Medical Pharmacology Practice Questions: Opioid Antagonists

Structural substitution to an opioid agonist by a larger group such as and ally- may transform an agonist to an opioid antagonist.(For example, conversion of oxymorphone to naloxone)
1. True
2. False
Most opioid antagonists, being lipid soluble, readily penetrate the blood brain barrier following administration. (An) exception(s) is/are:
1. Naltrexone
2. Naloxone
3. Methylnaltrexone
4. All of the above
Which one of these agents exhibits the higher oral activity along with extended duration of action.
1. Naloxone
2. Naltrexone
Administration of naloxone or naltrexone increases which one(s) of the following?
1. Gonadotropin-releasing hormone secretion
2. Corticotropin-releasing hormone secretion
3. LH, FSH, and ACTH plasma levels
4. A & B
5. A & C
6. B & C
7. A, B & C
Abrupt discontinuation after prolonged administration of naloxone results in typical opioid withdrawal syndrome.
1. True
2. False
Despite classification of naltrexone and naloxone as opioid antagonists, these agents at higher doses exhibit abuse potential.
1. True
2. False
In patients exhibiting respiratory depression due to opioid agonists, i.m or i.v. administration of a pure opioid antagonist typically induces an increase in respiratory rate in this time frame:
1. <30 seconds
2. 1-2 min.
3. About 5 min.
4. 5-10 min.
Administration of even small subcutaneous naloxone doses is sufficient to induce even a severe withdrawal symptom in an individual dependent on morphine-like opioids.
1. True
2. False
Following oral administration, naloxone undergoes nearly complete hepatic metabolism prior to entering systemic circulation.
1. True
2. False
Following parenteral administration, naloxone is metabolized in the liver mainly by:
1. The cytochrome P450 drug metabolizing system. (Phase I)
2. Conjugation with glucuronic acid (phase II)
3. Neither