Under existing law, a new drug may be labeled, promoted, and advertised only for those conditions in which safety and effectiveness have been demonstrated and which the Food and Drug Administration (FDA) has approved, or so-called approved uses. Other uses have come to be called "unapproved uses", and cannot be legally promoted. In a real sense, the term "unapproved" is a misnomer because it includes one phrase two categories of marketed drugs that are very different.
It is common for new research and new insights to identify valid new uses for drugs already on the market. Before such advances can result in new indications for inclusion in drug labeling, however, the available data must meet the legal standard of substantial evidence derived from adequate and well-controlled clinical trials. Such evidence may require time to develop, and, without initiative on the part of the drug firm, it may not occur at all for certain uses. However, because medical literature on new uses exists, and these uses are medically beneficial, physicians often use these drugs for such purposes prior to FDA review or changes in labeling. This is referred to as "unlabeled uses" of drugs. A different problem arises when a particular use for a drug has been examined scientifically and has been found to be ineffective or unsafe, and yet physicians who either are uninformed or who refuse to accept the available scientific evidence continue their use. Such use may have been reviewed by FDA and rejected, or, in some cases, the use may actually be warned against in the labeling. This subset of uses may be properly termed "disapproved uses".
Government policy should minimize the extent of unlabeled uses. If such uses are valid and many are -- it is important that scientifically sound evidence supporting them be generated and that the regulatory system accommodates them into drug labeling. Continuing rapid advances in medical care and the complexity of drug usage, however, make it impossible for government to keep drug labeling up to date for every conceivable situation. Thus, when a particular use of this type appears, it is also important, and in the interest of good medical care, that no label be attached to such use by practitioners while the formal evidence is assembled between the time of discovery and the time the new use is included in the labeling. In the case of disapproved uses, however, it is proper policy to warn against these in the package insert. Whether use of a drug for these purposes by the uninformed physician constitutes a violation of the cur rent Federal Food, Drug and Cosmetic Act is a matter of debate that involves a number of technical and legal issues. Regardless of that, the inclusion of disapproved uses in the form of warnings or other precautionary statements in package inserts is an important practical deterrent to improper use. Except for clearly disapproved uses, however, it is in the best interests of patient care that physicians not be constrained by regulation form exercising their best judgment ill pre scribing a drug for both its approved uses and any unlabeled uses it may have.
All of the following are mentioned in the passage as reasons for allowing unlabeled uses of drugs except ______.
A．tile increased cost to the patient of buying an FDA approved drug B．the availability of publications to inform physicians of the existence of such uses C．the time lag between initial discovery of a medical use and FDA approval of that use D．the possibility that a medically beneficial use may never be clinically documented