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Pharmacokinetics involves
absorption, distribution, metabolism and elimination).
Absorption:
absorption from the administration site either directly or indirectly into the blood/plasma.
Distribution:
reversibly or irreversibly move from the bloodstream into the interstitial and intracellular
Metabolism:
biotransformed via hepatic metabolism or by other tissues.
Elimination:
tissues. lastly, the drug and its metabolites are eliminated from the body.
route of administration with the highest bioavailability
intravenous; putting entire dose into a patient's vein and bypassing absorption.
avoids first-pass metabolism
Intravenous route
administration has variable and erratic absorption. n
Rectal administration
4. Steady state (SS)
absorption. n is usually reached within 4-5 half-lives of drug.
Half-life of a drug is
how long it takes for half the drug to be excreted from the body. Determines how
frequently the drug must be administered. Predicts how long toxic effects can last.is
constant with first-order pharmacokinetics of a drug.
Zero-order (nonlinear) pharmacokinetics
means a drug is metabolized at a constant rate per unit time.
CYP3A4 substrate drugs
may have enhanced activity if any CYP3A4 inducer drugs are used along with it.
Drug development process involves these steps according to the FDA:
Discovery: laboratory research to develop the new drug. Preclinical research with
animal testing for safety (Phase I). Clinical research on human subjects for medication
safety (Phase II). Clinical research in humans comparing the new drug to accepted
medications placebo depending on the study (Phase III). FDA review of the results to
determine approval. Post marketing study to identify adverse effects not found in earlier
clinical studies (Phase IV)
2. Medication safety organizations
The Institute for Safe Medication Practices (ISMP) The Institute of Medicine (IOM) The
Joint Commission The National Coordinating Council for Medication Error Reporting
and Prevention (NCC MERP) Food and Drug Administration (FDA) Safe Use Initiative
Two basic type of ADRS:
pharmacological and idiosyncratic.
85% to 90% of ADRS
are pharmacological.
Adverse drug reactions are usually preventable,
, frequently occur in a hospital or nursing home setting, and include medication errors,
adverse drug effects, and allergic idiosyncratic type reactions.
ADRS are not commonly reported;
the FDA does not mandate that ADRS be reported.
Polypharmacy
involves using multiple health care providers for care, using multiple medications, and
using several pharmacies prescription filling.
Angiotensin converting enzyme inhibitors (ACEIS):
lisinopril, captopril, enalapril, ramipril, benazepril, fosinopril.
ACEIS reduce blood pressure enzyme.
by suppressing the release of angiotensin-converting enzyme.
Important side effects of ACE inhibitors
Important include cough and angioedema; discontinue the ACEI if angioedema occurs.
Angiotensin II receptor blocking agents (ARBS):
Icandesartan (Atacand), eprosartan (Teveten), irbesartan (Avapro), losartan (Cozaar),
telmisartan (Micardis) and valsartan (Diovan).
ARBS reduce blood pressure
by blocking angiotensin II receptors.
Essential (primary) hypertension
Essential (primary) accounts for 90% of cases; secondary hypertension may caused by
chronic renal failure.
Nitroglycerin
Nitroglycerin is a nitrate drug that can be administered IV, SL, a topical ointment and as
a transdermal patch.
Nitrates are contraindicated
with PDE-5 inhibitors (e.g., sildenafil and vardenafil)
Amiodarone is the antiarrhythmic
Of choice when there is coexisting heart failure; can cause thyroid and pulmonary
toxicity.
Alpha-1 adrenergic stimulation
results in vasoconstriction and increased blood pressure.
Alpha-1 adrenergic blockade
results in vasodilation and reduced blood pressure.
Beta-1 adrenergic stimulation
by beta agonists (e.g., isoproterenol) results in increased heart rate, increased blood
pressure, and increased cardiac output.
Beta-1 adrenergic blockade results
in reduced heart rate, reduced blood pressure, and reduced cardiac output.
Left heart failure
causes reduced delivery of oxygenated blood to the body tissues.
Right heart failure
is associated with pulmonary disease and increased pulmonary vascular resistance.
drug that relieves heart failure symptoms but does not reduce mortality
furosemide.
Loop diuretics like furosemide