1.
What does ADME stand for?
A___ D___ M___ E___
Explanation
ADME stands for Absorption, Distribution, Metabolism, and Excretion. These are the four key processes involved in pharmacokinetics, which is the study of how a drug is processed by the body. Absorption refers to the movement of a drug from the site of administration into the bloodstream. Distribution is the process by which the drug is transported throughout the body. Metabolism involves the chemical transformation of the drug into different compounds. Excretion is the elimination of the drug or its metabolites from the body, usually through urine or feces.
2.
Which of the following are parenteral methods of administration (the others being enteral)?
Correct Answer(s)
B. Subcutaneous
E. Intramuscular
G. Intravenous
H. Intrathecal
Explanation
Enteral- via the gastrointestinal tract
Sublingual- under tongue
Buccal- under cheek
Rectal- where someone is vomiting, where a compound is volatile in the stomach (e.g. penicillin), less likely to be broken down, can be absorbed easily
Parenteral- Administered in some way other than by the gastrointestinal tract
Subcutaneous- Fatty layer under skin
Intramuscular
Intravenous
Intrathecal- Though membranes in the spinal olumn
3.
By definition, when a medication is administered _______, its bioavailability is 100%.
Correct Answer(s)
intravenously
Explanation
Bioavailability = Area under curve (particular route)/Area under curve (IV)
4.
Which of the following can be absorbed dermally?
Correct Answer(s)
A. Nicotine
B. Testosterone
C. Oestrogen
E. Fentanyl (a strong opiate to control pain in the terminally ill)
F. Nitroglycerine (releases NO to treat angina)
G. Lidocaine (local anesthetic which blocks Na+ channels)
I. Clonidine (high blood pressure treatment)
Explanation
All the substances listed in the answer choices can be absorbed dermally. When a substance is absorbed dermally, it means that it can be absorbed through the skin and enter the bloodstream. This route of absorption is commonly used for medications such as nicotine patches, hormone creams (testosterone and estrogen), pain medications (fentanyl and morphine), and treatments for angina (nitroglycerine) and high blood pressure (clonidine). Lidocaine is a local anesthetic that can also be absorbed dermally and used to numb an area of the skin.
5.
The partition coefficient logP=____
Correct Answer
A. Log([solute in octanol]/[solute in unionised water])
Explanation
A drug's distribution coefficient strongly affects how easily the drug can reach its intended target in the body, how strong an effect it will have once it reaches its target, and how long it will remain in the body in an active form. The distribution coefficient has a strong influence on ADME properties of the drug.
6.
Drugs with a higher partition coefficient...
Correct Answer(s)
A. Are better orally absorbed
B. May be less likely to partition out of the bilayer again
D. Are retained in the body for longer
F. Are often extensively metabolised
Explanation
Drugs with a higher partition coefficient are better orally absorbed because they can easily cross the lipid membranes in the gastrointestinal tract. They may be less likely to partition out of the bilayer again, meaning they have a higher tendency to stay within the cell membrane and exert their effects. These drugs are also retained in the body for longer periods of time, allowing for sustained therapeutic action. Additionally, drugs with higher partition coefficients are often extensively metabolized, which can contribute to their efficacy and safety profiles.
7.
What is the advantage of prodrugs?
Correct Answer
A. Greater oral bioavailability
Explanation
Prodrugs offer the advantage of greater oral bioavailability. This means that prodrugs are more easily absorbed and utilized by the body when taken orally. They undergo specific chemical modifications that enhance their ability to be absorbed through the gastrointestinal tract and enter the systemic circulation. This allows for more efficient and effective delivery of the active drug to its target site. By increasing oral bioavailability, prodrugs can improve the therapeutic efficacy of the drug and potentially reduce the required dosage.
8.
Why is the bioavailability of valaciclovir greater than aciclovir?
Correct Answer
B. Can be transported by branched chain amino acid carriers
Explanation
Valaciclovir can be transported by branched chain amino acid carriers, which allows for greater bioavailability compared to aciclovir. This means that valaciclovir can be more efficiently absorbed and utilized by the body, leading to higher levels of the active drug in the bloodstream. Aciclovir, on the other hand, does not have this specific transport mechanism, resulting in lower bioavailability. Additionally, valaciclovir is a prodrug, meaning it is converted into aciclovir in the body, which further enhances its bioavailability.
9.
Which one of the following Phase I reactions are most commonly carried out by Cytochrome P450 enzymes?
Correct Answer
A. Oxidation/hydroxylation
Explanation
Phase I reactions are catabolic and often more chemically reactive
They mainly take place on the ER of the liver
10.
Which of the following groups are drugs often conjugated to in Phase II metabolism?
Correct Answer(s)
A. Glucuronyl
B. Sulphate
D. Methyl
E. Acetyl
G. Glycyl
H. Glutathione
Explanation
Phase II metabolism involves conjugation to a hydrohillic molecule such as glucuronate, sulphate, glycine and glutathione. The resulting molecule is often pharmacologically inactive and excreted via the bile or urine
11.
How is caffiene metabolised?
Correct Answer(s)
A. 1-N demethyation
B. 3-N demethylation
D. 7-N demethylation
E. Hydroxylation
Explanation
Caffeine is metabolized in the liver by a series of enzymatic reactions. The primary pathway involves three steps: 1-N demethylation, 3-N demethylation, and 7-N demethylation. In the first step, the methyl group attached to the nitrogen atom at position 1 is removed. Then, in the second step, the methyl group attached to the nitrogen atom at position 3 is demethylated. Finally, in the third step, the methyl group attached to the nitrogen atom at position 7 is demethylated. Additionally, caffeine can also undergo hydroxylation, where a hydroxyl group is added to the molecule. These metabolic reactions help convert caffeine into its metabolites, which can be further processed and eliminated from the body.
12.
The drug C____ is a prodrug that forms an active metabolite with an exposed ___ group which covalently modifies a purinergic GPCR to prevent blood clots.
Correct Answer(s)
Clopidogrel, thiol
Explanation
Clopidogrel is a prodrug that undergoes metabolic activation to form an active metabolite. This active metabolite contains a thiol group, which is an important functional group for its mechanism of action. The thiol group covalently modifies a purinergic GPCR (G-protein coupled receptor), ultimately preventing blood clots. Therefore, Clopidogrel, with its thiol group, is the correct answer for the drug that forms an active metabolite with an exposed thiol group to prevent blood clots.
13.
Tyrosine is ____ to give tyramine, noradrenaline and 5-HT, the amino groups on which can be removed by _____ ____ to give an aldehyde which can then be oxidised to an ___. Blocking of this pathway can lead to cheese syndrome by activating the ____ pathway.
Correct Answer(s)
Decarboxylated, monoamine oxidase, acid, sympathetic
Explanation
Tyrosine undergoes decarboxylation to give tyramine, noradrenaline, and 5-HT. The amino groups on these compounds can be removed by the enzyme monoamine oxidase to give an aldehyde. This aldehyde can then be oxidized to an acid. Blocking this pathway can lead to cheese syndrome by activating the sympathetic pathway.
14.
Alcohol levels decrease:
Correct Answer
A. Linearly
Explanation
Alcohol is oxides first by alcohol dehydrogenase then aldehyde dehydrogenase. Methanol is oxidised to formaldehyde by alcohol dehydrogenase but is not recognised by aldehyde dehydrogenase.