MEDS2002 Notes
• Pharmacodynamics:
o the effects of the drug on the body
• Pharmacokinetics:
o the way the body metabolises the drug with time. Includes:
▪ absorption
▪ distribution
▪ metabolism
▪ excretion
▪ and their measurement
TGA (Therapeutic Goods Australia):
• Registered products
o Products with higher risk substances
• Listed products
o Products with lower risk substances
Typical Action of a Drug:
• A drug must bind to one or more cell constituents to produce a pharmacological response
• The ligand (molecule) and the binding site must be complementary
o Charge attracts ligand to binding site
o Three dimensional structure, ie: arrangement of functional groups, of both ligand
and binding site
• Drugs carry a charge which attracts them to the target.
• The shape of the drug holds the centres of charge in a conformation that complements the
target
Affinity:
• Refers to the drugs ability to bind to the target
• Quantified as concentration of drug required to occupy 50% of target proteins
o Drugs with higher affinity only need a very small concentration to bind to the target.
Intrinsic Efficacy:
• Term used as a measure of the ability of a drug to elicit a response
• Defined as the maximal effect a drug can produce on a specific tissue, expressed as a
proportion of the maximal effect of a full agonist on that tissue
• full agonists intrinsic efficacy = 1
• antagonists intrinsic efficacy = 0
• partial agonists intrinsic efficacy between 0 and 1
Potency:
• Refers to the concentration of a drug that causes a specified effect’
Selectivity:
, • ability of a given drug concentration to produce one effect over another (eg: therapeutic
effect over side effect)
• High selectivity means no side effects
• Ability of drug to bind preferentially to one site over another. As no drugs are entirely
specific, you get that one drug is more selective to a receptor over another à has preference
to one site over another, e.g. muscarine is more selective for muscarinic over nicotinic, beta
blockers are antagonists that bind to B receptors, non-selective would be something that
binds to either B1 or B2, or something else may be selective over B1 than B2
Specificity:
• Ability of a given drug concentration to produce one effect over another.
• Chemical binding interaction between the ligand and the receptor, desired outcome is to
have high specificity or binding but often never really achieved, can also work in reverse, the
receptor
Remember specificity→ to produce one effect over the other
Selectivity→ to act on site over another
Receptors:
• In Pharmacology a receptor is a specific type of drug target
o G protein-coupled receptors (metabotropic)
o Ligand-gated ion channels (ionotropic)
o Kinase-linked
o Nuclear
Ligand-Receptor Interaction
• 3 stages of drug action:
1. Binding
2. Conformational change and
transduction
3. Response (biological effect)
When an agonists binds It creases a
conformational change and transduces, ultimately
causing a response. However an antagonist does
not allow for conformational change and thus
does not transduce a response.
Drug Actions:
• Once the drug has bound, the effect on a particular system can be:
o activating (e.g. an agonist)
o enhancing (the activity of the cell) (e.g. a positive modulator)
o attenuating (interfere with the activity of the cell) (e.g. a negative modulator)
o interfering (e.g. an antagonist: no effect by itself, but lowers responses to other
agents)
, Ligand:
The drug
Receptor:
The site the drug will act
Agonist:
Ligand that binds to a receptor and activates it
Antagonist:
• Ligand that binds to a receptor and DOES NOT activate it
• Antagonists reduce the probability of an agonist binding to the site. The antagonist basically
block the receptor to the ligand
Remember: ALLOSTERIC→ means other site
ORTHOSTERIC→ means the same site
Nervous System:
Remember the nervous system can be broken down into peripheral nervous system and central
nervous system. The peripheral can be broken down erven further into SOMATIC (VOLUNTARY) &
AUTONOMIC (INVOLUNTARY). The Autonomic can be broken down into parasympathetic
(relaxation) & sympathetic (fight or flight response).
Both the parasympathetic and sympathetic stimulate the vagus nerve and either increase heart rate
(sympathetic) or decrease heart rate (parasympathetic)
Remember that in the preganglionic the receptor will be nicotinic (this is fast. Ligand gated). Now
depending on whether it is sympathetic the adrenergic receptors will release adrenaline. But if it is
parasympathetic the muscarinic receptor is stimulated (as this is slow. And para means slow and
relax)
Pathway for nerve stimulus:
- Preganglionic→ Ganglionic→ Postganglionic--< Effector
Acetylcholine Receptors
➔ Muscarinic Receptors (mAChR)
o Selective agonist is muscarine
o G-protein couple receptors (metabotropic).
o SLOW
➔ Nicotinic Receptors (nAChR)
o Selective agonist is nicotine
o Ligand gated ion channels (ionotropic)
o FAST
REMEMBER: Noradrenaline is synthesised from Dopamine. Also noradrenaline is a neurotransmitter.
Adrenaline is a hormone secreted form the adrenal medulla
Adrenergic Receptors:
• salbutamol (ASTHMA) agonises Beta 2 adrenoreceptors to relax the bronchial smooth
muscle
• Pharmacodynamics:
o the effects of the drug on the body
• Pharmacokinetics:
o the way the body metabolises the drug with time. Includes:
▪ absorption
▪ distribution
▪ metabolism
▪ excretion
▪ and their measurement
TGA (Therapeutic Goods Australia):
• Registered products
o Products with higher risk substances
• Listed products
o Products with lower risk substances
Typical Action of a Drug:
• A drug must bind to one or more cell constituents to produce a pharmacological response
• The ligand (molecule) and the binding site must be complementary
o Charge attracts ligand to binding site
o Three dimensional structure, ie: arrangement of functional groups, of both ligand
and binding site
• Drugs carry a charge which attracts them to the target.
• The shape of the drug holds the centres of charge in a conformation that complements the
target
Affinity:
• Refers to the drugs ability to bind to the target
• Quantified as concentration of drug required to occupy 50% of target proteins
o Drugs with higher affinity only need a very small concentration to bind to the target.
Intrinsic Efficacy:
• Term used as a measure of the ability of a drug to elicit a response
• Defined as the maximal effect a drug can produce on a specific tissue, expressed as a
proportion of the maximal effect of a full agonist on that tissue
• full agonists intrinsic efficacy = 1
• antagonists intrinsic efficacy = 0
• partial agonists intrinsic efficacy between 0 and 1
Potency:
• Refers to the concentration of a drug that causes a specified effect’
Selectivity:
, • ability of a given drug concentration to produce one effect over another (eg: therapeutic
effect over side effect)
• High selectivity means no side effects
• Ability of drug to bind preferentially to one site over another. As no drugs are entirely
specific, you get that one drug is more selective to a receptor over another à has preference
to one site over another, e.g. muscarine is more selective for muscarinic over nicotinic, beta
blockers are antagonists that bind to B receptors, non-selective would be something that
binds to either B1 or B2, or something else may be selective over B1 than B2
Specificity:
• Ability of a given drug concentration to produce one effect over another.
• Chemical binding interaction between the ligand and the receptor, desired outcome is to
have high specificity or binding but often never really achieved, can also work in reverse, the
receptor
Remember specificity→ to produce one effect over the other
Selectivity→ to act on site over another
Receptors:
• In Pharmacology a receptor is a specific type of drug target
o G protein-coupled receptors (metabotropic)
o Ligand-gated ion channels (ionotropic)
o Kinase-linked
o Nuclear
Ligand-Receptor Interaction
• 3 stages of drug action:
1. Binding
2. Conformational change and
transduction
3. Response (biological effect)
When an agonists binds It creases a
conformational change and transduces, ultimately
causing a response. However an antagonist does
not allow for conformational change and thus
does not transduce a response.
Drug Actions:
• Once the drug has bound, the effect on a particular system can be:
o activating (e.g. an agonist)
o enhancing (the activity of the cell) (e.g. a positive modulator)
o attenuating (interfere with the activity of the cell) (e.g. a negative modulator)
o interfering (e.g. an antagonist: no effect by itself, but lowers responses to other
agents)
, Ligand:
The drug
Receptor:
The site the drug will act
Agonist:
Ligand that binds to a receptor and activates it
Antagonist:
• Ligand that binds to a receptor and DOES NOT activate it
• Antagonists reduce the probability of an agonist binding to the site. The antagonist basically
block the receptor to the ligand
Remember: ALLOSTERIC→ means other site
ORTHOSTERIC→ means the same site
Nervous System:
Remember the nervous system can be broken down into peripheral nervous system and central
nervous system. The peripheral can be broken down erven further into SOMATIC (VOLUNTARY) &
AUTONOMIC (INVOLUNTARY). The Autonomic can be broken down into parasympathetic
(relaxation) & sympathetic (fight or flight response).
Both the parasympathetic and sympathetic stimulate the vagus nerve and either increase heart rate
(sympathetic) or decrease heart rate (parasympathetic)
Remember that in the preganglionic the receptor will be nicotinic (this is fast. Ligand gated). Now
depending on whether it is sympathetic the adrenergic receptors will release adrenaline. But if it is
parasympathetic the muscarinic receptor is stimulated (as this is slow. And para means slow and
relax)
Pathway for nerve stimulus:
- Preganglionic→ Ganglionic→ Postganglionic--< Effector
Acetylcholine Receptors
➔ Muscarinic Receptors (mAChR)
o Selective agonist is muscarine
o G-protein couple receptors (metabotropic).
o SLOW
➔ Nicotinic Receptors (nAChR)
o Selective agonist is nicotine
o Ligand gated ion channels (ionotropic)
o FAST
REMEMBER: Noradrenaline is synthesised from Dopamine. Also noradrenaline is a neurotransmitter.
Adrenaline is a hormone secreted form the adrenal medulla
Adrenergic Receptors:
• salbutamol (ASTHMA) agonises Beta 2 adrenoreceptors to relax the bronchial smooth
muscle
