Flashcards in pharmacodynamics Deck (107)
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1
drug interaction
1 + 1 = 2
Response elicited by combined drugs is equal to the combined response of the individual drugs
Sedative(chlorpheniramine maleate found in decongestants like Neozep + ethanol)
1. ADDITIVE
2
drug interaction
1 + 1 = 3
Response elicited by combined drugs is greater than the combined responses of each individual
Penicillin G (antibiotic) removes the cell wall of the organism
Gentamicin (aminoglycoside antibiotic) inhibits protein synthesis in the organism
2. SYNERGISTIC
3
drug interaction
0 + 1 = 2
Drug which has no effect enhances the effect of the second drug
Cimetidine + heparin (anticoagulant
(Cimetidine enhances the anticoagulation)
3. POTENTIATION
4
drug interaction
1 + 1 = 0
Drug inhibits the effect of another drug
Heparin + protamine
4. ANTAGONISM
5
study of detailed mechanism of action by which drug produce their pharmacologic effects
-provides a scientific basis for the selection and use of drugs
PHARMACODYNAMICS –
6
– specific cell molecules by which drugs interact to produce their effects
-most ligands (drugs or neurotransmitters) bind to protein molecules
-Determine the quantitative relations between dose or concentration of drug and pharmacologic effects
RECEPTORS
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– largest family of receptors for pharmaceutical agents
G protein-coupled receptors (GPCRs)
8
CLASSIFICATION OF RECEPTORS
• Best characterized drug receptors
• Mediates the action of endogenous chemical signals like neurotransmitters, autacoids and hormones
• Mediates the effects of the most useful therapeutic agents
1. REGULATORY PROTEIN
9
CLASSIFICATION OF RECEPTORS
• Inhibited (or less commonly, activated) by binding a drug
• Eg, dihydrofolate reductase, the receptor for methotrexate
2. ENZYMES
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CLASSIFICATION OF RECEPTORS
• Eg, tubulin, the receptor for colchicine, an anti-inflammatory drug
4. STRUCTURAL PROTEINS
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CLASSIFICATION OF RECEPTORS
• Eg, Na+/K+ ATPase, the membrane receptor for digitalis
3. TRANSPORT PROTEINS
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• Specific binding region of the macromolecule
• High and selective affinity to the drug molecule
• Interaction between the drug and the receptor is the fundamental event that initiates the action of the drug
RECEPTOR SITE/RECOGNITION SITE
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• Same site as the endogenous ligand
• Drugs directly compete for the receptor site
ORTHOSTERIC SITE
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• Different site
• Alters the response of the endogenous ligand binding to the ligand-gated ion channel and increase or decrease the flow of ions
ALLOSTERIC SITE
15
• Non-regulatory molecules of the body
• Binding with these molecules will result to no detectable change in the function of the biologic system
• Buffers the concentration of the drug
• Bound drugs do not contribute directly to the concentration gradient that drives diffusion
• Eg, albumin
INERT BINDING SITES
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• Receptor-like proteins predicted from the human genome for which an endogenous ligand is not identified
• Target for the development of new drugs
ORPHAN RECEPTORS
17
In most cases, drugs bind to their receptor by forming (what kinds of bonds) bonds with a receptor site.
hydrogen, ionic, or hydrophobic (van der Waals)
18
• weak bonds
• reversible and enable the drug to dissociate from the receptor as the tissue concentration of the drug declines
HYDROGEN, IONIC, OR HYDROPHOBIC (VAN DER WAALS) BONDS
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• Drug must bind to one stereoisomer only
STEREOSPECIFICITY
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• A substance that can exist in the L or D form
• L may be the better drug
ENANTIOMER
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• Drug having both the L & D form; cannot be separated
• Patient will experience both the therapeutic and toxic effects.
RACEMIC MIXTURE
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• Binding is permanent, irreversible
• Prolonged duration of effect
COVALENT BOND
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The weaker the bond, the more _____ it becomes.
selective
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• Tendency of a drug to combine with its receptor is
• A measure of the strength of the drug-receptor complex
•
AFFINITY
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↑ affinity, __ binding
↓
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• Describes the pathway from ligand binding to conformational changes in the receptor, receptor interaction with an effector molecule (if present), and other downstream molecules called second messengers.
• This cascade of receptor-mediated biochemical events ultimately leads to a physiologic effect.
• Pathway for drug to enter the cell
SIGNAL TRANSDUCTION
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• Ability of a drug to initiate a cellular effect
• Efficacy is not directly related to receptor affinity and differs among various drugs that bind to a receptor and start the signal transduction pathway.
EFFICACY OR INTRINSIC ACTIVITY
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• Binds to the receptor and directly or indirectly bring about an effect
• Full activation of the effector system
•
• Both agonists and antagonists have common components sufficient for receptor affinity, but only agonists have the structure required for efficacy.
AGONIST
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Drugs that have both receptor affinity and efficacy
AGONIST
30
