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33 Cards in this Set
- Front
- Back
What gets trapped in urine and is cleared quickly?
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Ionized species
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What drugs are weak acids? How does this affect their elimination?
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- Ex: phenobarbital, methotrexate, aspirin
- Weak acids are trapped in BASIC environments |
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How do you treat an overdose of a weak acid drug (eg, phenobarbital, methotrexate, aspirin)?
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Bicarbonate
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What drugs are weak bases? How does this affect their elimination?
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- Ex: amphetamines
- Trapped in ACIDIC environment |
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How do you treat an overdose of a weak base drug (eg, amphetamines)?
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Treat overdose of weak base with ammonium chloride
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What are the phases of drug metabolism?
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- Phase I
- Phase II |
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What happens in phase I drug metabolism? What does it yield?
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- Reduction
- Oxidation - Hydrolysis with cytochrome P-450 - Usually yields slightly polar, water-soluble metabolites (often still active) |
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What happens in phase II drug metabolism? What does it yield?
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- Conjugation (glucuronidation, acetylation, sulfation)
- Usually yields very polar, inactive metabolites (renally excreted) |
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What phase of drug metabolism do geriatric patients lose first?
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Phase I
- Reduction - Oxidation - Hydrolysis w/ cytochrome P-450 |
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What phase of drug metabolism do geriatric patients usually still have?
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Phase II
- Conjugation (glucuronidation, acetylation, sulfation) Geriatric patients have GAS |
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What type of abnormal drug metabolism in a patient causes greater side effects from certain drugs? Why?
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Slow acetylators - decreased rate of metabolism
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What is meant by drug "efficacy"?
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Maximal effect a drug can produce
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What is meant by drug "potency"?
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Amount of drug needed for a given effect
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What are some examples of high efficacy drug classes?
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- Analgesic (pain) meds
- Antibiotics - Antibiotics - Antihistamines - Decongestants |
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What mediates increased potency of a drug?
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Increased affinity for receptor
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What are some examples of high potency drug classes?
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- Chemotherapeutic (cancer) drugs
- Anti-hypertensive (blood pressure) drugs - Lipid-lowering (cholesterol) drugs |
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What is the effect of a competitive antagonist on potency and efficacy?
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- Shifts curve to right (decreased potency)
- No change in efficacy |
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How can you overcome a competitive antagonist?
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Increase the concentration of agonist substrate
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What is the effect of a non-competitive antagonist on potency and efficacy?
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Shifts curve down (decreased efficacy)
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How can you overcome a non-competitive antagonist?
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Cannot be overcome by increasing agonist substrate concentration
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What is the effect of an irreversible antagonist on potency and efficacy?
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Shifts curve down (decreased efficacy)
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How can you overcome an irreversible antagonist?
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Cannot be overcome by increasing agonist substrate concentration
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What is the effect of a partial agonist on potency and efficacy?
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- Acts at same site as full agonist, but with lower maximal effect (decreased efficacy)
- Potency is an independent variable |
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What is the relationship of flumazenil to diazepam?
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Competitive antagonist at GABA receptor
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What is the relationship of ketamine to glutamate?
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Non-competitive antagonist at NMDA receptor
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What is the relationship of phenoxybenzamine to norepinephrine?
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Irreversible competitive antagonist on α receptors
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What is the relationship of buprenorphine on morphine
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Partial agonist at opioid µ receptors
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What measurement is used to assess drug safety?
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Therapeutic Index
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How do you calculate the therapeutic index (TI)?
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TI = (TD50 / ED50) = (median toxic dose) / (median effective dose)
TITE: Therapeutic Index = TD50 / ED50 |
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What is the therapeutic window?
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Measure of clinical drug effectiveness for a patient
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What relative Therapeutic Index value do safer drugs have?
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Higher Therapeutic Index values
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What are some drugs with low Therapeutic Index values?
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- Digoxin
- Lithium - Theophylline - Warfarin |
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What value often replaces TD50 in animal studies?
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LD50 (lethal median dose)
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