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ts with drug design, which is the inventive process of finding new drugs.[25] In the most basic sense, this involves the design of molecules that are complementary in shape and charge to a given biomolecular target.[26] After a lead compound has been identified through drug discovery, drug development involves bringing the drug to the market.[24] Drug discovery is related to pharmacoeconomics, which is the sub-discipline of health economics that considers the value of drugs[27][28] Pharmacoeconomics evaluates the cost and benefits of drugs in order to guide optimal healthcare resource allocation.[29] The techniques used for the discovery, formulation, manufacturing and quality control of drugs discovery is studied by pharmaceutical engineering, a branch of engineering.[30] Safety pharmacology specialises in detecting and investigating potential undesirable effects of drugs.[31]

The drug discovery cycle

Development of medication is a vital concern to medicine, but also has strong economical and political implications. To protect the consumer and prevent abuse, many governments regulate the manufacture, sale, and administration of medication. In the United States, the main body that regulates pharmaceuticals is the Food and Drug Administration; they enforce standards set by the United States Pharmacopoeia. In the European Union, the main body that regulates pharmaceuticals is the EMA, and they enforce standards set by the European Pharmacopoeia.

The metabolic stability and the reactivity of a library of candidate drug compounds have to be assessed for drug metabolism and toxicological studies. Many methods have been proposed for quantitative predictions in drug metabolism; one example of a recent computational method is SPORCalc.[32] A slight alteration to the chemical structure of a medicinal compound could alter its medicinal properties, depending on how the alteration relates to the structure of the substrate or receptor site on which it acts: this is called the structural activity relationship (SAR). When a useful activity has been identified, chemists will make many similar compounds called analogues, to try to maximize the desired medicinal effect(s). This can take anywhere from a few years to a decade or more, and is very expensive.[33] One must also determine how safe the medicine is to consume, its stability in the human body and the best form for delivery to the desired organ system, such as tablet or aerosol. After extensive testing, which can take up to six years, the new medicine is ready for marketing and selling.[33]

Because of these long timescales, and because out of every 5000 potential new medicines typically only one will ever reach the open market, this is an expensive way of doing things, often costing over 1 billion dollars. To recoup this outlay pharmaceutical companies may do a number of things:[33]

Carefully research the demand for their potential new product before spending an outlay of company funds.[33]

Obtain a patent on the new medicine preventing other companies from producing that medicine for a certain allocation of time.[33]

The inverse benefit law describes the relationship between a drugs therapeutic benefits and its marketing.

When designing drugs, the placebo effect must be considered to assess the drug's true therapeutic value.

Drug development uses techniques from medicinal chemistry to chemically design drugs. This overlaps with the biological approach of finding targets and physiological effects.

Wider contexts

Pharmacology can be studied in relation to wider contexts than the physiology of individuals. For example, pharmacoepidemiology concerns the variations of the effects of drugs in or between populations, it is the bridge between clinical pharmacology and epidemiology.[34][35] Pharmacoenvironmentology or environmental pharmacology is the study of the effects of used pharmaceuticals and personal care products (PPCPs) on the environment after their elimination from the body.[36] Human health and ecology are intimately related so environmental pharmacology studies the environmental effect of drugs and pharmaceuticals and personal care products in the environment.[37]

Drugs may also have ethnocultural importance, so ethnopharmacology studies the ethnic and cultural aspects of pharmacology.[38]

Emerging fields

Photopharmacology is an emerging approach in medicine in which drugs are activated and deactivated with light. The energy of light is used to change for shape and chemical properties of the drug, resulting in different b