Chapter 2: Pharmacologic Principals Flashcards
What is the study of the physiochemical properties of drugs and how they influence the body called
pharmacodynamics: pharmacodynamics is the study of what drugs do to the body
the study of how the drug moves through the body, including absorption, distribution, metabolism, and excretion
pharmacokinetics
biotransformation
metabolism
A drug given by which route is altered by the first-pass effect?
oral
Medications absorbed in the stomach and small intestine travel through the portal system and are metabolized by the liver before they reach the general circulation.
Drug half-life is defined as the amount of time required for 50% of a drug to
be eliminated by the body.
In pharmacokinetics, the time required for half of an administered dose of drug to be eliminated by the body, or the time it takes for the blood level of a drug to be reduced by 50%, is the drug’s half-life (also called elimination half-life).
Highly protein-bound drugs
increase the risk of drug-drug interactions
What is the ratio between a drug’s therapeutic effects and toxic effects called?
therapeutic index
enteral dosage form
Tablets, capsules, oral soluble wafers, pills, timed-release
capsules, timed-release tablets, elixirs, suspensions,
syrups, emulsions, solutions, lozenges or troches, rectal
suppositories, sublingual or buccal tablets
topical dosage forms
Aerosols, ointments, creams, pastes, powders, solutions,
foams, gels, transdermal patches, inhalers, rectal and
vaginal suppositories
The presence of food may
enhance the absorption of
some fat-soluble drugs or of drugs
that are more easily broken down in an acidic environment
examples of drugs to be taken on empty stomach
alendronsate sodium and risedronate sodium
Medications that are generally taken with food include
carbamazepine, iron
and iron-containing products, hydralazine, lithium, propranolol, spironolactone,
nonsteroidal antiinflammatory drugs, and theophylline.
Macrolides and oral opioids are often taken with food
(even though they are
specified to be taken with a full glass of water and on an empty stomach)
Topically administered drugs can be applied
to the
skin, eyes, ears, nose, lungs, rectum, or vagina
All
topical routes of drug administration avoid
first-pass effects of
the liver, with the exception of rectal administration(some does)
First pass routes
hepatic arterial, oral, portal venous, rectal*
non first pass routes
Aural (instilled into the ear) Buccal Inhaled Intraarterial Intramuscular Intranasal Intraocular Intravaginal Intravenous Subcutaneous Sublingual Transdermal
areas of rapid distribution include
heart, liver, kidneys, brain
areas of slower distribution
muscle, skin, fat
a drug that is highly watersoluble
(hydrophilic) will have a
smaller volume of distribution
and high blood concentrations
fat-soluble drugs
(lipophilic) have a
larger volume of distribution and low blood
concentrations.
Hepatic metabolism involves the activity of a very large class of enzymes known as
cytochrome P-450 enzymes (or simply
P-450 enzymes), also known as microsomal enzymes
biliary excretion
The excretion of drugs by the intestines is another route
of elimination
enterohepatic
recirculation.
Once certain
drugs, such as fat-soluble drugs, are in the bile, they may be
reabsorbed into the bloodstream, returned to the liver, and
again secreted into the bile.
most drugs are considered to be effectively
removed from the body
After about five half-lives
The concept of half-life
clinically useful for determining
when steady state will be reached in a patient taking a particular
drug
Steady state refers to the
physiologic state in which the
amount of drug removed via elimination (e.g., renal clearance)
is equal to the amount of drug absorbed with each dose
Drugs can exert their actions in three basic ways:
through
receptors, enzymes, and nonselective interactions
The
degree to which a drug attaches to and binds with a receptor
is called
affinity
Enzyme interactions/selective interaction
For a drug to alter a physiologic
response in this way, it may either inhibit (more common) or
enhance (less common) the action of a specific enzyme.
Drug-enzyme interaction
occurs when the drug chemically binds to an enzyme molecule
in such a way that it alters (inhibits or enhances) the enzyme’s
interaction with its normal target molecules in the body
nonselective interactions
target cell membranes and cause a defect which that results in cell death
type of
therapy can be categorized as
acute, maintenance, supplemental
(or replacement), palliative, supportive, prophylactic, or empiric
palliative
The goal is to improve quality of life for both the patient
and the family
supportive therapy
maintains the integrity of body functions
while the patient is recovering from illness or trauma.
Empiric therapy…. example
use of antibiotics active against the organism most commonly
associated with a specific infection before the results of the culture
and sensitivity reports are available
additive effect example
antihistamine and opioid
combinations (e.g., promethazine and codeine) for treatment
of cold symptoms
Often drugs are used together for their additive effects so
that smaller doses of each drug can be given
synergistic effect example
hydrochlorothiazide
with lisinopril for the treatment of hypertension
antagonistic example
antibiotic ciprofloxacin is given simultaneously with antacids,
vitamins, iron, or dairy products. These drugs reduce the
absorption of ciprofloxacin and lead to decreased effectiveness
of the antibiotic
adverse drug
withdrawal event example
return
of infection caused by stopping antibiotic therapy too soon.
medication use process
prescribing,
dispensing, administering, or monitoring of drug therapy
