Respiratory Care Pharmacology Chapter 2: Principles of Drug Action

name the three major principles of drug action

-Drug Administration

-Pharmacokinetics

-Pharmacodynamics

the time course and disposition of a drug in the body; what the body does to the drug

Pharmacokinetics

the method by which the drug is made available to the body; drug formulation and delivery

Drug administration

the mechanism of drug action and its effect on the body; what the drug does to the body

Pharmacodynamics

tablets, capsules, and solutions are examples of

drug dosage forms

the physical state of a drug combined with it's non-drug components

drug dosage form

the active drug ingredient and inactive (non-drug) ingredients

drug formulations and additives

list the five routes of administration

-enteral

-parenteral

-transdermal

-inhalation

-topical

oral administration of a drug by use of the intestine

Enteral administration

"besides the intestine;" generally referring to injectable drug administration

parenteral administration

Intravenous (IV) and Intramuscular (IM) are examples of what route of administration?

parenteral administration

drug application to the skin i.e. patch or paste

Transdermal administration

administration of aerosols for either a systemic or local effect in the lungs

inhalation administration

drugs administered to directly to the skin or mucous membranes to produce a local effect

topical administration

name the four pharmacokinetic phases

-absorption

-distribution

-metabolism

-elimination

the mechanism by which drugs move across membrane barriers

Absorption

diffusion occurring in the fluid compartments of the body such as interstitial spaces or within the cell

Aqueous diffusion

non-polar, fat-soluble drugs are absorbed in the bloodstream by this mechanism

Lipid diffusion

polar molecules such as amino acids, sugars, and drugs that resemble these substances are absorbed by this mechanism

carrier-mediated transport

the process of incorporating a substance into a cell by membrane engulfment and transport of the substance into the cell

Pinocytosis

what factor determines which barriers to absorption must be crossed by a drug

route of administration

this route of administration bypasses the need for absorption by the GI tract, provides a rapid onset, and provides 100% availability of the drug in the bloodstream

Intravenous administration

the proportion of the drug that actually reaches the systemic circulation

bioavailability

the process by which a drug is transported to its sites of action

Distribution

relation of the total amount of a drug in the body to the plasma concentration

Volume of distribution (Vd)

volume of distribution formula

drug amount/plasma concentration

process by which drug molecules are biotransformed in the liver

metabolism

chronic administration or abuse of drugs that are metabolized by the liver enzyme systems can ____________ or _____________ levels of liver enzymes

induce (increase), inhibit (decrease)

If a drug is highly metabolized by the liver, most of the drug does not reach the rest of the body through the general circulation. This is known as...

First-Pass Effect

which route of administration does first-pass effect apply to?

enteral (oral)

drug excretion by the kidney

Elimination

the measure of the body's ability to rid itself of a drug

plasma clearance (Clp)

the time required for the plasma concentration of a drug to decrease by 50%

Plasma half-life (T1/2)

to sustain steady levels of a drug in the body, dosing must equal the rate of elimination. This is known as...

maintenance dose

the concentration of a drug in plasma over time is shown on...

Time-plasma curve

this occurs at the area of the body that has been in direct contact with the chemical

local effect

this occurs after the chemical has been absorbed and distributed from the entry point to other parts of the body

systemic effect

the portion of the drug available in the lung out of the total systemically available drug

L/T Ratio (Lung availability/Total Systemic Availability)

the higher the L/T ratio, the ______ _______ the aerosol drug delivery is to the respiratory tract

more efficient

extrapulmonary side effects of an inhaled aerosol drug is due to.....

GI absorption of the aerosol

list three factors that can increase the L/T ratio

-efficient delivery devices

-mouth washing, rinsing, spitting

-use of a reservoir device

the relationship between a drugs chemical structure and its clinical effect

structure-activity relationship

any cell component that combines with a drug to enhance the function of the cell; mostly polypeptides or proteins

drug receptor

the body's response to a drug is proportional to the drug concentration; as the concentration increases, the number of occupied receptors increases, and the drug effect increases up to a maximal point. this concept is known as...

dose-response relationship

this drug will produce a response at a low concentration

high potent drug

this drug only produces a response at much higher concentrations

low potent drug

the greatest response that can be produced by a drug; a dose above which no further response can be elicited.

maximal effect

this represents the safety margin of a drug; the smaller this number, the greater the possibility of a drug crossing from a healing effect to a toxic effect.

Therapeutic Index (TI)

a drug that combines to it's corresponding receptor to initiate it's intended response (has efficacy)

agonist

a drug that binds to a receptor site but cause no response (zero efficacy); rather, the drug only blocks the receptor site from accepting another drug.

antagonist

a drugs level of attraction to a receptor site

affinity

whether a drug initiates effect or has no effect

efficacy

when 2 drugs act on a target organ by different mechanisms of action, and the effect of the drug pair is greater than the sum of the separate effects of the drug

Synergism

when two drugs act on the same receptor and the combined effect is the simple linear sum of the the effects of the 2 drugs.

additivity

when one drug has no direct effect on the body but can increase the activity of another drug

Potentiation

an opposite or unusual effect of a drug compared to a predicted normal effect in an individual

idiosyncratic effect

an allergic or immune-mediated response to a drug; serious, life-threatening effect

Hypersensitivity

a decreased intensity of response to a drug over time

tolerance

rapid decrease in responsiveness to a drug

Tachyphylaxis

variations in patient response to a drug due to hereditary differences

Pharmacogenetics

ultra short-acting adrenergic bronchodilator agent (Ultra SABA) used to reduce upper airway edema

Racemic Epinephrine

name two brands of Racemic Epinephrine

Asthmanefrin, MicroNefrin

short acting adrenergic bronchodilator agent (SABA) that produces bronchodilation by stimulating beta 2 receptors on airway smooth muscle.

Albuterol

name 3 brands of albuterol and their respective forms and dosages

SVN: Accuneb- 0.5% solution, (1.25-2.5mg/0.5ml)

MDI: Proventil, Ventolin- 90mcg/puff (2 puffs, TID)

TAB: VospireER- 2,4,8mg (BID-QID)

name a brand of Levalbuterol

Xopenex