FDA Evaluates Safety and Effectiveness of Medicines
To evaluate the safety of any new veterinary drug, companies typically conduct a study in a small number of healthy animals in the same species that the drug is intended for (for example, if the drug is for dogs, it will be tried first in healthy dogs). The findings help the veterinarian anticipate potential side effects when the drug is used to treat a patient and help minimize adverse events that might affect the pet’s quality of life.
Companies also must show in controlled studies that the drug works—that it is effective when used according to the label. For example, for a drug intended for a particular kind of cancer, companies typically run a clinical trial at multiple animal hospitals where pets are being treated for that cancer. In these studies, the patients may receive either the drug being studied or a control. Although the owners and veterinarians are aware that their pets and patients could receive either the experimental drug or the control — a placebo — they don’t know which treatment they actually get. In either case, owners have the option to drop out of a study at any time.
When the goal is to treat a form of cancer that affects smaller numbers of animals, drug companies can use a pathway called conditional approval to bring drug treatments to market more quickly. Conditional approval allows a company to make its drug available to patients after proving the drug fully meets the FDA standard for safety, and showing that there is a reasonable expectation that the treatment is effective.
“Often small exploratory studies are conducted to support a reasonable expectation of effectiveness,” Troutman says.
Conditional approvals have both pros and cons. On the plus side, they allow sponsors to provide patients quicker access to innovative treatments without waiting for the development of evidence of effectiveness that would satisfy the requirement for a full approval.
“On the other hand, because the studies used to support a reasonable expectation of effectiveness are small, the drugs may not turn out to be effective when they are used in greater numbers of animals,” Troutman says.
FDA may allow, through annual renewals, the conditionally-approved products to stay on the market for up to five years while the company collects the required effectiveness data to support a new animal drug application for full approval. Conditional approval automatically expires at the end of five years and the drug is removed from the market if the company has not fully demonstrated that the drug is effective.