Tolerance and Dependance Flashcards
Tolerance
requiring increase amounts of a drug to get the same effect and requiring more frequent administration to avoid withdrawal.
Drug dependance
a phenomenon involving pharmacodynamic tolerance and avoidance of the withdrawal reaction. (which requires continuous administration of the drug.)
Cross tolerance
mechanism of tolerance that develops for one drug will be the same for other drugs in that family.
T or F: Drugs all activate the mesolimbic reward pathway.
True. But slightly different mechanisms.
Neuroplasticity
phenomenon that occurs with chronic drug use which you get change in neurons addition to standard effect.
Pharmacokinetic tolerance happen when:
the drug is broken down more and more rapidly, decreasing the concentration at the site of action and requiring more to get the same effect.
Pharmacodynamic tolerance happen when:
the drug has a decreased effect when it gets to the site of action (biological adaptation/no longer responsive to the drugs).
T or F: By looking at the dose-response curve, we can know either is a pharmacokinetic tolerance or a pharmacodynamic tolerance.
False. We need to know the drug concentration in the blood to
Receptor desensitization can be responsible for
pharmacodynamic tolerance
Desensitization is a mechanism which:
the cell uses to protect itself from continuous stimulation of a certain type of receptor.
Acute tolerance:
eg.:
there is a much lower response in the second dose as compared to the first dose.
Eg.: Cocaine
Dependence vs Addiction
It is possible to be dependent on a drug but not addicted (ex. antihypertensive drug)
Drug withdrawal:
is the reaction that occurs when you stop taking a drug that you have become dependent on.
Why is there down-regulation of receptors?
(agonists) decreasing their number in order to counterbalance their stimulating effects.
Why is their up-regulation of receptors?
(antagonists) increasing their number to overcome their inhibitory effects.
