Question 1

Drugs are metabolised by the liver to make them more:&#10;A) amphipathic.&#10;B) hydrophilic.&#10;C) lipophilic.&#10;D) hydrophobic.

Accepted Answer

Drugs are metabolised by the liver to make them more hydrophilic, which makes it easier for them to be excreted from the body. This process is called biotransformation or metabolism.

Question 2

To elicit a rapid systemic effect,the route that will enable the maximum bioavailability is:&#10;A) intramuscular.&#10;B) oral.&#10;C) intravenous.&#10;D) intradermal.

Accepted Answer

Intravenous administration allows for direct injection of the drug into the bloodstream, bypassing absorption barriers in the gastrointestinal tract or skin. This results in maximum bioavailability and a rapid systemic effect.

Question 3

Explain what is meant by drug clearance.

Accepted Answer

The volume of blood cleared of a drug per period of time (L/h).Clearance takes into account both the metabolism and the excretion of a drug.It is summative:total clearance is the sum of individual clearances from various body sites (liver,kidneys,GI tract,lungs and so on).

Question 4

Phase 1 metabolism of a drug can involve:&#10;A) glucuronidation.&#10;B) sulphation.&#10;C) conjugation.&#10;D) oxidation.

Accepted Answer

Phase 1 metabolism of a drug typically involves chemical modifications such as oxidation, reduction, or hydrolysis. Oxidation is a common phase 1 reaction, often mediated by enzymes such as the cytochrome P450 family. Glucuronidation, sulphation, and conjugation are generally considered phase 2 reactions, where the drug or its phase 1 metabolites are conjugated with an endogenous substrate to increase solubility for excretion.

Question 5

Glyceryl trinitrate is almost 96 per cent destroyed by the liver on its first journey through.It is therefore referred to as having a:&#10;A) low hepatic first-pass effect.&#10;B) medium hepatic first-pass effect&#10;C) high hepatic first-pass effect.&#10;D) high metabolic first-pass effect.

Accepted Answer

Glyceryl trinitrate is almost 96 per cent destroyed by the liver on its first journey through, indicating a high hepatic first-pass effect.

Question 6

Which of the following drugs is not excreted by the lungs?&#10;A) Ethanol&#10;B) Salbutamol&#10;C) Isoflurane&#10;D) Metoprolol

Accepted Answer

Metoprolol is primarily eliminated by the liver and kidneys, with only a small fraction excreted by the lungs. Ethanol, salbutamol, and isoflurane are all drugs that can be excreted by the lungs to some extent.

Question 7

Clearance of an acidic drug by the kidneys may be increased by:&#10;A) alkalising the urine.&#10;B) administering amphetamines.&#10;C) administering ascorbic acid.&#10;D) administering sodium hydrogen carbonate.

Accepted Answer

Alkalising the urine increases the ionization of acidic drugs, promoting their elimination through renal excretion. This can be achieved by administering substances that increase the pH of the urine, such as sodium bicarbonate or citrate, which bind to hydrogen ions and reduce their concentration in the urine. Administering amphetamines or ascorbic acid is unlikely to increase renal clearance of an acidic drug.

Question 8

After a single dose of a drug with a half-life of 8 hours,how much of the drug remains after 16 hours?&#10;A) 50 per cent&#10;B) 12.5 per cent&#10;C) 100 per cent&#10;D) 25 per cent

Accepted Answer

After 16 hours, which is two half-lives (8 hours each), the drug amount is reduced to 25% of the original dose.

Deck 14: Pharmacokinetics Metabolism and Excretion