Problem Set "Drug Absorption"
1. From the figure shown below it follows that riboflavin absorption is dose dependent. Which of the following absorption mechanisms are responsible?
Relative bioavailability of riboflavin (expressed as percent of dose) as a function of oral dose administered to fasting subjects.
2. Phenytoin was given orally for 20 days, then i.m. for 20 days and then again orally for 20 days. Phenytoin levels were measured and are shown in the graph below. Discuss the results.
3. The rate of insulin absorption after subcutaneous injection of insulin zinc suspension depends on:
rate of injection particle size of insulin crystal form of insulin vascularization of the tissue
rate of injection
particle size of insulin
crystal form of insulin
vascularization of the tissue
4. Discuss the advantages and disadvantages of sublingual administration.
5. Which of the following formulations are for systemic administration. Mark True or False
peptide nasal spray nitroglycerin transdermal system antiacid suspension (Maalox) antiseptic throat lozenges antipyretic suppository
peptide nasal spray
nitroglycerin transdermal system
antiacid suspension (Maalox)
antiseptic throat lozenges
antipyretic suppository
6. Increasing the following parameters will result in faster passive diffusion of a drug? Mark whether this is true or false for the following parameters.
surface area of the absorption site membrane thickness partition coefficient of the drug between lipid and water< gradient between drug concentrations on both sides of the membrane ATP-concentration in the membrane
surface area of the absorption site
membrane thickness
partition coefficient of the drug between lipid and water<
gradient between drug concentrations on both sides of the membrane
ATP-concentration in the membrane
7. Mark whether the following statements are True or False. (5 pts)
when distribution across a membrane is perfusion-rate limited, the ratio of concentrations across the membranes is virtually one at all times. when the surface area of a membrane is doubled, so is its permeability constant passive diffusion across a membrane stops when to concentration on both sides are the same ( No molecules cross the membrane anymore). carrier mediated transport is one in which energy is always needed to transfer drug across a membrane.
when distribution across a membrane is perfusion-rate limited, the ratio of concentrations across the membranes is virtually one at all times.
when the surface area of a membrane is doubled, so is its permeability constant
passive diffusion across a membrane stops when to concentration on both sides are the same ( No molecules cross the membrane anymore).
carrier mediated transport is one in which energy is always needed to transfer drug across a membrane.
drugs are always more slowly absorbed from the muscle than from the GI tract.
Return to HomePage Return to Problem Set List