1. D. The purpose of this question is to identify first opioids that produce analgesia and then those with a metabolite that compounds the analgesic effects of the drug by being an active analgesic. Naloxone and nalmefene are not analgesics but opioid antagonists. Codeine is metabolized to an active analgesic metabolite, morphine. Meperidine and propoxyphene have nonanalgesic, excitatory, and proconvulsant metabolites.
2. B. The purpose of this question is to clarify the uses and limitations of use of the COX-2 selective inhibitor celecoxib. Celecoxib, by inhibiting COX-2 reversibly, will block the activity of both injury-
inducible COX-2 and the small amount of constitutive COX-2. COX-2 inhibition has been shown to produce some GI bleeding, albeit less than with the nonselective COX inhibitors. If a patient has ulcerations and bleeding, COX-2 inhibitors will prolong healing by blocking the protective effects of COX-2 in the GI tract. Celecoxib is indicated for both os-teoarthritis and rheumatoid arthritis.
3. C. The purpose of this question is to clarify the cellular mechanism of analgesia produced by morphine. First, morphine blocks the transmission of nociceptive impulses. In that case, the relevant question is how nociceptive impulses are transmitted via the release of pronociceptive neurotransmitters. The question then is to determine which intracellular process favors a block of release of neurotransmit-ters. The correct answer is C because calcium is required for neurotransmitter release. Blocking potassium efflux and increasing calcium channel phosphorylation produce functional depolarization and neurotransmitter release. Opioids are coupled to Gi (inhibitory proteins) that decrease cAMP.
4. C. The purpose of this question is to clarify the functional significance of the activation of opioid receptor types. Respiratory depression and bradycardia are associated with the ^2-opioid receptor. Mydriasis is associated with the a-receptor, which is no longer thought of as opioid. Opioids, via respiratory depression, induce hypercapnia, a build-up of carbon dioxide. The clinically relevant sign of opioid overdose and opioid use is miosis, pinpoint pupils, mediated by K-receptor activation.
5. E. Fentanyl patches have the same effect as fen-tanyl, only in a time-release manner. Thus, the purpose of the question is delineation of opioid effects—respiratory depression and constipation. The respiratory depression is life-threatening when the patch is used in nonambulatory patients, and it is therefore contraindicated for that purpose. Similarly, fentanyl is a teratogenic drug contraindi-cated for use during pregnancy. The fentanyl patch does not induce anesthesia (loss of consciousness) but does produce analgesia.
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