PHA2022 Lecture Notes - Lecture 7: Muscle Relaxant, Codeine, Antiemetic
15 Nov 2018
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Dab: explain psychological (reward) and physical dependence (tolerance and withdrawal) Ans: addictive drugs are both rewarding and reinforcing (positive and negative). reward and positive reinforcement is largely (but not exclusively) related to psychological dependence. negative reinforcement is associated with physical dependence and withdrawal. Rewarding effect: this is manifested as positive reinforcing behavior (where animals will self-administer drugs). Strong positive reinforcers tend to be associated with strong psychological dependence. addictive drugs can show tolerance and withdrawal leading to physical dependence: explain how some drugs may share a common target for producing reward and psychological dependence. Ans: the positive reinforcing effects and psychological dependence of drugs of abuse are due to increased dopamine release in specific brain areas. Addictive drugs increase dopamine levels in the nucleus accumbens. During the development of tolerance, the drug adaptive changes are made (pharmacokinetic and/or pharmacodynamic). These changes are usually reversed or uncompensated for when drug is absent.
