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23 Cards in this Set
- Front
- Back
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Five Rights
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Patient
Time Dose Route Medication |
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Pharmacokinetic Phase
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Movement of a drug through the body
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Pharmacodynamic Phase
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The study of drugs mechanisms of action
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5 Phases of Pharmokinetics
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1. Liberation
2. Absorption 3. Distribution 4. Metabolism (biotransformation) 5. Excretion |
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Liberation
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-Breakdown of the manufactured drug form to liquid form
-Disintegration of drug -Drug dissolves in the gastrointestinal fluid |
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Absorption
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-Most drugs taken orally move from the small intestine into the circulation
-Drugs that are lipid soluble are absorbed faster |
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Factors affecting Absorption
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Pain
Stress Exercise pH *IV drugs do NOT undergo absorption *Some drugs undergo first-past effect |
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First Pass Effect
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phenomenon of drug metabolism whereby the concentration of a drug is greatly reduced before it reaches the systemic circulation
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Bioavailability
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amount of the drug available after absorption and first-pass
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Distribution
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-Drug becomes available to body fluids and tissues - Drug has to get to and into the cell.
-Influenced by protein-binding -Drug has to be unbound to act. *Assess client’s serum protein level Only drugs not bound to plasma protein are free to reach receptor sites and produce a pharmacologic effect! HIGHLY BOUND DRUGS (more than 89%) Ibuprofen 98% MODERATELY HIGHLY BOUND (61-89%) Erythromycin 70% MODERATELY BOUND DRUGS (30-60%) Aspirin 49% LOW PROTEIN BOUND (< 30%) Digoxin 25% |
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Unique situations that effect distribution
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Blood brain barrier
Placenta Breast (Lactation) |
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Metabolism
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Primary site is the liver
Drug is changed to water-soluble substance Drug may take more than one “trip” through the liver for it to be completely metabolized |
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Half-life
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Half Life – the time it takes for ½ of the drug concentration to be eliminated by the kidneys
The longer the half life, the longer the drug remains active in circulation |
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Excretion
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Main route is via urine
Also feces, lungs, breast milk Must be unbound, water-soluble Renal disease can affect excretion acidic urine increases excretion of alkaline drugs alkaline urine increases excretion of acidic drugs |
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Glomerular filtration rate (GFR)
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Rate at which the kidneys are able to filter the blood and the effectiveness of renal tubular secretion (urine production)
Creatinine Clearance test measures GFR |
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Pharmacodynamics
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Effect of drug on cellular physiology and chemistry
Drug’s mechanism of action Primary and secondary effects Desirable or undesirable |
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Response to a drug
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Onset –the time it takes to see a response
Peak –the highest blood or plasma level reached Duration –the length of time the drug will produce a pharmacologic response |
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Minimum Effective Concentration
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The lowest blood level of the drug required to produce a therapeutic effect
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Minimum Toxic Concentration (MTC)
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the lowest blood level of the drug required to produce toxic effects
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Therapeutic Window
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Between the MEC and the MTC:
Low therapeutic index (TI)-narrow margin of safety High therapeutic index (TI) – wide margin of safety Monitor client closely if TI is narrow |
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Therapeutic Index
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Estimates the margin of safety of a drug
Is determined by a ratio between the effective concentration of the drug and the lethal dose The closer to “1” the greater the danger of toxicity TI = LD/ED |
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Peak and Trough Levels
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PEAK: highest plasma concentration
TROUGH: lowest plasma concentration Affected by: Rate of absorption Rate of elimination PEAK should not be above the MTC TROUGH should not be below the MEC PEAK level is determined by the rate of absorption TROUGH level is determined by the rate of metabolism and elimination |
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Loading Dose
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Purpose: to achieve MEC rapidly
Client then placed on maintenance dose to keep serum level therapeutic |
