Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
34 Cards in this Set
- Front
- Back
|
Pharmacokinetics
|
The study of the action of drugs in the body, including the processes of absorption, distribution, metabolism, and elimination
|
|
|
Pharmacodynamics
|
The study of the biochemical and physiologic effects of drugs on the function of living organisms and of their component parts
|
|
|
Absorption
|
How much of the drug is present and how fast it leaves its site of administration.
|
|
|
Factors Affecting Absorption
|
Drug characteristics,
1. formulation 2. concentration 3. lipophilicity 4. ph. Routes of Administration 1. oral 2 sublingual 3. rectal 4. topical 5. inhalation 6 othalmic Blood Flow Cell Membrane Characteristics |
|
|
Distribution
|
The transport of a drug in body fluids from the point of absorption to the blood stream to the point of action
|
|
|
VD
|
Volume of Distribution
Blood concentration = dose/vd Vd - dose/concentration |
|
|
Factors affecting volume of distribution
|
plasma protein binding
obesity edema tissue binding |
|
|
Biotransformation
|
The chemical inactivation of a drug through conversion to a more water soluble compound that can be extracted from the body.
|
|
|
Where does biotransformation normally occur?
|
Liver
|
|
|
Two Steps of Biotransformation
|
Phase I
Phase II |
|
|
Phase I
|
Makes drug more hydrophillic through oxidation, reduction or hydrolysis
-cytochrome P450 enzyme system |
|
|
Phase II
|
Glucuronidation
-involves conjugation which makes it highly water soluble |
|
|
Conjugation
|
Biotransformation during phase I, drug converted into a more water soluble substance with little to no pharmacologic activity
|
|
|
Cytochrome P450
|
concentrated in liver, intestines and lungs
Resides in ribosomes Part of group of Phase I biotransformers. |
|
|
Most important P450 enzymes
|
CYP2D6
CYP 3A3/4 CYP 1A2 CYP 2C9/10 CYP 2C19 |
|
|
Genetic Polymorphism
|
genetic tendency determines individual variations in enzyme action
may vary by race or gender |
|
|
Substrate
|
A drug that is affected by a change in its enzyme metabolism
|
|
|
Inducer
|
A drug that causes acceleration in the enzyme metabolization of another drug
|
|
|
Inhibitor
|
A drug that causes inhibition in the enzyme metabolization of another drug
|
|
|
Glucuronidation
|
Conjugate reactions in which a chemical group compound is added to the drug via a covalent link. Renders drug water soluble and inactive (generally)
|
|
|
First Pass
|
Oral meds pass from intestine directly to liver by way of hepatic portal flow. Nitro and estrogen are highly metabolized and rendered inert this is why sublingual or increased amounts.
|
|
|
Prodrug
|
A chemical that is pharmacologically inactive
Biotransformed into a biologically active metabolite. eg. enlapril- angiotensin converting enzyme |
|
|
Elimination
|
process by which drugs and metabolites are removed from the body.
Primarily occurs in liver and kidney |
|
|
Processes involved in renal elimination
|
Glomerular filtration, tubular secretion, partial reabsorption
|
|
|
Renal insufficiency
|
makes drug stay in blood longer
|
|
|
Calculation of Creatinine Clearance
|
Calculation estimated creatinine clearance
|
|
|
Other routes of elimination
|
Fecal
Respiratory Breast Milk Perspiration, saliva, hair, skin (not clinically significant) |
|
|
Clearance
|
The volume of plasma from which all drug is removed within a given time
Drugs stored in adipose tissue cannot be cleared Volume of distribution affects the clearance of a drug and half-life |
|
|
Clearance Calculation
|
Clearance = rate of removal(mg/min)/plasma concentration of drug (mg/ml)
|
|
|
Steady State
|
Drug administration rate = elimination rate
|
|
|
Intermittent Administration Steady State
|
Frequency adjustments, administration amount adjustments necessary to
eg. carbidopa/levidopa |
|
|
Decrease Dosing re steady state
|
For patients who eliminate slower
|
|
|
First Order/Linear Kinetics
|
Drug concentration is increased or decreased in a linear fashion depending on dosage, clearance, volume of distribution and half life
|
|
|
Half-Life
|
Length of time required for the amount of the drug in body to decrease by one half.
Dependent on clearance and volume of distribution |
