How do drug-receptor relationships relate to dose-response relationships?
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Drug-receptor models --> depict the amount of ligand needed to achieve a
specific amount of receptor saturation
Dose-response models --> depict the amount of ligand needed to produce
a response of a specific magnitude
In most cases the magnitude of response is proportional to receptor
saturation.
Absorption, distribution, metabolism, and excretion all require that the drug be
transported across cell membranes. What are the four physiochemical characteristics
that affect drug transport across cell membranes?
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, 1. Molecular size and structural features
2. Degree of ionization
3. Relative lipid solubility of ionized/non-ionized forms
4. Affinity and binding to serum tissues and proteins
Apart from physiochemical properties (i.e: lipid solubility, size, and ionization), what
other factors affect distribution of a drug?
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a) Tissue perfusion: initially vessel rich tissues (liver, kidney,
brain, etc) receive the greatest distribution of the drug
however as time passes the drug distributes to more poorly
purfused tissues and this accounts for most of the
extravascular drug.
b) Non-target binding of drug: drugs which bind to plasma
proteins cannot pass from vascular space to tissues. Drugs
that bind to tissue proteins (cellular proteins, phospholipids,
etc) can exhibit prolonged drug action.
What are suicide substrates?
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Drugs that bind to their receptor via covalent bonds which are usually
irreversible. Cells must synthesize new receptors to replace those bound to
the suicide substrate.
Describe the typical activation of a G-protein coupled receptor.
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1. Agonist binds to the transmembrane receptor and activates G-protein
(GDP bound to the heterotrimeric G-protein is exchanged for GTP).
2. α-GTP subunit of the protein diffuses and binds to and activates the
effector.
3. Effector activation is terminated when the agonist unbinds from the
transmembrane receptor; GTP is hydrolyzed to GDP and the heterotrimeric
G protein is reconstituted.
Describe signal transduction through M1, M3, and M5 receptors.
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1. agonist binds to and activates receptor which activates a G-protein
2. G-protein cleaves and activates phospholipase C which cleaves PIP2
producing IP3 and DAG
3. DAG activates protein kinase C and IP3 releases stored Ca++ which
activates Ca++ dependent kinases.
stimulatory
What 4 factors do dosing regimens consist of?
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1. Dose (in mg)
2. Route of administration
3. Frequency of administration
4. Duration of therapy
, Parenteral administration of drugs includes injection (SQ, IM, IV), transdermal, and
topical routes of administration. How are topical medications administered? What are
the advantages/disadvantages of topical administration?
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Topical drugs are applied topically to the eye, skin, and other mucous
membranes.
Advantages: drug is delivered locally (can achieve very high concentration)
Disadvantages: may be absorbed systemically, may not remain at desired
site
How is the eye structured? How is intraocular pressure regulated?
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Sphincter surrounds pupil and expresses M3 receptors.
Dilator surrounds sphincter and expresses α1 receptors.
Intraocular pressure is determined by the amount of
aqueous humour in the eye.
α -> decreases production of aqueous humour
β -> increases production of aqueous humour
M3 -> increases drainage into the canal of Schlemm
(contraction of ciliary muscle)
What are the kinetics of drug-elimination reactions?
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Give this one a try later!
Drug-receptor models --> depict the amount of ligand needed to achieve a
specific amount of receptor saturation
Dose-response models --> depict the amount of ligand needed to produce
a response of a specific magnitude
In most cases the magnitude of response is proportional to receptor
saturation.
Absorption, distribution, metabolism, and excretion all require that the drug be
transported across cell membranes. What are the four physiochemical characteristics
that affect drug transport across cell membranes?
Give this one a try later!
, 1. Molecular size and structural features
2. Degree of ionization
3. Relative lipid solubility of ionized/non-ionized forms
4. Affinity and binding to serum tissues and proteins
Apart from physiochemical properties (i.e: lipid solubility, size, and ionization), what
other factors affect distribution of a drug?
Give this one a try later!
a) Tissue perfusion: initially vessel rich tissues (liver, kidney,
brain, etc) receive the greatest distribution of the drug
however as time passes the drug distributes to more poorly
purfused tissues and this accounts for most of the
extravascular drug.
b) Non-target binding of drug: drugs which bind to plasma
proteins cannot pass from vascular space to tissues. Drugs
that bind to tissue proteins (cellular proteins, phospholipids,
etc) can exhibit prolonged drug action.
What are suicide substrates?
Give this one a try later!
Drugs that bind to their receptor via covalent bonds which are usually
irreversible. Cells must synthesize new receptors to replace those bound to
the suicide substrate.
Describe the typical activation of a G-protein coupled receptor.
,Give this one a try later!
1. Agonist binds to the transmembrane receptor and activates G-protein
(GDP bound to the heterotrimeric G-protein is exchanged for GTP).
2. α-GTP subunit of the protein diffuses and binds to and activates the
effector.
3. Effector activation is terminated when the agonist unbinds from the
transmembrane receptor; GTP is hydrolyzed to GDP and the heterotrimeric
G protein is reconstituted.
Describe signal transduction through M1, M3, and M5 receptors.
Give this one a try later!
1. agonist binds to and activates receptor which activates a G-protein
2. G-protein cleaves and activates phospholipase C which cleaves PIP2
producing IP3 and DAG
3. DAG activates protein kinase C and IP3 releases stored Ca++ which
activates Ca++ dependent kinases.
stimulatory
What 4 factors do dosing regimens consist of?
Give this one a try later!
1. Dose (in mg)
2. Route of administration
3. Frequency of administration
4. Duration of therapy
, Parenteral administration of drugs includes injection (SQ, IM, IV), transdermal, and
topical routes of administration. How are topical medications administered? What are
the advantages/disadvantages of topical administration?
Give this one a try later!
Topical drugs are applied topically to the eye, skin, and other mucous
membranes.
Advantages: drug is delivered locally (can achieve very high concentration)
Disadvantages: may be absorbed systemically, may not remain at desired
site
How is the eye structured? How is intraocular pressure regulated?
Give this one a try later!
Sphincter surrounds pupil and expresses M3 receptors.
Dilator surrounds sphincter and expresses α1 receptors.
Intraocular pressure is determined by the amount of
aqueous humour in the eye.
α -> decreases production of aqueous humour
β -> increases production of aqueous humour
M3 -> increases drainage into the canal of Schlemm
(contraction of ciliary muscle)
What are the kinetics of drug-elimination reactions?
Give this one a try later!
