How does pKa affect drug distribution?
The pKa of a drug influences lipophilicity, solubility, protein binding and permeability which in turn directly affects pharmacokinetic (PK) characteristics such as absorption, distribution, metabolism and excretion (ADME)1–5.
What does AUC tell you PK?
The AUC (from zero to infinity) represents the total drug exposure across time. AUC is a useful metric when trying to determine whether two formulations of the same dose (for example a capsule and a tablet) result in equal amounts of tissue or plasma exposure.
How does pKa affect drug solubility?
The higher the pKa, the stronger the acid ( the more dissociated into protons). A weak acid will be neutral until it dissociates into a negatively charged ion (anion) and a proton. While it hangs onto its proton, it is still neutral and thus lipid-soluble.
What does pKa tell us about a drug?
The pKa of a drug is the hydrogen ion concentration (pH) at which 50% of the drug exists in its ionized hydrophilic form (i.e., in equilibrium with its un-ionized lipophilic form). All local anesthetic agents are weak bases. At physiologic pH, the lower the pKa the greater the lipophilicity.
When pKa is higher than pH?
If the pH of solution is greater than the pKa, the group is in the conjugate base form (deprotonated). If the pH of solution is less than the pKa, the group is in the conjugate acid form (protonated).
What does AUC 0 mean?
When AUC is approximately 0, the model is actually reciprocating the classes. It means the model is predicting a negative class as a positive class and vice versa.
How does pKa affect pH?
The lower the pH, the higher the concentration of hydrogen ions [H+]. The lower the pKa, the stronger the acid and the greater its ability to donate protons. pH depends on the concentration of the solution. This is important because it means a weak acid could actually have a lower pH than a diluted strong acid.
Are acidic drugs more ionized when pH is below pKa?
The degree of ionization is determined by the drug’s pKa and the pH of its environment. Weak acids and bases are 50% ionized and 50% unionized when the surrounding pH equals the drug’s pKa. At 2 pH units above or below the pKa of the drug, nearly 100% of the drug is ionized or unionized.
Under which conditions is pH pKa?
When the moles of base added equals half the total moles of acid, the weak acid and its conjugate base are in equal amounts. The ratio of CB / WA = 1 and according to the HH equation, pH = pKa + log(1) or pH = pKa.
Where is pKa on titration curve?
The pH at the midpoint, the point halfway on the titration curve to the equivalence point, is equal to the pKa of the weak acid or the pKb of the weak base. Thus titration methods can be used to determine both the concentration and the pKa (or the pKb) of a weak acid (or a weak base).
What is area under the curve in pharmacokinetics?
Area under the curve (pharmacokinetics) In the field of pharmacokinetics, the area under the curve (AUC) is the definite integral in a plot of drug concentration in blood plasma vs. time.
What is the area under the plasma drug concentration-time curve?
The area under the plasma drug concentration-time curve (AUC) reflects the actual body exposure to drug after administration of a dose of the drug and is expressed in mg*h/L. This area under the curve is dependant on the rate of elimination of the drug from the body and the dose administered.
What is PK (pharmacokinetics)?
Pharmacokinetics (PK) is talked about a lot in the HIV community. PK is the study of what the human body does to drugs to get the drug out of the body. The main ways the human body handles drugs are listed below. These are all a part of PK.
What is the area under the curve (AUC)?
Jump to navigation Jump to search. In the field of pharmacokinetics, the area under the curve (AUC) is the definite integral in a plot of drug concentration in blood plasma vs. time. In practice, the drug concentration is measured at certain discrete points in time and the trapezoidal rule is used to estimate AUC.