Podcast
Questions and Answers
What primarily determines the distribution of a drug within the body?
What primarily determines the distribution of a drug within the body?
Which type of drugs can cross the blood-brain barrier (BBB)?
Which type of drugs can cross the blood-brain barrier (BBB)?
What effect does the binding of drugs to plasma proteins have on their action?
What effect does the binding of drugs to plasma proteins have on their action?
Which organ typically has the highest blood flow impacting drug distribution?
Which organ typically has the highest blood flow impacting drug distribution?
Signup and view all the answers
What is the role of the placenta in drug distribution?
What is the role of the placenta in drug distribution?
Signup and view all the answers
In drug distribution, what type of drugs typically bind to albumin?
In drug distribution, what type of drugs typically bind to albumin?
Signup and view all the answers
Which of the following is TRUE about the distribution of warfarin and morphine?
Which of the following is TRUE about the distribution of warfarin and morphine?
Signup and view all the answers
What is a consequence of having a drug that is 0% bound to proteins?
What is a consequence of having a drug that is 0% bound to proteins?
Signup and view all the answers
Which class of drugs is characterized by a low dose/capacity ratio and a high bound-drug fraction?
Which class of drugs is characterized by a low dose/capacity ratio and a high bound-drug fraction?
Signup and view all the answers
What is the clinical consequence of administering a class II drug to a patient taking a class I drug?
What is the clinical consequence of administering a class II drug to a patient taking a class I drug?
Signup and view all the answers
What determines a drug's volume of distribution (Vd) when it is mostly retained in the plasma?
What determines a drug's volume of distribution (Vd) when it is mostly retained in the plasma?
Signup and view all the answers
Why are drugs with a large volume of distribution (Vd) like pithidine not easily removed by hemodialysis?
Why are drugs with a large volume of distribution (Vd) like pithidine not easily removed by hemodialysis?
Signup and view all the answers
Which of the following statements regarding binding of drugs to albumin is true?
Which of the following statements regarding binding of drugs to albumin is true?
Signup and view all the answers
What is the role of free, unbound drugs in the body?
What is the role of free, unbound drugs in the body?
Signup and view all the answers
How does hypoalbuminemia affect drug distribution?
How does hypoalbuminemia affect drug distribution?
Signup and view all the answers
What percentage of body weight is total body water in an average 70-kg individual?
What percentage of body weight is total body water in an average 70-kg individual?
Signup and view all the answers
Which factor primarily influences the half-life of a drug?
Which factor primarily influences the half-life of a drug?
Signup and view all the answers
What happens when a highly bound drug like warfarin is displaced from plasma proteins?
What happens when a highly bound drug like warfarin is displaced from plasma proteins?
Signup and view all the answers
What is the relationship between volume of distribution and drug availability to excretory organs?
What is the relationship between volume of distribution and drug availability to excretory organs?
Signup and view all the answers
Which of the following statements about tissue binding is incorrect?
Which of the following statements about tissue binding is incorrect?
Signup and view all the answers
What is the primary binding protein for drugs in plasma?
What is the primary binding protein for drugs in plasma?
Signup and view all the answers
Which type of drugs tend to have a large volume of distribution?
Which type of drugs tend to have a large volume of distribution?
Signup and view all the answers
How does drug structure influence pharmacokinetics?
How does drug structure influence pharmacokinetics?
Signup and view all the answers
What is a significant clinical relevance of knowing a drug’s volume of distribution (Vd)?
What is a significant clinical relevance of knowing a drug’s volume of distribution (Vd)?
Signup and view all the answers
What is one effect of competition for plasma protein binding between two drugs?
What is one effect of competition for plasma protein binding between two drugs?
Signup and view all the answers
What is one consequence of chronic renal failure on drug binding?
What is one consequence of chronic renal failure on drug binding?
Signup and view all the answers
What effect does tissue accumulation of drugs have on elimination?
What effect does tissue accumulation of drugs have on elimination?
Signup and view all the answers
In cases of drug poisoning, which type of drug is typically harder to remove via hemodialysis?
In cases of drug poisoning, which type of drug is typically harder to remove via hemodialysis?
Signup and view all the answers
If a drug is mostly retained in the plasma, what can be inferred about its volume of distribution?
If a drug is mostly retained in the plasma, what can be inferred about its volume of distribution?
Signup and view all the answers
What is the primary characteristic of hydrophilic drugs that limits their ability to penetrate cell membranes?
What is the primary characteristic of hydrophilic drugs that limits their ability to penetrate cell membranes?
Signup and view all the answers
How is the volume of distribution (Vd) defined?
How is the volume of distribution (Vd) defined?
Signup and view all the answers
What is the equation used to calculate the plasma concentration of a drug?
What is the equation used to calculate the plasma concentration of a drug?
Signup and view all the answers
If a drug has a molecular weight that is very high, what will most likely happen?
If a drug has a molecular weight that is very high, what will most likely happen?
Signup and view all the answers
What is true regarding the distribution of hydrophilic drugs?
What is true regarding the distribution of hydrophilic drugs?
Signup and view all the answers
How is apparent volume of distribution (L/kg) calculated?
How is apparent volume of distribution (L/kg) calculated?
Signup and view all the answers
In an example where a 500 mg dose of a drug results in a plasma concentration of 10 mg/L, what is the volume of distribution?
In an example where a 500 mg dose of a drug results in a plasma concentration of 10 mg/L, what is the volume of distribution?
Signup and view all the answers
Aminoglycoside antibiotics are known to have which type of drug distribution?
Aminoglycoside antibiotics are known to have which type of drug distribution?
Signup and view all the answers
Study Notes
Drug Distribution
- Drug distribution is the movement of a drug from the bloodstream into the interstitial fluid and/or tissues.
- Factors influencing drug distribution include blood flow, capillary permeability, protein binding, and tissue binding.
Blood Flow
- Blood flow varies between tissues, impacting drug distribution.
- Organs like the brain, liver, and kidney receive more blood flow than skeletal muscles.
- Adipose tissue has lower blood flow.
- High blood flow and lipid solubility allow drugs like thiopental to rapidly reach the central nervous system (CNS) for anesthesia.
Capillary Permeability
- Capillary structure varies depending on the junctions between endothelial cells.
- The blood-brain barrier (BBB) is formed by tight junctions between endothelial cells and surrounding glial cells.
- Only lipid-soluble, unionized drugs can cross the BBB.
- The placental barrier allows lipid-soluble, unionized drugs to pass through, potentially affecting the fetus.
Drug Binding
Plasma Protein Binding
- Most drugs in the bloodstream bind to plasma proteins, primarily albumin for acidic drugs and alpha-acid glycoprotein for basic drugs.
- Only the unbound fraction of a drug is pharmacologically active, while the bound fraction acts as a reservoir.
- Protein binding varies for each drug, influencing its duration of action.
- Hypoalbuminemia can alter the level of free drug.
Tissue Binding
- Drugs can accumulate in tissues, leading to higher concentrations compared to plasma.
- Tissue binding can prolong drug action or cause local toxicity.
- Examples include the accumulation of acrolein, a cyclophosphamide metabolite, in the kidney leading to renal toxicity.
Volume of Distribution (Vd)
- Vd is a hypothetical volume representing the distribution of a drug throughout body compartments.
- Vd is calculated by dividing the amount of drug in the body by the plasma concentration.
- Vd is influenced by drug properties and body composition.
- A large Vd implies that the drug is widely distributed in the body, potentially leading to a longer half-life.
Body Water Compartments
- Drugs distribute into different body water compartments based on their properties.
- Plasma compartment: Drugs with large molecular weight or high plasma protein binding remain confined to the plasma.
- Extracellular fluid: Hydrophilic drugs with low molecular weight distribute into the plasma and interstitial fluid.
- Total body water: Hydrophobic drugs with low molecular weight can distribute into plasma, interstitial fluid, and intracellular fluid.
Drug Displacement
- Drugs with high affinity for albumin can compete for binding sites.
- Displacement interactions can occur when two drugs compete for the same binding site, potentially altering the free drug concentration and therapeutic effects.
- For example, sulfonamide antibiotics can displace warfarin from albumin, increasing the free warfarin concentration and the risk of bleeding.
Clinical Significance of Vd
- Vd is important for calculating drug dosage and understanding drug elimination.
- Drugs with large Vd are harder to remove by hemodialysis due to their extensive distribution.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
This quiz covers essential concepts of drug distribution, including factors such as blood flow, capillary permeability, and tissue binding. It explores how these elements impact the movement of drugs throughout the body and their accessibility to various organs. Mastering these concepts is crucial for understanding drug action and efficacy.
