Farmakokinetika (1): Absorpsi & Distribusi

Summary

This video explains the mechanisms of how drugs work in the body, focusing on two key concepts: pharmacokinetics and pharmacodynamics. Pharmacokinetics is the study of how drugs are absorbed, distributed, metabolized, and excreted in the body, while pharmacodynamics examines the effects drugs have on the body. The video covers how drugs enter the bloodstream, their distribution, the impact of various factors like solubility and protein binding on distribution, and the process of metabolism, including first-pass metabolism. It also explores different drug administration methods and the physiological processes that influence their effectiveness and elimination.

Takeaways

• 😀 Pharmacokinetics studies the journey of drugs in the body, while pharmacodynamics focuses on the drug's effects on the body.
• 😀 The main phases of pharmacokinetics include absorption, distribution, metabolism, and excretion (ADME).
• 😀 Absorption is the process where the drug enters the bloodstream from the site of administration.
• 😀 Distribution refers to how the drug spreads through the blood to reach the target tissues and organs.
• 😀 Metabolism involves the transformation of the drug, mainly by the liver, into more easily excretable forms.
• 😀 Excretion is the elimination of the drug and its metabolites from the body, primarily through the kidneys.
• 😀 Various factors like the drug's physical form, chemical composition, and method of administration affect absorption.
• 😀 Drugs can be administered via different routes such as oral, sublingual, intramuscular, intravenous, and topical.
• 😀 The bioavailability of a drug refers to the fraction of the drug that reaches the systemic circulation in its active form.
• 😀 The 'first-pass effect' occurs when a drug is metabolized in the liver before reaching systemic circulation, reducing its active form in the bloodstream.
• 😀 Drug distribution is influenced by factors like blood flow, solubility (lipophilic drugs cross membranes easily), and protein binding.

Q & A

What is pharmacokinetics?

Pharmacokinetics is the study of the fate of drugs within the body, focusing on the processes of absorption, distribution, metabolism, and excretion.

What is the difference between pharmacokinetics and pharmacodynamics?

Pharmacokinetics deals with how the body processes a drug, while pharmacodynamics focuses on the drug's effects on the body.

What are the four main phases of pharmacokinetics?

The four main phases of pharmacokinetics are absorption, distribution, metabolism, and excretion.

What factors can influence drug absorption?

Factors that influence drug absorption include the drug's physical and chemical form, its dosage form, the contact surface area, the formulation, and the method of administration.

How does drug absorption occur through oral administration?

Drugs taken orally pass through the digestive tract and are absorbed into the bloodstream via four mechanisms: passive diffusion, facilitated diffusion, active transport, and endocytosis.

What is passive diffusion in drug absorption?

In passive diffusion, molecules move from an area of high concentration to low concentration through a membrane without the need for energy or assistance.

What is the 'first-pass effect' in drug metabolism?

The first-pass effect refers to the metabolism of a drug in the liver before it enters systemic circulation, which reduces the active drug that reaches the bloodstream.

What is bioavailability?

Bioavailability is the fraction of the drug's dose that reaches systemic circulation in its active form, after processes like first-pass metabolism.

What are the different methods of drug injection and how do they affect drug absorption?

Drugs can be injected intramuscularly, subcutaneously, intravenously, or intradermally, with each method affecting the speed and intensity of the drug's effect, as well as the risk of side effects.

How does drug distribution work in the body?

Drug distribution involves the movement of drugs through the bloodstream to target tissues. Factors affecting distribution include blood flow to organs, drug solubility, protein binding, nutritional status, and body composition.