Pharmacokinetics Questions Quiz! Trivia Test

Phase I reactions are catabolic and often more chemically reactive
They mainly take place on the ER of the liver

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.

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.

The nasal muscosa allows peptides such as insulin to pass into the circulation

Aspirin is absorbed rapidly by he stomach and intestine by passive diffusion. Aspirin is a prodrug, which is transformed into salicylate mainly in the liver. Salicylate is the active metabolite responsible for most anti-inflammatory and analgesic effects.



When taken orally, heroin undergoes first-pass metabolism via deacetylation to morphine.  When  injected, however it rapidly crosses the blood–brain barrier because of the presence of the acetyl groups. Once in the brain, it then is deacetylated to eventually give morphine, which bind to μ-opioid receptors.

Bioavailability = Area under curve (particular route)/Area under curve (IV)

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.

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

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.

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.

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.

Dioxin is a toxin containing chlorine, making it difficult to metabolise (half life 10-50yrs) and causing the cyst like skin condition chloroacne. Olestra, a calorie free fat substitute (sucrose with fatty acids substituted to it) may act as treatment by absorbing dioxins

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.

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.

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

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.

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.