Recent scientific development has allowed a series of drugs with new Mechanisms of Action (M.O.A.) to be developed. These new drugs have made it possible to treat various diseases and contribute to the welfare of humanity.

Regrettably, however helpful these new drugs may be, a number have potentially adverse side-effects, depending on their usage.
Moreover, as we become an aging society the number of elderly patients with multiple medical conditions increases. This polypharmacy adds complexity to the situation.
In such cases the traditional methods of prescription, which relied on a physician's experience and intuition, is made impossible.

For the sake of safety and efficiency it is imperative to establish a scientific approach to pharmacotherapy when determining application and dosage which corresponds to pharmacokinetic changes and specific medical conditions.
Clinical pharmacology begins with drug evaluation and has allowed pharmacotherapy to move beyond experience or intuition.

As stated by the Japanese Society of Clinical Pharmacology, clinical pharmacology is the science of establishing rational pharmacotherapy through researching drug actions and the study of pharmacokinetics.

The research areas of Clinical Pharmacology include human pharmacological studies, clinical pharmacokinetic studies, clinical drug evaluation and, most recently, pharmacogenetics/genomics which have made rapid progress in recent years.
Through the integration of the above mentioned disciplines, Clinical Pharmacology aims to create a rational approach to pharmacotherapy.

In the old days, one of a doctor's chief skills was the "art" of prescribing. Even today, this "art" remains important in individualized pharmacotherapy. However, rational pharmacotherapy must be based on scientific evidence established through clinical trails.
The concept of optimizing pharmacotherapy through evidence based research makes the practice of Evidence Based Medicine (E.B.M) possible.