Are me-too drugs justified?

The successful progress of pharmacology in the treatment of several diseases has led to the development of a powerful pharmaceutical industry with an estimated market of over $250 billion. It is therefore understandable that as drug development and marketing has become a major business it has adopted the rules common to other commercial fields. This is a potentially dangerous trend because it undermines what should be the main goal of drug development, i.e. to make active medicinal agents available to the patient with precise and reliable information, at the lowest possible cost, particularly when a national health system has to supply the drugs to patients who have too low an income to pay for them. The huge drug market has also set in motion a competition among pharmaceutical firms. This has meant that as soon as a prototype drug becomes available several other similarly active compounds immediately follow. These followers are usually called "me-too drugs". Me-too drugs can be broadly defined as chemically related to the prototype, or other chemical compounds which have an identical mechanism of action. This increasing marketing of me-too drugs has been questioned, so pharmaceutical firms are justifying the development of not-so-innovative drugs. The most common arguments can be summarized as follows: me-too drugs offer an improvement on the efficacy of the prototype; they show a different profile of adverse effects; they are effective in patients resistant to the prototype; they improve compliance in long-term treatment; they are less expensive than the prototype. It is the purpose of this paper to review the evidence substantiating these statements, giving some figures regarding me-too drugs and presenting a few examples.