Small lipid-soluble can pass, but not larger water soluble molecules
What can pass to the placental barrier?
lipid-soluble can pass readily and without limitation primarily by passive diffusion
What does Renal mean?
What does Hepatic mean?
What is the major route of drug elimination from the body?
Major route of elimination is renal (kidney) excretion of drug metabolites produced by hepatic (liver) metabolism of the parent drug
What are the Roles of kidney in drug elimination (2)?
Excretion of products of body metabolism; maintenance of body fluid levels
What are theRoles of liver in drug elimination (2)?
Converting psychoactive parent drugs to inactive metabolites (deactivate); converting highly lipid-soluble molecules to water-soluble metabolites
What factors can affect drug biotransformation by increasing or decreasing the rate of drug elimination
Genetic, environmental and physiological factors
What is drug half-live?
The time for the plasma level to drop by 50%
How many half-lives does it take for 94% to be eliminated?
How many half-lives does it take for 98% to be eliminated?
What drug is an exception to to drug elimination?
Ethyl Alcohol - constant amount of alcohol is metabolized per hour
What is the definition of drug tolerance?
A state of progressively decreasing responsiveness to a drug; a person requires a larger dose of a drug to achieve the originally obtained effect by a smaller dose.
What is Metabolic tolerance?
The increased capacity of the liver to metabolize the parent drug molecule through increased enzyme levels.
What is Cellular-adaptive or pharmacodynamic tolerance?
The adaptation of the brain cells to the continued presence of the drug by down regulation.
What is down regulation?
The reduction of the number of receptors available to the drug and reduction of the sensitivity to the drug.
What is behavioral conditioning?
Comes from routinely pairing environmental cues with drug administration so that the conditioned stimuli will elicit a conditioned response that is opposite in direction or compensation for the direct effects of the drug.
What is physical dependence?
Means a person needs to continue the use of a drug to avoid withdrawal symptoms (occurrence of physical and/or psychological changes.)
What is psychological dependence?
Means a person craves the drug long after the withdrawal symptoms have subsided.
What is positive reinforcement?
Refers to the likelihood of repeating a given behavior that elicits or produces a desired effect.
What is negative reinforcement?
Refers to the likelihood of repeating a given behavior for the removal or avoidance of a negative or undesirable effect. Explains the motivation to re-administer a drug after becoming physically dependent (to avoid withdrawal).