Partition

Difference Between True and Apparent Partition Coefficient

Difference Between True and Apparent Partition Coefficient

True and apparent partition coefficients describe the distribution of a drug through the system. The key difference between true and apparent partition coefficient is that true partition coefficient is defined for a unionized system whereas the apparent partition coefficient is defined for an ionized system.

  1. What is apparent partition coefficient?
  2. What is true partition coefficient?
  3. Is a high partition coefficient better?
  4. Does partition coefficient vary with concentration?
  5. What is the formula for partition coefficient?
  6. What is a good logP value?
  7. How do I increase my partition coefficient?
  8. What is the distribution coefficient k?
  9. How does pH affect partition coefficient?
  10. What does it mean if a drug is lipophilic?
  11. How do you calculate the partition coefficient of benzoic acid?
  12. Why do we use octanol in partition coefficient?

What is apparent partition coefficient?

In the physical sciences, a partition coefficient (P) or distribution coefficient (D) is the ratio of concentrations of a compound in a mixture of two immiscible solvents at equilibrium. ... Hence the partition coefficient measures how hydrophilic ("water-loving") or hydrophobic ("water-fearing") a chemical substance is.

What is true partition coefficient?

a. Partition Coefficient. The partition coefficient is the measure of the lipophilicity of a drug and an indication of its ability to cross the cell membrane. It is defined as the ratio between un-ionized drug distributed between the organic and aqueous layers at equilibrium.

Is a high partition coefficient better?

unit of measure called the partition coefficient. The greater the solubility of a substance, the higher its partition coefficient, and the higher the partition coefficient, the higher the permeability of the membrane to that particular substance.

Does partition coefficient vary with concentration?

in principle partition coefficient should not change with the change in concentration but in practice one may observe the change because the drug molecules often get self associated particularly in conc.

What is the formula for partition coefficient?

A partition coefficient is the ratio of the concentration of a substance in one medium or phase (C1) to the concentration in a second phase (C2) when the two concentrations are at equilibrium; that is, partition coefficient = (C1/C2)equil.

What is a good logP value?

A drug targeting the central nervous system (CNS) should ideally have a logP value around 2;2 for oral and intestinal absorption the idea value is 1.35–1.8, while a drug intended for sub-lingual absorption should have a logP value >5. Not only does logP help predict the likely transport of a compound around the body.

How do I increase my partition coefficient?

The partition coefficient can be altered by modifying the sample matrix. A common technique is the use of the salting-out effect. For aqueous samples with a high partition coefficient (e.g. ethanol in water), the addition of salt may enhance the sensitivity by up to a factor of 10.

What is the distribution coefficient k?

When equilibrium has established, the ratio of concentration of solute in each layer is constant for each system, and this can be represented by a value K (called the partition coefficient or distribution coefficient). K=Molarity in organic phaseMolarity in aqueous phase.

How does pH affect partition coefficient?

The partition coefficient of benzoic acid in benzene-water system was found to be 0.636 and in buffer solutions of pH 4.0, pH 7.0 and pH 9.0 were 0.841, 0.624 and 0.589 respectively. Graphically it was observed that partition coefficient of benzoic acid in acidic pH was higher than neutral and basic medium.

What does it mean if a drug is lipophilic?

Lipophilicity is defined as the affinity of a drug for a lipid environment. It has become a critical parameter in the Pharmaceutical industry, which indicates the relationship of a drug with their biological, pharmacokinetic, and metabolic properties.

How do you calculate the partition coefficient of benzoic acid?

log Caq

  1. Vaq= Volume in ml of 0.01N Sodium hydroxide per 10ml of aqueous layer.
  2. Naq= Normality of aqueous layer.
  3. Caq= Concentration of aqueous layer in g mole/lit = Normality (Naq)
  4. K= Caq/Corg½= Partition coefficient of benzoic acid in water and benzene.

Why do we use octanol in partition coefficient?

Kow serves as a measure of the relationship between lipophilicity (fat solubility) and hydrophilicity (water solubility) of a substance. The value is greater than one if a substance is more soluble in fat-like solvents such as n-octanol, and less than one if it is more soluble in water.

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