Animal drug products may not be expected to meet the same standards for safety and efficacy as their human-intended counterparts, but that doesn't mean that their eventual recipients don't appreciate a product that's easy on both their taste buds and sense of smell.

That's the finding of a new draft guideline out from the European Medicines Agency (EMA), On the Demonstration of Palatability of Veterinary Medicinal Products, which lays out the requirements for veterinary products where a good-tasting or -smelling product is necessary for the drug to be effective.

The old adage, "You can lead a horse to water, but you can't make him drink," is perhaps as fitting as any. EMA explains in the guidance that "voluntary uptake"-i.e. the animal actually wants to consume the medicine-is a positive quality for a medicine to have.

Much like medicines for children, flavoring components are often mixed in with the drug product, increasing the chance of voluntary update by improving its palatability.

But be warned, said EMA: Your oral-dose veterinary product may be delicious or smell like roses, but you're still going to have to prove it-with data, no less.

"For oral formulations intended for group treatment, correct uptake of the medicated food or water is a prerequisite for sufficient exposure and thus effective treatment," EMA explained. Original products have this requirement built into their approval process-if it's not palatable, it's unlikely to be approved-but EMA implied that it remains concerned that generic formulations could have a different palatability profile capable of affecting the uptake of the medicine.

So what are some of the factors that make a product palatable? Shape, size, texture, density, and color, to name a few. Anyone who's ever been required to ingest a pill more similar in size to a golf ball than an M&M can likely envision why some of those factors might be relevant.

But beyond qualitative feelings, EMA said it wants hard data to support palatability assessments.

In vivo studies will be required for palatability studies, which may differ between animals in controlled conditions and those under field conditions, as well as between sick and healthy animals. Endpoints to be considered in a palatability study include time to uptake, completeness of uptake, regurgitation, consumption only when hidden, need for non-voluntary administration and outright refusal by the animal subjects.

EMA defines voluntary acceptance as "good" if "most of the animals will voluntarily ingest the complete dose throughout the entire course of therapy."

Studies may be waived for generic products if they are "qualitatively and quantitatively comparable to the reference product"-undefined by EMA, but likely meaning an exact copy of the original veterinary product.

Comments on the guideline are due by 31 May 2013.