Pharmacokinetics

Anesthesia Pharmacology Chapter 2: Pharmacokinetics Practice Questions

Choose the correct answer for each question.

Aqueous diffusion:
1. within large aqueous components
2. across endothelial blood vessel lining
3. across epithelial membrane tight junctions
Important factor(s) in determining flux (molecular transport per unit time)
1. concentration gradient
2. area across which diffusion occurs
3. lengthly of diffusion path
4. A & C
5. B & C
Lipid diffusion:
1. uncharged form: lipid-soluble
2. charged form: lipid-soluble
3. charged form: lipid insoluble
4. charged and uncharged forms equally lipid-soluble
The lower the pH relative to the pKa the greater fraction of protonated drug is found
1. true
2. false
A weak acid at acid pH:
1. likely to be lipid-soluble
2. probably will be uncharged
3. both
4. neither
Weak base at alkaline pH:
1. relatively lipid-soluble
2. probably uncharged
3. both
4. neither
Weak acid:
1. morphine
2. chlordiazepoxide (Librium)
3. phenobarbital (Luminal)
4. cocaine
5. ephedrine
Weak base:
1. phenobarbital (Luminal)
2. acetaminophen (Tylenol, Panadol)
3. morphine
4. aspirin
5. pentobarbital (Nembutal)
Transport system requiring energy, e.g. ATP hydrolysis
1. facilitated diffusion
2. active transport
3. both
4. neither
Release of neurotransmitter by synaptic terminal:
1. endocytosis
2. exocytosis
3. both
4. neither
More likely to require transport system to cross biological membranes:
1. glucose
2. ethanol
3. both equally likely
4. both equally unlikely to require transport systems
Percentage of oral digoxin (Lanoxin, Lanoxicaps) dose likely to reach systemic circulation:
1. 100%
2. 90%
3. 70%
4. 30%
5. 10%
Drug transport:
1. Very hydrophilic drugs may not be well absorbed
2. Excessively lipid-soluble (hydrophobic) drugs may not be soluble enough to cross a water layer near the cell membrane
3. both
4. neither
Renal pharmacology/pharmacokinetics:
1. Most drugs are not filtered by the glomerulus
2. lipid-soluble drugs are typically reabsorbed by passive diffusion after glomerular filtration
3. weak acids tend to be excreted faster in alkaline pH
4. weak bases tend to be excreted faster in alkaline pH
Ion trapping:
1. the fetal pH is higher than maternal pH
2. in fetal distress alkalosis contributes to local anesthetic accumulation
3. local anesthetics may tend to accumulate in the fetus
4. A & C
5. B & C
Quaternary amine
1. permanently charged
2. charge dependent on pH relative to pKa
3. uncharged
Disadvantages of the oral route of drug administration
1. emesis
2. gastric acidity may destroy the drug
3. inconsistent absorption due to food or other effects
4. usually expensive
Primary factor in determining the rate of an orally ingested drug onset: rate and absorption extent by the gastrointestinal tract
1. true
2. false
First pass effect:
1. requires passage of the drugs through the portal venous system
2. lidocaine (Xylocaine)
3. may result in minimal drug delivery to the systemic circulation
4. A & C
5. A, B & C
Optimal factors contributing to reliable transdermal drug absorption:
1. drug promotes histamine release
2. molecular weight < 1000
3. daily drug requirement < 10 mg
4. pH range < 4
Rectal administration:
1. Absorption of drug into superior hemorrhoidal veins results in the absence of the first-pass effect
2. Low rectal administration may allow drugs to enter the systemic circulation without passing to the liver
3. both
4. neither
Transdermal delivery
1. clonidine (Catapres)
2. fentanyl (Sublimaze)
3. scopolamine
4. nitroglycerin
5. none of the above
Parenteral administration:
1. less likely to be certain of active drug absorption
2. acceptable route of administration for the unconscious patient
3. rated systemic absorption will depend on drugs solubility in interstitial fluid
4. aqueous channels (vascular endothelium) promote high diffusion rates of drugs, independent of their lipid solubility
Magnitude of first-pass hepatic effect
1. depends on hepatic blood flow (Q)
2. depends on clearance
3. both
4. neither
Site(s) of drug metabolism following oral ingestion:
1. blood
2. intestinal wall
3. liver
4. A & C
5. A, B & C