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23 Cards in this Set
- Front
- Back
GRADED DOSE-RESPONSE RELATIONSHIP |
- Response increases with increasing dose - Commonly used to assessing safety and efficiacy - E.g: Psychomotor (relationship between cognitive functions and movement) effects of alcohol |
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QUANTAL DOSE-RESPONSE RELATIONSHIP |
- All or none dose-response - Commonly used for assessing safety - E.g: effectiveness of an oral contraceptive, percentage of rodant death at particular dose of sedatives. |
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DRUG-RESPONSE CURVE FOR GRADED RESPONSE |
- Hyperbolic curve which makes it difficult to extrapolate information from |
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SEMI-LOG DRUG-RESPONSE CURVE FOR GRADED RESPONSE |
- Log one axis (drug conc) which allows you to extrapolate from big linear part |
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DOSE-RESPONSE CURVE FOR QUANTAL RESPONSE |
- Hyperbolic curve, difficult to extrapolate information |
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SEMI-LOG DOSE-RESPONSE CURVE FOR QUANTAL RESPONSE |
- Log one axis (drug conc) which allows you to extrapolate information easier |
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Emax |
Maximum response of drug. No more increase in response when dose is continued to be increased. |
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THRESHOLD DOSE |
First dose of the drug that will give you a response. |
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CEILING DOSE |
The maximum biological effect that can be induced in a tissue by a given drug, regardless of how large a dose is administered. |
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EFFECTIVE CONCENTRATION |
The dose at 50% of the maximum response. |
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THERAPEUTIC INDEX |
Therapeutic index (TI) = LD50 (lethal dose that would kill 50% of population) or TD50 (toxic dose that would effect 50% of population)/ ED50 (effective dose of 50% of population) |
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THERAPEUTIC INDEX CURVES |
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FACTORS INFLUENCING AN INDIVIDUALS RESPONSE TO DRUGS |
- Age - Gender - Body weight - Liver function - Kidney function - Ethnic origin - Genetic make up (pharmacogenetics) - Interactions: drug-drug, drug-nutrients, drug-disease |
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LOCK AND KEY HYPOTHESIS |
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AGONIST |
- A drug that binds to an activates a receptor - Intrinsic activity = 1 |
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ANTAGONIST |
- A drug that attenuates(reduces) the effect of an agonist - Intrinsic activity = 0 - Competitive antagonist: binds to the same receptor site as the agonist does, blocking the action of the agonist - Non-competitive antagonist: binds to allosteric (non-agonist) site of the receptor preventing activation of receptor |
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DRUG-DOSE RELATIONSHIP WITH AGONISTS AND ANTAGONISTS |
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AFFINITY (Ka) |
Affinity (Ka) = association constant (K1)/dissociation constant (K-1)
How tightly a drug bounds to the receptor |
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POTENCY |
- The amount of response a drug causes at specific concentrations - A highly potent drug will cause a great response at a small dose |
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EFFICIACY |
A drugs capacity to produce an effect. |
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TYPES OF RECEPTORS |
- Type 1: Ionotropic receptors (ligand gated ion channels) - Type 2: Metabotropic receptors (G-protein coupled receptors) - Type 3: Enzyme-linked receptors ( - Type 4: Intracellular receptors |
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SWITCHING OFF: DRUG DESENSITISATION |
When an agonist is administered continuously or receptors are being activated constantly, desensitisation of receptors takes place until the agonist falls below a certain threshold and the system can become sensitive again. |
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5 TYPES OF DRUG DESENSITISATION |
- Receptor sequestration - Receptor down regulation - Receptor inactivation - Inactivation of signalling proteins - Production of inhibitory protein |