Wk.9 L1 - Small molecules Flashcards
(12 cards)
LO
- Define the term “drug”
- Describe how a drug can bind to a target
- Describe drug affinity and drug selectivity
- Give examples of drug targets
- Describe the different ways in which drugs can modify function
What is a drug?
Is a substance of known structure
which produces a biological effect
Drugs may be:
Chemicals - derived from plants, animals or synthetics
Biologicals - antibodies, enzymes, growth factors, cytokines etc. (produced by genetic engineering)
Drug nomenclature
- Chemical name
- CAS registry number
- Code number
- Generic name (eg. paracetamol)
- Proprietary name (brand name)
Pharma use generic
Drug actions
to be useful it must act selectively on particular
cell or tissue constituents
The drug and binding site are complementary
Drug has to be attracted to the binding site
The drug and binding site
- +ve and -ve charged
- Shape and 3D structure
- Size has to be right
Types of Drug-target bonding
- Ionic bonds (cation-anion)
- Ion-dipole and dipole-dipole bonds (close proximity to target)
- Hydrogen bonds
- Covalent bonds (irriversible)
- Cation-π interactions
Affinity
- The drugs ability to bind to the target/ strength of binding connection
- Higher affinity drugs only need a very small
- concentration
Affinity and Selectivity
drug can (and does) have affinity for more than one target
A drug that binds with higher affinity to its
preferred target is called selective
Drug targets
4 main targets:
Receptors
- Ligand-gated ion channels (LGICs)
- G protein-coupled receptors (GPCRs)
- Kinase-linked receptors
- Nuclear receptors
Ion channels
- Ligand-sensitive ICs
- Voltage-gated ICs (VGICs)
Enzymes
- Synthetic or degradative
Transporters
- Transport ions and molecules into and out of cell
Gene family distribution of current drugs
- G protein-coupled receptors
- Nuclear receptors
- Ligand-gated ion channels
- Voltage-gated ion channels
- unknown
Drug actions
Once binded, the effect can be:
* activating
* enhancing
* attenuating
* interfering
Summary
- Most drugs are small molecules interacting with macromolecules to create a biological effect
- Drugs bind to their targets through chemical bonds
- Drug binding to a target relies on complementary charge and bonds, shape, and size
- The main targets of drug action are receptors, ion channels, enzymes and transporter proteins
- Drugs may activate, enhance, attenuate or interfere with their targets
