Lipophilicity and pka-E-3

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Questions and Answers

Which process of drug transport across the lipid cell membrane depends on size, concentration, polarity, degree of ionization, partition coefficient, surface area of absorption site, and blood flow?

Active transport

Metabolism

Carrier-mediated transport

Passive diffusion (correct)

What is the effect of lipophilicity on the distribution of drugs in the body?

Increases the volume of distribution (correct)

Increases the rate of drug metabolism

No effect on the volume of distribution

Decreases the volume of distribution

Which type of molecules are poorly absorbed through passive diffusion?

Lipophilic molecules

Highly ionized molecules

Polar hydrophilic molecules (correct)

Neutral molecules

What is the process of drug transport across a biological membrane against a concentration gradient called?

Active transport Signup and view all the answers

Which process of drug transport involves a carrier protein or transporter protein?

Carrier-mediated transport Signup and view all the answers

What is the process called when a solute is transferred from one compartment to another through a biological membrane against a concentration gradient?

Active transport Signup and view all the answers

Which type of drug molecules can be predicted for their hydrophilicity/lipophilicity?

Lipophilic molecules Signup and view all the answers

Which of the following is a lipid-soluble ester used to enhance the duration of action of a drug?

Haloperidol decanoate Signup and view all the answers

Which of the following is a chemical approach used to improve CNS delivery of drugs?

Adding lipid groups to drug molecules Signup and view all the answers

Which of the following is an example of a prodrug used to improve CNS bioavailability?

L-DOPA Signup and view all the answers

Which of the following factors control the penetration of drugs across the blood-brain barrier (BBB)?

Lipophilicity and molecular weight Signup and view all the answers

Which of the following is true about renal excretion of drugs?

Reabsorption is pH sensitive Signup and view all the answers

Which of the following drugs is extensively metabolized to its active metabolite?

Propranolol Signup and view all the answers

Which of the following is true about the reabsorption of weak acids or weak bases?

Reabsorption is influenced by urine pH and pKa of the drug Signup and view all the answers

Which of the following drugs is reabsorbed in the urine when the pH is 6?

Propoxyphene Signup and view all the answers

Which of the following drugs has a low solubility and high permeability?

Atenolol Signup and view all the answers

Which functional groups are considered hydrophilic in drug molecules?

Hydroxy groups, carboxy groups, amino groups Signup and view all the answers

What is the partition coefficient, K, used to measure?

Drug distribution Signup and view all the answers

What is the log P value for mannitol?

-4.67 Signup and view all the answers

What is the volume of distribution (Vd) used to determine?

Drug distribution Signup and view all the answers

What is the pH range in the stomach?

1-3 Signup and view all the answers

Which of the following is true about the lipophilicity of temazepam and quazepam?

Quazepam is more lipophilic than temazepam. Signup and view all the answers

Which of the following is true about the half-life of temazepam and quazepam?

Quazepam has a longer half-life than temazepam. Signup and view all the answers

Which of the following is true about the lipophilicity of barbiturates?

Hexethal is more lipophilic than Barbital. Signup and view all the answers

Which of the following is true about the lipophilicity of pentobarbital and thiopental?

Pentobarbital is more lipophilic than thiopental. Signup and view all the answers

Which of the following is true about the lipophilicity of atenolol and propranolol?

Propranolol is more lipophilic than atenolol. Signup and view all the answers

Which of the following is true about prodrugs?

Prodrugs are bio-reversible derivatives of drug molecules. Signup and view all the answers

Study Notes

Drug Transport Mechanisms

Passive diffusion of drugs across lipid membranes is influenced by size, concentration, polarity, degree of ionization, partition coefficient, surface area, and blood flow.
Lipophilicity affects drug distribution by enhancing membrane permeability, allowing for easier passage through lipid bilayers.
Polar and large molecules are typically poorly absorbed via passive diffusion.

Active Transport Processes

Transport of drugs against a concentration gradient is referred to as active transport.
Facilitated transport involves specific carrier proteins or transporter proteins that aid in drug movement across membranes.

Membrane Transport Dynamics

The process of moving solutes from one compartment to another against a concentration gradient is known as active transport.
Predicting the hydrophilicity or lipophilicity of drug molecules is based on their chemical structure and functional groups.

Drug Formulation and Optimization

Lipid-soluble esters are employed to prolong the duration of drug action by enhancing lipid solubility.
Chemical strategies to enhance Central Nervous System (CNS) drug delivery include modifying molecular structures for better permeability.

Prodrugs and Drug Bioavailability

Prodrugs are chemically modified drugs designed to improve bioavailability, especially in the CNS.
The factors influencing drug penetration across the blood-brain barrier include molecular size, charge, and lipophilicity.

Renal Excretion and Drug Reabsorption

Renal excretion dynamics indicate that certain drugs are extensively metabolized to active metabolites before excretion.
Weak acids or bases can be reabsorbed in the renal tubules depending on urine pH.

Drug Solubility and Permeability

Drugs showing low solubility but high permeability are particularly relevant for absorption profiles.
Hydrophilic functional groups in drug molecules include hydroxyl, carboxyl, and amine groups.

Pharmacokinetics and Measurement

The partition coefficient (K) assesses drug solubility in organic versus aqueous solvents.
Mannitol has a log P value indicating its hydrophilic nature, making it poorly lipophilic.

Pharmacokinetic Parameters

Volume of distribution (Vd) is crucial for determining how extensively a drug distributes into body tissues.
The typical pH range in the stomach is about 1.5 to 3.5, crucial for drug solubility and absorption.

Lipophilicity and Drug Characteristics

Temazepam and quazepam have specific lipophilicity profiles influencing their pharmacological impacts.
The half-life of temazepam and quazepam varies, affecting their duration of action.
Barbiturates display diverse lipophilicity, impacting their clinical use and metabolism.
Atenolol is more hydrophilic compared to propranolol, affecting their CNS penetration and action.
Prodrugs can optimize therapeutic effects by enhancing systemic availability post-administration.

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Description

Test your knowledge on the lipophilicity of different compounds with this quiz. Explore the effects of various chemical substitutions and their impact on lipid solubility. Determine which compound, Temazepam or Quazepam, is more lipophilic based on their molecular structures.