1. drug response: the intensity of the drug response is directly related to the
concentration of the drug at the SITE OF ACTION
Goal is to:
- maximize the beneficial effects- concentration high enough for desired response
- minimize harm- avoid to high a concentration
2. Three phases of drug action: 1. pharmaceutic phase (dissolution)
2. pharmacokinetic phase (drug moving through the body)
3. pharmacodynamic phase (what the drug does to the body)
3. 1. pharmaceutic phase: the drug goes into solution
- Dissolution: the process by which a drug goes into solution and becomes
available for absorption
- must be dissolved before it can be absorbed
- most absorption takes place in the small intestine
4. 2. pharmacokinetic phase: four processes: "what the BODY does to the
drug" - absorption
- distribution
- metabolism/ biotransformation
- exertion
5. pharmacokinetic phase: Absorption: (small intestine) the movement of a
drug from its site of administration into the blood
6. pharmacokinetic phase: Distribution: drug moves from blood --> cell
membrane
7. pharmacokinetic phase: Metabolism/biotransformation: lipid soluble
metabolite (liver) --> a water soluble metabolite
8. pharmacokinetic phase: Excretion: water soluble metabolite (kidneys)
9. liver: breaks down the drug
10. kidneys: excretes the drug
11. Pharmacokinetic phase movement process: orally --> stomach --> SI -->
bloodstream --> site of action --> liver (broken down) --> kidneys (excreted)
IV --> bloodstream --> cite of action --> liver --> kidneys
, NUR 210 exam 1 material Pharmacology Principles
12. drugs crossing the cell membranes phospholipid cell layer: -drugs must
be LIPID SOLUBLE in order to pass through the membrane
- WATER SOLUBLE drugs penetrate the cell membrane through channels and
pores
13. Absorption
1. direct penetration of the membranes
2. channels and pores
3. transport systems: the movement of a drug from its site of administration to
the blood
How do drugs cross membranes?
14. 1. Direct penetration of the membranes: - use by MOST drugs
- most drugs to large to pass thru channels and pores
- most drugs lack transport systems
- drugs must be lipid soluble to be able to penetrate cellular membranes =
lipophilic drugs
15. 2. channels and pores: only very small ions such as potassium and sodium
can pass through cell membranes
16. 3. transport systems: - are carriers that can move drugs from one side of
the membrane to the other - are selective
17. Movement of drugs across membranes: -drugs must cross membranes
(pass through cells) to enter the blood from their site of administration
- drugs must then leave the blood (vascular systems) to get to their SITE OF
ACTION
- drugs must then cross membranes again to be metabolized and excreted
18. pharmacokinetic phase: Absorption: process that occurs between the time
a drug enters the body and the time it enters the bloodstream to be circulated
- Rate of absorption -> depends on the formulation of drug (tablet, liquid, etc.)
- Amount of absorption -> how effective drug will be absorbed
, NUR 210 exam 1 material Pharmacology Principles
Major determinants of rate of absorption:
- blood flow -> higher blood flow, the faster the drug is absorbed
- lipid solubility -> higher lipid soluble drugs faster than drugs whose lipid solubility
is low
- pH -> acidity of the stomach can break down the drug
19. what is the first-pass effect?: affects amount of drug absorbed
- the metabolism of a drug by the liver BEFORE it reaches systemic circulation - is
the % of the drug that is broken down in the liver
- "bioavailability" : the fraction of administered drug that actually reaches systemic
circulation
- IV bioavaiability= 100%
- oral bioavailability will vary
20. Three Routes of Absorption: 1. Enteral
2.Parenteral
3. Topical
21. Enteral route of absorption: Defined by the way of GI tract (oral/gastric
mucosa, small intestine, rectum) - any drug given via GI tract
- EC (enteric coated): intended to break down in the small intestine NOT the
stomach
--> must undergo the "first pass effect"
- PO --> portal circulation --> must undergo the first pass effect
- SL, buccal, rectal --> absorbed into highly vascular tissue under tongue or in the
rectum (by passes liver so little to NO first pass effect)
22. Enteral routes of absorption: EC
PO
SL, buccal, rectal
23. Parenteral route of absorption: SQ, IM, IV, intrathecal (into special cord),
epidural (into spine)
IV fastest route (NO barriers to absorption- absorption instant, complete, and
irreversible) - most common route
24. Topical (transdermal) route of absorption: application of meds to body
surfaces
- skin, eyes, ears, nose, lungs
25. important: all meds given PO have some first pass effect
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