Drug Absorption Flashcards
What type of transfer (active/passive) is most common for drugs?
Passive aqueous diffusion
How does the solubility of an ionized and non-ionized drug differ?
An ionized drug is H2O soluble, but not very lipid soluble. It does not effectively penetrate the plasma membrane. A non-ionized drug is very lipid soluble, but not very H2O soluble. It does penetrate the plasma membrane
What does the pKa of a drug indicate?
The pH at which the drug is 50% ionized and 50% non-ionized
The pH of a liquid is below the pKa of a given drug. In what state (ionized/non-ionized) is the most of the drug?
Non-ionized
A drug is in it’s ionized form. What is the relationship between the pH and the pKa?
The pH is higher than the pKa of the drug
What is the primary factor affecting absorption of a drug?
Lipid solubility
At equilibrium, the concentration of non-ionized drug is equal inside and outside the cell. On which side is the total amount of drug greatest?
Cannot determine - this depends on the side of the cell with the greatest amount of ionized drug since the drug becomes trapped when ionized
True/False. Carrier-facilitated transfer of a drug can go up or down a concentration gradient.
False. Carrier-facilitated transfer cannot go up a concentration gradient. Only active transport can go up a concentration gradient.
Active transport can be inhibited by drugs. What type of inhibition are most drugs? Why?
Most drugs are competitive inhibitors. Non-competitive inhibitors are non-specific and interfere with energy production. This makes them non-specific poisions.
Large molecules are most likely transferred by what process?
Endocytosis
Ingestion of drugs via which routes will result in biotransformation / first-pass effect?
Oral or rectal ingestion of a drug - the drug will first be metabolized in the liver, GI tract, and/or kidneys before entering systemic circulation
A patient is diagnosed with congestive heart failure. How does this affect the dosage of drugs administered to the patient?
Doses should be decreases since less blood flow is entering the liver and metabolizing less of the drug. Maintaining the initial dose could lead to adverse affects.
True/False. Sublingual administration of a drug can be as fast as intramuscular or subcutaneous injection.
True. The drug will also bypass the first-pass effect.
How does the presence of food affect drug absorption?
In general, food decreases drug absorption and leads to increased drug in the blood
What is hypodermoclysis? Why is it used?
Hypodermoclysis is used when a large volume of fluid needs injected. It involves injecting hyaluronidase to increase the spread and rate of injected fluid
