Basics of Pharmacology Part I

Summary

This Pharmacology Part 1 lecture introduces the fundamental concepts of drug action, including drug receptors and the drug cycle. It explains how drugs bind to receptors to trigger responses, distinguishing between agonists and antagonists, and emphasizes understanding drug action to make side effects logical. The lecture outlines the pharmacokinetic phases: absorption, distribution, metabolism, and excretion, highlighting factors affecting absorption and the importance of physiological barriers in drug distribution. It concludes with the significance of metabolism and excretion in preventing drug accumulation and toxicity.

Takeaways

• 💊 Drugs act by altering existing activities in the body rather than creating new responses.
• 🔒 Medications bind to specific receptors, which are specialized proteins on cells, to trigger a response.
• 🔑 Agonists are drugs that activate receptors, while antagonists block them, preventing a response.
• 📚 Understanding a drug's action on receptors can help predict and make sense of its side effects.
• 🔄 Pharmacokinetics involves the drug cycle, which includes absorption, distribution, metabolism, and excretion (ADME).
• 🩸 Absorption is how a drug enters the bloodstream, which can vary based on the route of administration.
• 🚀 Intravenous administration is the fastest way for a drug to be absorbed, followed by intramuscular injections.
• 🌡️ Factors like solubility, pH, and contact time can affect how a medication is absorbed by the body.
• 🛡️ Physiological barriers, such as the blood-brain barrier, can limit the distribution of drugs to certain areas.
• ⚗️ Metabolism, or biotransformation, is the process where the body breaks down medication into less active forms, primarily in the liver.
• 🚰 Excretion is the body's way of eliminating drugs and preventing accumulation and potential toxicity.
• ⚠️ Accumulation can lead to increased toxicity, so understanding the drug cycle is crucial for safe medication use.

Q & A

What is the fundamental principle of how drugs work in the body according to the lecture?

Drugs do not create new responses in the body but modify existing activities. They bind to receptors, specialized proteins on cells, to cause an effect.

What is a receptor in pharmacology?

A receptor is a specialized protein on a cell to which drugs bind to cause an effect, acting like a lock that the medication, the key, seeks.

What are the two main types of drugs mentioned in the lecture?

The two main types of drugs are agonists, which stimulate and activate the receptor, and antagonists, which block the receptor's response.

How can understanding the action of a drug help in grasping its side effects?

Understanding whether a drug turns a receptor on or off can make the side effects more logical and easier to predict, as they are often related to the drug's primary action.

What is an example of a drug and its side effects as discussed in the lecture?

Aspirin is given as an example; it blocks the enzyme Cox-1, leading to potential side effects like gastrointestinal distress and bleeding due to the loss of stomach mucosa protection.

What does Pharmacokinetics refer to in the context of the drug cycle?

Pharmacokinetics refers to what the body does to the drug, encompassing the drug cycle's four main phases: Absorption, Distribution, Metabolism, and Excretion (ADME).

How does the route of administration affect the speed of drug absorption?

The route of administration influences how fast a medication is absorbed, with intravenous administration being the fastest and oral and transdermal being the slowest.

What factors can affect the absorption of a medication?

Factors affecting medication absorption include solubility, pH, medication concentration, length of contact, age, food, and depth of breathing.

What are some physiological barriers that can affect drug distribution in the body?

Physiological barriers such as the Blood-Brain Barrier, Blood-Placental Barrier, and Blood-Testicular Barrier can restrict drug access to certain organs or tissues.

Why is metabolism, also known as biotransformation, an essential process in pharmacology?

Metabolism is crucial as it transforms the medication into a less active or inactive form, preparing it for excretion and preventing accumulation and potential toxicity.

What role do the kidneys play in the context of drug excretion?

The kidneys are the primary organs responsible for drug excretion, ensuring that waste products are removed and preventing the buildup of medications that could lead to toxicity.