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46 Cards in this Set
- Front
- Back
Pharmacokinetics
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study of drug movement throughout the body
absorption, distribution, metabolism, excretion |
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absorption
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movement of a drug from its site of administration into the blood
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distribution
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movement from blood to interstitial space of tissues then into cells
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metabolism
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enzymatically mediated alteration of drug structure
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excretion
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movement of drugs and their moetabolism out of the body
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Benefits of pharmacokinetics to nurses
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1. less likely to commit med errors
2. challange physicians 3. increase job satisfaction |
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Rate of absorption determines....
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physical and chemical properties of drug and the physiologic and anatomic factors at site of absorption
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The amount of absorption determines
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how intense the effect will be
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5 factors to drug absorption
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1. rate of dissolution
2. surface area 3. blood flow 4. lipid solubility 5. pH partioning |
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How does rate of dissolution affect absorption
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the drug has to be dissolved before it can be absorbed
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How does the surface area affect absorption
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the larger the surface area, the faster the drug can absorb
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How does blood flow affect absorption
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drugs are absorbed more rapidly where blood flow is highest
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How does lipid solubility affect absorption
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high lipid-soluble drugs are absorbed more rapidly and can readily cross the membranes that seperate them from the blood
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Enteral
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through the GI tract
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Parenteral
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Anything you do not swallow
outside the GI tract |
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There are no barriers to absorption when
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the drug is administered IV right into the blood
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4 advantages of IV administration
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1. rapid onset-emergencies
2. control 3. use of large fluid volumes 4. use of irritant drugs- not as irritant through IV |
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5 disadvantages of IV administration
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1. high cost, difficulty, inconvenience
2. irreversibility 3. fluid overload 4. infection 5. embolism |
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Barrier to IM administration
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capillary walls- not significant barrier
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2 factors affecting rate of absorption during IM route
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1. water solubility
2. blood flow |
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2 advantages of IM route
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1. rate of absorption
2. depot preperations- drug is absorbed slowly over long periods of time |
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2 disadvantages of IM route
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1. discomfort
2. inconvenience |
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Major barrier to absorption when drugs are given orally
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epithelial cells in GI tract
capillary walls |
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6 factors that can affect rate and extent of absorption administered orally
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1. solubility and stability
2. gastric and intestinal pH 3. gastric emptying time 4. food in gut 5. coadministration of drugs 6. special coating on drugs |
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When a drug is swallowed and absorbed in the GI tract, what organ must it pass through
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liver
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2 advantages of oral route
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1. convenient
2. inexpensive |
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4 disadvantages of oral route
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1. variability- difficult to control concentration
2. inactivation 3. patient requirements- requires concious and cooperative 4.local irritation |
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Chemical equilalence
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if they contain the same amount of a drug
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Bioavailability
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if the drug they contain is absorbed at the same rate and to the same extent
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2 purposes of enteric coated tablets
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1. protect drug from acid and pepsin in stomach
2. protect stomach from drugs which could cause gastric upset |
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How do sustained release capsules work
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filled with spheres that contain drug, spheres have coatings that dissolve at variable rates
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6 aditional routes of administration
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1. topically
2. transdermal 3. rectal supositories 4. vaginal supositories 5. inhaled 6. direct injection |
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Topical
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local therapy of skin, eyes, ears, nose, mouth and vagina
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Transdermal
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through skin
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3 major factors affeting distribution
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1. blood flow
2. ability of drug to exit vascular system 3. ability of drug to enter cells |
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Where does most drug metabolism take place
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liver
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Most important consequence of drug metabolism
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promotion of renal drug excretion
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Prodrug
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compound that is pharmacologically inactive as administered and then undergoes conversion to active within the body
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Drug excretion
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removal of drugs from body
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6 ways drugs can exit the body
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1. urine
2. bile 3. sweat 4. saliva 5. breast milk 6. expired air |
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3 processes that result in urinary excretion of drugs
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1. glomerular filtration
2. passive tubular reabsorption 3. active tubular secretion |
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Minimum effective concentration
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the plasma drug level lowest at which therapeutic effects will not occur
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Toxic concentration
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when plsma drug levels are too high
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Therapeutic Range
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enough drug present to produce therapeutic responses but not too much to be toxic
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Loading Dose
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large initial dose
shorten times to plateau |
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Maintenance Dose
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smaller doses to maintain a therapeutic level
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