Week 5 Flashcards
Water soluble drugs
dissolve in the watery contents of the GI tracts, rapidly absorbed and take effect faster
Lipid soluble drugs
can penetrade lipid cell membrance
why you should never crush or break enteric coated and time released medication
to do so would destroy their protective coatings
how antacid does to ph. and acidity level in stomach ?
Antacids are medications that are used to neutralize excess stomach acid, and they can have an impact on the pH level in the stomach.
Stomach acid, which is primarily composed of hydrochloric acid (HCl), has a very low pH (highly acidic), typically around 1.5 to 3.5. When you take an antacid, it works by raising the pH of the stomach contents, making it less acidic.
pharmacology
the study or science of drugs
Pharmaceutics
- form determines rate of drug dissolution and absorption
- Example: liquid absorbed faster than tablets
Drug Absorption of Various Oral Preparations
Buccal is drug place in the cheek
SL is sublingual, place it under the tongue
Cheeks and under tongue absorbed fast because they have lot of blood vessels.
capital letters for extended release
(CR, SA, XL, XT,
CD, TR, ER, LA)
CR: Controlled-Release
SA: Sustained-Action
XL: Extra Long
XT: Extra Time
CD: Controlled-Delivery
TR: Time-Release
ER: Extended-Release
LA: Long-Acting
cannot be crushed or chewed > possible toxicity
Pharmacokinetics:
Pharmacokinetics: “kinetics” = movement
* study of the drug movement throughout
the body (parent drug to all metabolites
leaving the body
4 processes: absorption, distribution,
metabolism, and excretion
Pharmacokinetics
Image
PHARMACOKINETICS
Absorption
- site of administration into the bloodstream for
distribution - bioavailability & first-pass effect
- absorption rate affected by route:
enteral, parenteral (anything that do not go into GI), topical
PHARMACOKINETICS
Distribution
Distribution
* transport of drug from bloodstream to its site of action
* heart, liver, kidneys, & brain receive
drug more rapidly
* muscle, skin, fat receive drug more
slowly
* unbound drugs free to distribute and
reach site
* drugs bound to plasma proteins (too large) are
pharmacologically inactive
* low albumin levels increase risk of toxicity
warfarin bounds to albumins 99%
geriatric starts with low dosages.
Some parenteral routes
Intravenous (IV)
Intramuscular (IM)
Subcutaneous (SC or SQ)
Intradermal (ID)
Intrathecal
Intraventricular
Intra-articular
Bioavailability
- Bioavailability: extent of
drug absorption - oral drug absorbed via
stomach or intestine =>
liver => bloodstream - liver changes drug into
inactive metabolites =>
less drug into circulation
=> high first-pass effect
=> bioavailability < 100%
First pass effect image
Distribution Image
Topical route
over longer period, slow onset, but more prolonged
topical routes avoid first pass effects of the liver, except rectal administration (mixed first pass and non first pass effect for rectal)
PHARMACOKINETICS
Metabolism (biotransformation)
Metabolism (biotransformation)
* biochemical alteration >inactive metabolite
* except prodrug- converted to active form
* liver is mostly responsible for drug
metabolism
* involves variety of enzymes
Cytochrome P-450 enzymes
hepatic metabolism
large enzymes
responsible for metabolize most drugs
target lipid soluble drugs
PHARMACOKINETICS
Excretion
Excretion
* elimination of metabolites or active drug
* kidneys primarily responsible (liver and the bowel play some roles)
* extensive transformation taken place
FIRST-PASS EFFECTS: OTHER
CONSIDERATIONS
Enteral drugs: also include orally
disintegrating tablets (ODTs), oral
soluble films, sublingual, and buccal
(transmucosal)
–oral cavity highly vascularized
–do not undergo first-pass effects
Rectal drugs:
* used for both local and systemic
delivery
* may be considered enteral or topical
* mixed first-pass and non-first-pass
absorption and metabolism
First pass effect Image
fentanyl lollipop
Do not undergo first pass effects
First pass effect or not
Onset of action
time for drug to start physiologic response
Peak effect
time required for drug to reach max. therapeutic response
Duration of action
length of time drug conc. is sufficient to elicit therapeutic
response
Half-life
time required for 50% of drug to be eliminated by the body
Drug effect
onset of action
peak effect
duration of action
glyburide
sample of time action profile
Pharmacodynamics:
relates to the mechanisms of drug action in living tissues.
A/ high affinity, the greater response
B/ Agonist, fit perfectly to the receptor site
C/
Agonist
Drug binds to the receptor, there is a response
Partial agonist
drug binds to the receptor, the response is diminished compare with that elicited by an agonist
Antagonist
drug binds to the receptor, there is no response. Drug prevents binding of agonist
Narcan naloxone, block the Mu receptor, preventing overdose of morphine
PHARMACOLOGIC PRINCIPLES
Food drug interaction
Leafy green veggies
Food drug interaction
Grapefruit juice
Food drug interaction
Dairy products and iron
Food drug interaction
Valerian root
polypharmacy
the simultaneous use of multiple medications is called polypharmacy
Aging effects on pharmacokinetics
DOSING VARIATIONS FOR THE ELDERLY
