Pharmacokinetic Principles of Pharmacology Flashcards
what the body does to the drug
pharmacokinetics
what the drug does to the body
pharmacodynamics
clinical pharmacokinetics is the discipline that describes the 1 2 3 4
absorption, distribution, metabolism, excretion
half life is the time required for serum concentration of a drug to decrease by ____ after absorption and distribution are complete
example drug A half life is 2 hours - 100%
1 hour is 50%
50%
a drug given orally has to first pass through this organ _____________ before it reaches its site of action
hepatic first pass effect
___________ is a generic name for the group of enzymes that are responsible for most drug metabolism _______ reactions. They are produced in the _______
cytochrome p450
oxidation
physiologic barriers
physical, chemical and biological barriers
epithelial lining of GIT is a __________
pH difference between stomach and fundal veins is a _________
blood barrier/blood placental barrier is a _________
bi-lipid layer: _________, ______, ________
transmembrane proteins (__ proteins)
___________ core and 2 _______ surfaces
physical barrier chemical barrier biological barrier phospholipids, sterols, glycolipids G proteins hydrophobic hydrophilic
drug concentration at sites of action influenced by several factors such as:
1
2
3
route of administration
dose
characteristics of drug molecules
drug absorption routes of drug administration 1 2 - vapors, gases, smoke 3 - \_\_\_\_\_\_\_ - \_\_\_\_\_\_\_\_ -\_\_\_\_\_ suppositories 4. injection (parenteral) - \_\_\_\_\_\_\_ -\_\_\_\_\_\_\_\_ -\_\_\_\_\_\_ -\_\_\_\_\_\_\_\_ -\_\_\_\_\_\_ -\_\_\_\_\_\_\_\_ 5. \_\_\_\_\_\_\_\_\_
oral inhalation mucous membranews intranasal sulingual rectal intravenous intramuscular subcutaneous intraperitoneal intra-arterial intra-articular transdermal
drug absorption
lipid solubility
pKa = pH at which __% of drug molecules are ionized
-uncharged (_______) molecules are lipid ______
-the pKa of a molecule influences its rate of ________ through tissues into the blood stream
-pH trapping (___________ equation)
-consider a weakly acidic drug ___
pH trapping
- aspirin is _______ in an acidic environment and 1000x faster in diffused through the GI mucosa into the plasma which has a pH of 7.4
- once in the plasma, this acidic drug is _______ and cannot reneter the GI trapped
pH varies: _______ (1-2), intestines (6-7)
50 unprontonated soluble absorption henderson-hasselbalch equation neutral pH trapped stomach intestines
routes of drug administration
oral drug administration:
advantages:
safe, economical, convenient, practical
disadvantages
- ___________
- _____ levels are difficult to predict due to multiple factors that limit absorption
- some drugs are destroyed by _________
- drugs may get activated and then broken down
- some drugs irritate the ___ system
first pass effect
blood
stomach acids
GI
routes of drug administration
advantages of injection routs
- absorption is more ____ than with oral administration
-rate of absorption depends on blood flow to particular tissue site (___> ___ > ___)
advantages specific to IV injection
- no absorption involved ( inject directly into blood)
- rate of _____ can be controlled
- a more accurate prediction of ____ is obtained
rapid
IP, IM, SC
infusion
dose
routes of drug administration
disadvantages/risks of injection
-a rapid onset of action can be dangerous if _______ occurs
-recovery from ________ or shock
-if administered too fast, ____ and ____ function could be compromised
-drugs insoluble in water or dissolved in oily liquids can not be given ___
-_______ techniques are neccessary
overdosing dehydration heart, respiratory IV sterile
______: the fraction of an administered dose of drug that reaches the blood stream
- physical properties of the drug (______, ______, ________)
- drug formulation (_______, ______, ______)
- _____ state
- _______ emptying rate
- interactions with other drugs
- ____ and ___
- _____
- genetic, disease, ethnocultural, socioeconomic
bioavailability hydrophobicity, pKA, solubility sustained release, troche, pessary fasting gastric age, gender diet
__________: the passage of drug from site of administration into the circulation
__________: drugs given in solid form muset dissolve in the _______ bio-phase before they are absorbed. poorly water soluble drugs (______)
- passive transport depends on the _________ gradient
- area of absorbing surface: if the area is _____, the absorption is faster
- ________ of absorbing surface. Blood circulation _____ the drug from the site of absorption and maintains concentration gradient across the ________. _____ blood flow hastens drug absorption
absorption aqueous solubility aqueous Griseofulvin concentration larger vascularity membrane increased
route of administration affects drug absorption because each route has its own pecularities
oral application
- unionized lipid soluble drugs (______) are readily absorbed from GIT
- acid drugs (____) acid drug absorption from the stomach is faster due to non-ionized properties
- basic drugs (______, ______) are largely ionized in the _______ and are absorbed only from the ______
ethanol aspirin atropine, morphine stomach duodenum
presence of food
-dilutes the ____ and retards ______
-_______ with calcium present in milk
-_______ hormone (_______: synthroid USP)
-food delays gastric _______. Most drugs are absorbed better if taken on an empty stomach
-certain drugs are degraded in the GIT _______ by acid, _____ by peptidases - ineffective _____
-enteric coated tablets (______ coating)
and sustained released preparations can be used to overcome ______ ability, _____ irritancy and ____ duration of action
drug, absorption tetracyclines thyroxine levothyroxine emptying penicillin G, insulin orally acid resistant acid, gastric, brief
presence of other drugs
-drugs can also alter absorption by gut wall:
altering motility (_______, ________)
-causing mucosal damage (_______)
-alteration of gut flora by _______ may disrupt the __________ circulation
intestinal absorption
-ileum (_, _, _, _)
motility atropine, metoclopramide methotrexate antibiotics enterohepatic ADEK
Subcutaneous and IM
- drug deposited in the vicinity of the _________
- _______ drugs pass readily across the surface of the capillary endothelium
- absorption from SC site is ______ than that from IM
- application of ___ and ______ accelerate drug absorption by increasing blood flow
- _____ preparations (preparations with a long action) such as _______ and __________ can be given by these routes
vaccines
capillaries lipid soluble slower heat, muscular exercise depot benzyl penicillin protamine zinc insulin
topical application
(skin, cornea, mucous membrane)
systemic absorption depends on ________
only a few drugs significantly penetrate intact skin
-_______, ______, and _______
-______ applied over extensive areas can produce systemic effects and ________ suppression
-mucous membranes of the mouth, rectum, and vagina absorb ______ drugs (example: ______)
lipid solubility
nitroglycerine, scopolamine, estradiol
glucocorticosteroids
estrogen creams
______: passage of a drug from the circulation to the tissue and the site of its action
-the extent of distribution of a drug depends on its _______, _______ at physiological pH, extent of binding to _____ and ________, and differences in regional _______
movement of a drug proceeds until an ______ is established between unbound drug in plasma and tissue fluids
distribution lipid solubility ionization plasma, tissue proteins blood flow equilibrium
