Pharmacokinetics I, II, III Flashcards
____________ is defined as the movement of a drug molecule across biological barriers, or the process by which a drug enters the bloodstream without being chemically altered.
Drug absorption
___________ is the cellular uptake of exogenous molecules or complexes inside the plasma membrane.
Endocytosis
Urea is an example of a small, water-soluble solute through an aqueous pore that traverses the lipid bilayer. What else describes this process of absorption?
A. Major pathway of drug absorption
B. Involves the movement of a molecule against its concentration gradient
C. Depends on existence of a pressure gradient as a driving force
D. Involves cellular uptake of exogenous molecules inside the plasma membrane
C - this example describes filtration.
Note: A describes passive diffusion, B describes active transport, and D describes endocytosis.
Which is characteristic of a drug that would generally increase absorption?
A. very hydrophilic drug
B. ionized drug
C. drug in contact with an area of low surface area, such as the buccal cavity
D. a highly lipophilic drug absorbed into an area of high blood flow
D
Which is not a factor that influences bioavailability?
A. First-pass effect
B. Solubility of drug
C. Chemical instability
D. Nature of drug formulation
E. All of these influence the fraction of administered drug that reaches systemtic circulation
E
___________ is an efflux transporter initially identified as being over-expressed in tumor cells and responsible for multidrug resistance.
P glycoprotein
Which route of drug administration is suitable for drugs with an extensive first-pass effect and contain high levels of molecular protein?
Intravenous (IV) administration
Bacteria in the G.I. tract is a mechanism of destruction of a drug at or near the site of absorption. This process plays a role in the toxic interaction between digoxin and which other drug?
A. Penicillin
B. Erythromycin
C. Aspirin
D. Pro-drugs such as Codeine
B - erythromycin inhibits the bacterium that converts digoxin into digoxin-reduced products
What structure is responsible for pumping drugs out of endothelial cells?
p-glycoprotein
Which disease state would be most likely to affect the distribution of an acidic drug?
A. Hypoalbuminemia
B. Acute myocardial infarction
C. Cancer
D. Cirrhosis and nephrotic syndrome
A. Weak acid drugs bind to albumin, meaning they are affected by changes in binding affinity/capacity and the amount of circulating albumin. This is also true in neonates, who have reduced plasma protein.
Note: the other options affect basic drugs.
Which disease state is most likely to lead to increased free-unbound fractions of basic drugs?
A. Inflammatory disease
B. Surgery
C. Cancer
D. Nephrotic syndrome
D - severe liver disease leads to decreased plasma levels of a1-acid glycoprotein, meaning less basic drugs will bind to the protein.
Which of the following drugs is most likely to have reduced plasma protein binding in uremic patients only?
A. Sulfonamides
B. Phenytoin
C. Valporic acid
A - although B and C are found in higher levels of free, unbound form when the binding capacity of albumin is reduced.
Treatment with overdoses of ______, an acidic drug, can be accomplished by ion trapping and alkalizing the urine with systemic administration of sodium bicarbonate.
A. aspirin only
B. aspirin and phenobarbital
C. phenobarbital and amphetamines
D. phenobarbital only
E. amphetamines only
B - these are both acidic drugs.
Note: Amphetamine OD is treatmed by systemic administration of ammonium chloride.
