Drug classification and targets

Flashcards by sophietevans, updated more than 1 year ago
Created by sophietevans over 7 years ago


From the 23-09-13 Medicinal Chemistry lecture.

Resource summary

Question Answer
What is the pharmacophore of a drug? The structural part of the molecule that is essential for its biological activity.
What are the four main areas of pharmacokinetics? Administration, distribution/transport, metabolism, and excretion.
If everything can be considered toxic, what is the factor which regulates this? Dosage.
Which two measures does the therapeutic index exist between? The ED50 (the effective dose in 50% of the population) and the LD50 (the lethal dose in 50% of the population). The safest drugs have a wide therapeutic index.
Which term describes the movement of molecules relating to their toxicity? Toxicokinetics.
What is pharmacodynamics? The biological effect of a drug, and how it alters function.
List 6 ways of classifying drugs. By: chemical structure; illegality/toxicity/dependency; source; activation or precursor; effect on the body; or molecular target.
What is the most common way that drugs are classified by the population in general? By illegality/toxicity/dependency e.g. 'class A drugs'. This may be useful to police officers or forensic scientists when determining the severity of a crime, to politicians when making laws about drugs, and to medical practitioners when establishing the level of support to give to a patient.
What does the general public consider a 'hard' drug to be? What does a medicinal chemist consider a 'hard' drug to be? What might the benefit of a 'hard' drug (in terms of medicinal chemistry) be? The public considers 'hard' drugs to be those to which it is easy to become addicted, while a medicinal chemist considers a 'hard' drug to be one that is difficult to metabolise and thus has a long residency time in the body. The benefit of the latter might be in aiding patients who have difficulty remembering to take multiple doses in maintaining a therapeutic dose of a drug.
What grey area does classifying drugs by 'legality' introduce? It suggests that drugs must be inherently 'good' or 'bad', whereas in fact drugs frequently have aspects of both to them e.g. morphine is an excellent analgesic but is highly addictive, while alcohol is a legal recreational drug which can be toxic and fatal. It is hard to define legality by purpose or outcome, so it is best to consider all chemicals which can have a biological effect equally.
What must drugs have in common to be classified by chemical structure? What might they also have in this classification? They must have a common skeleton, but may also have the same function because biological activity and mechanism of action can be the same.
What are 'me too' drugs? Or 'me better' drugs? ‘Me too’ or ‘me better’ drugs are those with similar functions, and so frequently have similar structures, that are perhaps cheaper or effective at a lower dose, and are thus competitive in the pharmaceutical industry.
Which system of classifying drugs is most rarely used? Classification by source, e.g. animals/plants, synthetic/non-synthetic. This tends to be used by health stores or occasionally be pharmaceutical companies.
What are 'sleeping drugs'? Those which are inactive when administered and activated when they reach their target e.g. by laser light.
What are 'pro-drugs'? Those which are inactive when administered and activated by metabolism in the body, frequently by P450 enzymes in the liver.
Which system of classification, used by medicinal chemists, considers sleeping drugs and pro-drugs? Classification by activation or precursor.
What is a very general way of classifying drugs? By their effect on the body e.g. antibiotics, antihistamines etc. There is often no common mechanism or chemical structure between these drugs, but a common function/effect.
Which is the most useful method of drug classification for drug design and development? Classification by molecular target, which allows for common interactions and mechanisms.
Even if we know the drug target, what might we not know about this? Why it is important.
List 6 molecular targets of drugs. Receptors, nucleic acids (DNA/RNA), enzymes, structural proteins, transport proteins, and protein-protein interactions.
Which is the rarest protein target for a drug? Structural proteins.
Give an example of a structural protein being a target of a drug. Tubulin, which polymerises to form microtubules, can be targeted to inhibit polymerisation and prevent cell division to prevent cancer growth.
Give two examples of how drugs targeting transport proteins might work. Inhibiting transport proteins can prevent re-uptake of neurotransmitters. Binding to transport proteins can upregulate their activity to encourage influx or efflux of small molecules to cells.
Why might drugs target 'protein-protein interaction'? Proteins frequently consist of subunits which must interact for a process, such as signal transduction or insulin action, to occur so preventing their association can stop a sequence of reactions ‘downstream’.
How do allosteric inhibitors of enzymes work pharmacodynamically? Allosteric inhibitors of enzymes bind to a different site from the substrate binding site/active site such that the active site changes conformation and is no longer recognisable.
What is the ID50 of an enzyme inhibitor? The ID50 of an inhibitor is the concentration at which a drug inhibits an enzyme in 50% of the population.
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