cats are often tenacious about rejecting pills, but a transdermal route—such as through the skin of the ear—is usually accepted much more easily. The downside is that, in some cases, compounded drugs may not be absorbed in the same manner as their non-compounded counterparts, resulting in variability in drug absorption.
Compounded drugs are “not subjected to the quality testing that traditionally manufactured products are,” according to the Veterinary Information Network. The product may contain more or less of the active ingredient. The stability of the product may also be variable, despite being labeled with a “beyond use date.” Expiration dates are rarely used because the drugs are not tested over long periods of time. The “beyond use date” is an approximation of when the drug is no longer stable.
When choosing to use a compounded drug for your cat, ask your veterinarian these two important questions:
-Does the pharmacy conform to the United States Pharmocopeia guidelines?
-Is the pharmacy accredited by the Pharmacy Compounding Accreditation Board?
These two boards offer guidelines for best practices, as well as information about compounded products. While they are not regulatory boards like the FDA, they can help in ensuring a compounded medication’s quality and consistency.
A good example of a commonly compounded medication is methimazole, which is used to treat hyperthyroidism, a common disease of older cats. Both brand name and generic methimazole tablets are available, and these are usually the first choice in treatment of hyperthyroidism.
However, because many cats are difficult to give pills to, transdermal methimazole has become popular. Since there is no approved transdermal methimazole available, a compounded drug is the only option. Other frequently compounded medications include buprenorphine, metronidazole, and fluoxetine.
It is important when deciding to use a compounded medication—or any medication for that matter—that your cat is monitored closely for response to therapy. Your veterinarian may require more frequent bloodwork and check-ups to ensure that the medication is working properly.
Rules Surrounding Compounded Drugs
The prescription of veterinary drugs is regulated by the Food and Drug Administration (FDA). In 1994, the Animal Medicinal Drug Use Clarification Act (AMDUCA) legalized the use of compounded drugs and established the conditions under which they can be prescribed. Compounding is the preparation of a drug according to a veterinarian’s prescription. This must be done for a medical condition and within an established veterinary/client/patient relationship. It is popular in veterinary medicine because of the unique demands of animal patients.
The AMDUCA allows compounding under these conditions:
-An approved drug is not available for the condition
-A drug is on back order
-Administering the medication is not possible (i.e. oral versus transdermal)
-A different strength is needed
Note that cost is not a valid reason to prescribe a compounded medication.