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21 Cards in this Set
- Front
- Back
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Lab tests to evaluate renal function |
Creatinine and BUN |
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Lab tests to evaluate liver function |
AST and ALT |
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Plasma half-life |
-Drugs duration of action -length of time it takes for med to ↓ concentration in plasma by ½ after admin -Greater half-life, longer it takes to excrete the med -Drugs with short half-lives must be given 3-4x day -Drugs with longer half-lives need only be given once daily |
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Half-life and renal/liver disease |
Half-life ↑ & drug concentration may reach toxic levels at normal dose→ give meds less frequently OR reduce dosages |
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CytochromeP-450 (CYP450) enzyme system (4 possible functions) |
-Promote & accelerate renal excretion of the drug (convert lipid-soluble drugs into less lipid-soluble) -Inactivate the drug (can decrease risk of toxicity) -Transform drug to a more active form (Can increase potency ex-codeine to morphine) (Can increase risk of toxicity ex- Acetaminophen to hepatotoxic metabolite) -Activate Prodrugs |
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Additive effect |
1+1=2 Ex:one ASA and one Tylenol= relieve headache |
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Synergistic effect |
1+1=3 Ex: combination of CNS depressants can lead to overdose |
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Antagonistic effect |
2+2=1 Ex: Narcan for opiate OD |
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Agonist |
Activates the receptor |
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Antagonist |
Blocks the receptor |
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Affinity |
Strength of a drug and its receptor site High-affinity= high-potency (if anagonist) (drugs with a high affinity are capable of producing effects at a lower dose) |
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Intrinsic Activity |
Ability of a drug to activate a receptorupon binding; reflected in maximal efficacy. -High-intrinsic activity= high receptor activation= intense responses -Low-intrinsic activity= low receptor activation= minimal responses |
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How many half-lives to get to therapeutic effect? |
-takesapproximately 4 half-lives to reach the drug level where the plasma therapeuticlevel is continuously maintained |
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Loading Dose |
1 or 2 large doses given followed by maintenance doses to achieve therapeutic level. |
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Protein-Binding (warfarin example) |
Decreases the availability of medication due to lack of recognition by receptors
-Major protein is albumin EXAMPLE -99% of warfarin is bound to albumin. ASA also binds to albumin. -ASA displaces warfarin, and puts free warfarin into the blood which increases the risk for hemorrhage |
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Potency |
Amount of drug given to elicit an effect. A potent drug elicits an effect at a lower dose (ex levothyroxine) |
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Efficacy |
Magnitude of maximal response that can be produced from a particular drug. Almost always more important than potency |
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Therapeutic Index |
ED-50/LD-50=TI (closer ED is to LD, the more narrow the TI) (OTC drugs have a wide TI) |
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First-Pass Effect |
-Phenomenon of drug metabolism whereby the concentration of a drug is greatly reduced before it reaches the systemic circulation -Greatly reduces bioavailability |
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Alternatives to First-Pass |
suppository, intravenous, intramuscular, inhalational aerosol, transdermal and sublingual -avoid the first-pass effect because they allow drugs to be absorbed directly into the systemic circulation. |
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Enterohepatic Recirculation |
Biliary recirculation prolongs the action of a drug. May continue for several weeks after therapy has been discontinued. |
