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How does the body impact or interact w/ the drug? (use mnemonic)
- A: absorption
- D: distribution
- M: metabolism
- E: excretion
What is the therapeutic dose?
Amount of drug rqd to achieve the desired affect.
Effectiveness of a drug.
Define critical concentration.
Define loading dose.
CC: amt of drug needed to cause a therapeutic effect.
LD: giving a large dose initially to become effective faster than usual dose.
What is "absorption?"
Where does absorption begin?
Movement of drug from site of admin. to the bloodstream.
Absorption begins in the SI.
From slowest to fastest, identify the routes of admin.
Name factors that impact rate of absorption (4)
- 1) Route
- 2) Presence of other substances (food, other drugs)
- 3) Blood flow (good flow = faster rate of absorption)
- 4) Lipid solubility (lipid solubility = faster rate of absorption)
What is a barrier to absorption?
Oral: gastric pH b/c food increases stomach pH and slows emptying of stomach--drugs stay in stomach longer.
Parenteral: (IM) drugs peak faster in women than in men.
Subq: peak dependent on fat concentration & circulation.
Define "distribution" of a drug in the body.
What are some factors that affect distribution?
bloodstream --> tissues --> cells
- -lipid solubility
- -tissue perfusion (e.g., scars would block perfusion)
- -drug's ability to leave the blood (protein-binding capacity)
- -drug's ability to enter the cells
Explain the "protein-binding" capacity.
What may cause drug toxicity?
- Drug binds w/ protein.
- Creates larger molecule that cannot pass through the cell membrane unless bound is broken.
- Drug remains in blood, less drug is free to work in cells.
*Only unbound drugs can pass through the cell membrane.
*Drug toxicity may be caused by: low protein = low drug binding = more drug free to act
What drugs CANNOT pass the BBB?
What drugs CAN pass the BBB?
Where do most drugs pass in women?
- X = water-soluble
- O = lipid soluble
Placenta & breast milk.
Where does drug metabolism (biotransfusion) occur?
Other sites: SI, lungs, kidney, brain, skin
What is the "first-pass effect" (of drugs)?
Conversely, what is Bioavailability?
Factors that impact rate of metabolism of drug.
Drugs that are metabolized IMMEDIATELY and not available for use.
*Oral only. Expressed as a %.
Bioavailability: % of drug available for use.
Factors: the drug, 1st pass effect, presence of hepatic enzymes that metabolize drugs.
What do the P450 enzymes assist in?
Assist in breakdown of foreign chemicals, bilirubin & estrogen, & drug metabolism.
What "fruit" decreases actions of CYP3A4 & increases the serum levels of drugs?
What is "excretion" (elimination) of a drug?
What is the most common route?
What are 3 processes that impact excretion?
Removing the drug or remnants from the body.
Most common route is the urinary tract.
- 1) GFR
- 2) Pass tubular reabsorption
- 3) Active tubular secretion
Factors that influence exretion. (3)
- 1) urine acidity
- 2) Two drugs competing to enter renal sys.
- 3) Whether drug is protein-bond (unbind before entering renal)
What is "half life"?
Amount of time it takes 50% (half) of drug to be removed from the blood.
EX: 2hr half life, 10 mg = 2hrs later = 5 mg
Interactions btwn chemical systems and the drugs that enter those systems.
What are 4 ways that drugs act?
- 1) Replace or substitute
- 2) Increase or stimulate cell activity
- 3) Decrease or slow cell activity
- 4) Interfere w/ functioning of foreign cells.
What is the difference btwn an Agonist and Antagonist?
Agonist: causes a cell to act.
Antagonist: (blockers) prevent cell to act.