“Compounding pharmaceuticals are drugs that we start with an approved drug in livestock and poultry,” says Dr. Brian Payne, veterinarian and director of research and development and technical services for Veterinary Pharmaceutical Solutions on a recent episode of DocTalk. “We change the format of it so that it’s more applicable to the livestock species.”
In livestock medicine, you may face situations where no labeled drug exists for a specific species, condition or route of administration. In those cases, compounded drugs may provide an alternative by adapting approved medications into formulations better suited for food animal production systems.
Why Compounded Drugs Are Used in Livestock Medicine
One reason compounding plays a role in food animal medicine is the limited number of pharmaceuticals developed specifically for livestock species.
“There’s a limited amount of resources being spent on livestock today on new pharmaceuticals,” Payne says. “But there’s a lot of really good pharmaceuticals out there that veterinarians want to use for livestock. If we can take those active ingredients from FDA-approved products and get them into the right format, you have a whole other tool for your producers.”
Rather than creating entirely new drugs, compounding allows veterinarians and pharmacists to modify existing FDA-approved medications into formats better suited for livestock production.
How Compounded Drugs Improve Drug Delivery
One advantage of compounding is the ability to create alternative delivery methods that may better fit livestock production systems.
Many treatments traditionally require injections or running cattle through a chute, which can increase labor and stress for animals and handlers. Compounded formulations may allow treatments to be delivered through oral suspensions or drinking water systems when appropriate.
“If you’re putting it through the water, it can minimize handling, which is always a positive,” Payne says. “And also if you need to choose a drug that’s different, now you have the ability to administer it that way.”
Alternative delivery routes may also allow veterinarians to select drugs with different pharmacologic profiles when needed.
“It gives you the ability to choose a drug that’s different and administer it in a way that works for the operation,” Payne says.
Veterinary Regulations for Compounded Drugs
Despite some misconceptions, compounded drugs used in livestock are subject to regulatory oversight.
“We always have to start with an FDA-approved product,” Payne says. “Once we start manipulating or compounding those drugs, we have to follow procedures to make sure that’s cleanly done.”
Compounding itself can be performed either by a veterinarian or a pharmacist.
“Once a veterinarian gets their license, they have the full ability to compound themselves or a pharmacist can compound,” Payne explains. “A producer can’t compound on their own.”
A decision framework from the Animal Medicinal Drug Use Clarification Act and FDA guidance that prioritizes approved treatments before considering compounded options should be followed:
- Use an FDA-approved drug for the species, condition and route of administration when available.
- Consider extra-label use of an approved product when appropriate.
- Use compounded formulations when no approved option meets the clinical need.
- Ensure the compounded drug begins with an FDA-approved product.
- Establish appropriate withdrawal intervals to prevent residues.
Withdrawal Times and Quality Control
Residue avoidance remains a critical responsibility when using compounded drugs in food animals.
“There’s zero tolerance for any residues in compounded products, and we have to keep that in mind,” Payne says. “It’s the responsibility of the veterinarian to prescribe that with a withdrawal period.”
Withdrawal intervals may be determined using pharmacokinetic information, including drug half-life and available research data, to estimate when residues are no longer present in the animal.
Quality control is another important component of pharmaceutical compounding. Compounding pharmacies may test compounded batches to ensure the drug concentration matches the intended formulation.
“We want to check to understand if the potency we say is in there is actually in there,” Payne says.
Compounded Drugs as an Additional Tool for Livestock Veterinarians
Compounded drugs are not intended to replace approved pharmaceuticals. Instead, they provide another option when labeled products are unavailable or impractical for a particular situation.
For veterinarians managing herd health across diverse livestock systems, that flexibility can be valuable.
“It gives you another set of tools to utilize,” Payne says.
