Why do medicines have two names - brand and generic?

Many medicines have two names:

• The brand name given to a medicine by the drug company that makes the medicine.
• The scientific or generic name for the active ingredient of the medicine that is decided by an expert committee.

An example is the generic medicine sildenafil used to treat impotence, brand named as Viagra by the manufacturer Pfizer.

About 10-12 years after a new medicine is introduced, the patent (exclusive rights) runs out, and then other drug manufacturers are allowed to produce it. These are often cheaper than the original brand, and may be sold under the generic name or new brand names. For example, the generic medicine acetaminophen, which is now sold under many brand names including Panadol and Calpol.

Doctors often prescribe generic medicines because pharmacies may not stock every brand. All generic medicines must meet the same strict standards as the original branded medicine, so while they may look or taste different they are clinically identical and provide the same treatment as the original branded medicine.

The exceptions to this rule are anti-epilepsy medicines and some long acting preparations such as diltiazem and nifedipine. Here, it does make a difference if you change from one brand to another. These medicines should all be prescribed by their brand name to ensure that you can continue to use the same brand and preparation.