Evaluation of new drugs
Development of new drug may take 6-12 years because of rigorous testing needed for safety and effectiveness reasons. It is expensive and complex.
Stages of development of new drug:
Investigation of a compounds toxicity, potential biological affects/activities, dose response and pharmacokinetic properties in animals. Computer modelling is being used more due to ethics of using animals. <1% of compounds proceed on to clinical evaluationsClinical evaluation (in humans): Phase 1 - Clinical pharmacology - small number of healthy normal volunteers are used to assess pharmacokinetics (absorption, distribution, metabolism, excretion) and pharmacodynamics (biological effects). - Low doses used initiallyPhase 2 - Clinical investigation - Small number of patients are used for pharmacokinetics, pharmacodynamics, dosages, efficacy, safety – aim is to determine therapeutic effects - Lower doses used initiallyPhase 3 - Clinical/therapeutic trials - efficacy in large randomised clinical trial(s) – usually compared to other drugs - used to establish efficacy and safety compared to placebo or another active agent - at the end of this stage the information is submitted to regulatory authorities for approval to marketPhase 4 - Post marketing studies - surveillance for safety and efficacy – also includes other formal trials - especially for the detection of rare and unusual adverse effects that the previous studies may not have detected; unexpected benefits of drug may also be detectedPatents:Generic brand names are retained by the manufacture when patent expires several brands come on to the market.