In: Biology
The efficacy of a drug is dependent on a therapeutic concentration reaching its target site of action. If the too little drug is present there may be no therapeutic benefit, too much and over-dosage might occur. Describe in detail the pharmacodynamic and pharmacokinetic properties that need to be ascertained in order to use a drug properly. Your answer should include how these properties can be determined, why they are important to the functioning of a particular drug and what might go wrong if these properties are determined incorrectly.
Ans: Pharmacokinetic characters that have to be pre-determined include drug absorption, distribution, metabolism, and excretion. A correlation has to be developed between drug concentration and pharmacokinetic responses before it could be actually administered into a patient. The concentration of the drug in blood plasma indicates drug concentration in tissues. Route of drug administration (intravenous, intraperitoneal, or subcutaneous) should also be optimized.
Distribution volume could be determined by dividing amount of drugs in the body by the concentration in plasma.
Pharmacodynamics reflects the relation between drug concentration at a tissue site and effect like therapeutic and adverse effect, time course. Drug potency can be determined by EC50 value. The drug which has lower EC50 is more effective.
If the estimation of pharmacokinetic and pharmacodynamics characters is incorrect, we might inject higher or lower dosage of the drug than optimum value and high concentration may elicit adverse side effects while low concentration won't show therapeutic effects.