Narcotic And Non-Narcotic Analgesics

• Narcotic and Non-Narcotic Analgesics relieve pain, ranging from mild headaches to severe postoperative pain.
• It acts via opioid receptors or peripheral pathways to reduce pain perception.

1. Narcotic (Opioid) Analgesics

• These drugs act on the opioid receptors (μ, κ, δ) in the central nervous system (CNS).

• Mechanism:

  • Agonist activity at μ-opioid receptors leads to:
  • Inhibition of adenylate cyclase → decreased cAMP
  • Opening of K⁺ channels → hyperpolarization (reduced neuronal excitability)
  • Inhibition of Ca²⁺ channels → decreased neurotransmitter release
  • Overall: Inhibits pain transmission in spinal cord and brain.

• Examples:

  • Morphine sulphate
  • Codeine
  • Meperidine hydrochloride
  • Anileridine hydrochloride
  • Diphenoxylate hydrochloride
  • Loperamide hydrochloride
  • Fentanyl citrate
  • Methadone hydrochloride
  • Propoxyphene hydrochloride
  • Pentazocine
  • Levorphanol tartrate

2. Narcotic (Opioid) Antagonists

• These are competitive opioid receptor antagonists, especially at the μ-receptor.

• Mechanism:

  • Block opioid receptors → prevent or reverse effects of opioid agonists.
  • Used in opioid overdose, respiratory depression, or to reverse anesthesia.

• Examples:

  • Nalorphine hydrochloride
  • Levallorphan tartrate
  • Naloxone hydrochloride

3. Non-Narcotic Analgesics / Anti-inflammatory Agents (NSAIDs and others)

• Most of these drugs act by inhibiting cyclooxygenase (COX) enzymes, which reduces prostaglandin synthesis.

• General Mechanism:

  • Inhibit COX-1 and/or COX-2 → decreased prostaglandins → reduced inflammation, pain, and fever.

• Examples:

  • Sodium salicylate
  • Aspirin
  • Mefenamic acid
  • Meclofenamate
  • Indomethacin
  • Sulindac
  • Tolmetin
  • Zomepirac
  • Diclofenac
  • Ketorolac
  • Ibuprofen
  • Naproxen
  • Piroxicam
  • Phenacetin
  • Acetaminophen
  • Antipyrine
  • Phenylbutazone

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