Pharmacy Author: Omudhome Ogbru, Pharm.D.
Medical Editor: Jay Marks, M.D.
In medical terminology, an "indication" for a drug refers to the use of that drug for treating a particular disease. For example, diabetes is an indication for insulin. Another way of stating this relationship is that insulin is indicated for the treatment of diabetes. Drugs often have more than one indication, which means that there is more than one disease for which it is used. The Food and Drug Administration (FDA) classifies indications for drugs in the United States. Indications for drugs can be classified in two categories:
- FDA-approved, also called labeled indications, and
- Non FDA-approved, also called off-label indications.
We will discuss how indications for drugs are established and the differences between these two categories of indications.
Early in the process of developing a drug, the drug's manufacturer decides what disease(s) the drug might treat effectively based on the drug's known effects on the body. The manufacturer then conducts studies using people with the disease(s) to determine if the drug is, in fact, effective. These studies are designed and conducted under strict FDA guidelines and under the watchful eye of the FDA. If the studies show efficacy (benefit to patients with the disease) and no serious side effects for the drug, the manufacturer applies to the FDA for approval of the drug for that indication (disease).
- Labeled indications
If the FDA determines that there is enough evidence to approve the drug for the indication (treatment of the disease), the indication becomes a labeled indication for the drug. The approval by the FDA means that the company can include the information in their package insert (product label) regarding the use of the drug for that indication. More importantly, the manufacturer can claim that the drug is effective for the approved indication and use this information to market their drug to patients and physicians.
Manufacturers are not allowed to market their drugs for indications that have not been approved by the FDA. Since marketing is very important for selling drugs, FDA approval of indications is critical to the financial success of a drug. The decision by the manufacturer to apply for approval for a particular indication is primarily economic. Manufacturers seek approval for indications that allow the broadest use of the drug in order to maximize the drug's use and the financial return on their investment in developing the drug. Once a drug is marketed for one FDA-approved indication, the manufacturer can add indications for the drug by meeting FDA requirements for the additional indications. Thus, approved use of the drug can be expanded, and the drug can be marketed to a broader population.
- Off-label indications
Once a drug has been approved by the FDA for an indication and then marketed for that indication, physicians are allowed to prescribe the drug for any other indication (treatment for other diseases or conditions) if there is reasonable scientific evidence that the drug is effective for that indication. These uses that have not been approved by the FDA are the off-label indications. This means that the drug manufacturer has not gone through the process of applying to the FDA for approval of the indication. Off-label indications typically are supported by less extensive studies than labeled indications; however, this does not necessarily mean that the drugs are less effective when prescribed for off-label indications than for FDA-approved indications.
There are several reasons why manufacturers do not apply to the FDA for certain indications. Most often, it is because the number of people with the disease for which the drug might be indicated is small, and sales will not generate enough revenue to justify the cost of the studies required by the FDA. Sometimes, there is a similar drug on the market that already has the disease as a labeled indication, and the manufacturer assumes that its own drug also will be used as a treatment for the disease because the two drugs have similar effects. In still other instances, off-label use of the drug may be so common that obtaining FDA approval for the indication would not make much of a difference in the use of the drug and the revenue that is generated.
The difference between labeled and off-label indications are important to the drug manufacturer but not as important to the patient. Because drugs have many uses, most medical references include only labeled indications and the most common off-label indications. Regardless of whether drugs are prescribed for labeled or off-label indications, what is important is that the drug is effective and safe for the condition for which it is prescribed.