C2 Flashcards
(21 cards)
What is lipophilicity?
Lipophilicity refers to the ability of a drug or molecule to distribute between fat and water, which helps predict its behavior in the body.
What does LogP represent?
LogP is the ratio of drug concentration in lipid versus water, indicating how fat-soluble a drug is.
What does a high LogP value indicate?
A high LogP value indicates that the drug is more fat-soluble and crosses membranes easier.
What does a low LogP value indicate?
A low LogP value indicates that the drug is more hydrophilic and easier to dissolve in water.
What is required for hydrophilic drugs to cross membranes?
Hydrophilic drugs need a transporter to get through a membrane.
What is pKa?
pKa is the pH at which 50% of the drug is ionized.
How does ionization affect drug solubility?
Ionized drugs are more water-soluble and cannot cross membranes easily, while unionized drugs can cross membranes more easily.
What is LogD?
LogD is the ratio of all forms (ionized and unionized) of the drug between lipid and water at a specific pH.
Why is n-octanol used in drug solubility studies?
n-Octanol is a nonpolar, oily liquid that mimics the lipid layer of biological membranes, helping to measure drug preference for fat versus water.
What does the Henderson-Hasselbalch equation show?
The equation shows that if the pH is above the pKa, the solution is more basic (more deprotonated A⁻), and if the pH is below the pKa, the solution is more acidic (more HA).
What determines drug solubility?
Solubility determines how well a drug dissolves in bodily fluids; poor solubility leads to poor absorption.
How can solubility be improved?
Drugs can be formulated with salts, surfactants, or nanoparticles to improve solubility.
What are hydrogen bond donors (HBD)?
HBD are groups that can donate a hydrogen atom, such as -OH and NH2.
What are hydrogen bond acceptors (HBA)?
HBA are groups that can accept hydrogen atoms, such as O and N.
How do hydrogen bonds affect solubility and permeability?
More hydrogen bonds increase solubility but can reduce permeability due to increased connections.
What is Lipinski’s rule of five?
A set of rules predicting oral bioavailability, including: HBD ≤ 5, HBA ≤ 10, molecular weight < 500 g/mole, LogP ≤ 5.
What does it mean if a compound violates Lipinski’s rule of five?
If a compound violates this rule, it is less likely to be orally active.
What is the biopharmaceutics classification system?
A classification of drugs based on solubility and permeability.
What are the classes in the biopharmaceutics classification system?
Class I: High solubility, high permeability; Class II: Low solubility, high permeability; Class III: High solubility, low permeability; Class IV: Low solubility, low permeability.
What are the implications for absorption in the biopharmaceutics classification system?
Class I drugs have excellent oral absorption, while Class IV drugs have poor oral bioavailability and often require alternative routes.
What can be done if a drug is poorly soluble and poorly absorbed?
Options include modifying the chemical structure, creating a prodrug, changing the formulation, or using alternative routes.
