Pharmacokinetics and pharmacodynamics are distinct concepts, related to the action of drugs in the body and vice versa.
Pharmacokinetics is the study of the path that the drug takes in the body from the moment it is ingested until its excretion, while pharmacodynamics is the study of the interaction of this drug with the binding site, which will occur during this path.
- Pharmacokinetics is the study of the evolution of the drug from its administration to its elimination.
- Through the processes of absorption.
- Distribution.
- Metabolism and excretion.
- This way.
- The drug will find a login site.
Absorption is the passage of the drug from the place where it is administered to the bloodstream. The drug can be administered enterally, meaning that the drug is ingested orally, sublingually or rectally or parenterally, meaning that the drug is administered intravenously, subcutaneously, intradermally or intramuscularly.
The distribution consists of the path that the drug takes after crossing the barrier of the intestinal epithelium into the bloodstream, which may be in free form or related to plasma proteins, and then reach several places:
When a drug binds to plasma proteins, it cannot cross the barrier to reach the tissue and perform a therapeutic action, so a drug that has a strong affinity for these proteins will have less distribution and metabolism. However, the time spent in the organism will be longer, as the active substance takes longer to reach the place of action and be eliminated.
Metabolism occurs mainly in the liver and the following events may occur:
Drug metabolism can also occur less frequently in the lungs, kidneys and adrenal glands.
Excretion involves the elimination of the compound through various structures, mainly in the kidney, in which the elimination is performed by urine. In addition, metabolites can also be eliminated by other structures such as the intestine, stool, lungs if volatile and skin by sweat, breast milk or tears.
Several factors can interfere with pharmacokinetics such as age, sex, body weight, organic diseases and dysfunction, or habits such as smoking and alcohol consumption, for example.
Pharmacodynamics consists of studying the interaction of drugs with their receptors, where they exert their mechanism of action, producing a therapeutic effect.
Action sites are places where endogenous substances, which are substances produced by the body, or exogenous, such as drugs, interact to produce a pharmacological response. The main objectives of action of active substances are receptors on which it is common to bind to endogenous substances, ion channels, transporters, enzymes and structural proteins.
The mechanism of action is the chemical interaction that a certain active substance has with the recipient, producing a therapeutic response.