Questions

Question 1

When the surface area of a membrane is doubled, so is its permeability.

Answer 1

False, permeability does not change

Question 2

When the initial rate of distribution of a drug into a tissue fails to increase with an increase in the rate of blood perfusing it, the distribution to that tissue is said to be permeability rate-limited.

Answer 2

True

Question 3

For rapidly dissolving products of a drug, small differences in rates of dissolution markedly affect the plasma-concentration time profile, when intestinal permeability is the rate-limiting step in absorption.

Answer 3

False, small dissolution rate differences do not affect the plasma concentration time profile

Question 4

Small molecule drugs administered in solution are more slowly absorbed from the muscle (IM) than from the small intestine (oral).

Answer 4

False, they are more quickly absorbed from muscle

Question 5

Only two major factors, solubility and permeability, determine whether a waiver of in vivo bioavailability and bioequivalence studies will be granted for an immediate release solid oral dosage form.

Answer 5

False, also need rapid dissolution

Question 6

A sparingly soluble weak acid with a MW of 1248 g/mol has a mean input time of 12 hours when administered by IM injection. The most likely explanation for the slow input time is that the drug is primarily absorbed through the lymphatic system.

Answer 6

False, likely due to precipitation at injection site

Question 7

Formulating a drug into micro particles rather than standard size particles increases the surface area, thereby increasing the rate of dissolution.

Answer 7

True

Question 8

Food causing an INCREASE in EXTENT

Answer 8

• Relatively insoluble drug
• Weak base that acid helps to dissolve
• Grapefruit juice inhibits CYP3A4, inhibiting metabolism in gut/liver so more gets
absorbed
• Food causes more drug to sit in stomach longer, slowly getting released to intestines, so transporters aren’t saturated
• Constant-release formulation with poor colon permeability - allows longer time in stomach for more to be released and absorbed in small intestines

Question 9

Food causing a DECREASE in EXTENT

Answer 9

• Acid-labile drug
• Chelation
• Adsorption/complex formation, bind to fiber
• Saturable first pass metabolism - in the fed state, with the drug moving slowly into the intestines, the first pass enzymes are no longer saturated, and so more drug is lost through the first pass effect

Question 10

What release characteristics of dosage form affect RATE of absorption?

Answer 10

• Disintegration/deaggregation
• Dissolution of drug from granules
- Also dependent on inactive ingredients and formulation variables

Question 11

What physicochemical properties of drug affect RATE of absorption?

Answer 11

• Complexation
• Ionization (acid/base)
• Partition coefficient (octanol/water)
• Solubility in water

Question 12

What GI physiology traits affect RATE of absorption?

Answer 12

• Colonic retention
• Gastric emptying
• Intestinal motility
• Perfusion of the gastrointestinal tract
• Permeability of gut wall

Question 13

What GI abnormalities affect RATE of absorption?

Answer 13

• Crohn’s disease
• Diarrhea
• Gastric resection or modification
• Ulcerative colitis