Questions and Answers
Which of the following is a key structural feature for opioid analgesic activity?
What is the primary receptor type for μ-opioid receptor agonists?
μ-receptor
Opioid receptors are not coupled to G-proteins.
False
What effects can agonists of the μ-opioid receptor produce?
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Morphine was isolated from _____ by a German pharmacist.
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What modifications are primarily involved in the metabolism of morphine?
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What is the solubility of morphine in water at 25°C?
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Identify one major class of opioid receptors.
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Basic nitrogen is sufficient for MOR opioid activity.
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Study Notes
Learning Objectives
- Understand the structure-activity relationship (SAR) of opioids and NSAIDs in pain treatment.
- Identify key structural features that contribute to opioid analgesic activity and how functional groups influence potency and metabolism.
- Describe the role and characteristics of different cyclooxygenase (COX) enzyme isoforms relevant to NSAIDs.
Opioids
- Opioids act on endogenous opioid peptide ligands, which include agonists and antagonists at opioid receptors.
- Opioid receptors are distributed throughout the human brain, spinal cord, and peripheral tissues.
Opioid Receptors
- Opioid receptors belong to the G-protein coupled receptor (GPCR) family, characterized by seven transmembrane (TM) domains.
- Three major classes of opioid receptors exist:
- μ-receptor (MOR)
- κ-receptor
- δ-receptor
μ-Opioid Receptor (MOR)
- MOR is the most clinically relevant receptor where agonists produce analgesia, respiratory depression, decreased gastrointestinal motility, and euphoria.
- Activation of MOR also influences feeding behavior and hormone release.
Structural Features Essential for Opioid Activity
- Key components for morphine and similar opioids:
- Aromatic A ring
- Basic nitrogen
- These components alone are insufficient without additional pharmacophoric groups.
Morphine
- First isolated from opium in 1806 by a German pharmacist, identified as a prototype μ-opioid receptor agonist.
- Primarily utilized for its analgesic properties, serving as a benchmark for comparison with other μ-opioid receptor agonists.
- Morphine is extensively metabolized in the liver, involving processes like N-demethylation and glucuronidation at specific positions (3 and 6).
- Exhibits poor water solubility (1g/5L at 25°C) and is usually administered as a sulfate salt.
Structure-Activity Relationship of Morphine Analogues
- The efficacy of morphine analogues is assessed by their equianalgesic doses, guiding the development of new analgesics.
- Variations in structure can significantly impact the potency and therapeutic effects of morphine-like compounds.
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Description
This quiz focuses on the medicinal chemistry of opioids as covered in the BPHARM312 module. It explores the structure-activity relationships of these drugs, emphasizing key structural features that contribute to analgesic activity. Additionally, it examines how different functional groups influence potency and metabolism.
