1. The passage from the stomach to the small intestine is called gastric emptying.
a) True
b) False
Explanation: The passage from the stomach to the small intestine is called gastric emptying. This also is the rate-limiting step in case of drug absorption because the major site of drug absorption is the small intestine
2. Which one of the following sentences will be the actual definition of distribution?
a) Transfer of drug from the administration dosage to surrounding fluid
b) Transfer of drug from the surrounding the fluid to the blood
c) Transfer of the drug from the oral cavity to the intestine
d) Reversible transfer of drug between blood and extravascular fluids and tissues
Explanation: Distribution is the reversible transfer of a drug between the blood and the extravascular fluids and tissues. The driving force for absorption is the concentration gradient.
3. What should be the molecular weight of the drug molecules so that they can easily pass through the membrane?
a) 600-800 Dalton
b) 500-600 Dalton
c) 300-500 Dalton
d) 200-400 Dalton
Explanation: Drugs with molecular weight less than 500-600 Daltons can easily cross the capillary membrane and diffuse into the extracellular interstitial fluids. Molecular size, ionization constant, and lipophilicity control the penetration of drugs from the extracellular fluid to the cells
4. Which type of drug cannot enter the cell membrane in the below picture?
a) Ionized drug
b) Unionized drug
c) Hydrolyzed drug
d) Unhydrated drug
Explanation: Most drugs are weak acids or weak bases. And their degree of ionization at plasma pH depends upon their pKa. Here the drug has shown which cannot enter the cell membrane is the ionized drug
5. Which drugs cannot pass the Capillary endothelial Barrier?
a) Molecular size less than 600 Dalton
b) Drugs bound to blood components
c) Drugs bound to a chemical moiety
d) All drugs can pass
Explanation: All drugs ionized, unionized but with a molecular size less than 600 Dalton can pass through the capillary endothelial into the interstitial fluid. Only drugs bound to the blood components are restricted because the molecular size becomes large.
6. Which of the following drug cannot pass through the plasma membrane barrier?
a) Drug size less than 50 Dalton
b) Lipophilic drugs 50-600 Dalton
c) Polar or ionized drugs of size greater than 50 Dalton
d) Drug size more than 600 Dalton
Explanation: Drugs size of fewer than 50 Daltons can only pass the plasma membrane barrier. Lipophilic drugs of molecular weight 50-600 Dalton, polarised drugs of size greater than 50deltons can also pass the given membrane.
7. Which cell make up the blood-brain barrier?
a) Squamous epithelium cells
b) Fat cells
c) Red blood cell
d) Endothelial cells
Explanation: The brain capillaries are made up of epithelial cells joined to one another by continuous tight intercellular junctions thereby making the blood-brain barrier. These are highly specialized capillaries which are much less permeable to water-soluble drugs.
8. What is the name of the specialized cells that support the blood-brain barrier tissue?
a) Astrocytes
b) Dendrites
c) Fat cells
d) Endothelial cells
Explanation: Specialised cells such as astrocytes, are the supporting tissue. These are found at the base of the endothelial membrane forming a solid envelope around the brain capillaries
9. Why dopamine cannot be administered for the disease Parkinsonism?
a) Don’t have a medicine
b) It is not the medicine
c) Cannot cross the blood-brain barrier
d) Forms aggregate and thus cannot cross the BBB
Explanation: The selective permeability of the lipid soluble moieties through the BBB does not allow several drugs to just pass the barrier. Parkinsonism cannot be treated by the administration of dopamine since dopamine cannot cross the BBB.
10. Which one of these is not an approach to make the drug cross the blood-brain barrier?
a) Using permeation enhancers
b) Osmotic disruption of the blood-brain barrier
c) Use of highly lipophilic drug only
d) Use of drug carriers to cross the BBB
Explanation: Three different approaches that have been used to promote crossing the BBB is the use of permeation enhancers such as DMSO, osmotic disruption of the BBB by infusing internal carotid artery with mannitol, Use of dihydropyridine redox system as drug carriers to the brain.