Clinical pharmacology is the science of drugs regarding their clinical use, the interaction of drugs with the human body. The pharmacological substances are studied from pharmacokinetic and pharmaco - toxicological point of view in patients (within their diseases) but in healthy volunteers too (this is the situation of the clinical trials).
Pharmacokinetics studies the metabolism of the substances inside the body : absorption, biodisponibility, distribution (protein binding), metabolism compounds and elimination.
Pharmacodinamics studies the effect of the substance inside the body (the therapeutical effect but also the undesired effects - adverse effects), the action mechanism and possible interactions with other medical and non-medical substances.
Pharmacotoxicology studies the toxicity of the medical substances (pre-clinical studies): one dose toxicity (parameters like DL50 - lethal dose for 50 % of the subjects; NOAEL - no adverse event level; NOEL - no event level), repeated dose toxicity - chronic toxicity, reproduction toxicity, carcinogenic potential, mutagenic potential, other particular toxicity aspects - as for external use pharmaceutical products, imuno-toxicity, excipients toxicity, environmental toxicity.
The main objective of Clinical pharmacology is to ensure rational drug therapy (using the right medication for a particular case, at the right dose, using the right route and frequency of administration for the patient, stopping the drug appropropriately, drug combining); research and development of drugs is another important objective (the clinical trials phase is situated towards the end of the complex process of finding new therapeutical molecules).