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19 Cards in this Set
- Front
- Back
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What is the definition of absorption of drugs? |
The transfer of the drug from the site of administration to the circulation |
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What are the 2 factors that affect drug absorption? |
Factors related to the drug Factors related to the animal |
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What are the 6 factors related to drug for absorption? |
Molecular size Lipid solubility Degree of ionization Dissolution of drug in water Conc. of drug at absorptive site Route of admininistration |
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How does the size of the molecule affect absorption? |
The SMALLER the molecule, the FASTER penetration through the pores |
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How does lipid solubility affect absorption? |
The HIGHER lipid solubility, the HIGHER absorption |
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How does the degree of ionization affect absorption? |
The HIGHER the ratio of N/I the FASTER absorption |
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How does the concentration of the drug affect absorption? |
-depends on dose and concentration The HIGHER the concentration the FASTER is absorption |
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How does the route of administration affect absorption? |
IV-absorbed instantly-fastest route Inhalation>sublingual>IM>SQ>enteral (oral) |
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What are the 5 factors related to the animal for absorption? |
Blood flow Absorbing surface area Connective Tissue Species Individual |
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What increases blood flow which increase absorption? |
-Blood flow -heat/massage (fentanyl patch) -Inflammed tissue (topical drugs) -Sympathetic stimulation to skeletal muscles |
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What decreases blood flow which decreases absorption? |
-Epinephrine (vasoconstriction) -Sympathetic stimulation to GI tract/SQ/skin -Shock and edema |
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Where is the main site of absorption and why? (for drugs given orally?) |
Small intestine because of the extensive surface area and rich blood supply |
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What are the factors that affect absorption from the GI tract? |
Absorption rate of solid drugs depending of their rate of dissolution (rate limiting step) Activity of gut Blood flow Species Individual Presence of other substances |
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How will the presence of other substances affect absorption? |
Food may absorb drug particles and prevent absorption |
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How does connective tissue affect absorption? |
The presence of connective tissue decreases absorption because its fibrous and not vascular *repeated injections in the same place will cause local tissue fibrosis (ex: insulin injections) |
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How do species differences affect absorption? |
The thickness of their skin The anatomy of the GI tract |
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How does the activity of the gut affect absorption? |
Rate of absorption depends on the rate of gastric emptying |
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How can each individual have different affects on absorption? |
age body condition medical state inter individual variability |
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What is the First-Pass effect? |
Drugs absorbed from the GI distribute to the liver for metabolism *some drugs will be metabolized before distribution to other tissues *drugs with HIGH first pass metabolism have LESS distribution |
