Respiratory Care Pharmacology Chapter 2: Principles of Drug Action

-Drug Administration

-Pharmacokinetics

-Pharmacodynamics

name the three major principles of drug action

Pharmacokinetics

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

Drug administration

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

Pharmacodynamics

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

drug dosage forms

tablets, capsules, and solutions are examples of

drug dosage form

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

drug formulations and additives

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

-enteral

-parenteral

-transdermal

-inhalation

-topical

list the five routes of administration

Enteral administration

oral administration of a drug by use of the intestine

parenteral administration

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

parenteral administration

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

Transdermal administration

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

inhalation administration

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

topical administration

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

-absorption

-distribution

-metabolism

-elimination

name the four pharmacokinetic phases

Absorption

the mechanism by which drugs move across membrane barriers

Aqueous diffusion

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

Lipid diffusion

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

carrier-mediated transport

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

Pinocytosis

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

route of administration

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

Intravenous 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

bioavailability

the proportion of the drug that actually reaches the systemic circulation

Distribution

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

Volume of distribution (Vd)

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

drug amount/plasma concentration

volume of distribution formula

metabolism

process by which drug molecules are biotransformed in the liver

induce (increase), inhibit (decrease)

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

First-Pass Effect

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...

enteral (oral)

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

Elimination

drug excretion by the kidney

plasma clearance (Clp)

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

Plasma half-life (T1/2)

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

maintenance dose

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

Time-plasma curve

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

local effect

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

systemic effect

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

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

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

more efficient

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

GI absorption of the aerosol

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

-efficient delivery devices

-mouth washing, rinsing, spitting

-use of a reservoir device

list three factors that can increase the L/T ratio

structure-activity relationship

the relationship between a drugs chemical structure and its clinical effect

drug receptor

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

dose-response relationship

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...

high potent drug

this drug will produce a response at a low concentration

low potent drug

this drug only produces a response at much higher concentrations

maximal effect

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

Therapeutic Index (TI)

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.

agonist

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

antagonist

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.

affinity

a drugs level of attraction to a receptor site

efficacy

whether a drug initiates effect or has no effect

Synergism

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

additivity

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.

Potentiation

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

idiosyncratic effect

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

Hypersensitivity

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

tolerance

a decreased intensity of response to a drug over time

Tachyphylaxis

rapid decrease in responsiveness to a drug

Pharmacogenetics

variations in patient response to a drug due to hereditary differences

Racemic Epinephrine

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

Asthmanefrin, MicroNefrin

name two brands of Racemic Epinephrine

Albuterol

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

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 3 brands of albuterol and their respective forms and dosages

Xopenex

name a brand of Levalbuterol