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47 Cards in this Set
- Front
- Back
the physiological movement of drugs within the body how drugs are absorbed, distributed, metabolized, and excreted by the body |
What is Pharmacokinetics |
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4 steps of pharmacokinetics |
absorption distribution biotransformation (metabolism) excretion |
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Mechanisms of drug movement |
passive diffusion facilitated diffusion active transport pinocytosis/phagocytosis |
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Passive Diffusion |
molecules move from an area of high concentration to an area of low concentration does not require energy |
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molecules are small, nonionic, and lipophilic in which type of diffusion? |
Passive |
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Facilitated Diffusion |
a type of diffusion that uses a special molecule to help the drug molecule cross the cell membrane |
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Active Transport |
a type of diffusion that uses a special carrier molecule and ATP to carry the drug molecules across the cell membrane |
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Pinocytosis |
the cell membrane surrounds and engulfs liquid molecules ie isulin |
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Phagocytosis |
the cell membrane surrounds and engulfs solid particles ie nutrients |
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which methods of drug movement require energy? |
active transport and phagocytosis/pinocytosis |
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Drug Absorption |
the movement of the drug from the site of administration to the bodily fluids that will carry it to the site of action (blood/plasma) |
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Drug factors that affect absorption |
drug pH solubility molecular size |
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the degree to which a drug is absorbed and reaches circulation-the percentage that actually reaches systemic circulation |
Bioavailability |
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Bioavailability of IV drugs |
1 |
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Bioavailability of other parenteral drugs |
<1 |
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First Pass Affect |
thedrug passes thru the liver first and may have extensive metabolism so themajority of the oral drug is destroyed |
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Factors that affect bioavailability |
blood supply to the area of entry (mm vs surface area for absorption mechanism of drug absorption |
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weakly acidic drugs are better absorbed where? |
the somach |
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hydrophilic drugs are better absorbed where? |
the small intestine |
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Patient factors that affect drug absorption |
blood flow pain stress hunger/fasting food consumption health age species |
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The movement of drugs from systemic circulation to the tissues -the target tissues |
Drug Distribution |
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factors that affect drug distribution |
membrane permeability tissue perfusion protein binding volume of distribution |
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which factor of drug distribution has the greatest effect on drug distribution |
membrane permeability |
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which type of drug can enter the CNS? |
Lipophilic drugs |
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which body tissues exhibit rapid distribution |
brain, heart, liver, kidneys highly perfused |
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body tissues with slow distribution |
fat, skin poorly perfused |
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poorly perfused tissues... |
maintain drug levels longer bc of poor blood flow to those tissues |
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some drugs bind to proteins in the blood, especially which protein? |
Albumin |
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how can liver dz affect protein binding |
albumin is made in the lover, dz will reduce albumin production making less available for protein binding which can result in toxicity from the extra drug available |
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Biotransformation |
metabolism the chemical alteration of the drug by the body to a metabolite |
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4 pathways of biotransformation |
oxidation reduction hydrolysis conjugation |
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where is the primary site of biotransformation |
the liver |
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other sites of biotransformation |
kidneys small intestines lungs brain skin |
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in what scenario are two drugs acting SYNERGISTICALLY? |
when 2 or more drugs administered together produce a greater response than they would individually |
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in what scenario are two drugs acting ANTAGONISTICALLY |
when the administration of one drug decreases the action of another drug
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Cytochrome P450 |
is a detoxifying enzyme found in the liver when stimulated it can reduce the body's response to drugs |
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Methods of drug excretion |
renal elimination hepatic elimination intestinal elimination elimination in the milk |
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Factors that affect biotransformation |
altered absorption competition for plasma proteins altered excretion altered metabolism |
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Drug Tolerance |
decreased response to a drug due to repeated use |
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Dose |
the amount of a drug administered at one time measured in a unit of mass -tab, mls, tbsp, mg/kg |
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the amount of drug and frequency of administration for a specific species mg/kg and SID |
dosage |
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Loading Dose |
the initial administration of the drug to achieve rapid therapeutic concentration -usual IV IM or infusion |
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Maintenance Dose |
administration continued throughout the remainder of the treatment period at a given interval and route |
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Dose Interval |
the time between treatments BID q12hr PRN QOD |
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Pill forms |
tablets capsules(glycerin or gelatin container) boluses molded tablets (chewable-heatworm) sustained release extracts |
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rule of thumb concerning cloudy liquids |
do NOT give IV!! |
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factors that alter drug metabolism |
liver dz drug tolerance species |