CLINICAL EVALUATION OF DRUGS
CLINICAL TRIALS ::
Clinical trials is a name given to a disciplined organized research conducted in human beings and is intended to shed light on the drug as a therapeutic agent for its efficacy and safety Science concerned with scientific studies of drugs in man is called Clinical Pharmacology and the essential feature of this branch is Clinical trials of drugs Perhaps the first ever clinical trial was james Lind s demonstration that citrus juice cures scurvy He compared the effects of various different acidic substances ranging from vinegar to cider on groups of afflicted sailors and found that the group who were given oranges and lemons had largely recovered from scurvy after 6 days
A new drug with a completely new structure and ideal pharmacological action is rarely born Many new drugs are being synthesized and studied for their therapeutic efficacy From extensive studies on animals they may be called as therapeutically effective but unless they are studied in human beings they cannot be marketed most of the time new drugs are similar to the known drugs In all cases prior to clinical trials the investigator must obtain reasonable answer for the following questions :
(a) Are the data from animal studies adequate ?
(b) Is there any need for a new drug for a particular disease under consideration and if so is the new remedy promising ?
(c) Which are the probable risks involved in giving drugs to humans ?
(d) What is its therapeutic index in animals ?
Thus before one can think about clinical trials one should have thoroughly investigated the actions of the new drug in animals and their acute sub-actue and chronic toxicity in various species of animals Although animal studies will tell us much about the efficacy and toxicity of the drug there are a number of limitations as well Many common unwanted effects such as malaise allergy neurological disorders blood - dyscrasias etc cannot be predicted from the animal studies Metabolism of drugs may differ qualitatively and quantitatively in different species Also the subjective responses like nausea vomiting headache weakness loss of libido etc are difficult to be discovered in animals Thus no matter how much we know of structure activity relationship or how much we have studied in animals ultimate evaluation of safety effectiveness and therapeutic efficacy has to be determined in human beings since drugs are to be finally used on the human
The most commonly pet-formed clinical trials evaluate new drugs medical devices biologies or other interventions on patients in stricity scientifically controlled settings and are required for regulatory authority approval of new therapies Trials may be designed to assess the safety and efficacy of an experimental therapy to assess whether the new intervention is better than standard therapy or to compare the efficacy of two standard or marketed interventions The trial objectives and design are usually documented in a clinical trial protocol
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