Clinical Pharmacology is defined as the study of the effects of drugs in human beings and Pharmacoepidemiology falls under the category of Clinical Pharmacology. Pharmacoepidemiology is the study of the effects of drugs in large number of people. The two distinct branches of Clinical Pharmacology are Pharmacokinetics and Pharmacodynamics. Pharmacokinetics primarily deals with absorption, distribution, metabolism and excretion of drugs in the body and Pharmacodynamics studies the relationship between drug level and drug effect, and thus, both these areas of Clinical Pharmacology helps one to predict the effect one might observe in a subject when a particular drug regimen is administered.
Pharmacoepidemiology broadly encompasses elements of both these fields, and explores the consequences achieved when a particular drug regimen is followed and administered. Though normally Pharmacoepidemiology does not involve or require measurement of drug levels, but can be used to shed light on the pharmacokinetics of a drug. For example, if a patient is being treated with the drug Aminophylline, it can be explored whether it is more likely to cause nausea in the same patient when simultaneously Cimetidine is being given to him.
Pharmacoepidemiology is effective in providing valuable information about the beneficial and harmful effects of drugs, permitting a better assessment of the risk/ benefit balance for the use of any particular drug in any particular patient. In conclusion it can be said that there is no drug which is 100% safe as all drugs have adverse effects. Pharmacoepidemiology may not stop Adverse Reactions, but it can definitely detect them at an early stage and hence educate physicians and other health care providers which in turn will lead to better use of medication. Pharmacoepidemiology is indeed a blessing in disguise for better public health.