Question 1

Highly lipophilic substances can cross the blood-brain barrier.Which of the following cannot cross the blood-brain barrier in normal circumstances?&#10;A) Alcohol&#10;B) Penicillin&#10;C) Glucose&#10;D) Antihistamines

Accepted Answer

Penicillin is a polar compound that cannot cross the blood-brain barrier. Alcohol, glucose, and antihistamines are all able to cross the blood-brain barrier to some extent due to their ability to dissolve in lipid membranes.

Question 2

Drugs are best absorbed from the gastrointestinal tract if they are:&#10;A) hydrophilic.&#10;B) amphipathic.&#10;C) lipophobic.&#10;D) lipophilic.

Accepted Answer

Lipophilic drugs are best absorbed from the gastrointestinal tract because they can easily pass through cell membranes and enter the bloodstream. Lipophilic drugs are also more likely to be distributed to fatty tissues and organs, where they may exert their effects. Hydrophilic drugs, on the other hand, have difficulty crossing cell membranes and may be excreted before they are fully absorbed. Amphipathic drugs have both hydrophilic and lipophilic properties and their absorption may vary depending on the relative amounts of each property. Lipophobic drugs are unlikely to be absorbed through cell membranes and may require special formulations or administration methods.

Question 3

By which route are drugs not subject to the physiological process of absorption through a blood vessel wall?&#10;A) Intramuscularly&#10;B) Intradermally&#10;C) Intravenously&#10;D) Subcutaneously

Accepted Answer

When drugs are administered intravenously, they are directly injected into a vein and bypass the process of absorption through a blood vessel wall. This allows the drug to quickly and completely enter the bloodstream, resulting in a rapid onset of action. Intramuscularly (A), intradermally (B), and subcutaneously (D) all involve absorption through a blood vessel wall to enter the bloodstream.

Question 4

If a drug accumulates in one tissue (that is,the drug is extensively bound to a tissue),its volume of distribution is low.

Accepted Answer

When a drug extensively binds to a tissue, it indicates that the drug is distributed widely outside the bloodstream, leading to a high volume of distribution.

Question 5

Drugs that are liver enzyme inducers may:&#10;A) increase a drug's half-life.&#10;B) increase a drug's metabolism.&#10;C) inhibit a drug's therapeutic effect.&#10;D) increase tissue distribution of another drug.

Accepted Answer

Liver enzyme inducers increase the activity of drug-metabolizing enzymes in the liver, causing an increase in the metabolism of drugs. This can lead to decreased effectiveness of the drug as it is eliminated from the body faster.

Deck 13: Pharmacokinetics: Absorption and Distribution