FARMACODINÂMICA COMPLETA (ENSINO SUPERIOR) - FARMACOLOGIA - MECANISMO DE AÇÃO DOS FÁRMACOS

Summary

In this video, Cleverson del Vec explores the concepts of pharmacodynamics and pharmacokinetics in the context of pharmacology. He explains how drugs interact with the body, focusing on how drugs act upon receptors to produce effects. Key points include the difference between extracellular and intracellular receptors, the types of receptors (ionic channels, G-protein coupled, and enzyme-linked), and the roles of agonists and antagonists. Additionally, the video highlights important concepts such as therapeutic index, drug potency, and efficacy, emphasizing the relevance of understanding receptor interactions for effective drug action.

Takeaways

• 😀 Pharmacodynamics refers to what the drug does to the body, focusing on how the drug interacts with receptors to generate a response.
• 😀 Pharmacokinetics is the opposite of pharmacodynamics—it describes what the body does to the drug, including absorption, distribution, metabolism, and elimination.
• 😀 Receptors can be located either on the cell's surface (extracellular) or inside the cell (intracellular), and the drug must bind to these receptors to trigger a response.
• 😀 Lipid-soluble drugs can pass through the cell membrane and bind to intracellular receptors, affecting genetic expression and cell division.
• 😀 There are different types of receptors, including ion channels, G-protein-coupled receptors, and enzyme-linked receptors, each triggering different cellular responses.
• 😀 The drug's effectiveness is influenced by the concentration of the drug and its interaction with the receptor. More receptor binding generally results in a stronger response.
• 😀 Receptors may exist in excess (reserve receptors) and are not always activated. The body only needs to bind enough receptors for the desired effect.
• 😀 Amplification of response can occur when enzymes or other factors increase the receptor's activation, leading to a stronger cellular response.
• 😀 The therapeutic index indicates the difference between the dose of a drug that produces a therapeutic effect and the dose that is toxic, with a wider therapeutic window being safer.
• 😀 Agonists are drugs that bind to receptors and generate a response. They can be full (producing 100% of the potential response) or partial (producing less than 100%).
• 😀 Antagonists, on the other hand, bind to receptors but do not generate a response. Competitive antagonists block the receptor site, while non-competitive antagonists alter the receptor's affinity for the endogenous substance.

Q & A

What is the difference between pharmacokinetics and pharmacodynamics?

Pharmacokinetics refers to what the body does to a drug, including its absorption, distribution, metabolism, and elimination. Pharmacodynamics, on the other hand, describes what the drug does to the body, primarily focusing on how it interacts with receptors to produce a response.

What is the role of receptors in pharmacodynamics?

Receptors play a critical role in pharmacodynamics as they are the sites where drugs bind to elicit a biological response. The drug must bind to a receptor—either extracellularly or intracellularly—for its action to occur. This can lead to various responses, depending on the type of receptor and drug involved.

How do lipophilic drugs differ from hydrophilic ones in terms of receptor interaction?

Lipophilic (fat-soluble) drugs can cross the plasma membrane and interact with intracellular receptors, such as those in the cytoplasm or nuclear membrane. Hydrophilic (water-soluble) drugs, however, generally bind to extracellular receptors on the cell membrane.

What is the significance of receptor reserves in pharmacodynamics?

Receptor reserves refer to receptors that are present but do not necessarily participate in a drug's action. A drug may achieve its maximum effect without binding to all available receptors, meaning not every receptor needs to be occupied to produce a full therapeutic effect.

What is the therapeutic window, and why is it important?

The therapeutic window, also known as the therapeutic index, is the range between the minimum effective dose and the minimum toxic dose of a drug. A larger therapeutic window indicates a safer drug, as there is a greater margin between beneficial and harmful effects.

What is the difference between agonists and antagonists?

Agonists are drugs that bind to receptors and activate them to produce a biological response. Antagonists, on the other hand, bind to receptors but do not produce a response; instead, they block or inhibit the action of agonists or endogenous substances.

What is the difference between a full agonist and a partial agonist?

A full agonist binds to a receptor and produces the maximum possible response, while a partial agonist binds to the receptor but produces a submaximal effect, even when occupying all available receptors.

What is the concept of drug potency?

Drug potency refers to the amount of drug required to produce a given effect. A more potent drug reaches its maximum effect with a lower dose, whereas a less potent drug requires a higher dose to achieve the same effect.

What is an inverse agonist, and how does it work?

An inverse agonist binds to a receptor and induces the opposite effect of an agonist. While an agonist activates a receptor to produce a response, an inverse agonist reduces the receptor's activity below its baseline level.

What is the difference between competitive and non-competitive antagonists?

A competitive antagonist binds to the same site on a receptor as the endogenous substance, blocking its effect. A non-competitive antagonist binds to a different site on the receptor, which alters the receptor's shape and reduces its affinity for the endogenous substance, thereby decreasing the effect.