Manufactured drugs are not subject to the same quality controls as certain other commodities. Many contain the same active principle but vary in therapeutic effectiveness. Animal and plant drugs may be well tested in so far as they relate to animals or plants (though the latter may upset the ecological balance), but not regarding their effect on humans. Medical drugs may be tested on animals but reactions in humans may be significantly different. The absence of standards and equivalences is a threat to public health and often results in unnecessary, costly purchases of ineffective medicines. If, at the national level, official supervision is inadequate, transfer to the international level by exporting the product magnifies the problem. Inadequate testing is compounded by a lack of internationally accepted standards for classifying and packaging drugs.
Adequate pharmaceutical research is complicated by high cost and long duration, inadequate national and international control, inadequate exchange of information on both the national and international level, and the attempt of legislation to break pharmaceutical monopolies, which results in the granting of licences to drug-copying firms which do no research of their own. Equally the lack of availability of human subjects for research may lead to unethical experiments without consent of the patient, or straightforward marketing of the product without further research. Lack of understanding of allergies and the effects of combination of substances is aggravated by a proliferation of new drugs and the increasing tendency of doctors to prescribe powerful drugs for ailments which were formally treated by less drastic means. New commercial drugs available without prescription are equally, if not more, dangerous (for example, thalidomide). The effects of animal and plant drugs may initially go unrecognized initially because of the indirectness of their entry into the human body.
Lack of coordination of knowledge regarding these three areas and effects noted in different countries contributes to delayed safety measures in the event of disaster (such as the fungicide infection in Turkey 1956). Irresponsibility and commercial interest also play a part. Inadequate general testing of drugs may occur, but there is also insufficient standardization of pharmaceutical manufacture and quality control of proven products.
Aminophenazone, chloramphenicol, clioquinol, diphenoxylate, phenylbutazone, practotol, tomotil and thalidomide are some of the drugs whose dangers were found out too late. In the USA, for example, it is thought that as many as 600 drugs are either ineffective or have minimal benefits which do not outweigh their side effects. As many as one in eight prescription drugs fall into this category, with a retail value of over $1,000 million.
Other drugs have unwanted effects, such as Valium and the benzodiazepines, which are addictive, or Prozac, which can give rise to suicidal tendencies, hallucination, muscle spasms, fever, confusion and tinnitus.
At the stage when a new drug is released on to the market, there is only limited evidence about its safety in human beings. Too often, drug companies rely on animal experiments before launching new drugs, even though such experiments are known to be unpredictable and unreliable; and using a double standard they still sell products which are known to cause cancer and other serious problems when given to animals (defensible because animal tests are unreliable).