active absorption
requires a carrier such as an enzyme or protein to move the drug against a concentration gradient. Energy is required for active absorption.
adverse reactions
more severe than side effects.
agonists
drugs that produce a response
antagonists
drugs that block a response
bioavailability
subcategory of absorption. It is the percentage of the administered drug dose that reaches the systemic circulation
creatinine clearance (CLcr)
compares the level of creatine in the urine with the level of creatine in the blood. Creatinine clearance varies with age and gender.
disintegration
is the breakdown of a tablet into smaller particles.
dissolution
the dissolving of the smaller particles in the GI fluid before absorption.
distribution
the process by which the drug becomes available to body fluids and body tissues. Drug distribution is influenced by blood flow, the drug's affinity to the tissue, and the protein-binding effect.
elimination
excretion
excipients
used in drug preparation to allow the drug to take on a particular size and shape and to enhance drug dissolution.
first-pass effect
The process in which the drug passes to the liver first. aka-hepatic first pass
free drugs
(drugs not bound to protein) are active and can cause a pharmacologic response.
half-life (t1/2)
the time it takes for one half of the drug concentration to be eliminated. Metabolism and elimination affect the half-life of a drug.
high therapeutic index
Drugs with a low therapeutic index have a narrow margin of safety (Figure 1-9, A). Drug dosage might need adjustment, and plasma (serum) drug levels need to be monitored because of the small safety range between ED and LD. Drugs with a high therapeutic in
ligand-binding domain
the site on the receptor at which drugs bind.
loading dose
given to achieve a rapid minimum effective concentration in the plasma.
low therapeutic index
Drugs with a low therapeutic index have a narrow margin of safety (Figure 1-9, A). Drug dosage might need adjustment, and plasma (serum) drug levels need to be monitored because of the small safety range between ED and LD.
metabolism
Drugs can be metabolized in both the GI tract and liver; however, the liver is the primary site of metabolism. Most drugs are inactivated by liver enzymes and are then converted or transformed by hepatic enzymes to inactive metabolites or water-soluble su
nonselective drugs
Drugs that affect various receptors are nonselective drugs or have properties of nonselectivity. Chlorpromazine (Thorazine) acts on the norepinephrine, dopamine, acetylcholine, and histamine receptors, and a variety of responses result from action at thes
nonspecific drugs
Drugs that affect various sites are nonspecific drugs and have properties of nonspecificity. Bethanechol (Urecholine) may be prescribed for postoperative urinary retention to increase bladder contraction.
onset of action
the time it takes to reach the minimum effective concentration (MEC) after a drug is administered.
passive absorption
occurs mostly by diffusion (movement from higher concentration to lower concentration). With the process of diffusion, the drug does not require energy to move across the membrane.
peak action
occurs when the drug reaches its highest blood or plasma concentration.
peak drug level
the highest plasma concentration of drug at a specific time. Peak drug levels indicate the rate of absorption. If the drug is given orally, the peak time might be 1 to 3 hours after drug administration. If the drug is given IV, the peak time might occur i
pharmaceutic phase
Approximately 80% of drugs are taken by mouth. The pharmaceutic phase (dissolution) is the first phase of drug action. In the gastrointestinal (GI) tract, drugs need to be in solution so they can be absorbed. A drug in solid form (tablet or capsule) must
pharmacodynamics
the study of drug concentration and its effects on the body. Drug response can cause a primary or secondary physiologic effect or both. The primary effect is desirable, and the secondary effect may be desirable or undesirable. An example of a drug with a
pharmacogenetics
the scientific discipline studying how the effect of a drug action varies from a predicted drug response because of genetic factors or hereditary influence. Because people have different genetic makeup, they do not always respond identically to a drug dos
pharmacokinectics
the process of drug movement to achieve drug action. The four processes are absorption, distribution, metabolism (or biotransformation), and excretion (or elimination). The nurse applies knowledge of pharmacokinetics when assessing the client for possible
pinocytosis
is a process by which cells carry a drug across their membrane by engulfing the drug particles (Figure 1-2).
placebo effect
is a psychological benefit from a compound that may not have the chemical structure of a drug effect. The placebo is effective in approximately one third of persons who take a placebo compound.
protein-binding effect
Drug distribution is influenced by blood flow, the drug's affinity to the tissue, and the protein-binding effect (Figure 1-3).
rate limiting
the time it takes the drug to disintegrate and dissolve to become available for the body to absorb it. Drugs in liquid form are more rapidly available for GI absorption than are solids. Generally, drugs are both disintegrated and absorbed faster in acidic
receptor families
There are four receptor families: (1) kinase-linked receptors, (2) ligand-gated ion channels, (3) G protein-coupled receptor systems, and (4) nuclear receptors. The term ligand-binding domain is the site on the receptor at which drugs bind.
� Kinase-linke
side effects
physiologic effects not related to desired drug effects. All drugs have side effects, desirable or undesirable. Even with a correct drug dosage, side effects occur and are predicted.
tachyphylaxis
refers to a rapid decrease in response to the drug. In essence, tachyphylaxis is an "acute tolerance." Drug categories that can cause tachyphylaxis include narcotics, barbiturates, laxatives, and psychotropic agents.
therapeutic index (TI)
estimates the margin of safety of a drug through the use of a ratio that measures the effective (therapeutic or concentration) dose (ED) in 50% of persons or animals (ED50) and the lethal dose (LD) in 50% of animals (LD50) (Figure 1-8). The closer the rat
therapeutic range (therapeutic window)
The therapeutic range (therapeutic window) of a drug concentration in plasma should be between the minimum
FIGURE 1-8 The therapeutic index measures the margin of safety of a drug. It is a ratio that measures the effective therapeutic dose and the lethal
time response curve
A time-response curve evaluates three
FIGURE 1-4 The time-response curve evaluates three parameters of drug action: (1) onset, (2) peak, and (3) duration. MEC, Minimum effective concentration; MTC, minimum toxic concentration.
parameters of drug action: t
tolerance
refers to a decreased responsiveness over the course of therapy.
toxic effects
or toxicity, of a drug can be identified by monitoring the plasma (serum) therapeutic range of the drug. However, for drugs that have a wide therapeutic index, the therapeutic ranges are seldom given. For drugs with a narrow TI, such as aminoglycoside ant
toxicity
or toxicity, of a drug can be identified by monitoring the plasma (serum) therapeutic range of the drug. However, for drugs that have a wide therapeutic index, the therapeutic ranges are seldom given. For drugs with a narrow TI, such as aminoglycoside ant
trough drug level
the lowest plasma concentration of a drug, and it measures the rate at which the drug is eliminated. Trough levels are drawn immediately before the next dose of drug is given, regardless of route of administration. Peak levels indicate the rate of absorpt