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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

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drug interaction

 1 + 1 = 0
 Drug inhibits the effect of another drug
 Heparin + protamine


4. ANTAGONISM

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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 –

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– 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)

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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

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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

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• 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

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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)

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• 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

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Produce the maximal response obtainable in a tissue

FULL AGONISTS

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