Ch. 1 - Drug Action Flashcards Preview

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Flashcards in Ch. 1 - Drug Action Deck (34):
1

Drug

any chemical substance that affects living systems by changing their structure or function

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3 phases of drug action:

1.) Pharmaceutic phase
2.) Pharmacokinetic phase
3.) Pharmacodynamic phase

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*******Pharma(ceutic) phase***********

(Dissolution)
-Solid form: needs to disintegrate
*Tablet > disintegration > dissolution
-Liquid form

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Pharma(ceutic) phase: Enteric Coated

RESIST disintegration in STOMACH
-------------------------------------------------------------
DISINTEGRATES in the SMALL INTESTINE
_________________________________
should NOT be crushed

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Pharma(ceutic) phase cont...

Food in GI tract:
*may interfere
*may enhance

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******Pharmaco(kinetic )Phase*********

*kinetic* = means 'movement'
-process of drug movement to achieve drug action
1.) Absorption
2.) Distribution
3.) Metabolism (biotransformation)
4.) Excretion (elimination)

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Pharmaco(kinetic )Phase: *Absorption*

Movement of drug particles from GI tract to body fluids
------------------------------------------------------
Gastric absorption influnced by:
*food, gastric pH

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Absorption cont.

bioavailability (subcategory)
* % of drug dose that reaches the system circulation
*Ex: taking it orally compared to intravenously

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Pharmaco(kinetic )Phase: *(1) Distribution*

drug becomes available to body fluids and body tissues

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Distribution (2)

****Drug carried from site of absorption to site of action (definition)
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Drug enters bloodstream --> rapidly carried to organs with blood supply

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Distribution (3)

Influenced by:
-blood flow
-drug's affinity to the tissue
-protein-binding effect

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Pharmaco(kinetic )Phase: Protein-binding Effect

-portion of the drug that is bound (to protein):
*inactive (not available to receptors)
-------------------------------------------------------
-Unbound portion:
*free (active) = pharmacologic effect

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3.) Metabolism (biotransformation):

drug needs to be WATER SOLUBLE
----------------------------------------------------
IF NOT water soluble = biotransformation occurs to convert to a more water soluble form

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Metabolism (biotransformation): cont..

Helps inactivate potent drug before it builds up (toxic)
----------------------------------------------------------
Age, hepatic disease = slow down ability
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Liver = primary source of metabolism

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Half-Life:

-time it takes for 1/2 of drug to be eliminated from body
(Ex:)
Half-life: 4 hrs
{Every 4 hr interval drug conc. decreases 50%}
*Initial (8am) = 100% (500mg)
*After 4 hrs = 50% (250mg)
*After 8 hrs = 25% (125mg)
*After 12 hrs = 12.5% (62.5mg)
*After 16hrs = 6.25% (31.25mg)

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4.) Excretion (Elimination):

Kidneys = most important route
------------------------------------------------------
Kidney function affected by:
*age, kidney disease

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*****Pharmacodynamic phase*******

drug concentration & its effects on the body
*Mechanism of action

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Drug Response: Primary or Secondary

diphenhydramine (Benadryl)
----------------------------------------------
*Primary effect:
-treat symptoms of allergy
*Secondary effect:
-CNS depression --> drowsiness

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Onset:

time it takes to reach minimum effective concentration (occur)

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Peak:

drug reaches its highest blood concentration (level)

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Duration:

length of time drug has a pharmacologic effect

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Receptor Theory:

-drugs most commonly form a chemical bond with specific receptors in the body
*lock & key relationship

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Agonist:

interacts with receptor to produce a response

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Antagonist:

inhibits or prevents action of an agonist or blocks a response

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Therapeutic Range (Window):

difference btwn therapeutic level (bl concentration) & toxic level
---------------------------------------------------------
Low Therapeutic Index (TI) = narrow margin of safety
---------------------------------------------------------
High TI = wide margin of safety

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Peak level:

highest plasma concentration at a specific time ----(measures rate of absorption)

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Trough level:

lowest plasma concentration (measures rate of excretion)

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Loading Dose:

Large initial first dose when an immediate drug response is desired
**Ex: Z-pack = take 2 doses first day, then 1 dose after that

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Side effects:

acts on other tissues besides specific intended issue

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Adverse effects:

unpredictable (idiosyncratic) adverse effects
-allergic hypersensitivity d/t individuals immune system
--------------------------------------------------------------
Severe allergic reaction > anaphylaxis > resp./circ. collapse > death

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Toxicity

*ALL drugs are able to be toxic if dosage is high enough*
-related to dosage

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Teratogenic Effect:

congenital defect in fetus whose mom took drug during pregnancy

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Drug Tolerance:

resistance to effect of drug
-need higher dosage/frequency to produce desired effect

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Placebo Effect:

Psychological benefit from taking a chemical compound
- Persons feels that the pill will make them feel better