Pain Pharmacotherapy

Pharmacotherapy of Pain: A ppt by Dr Shirish Amatya
Pain Pharmacotherapy: A lecture by Shirish Amatya

An Outline of Pain Pharmacotherapy: Analgesics and Co-Analgesic Medications

The pharmacological management of pain encompasses a diverse array of medications classified into analgesics—opioids and non-opioids—and co-analgesics. Let’s explore these categories, their commonly used medications, mechanisms, uses, and potential side effects.

Classification of Analgesics:


  • Mechanism: Act on opioid receptors in the brain and spinal cord, altering pain perception and response.
  • Common Drugs: Morphine, oxycodone, codeine.
  • Uses: Severe acute pain, post-operative pain, cancer pain management.
  • Side Effects: Constipation, nausea, sedation, respiratory depression, potential for tolerance and dependence.


  • NSAIDs (Non-Steroidal Anti-Inflammatory Drugs):
    • Mechanism: Inhibit COX enzymes, reducing prostaglandin production, and subsequent pain and inflammation.
    • Common Drugs: Ibuprofen, naproxen, diclofenac.
    • Uses: Mild to moderate pain, inflammation, fever.
    • Side Effects: GI disturbances, ulcers, kidney issues, cardiovascular complications.
  • Paracetamol (Acetaminophen):
    • Mechanism: Believed to inhibit COX enzymes primarily in the central nervous system, affecting pain and fever.
    • Uses: Mild to moderate pain, fever reduction.
    • Side Effects: Generally well-tolerated; high doses can cause liver damage.
  • COX-2 Inhibitors:
    • Mechanism: Selectively inhibit COX-2 enzymes, reducing inflammation and pain without affecting COX-1.
    • Common Drugs: Celecoxib.
    • Uses: Management of osteoarthritis, rheumatoid arthritis, acute pain.
    • Side Effects: Reduced gastrointestinal issues compared to NSAIDs; potential cardiovascular risks.

Co-Analgesic Medications:


  • Types: Tricyclic antidepressants (e.g., amitriptyline), SNRIs (e.g., duloxetine).
  • Mechanism: Alter neurotransmitter levels to modulate neuropathic pain; elevate pain threshold.
  • Uses: Neuropathic pain, fibromyalgia, chronic pain syndromes.
  • Side Effects: Sedation, dry mouth, constipation, potential cardiac issues.


  • Examples: Gabapentin, pregabalin.
  • Mechanism: Stabilize neuronal membranes and modulate calcium channels, reducing neuropathic pain.
  • Uses: Neuropathic pain, fibromyalgia.
  • Side Effects: Dizziness, drowsiness, weight gain, potential cognitive issues.

Muscle Relaxants:

  • Common Drugs: Baclofen, cyclobenzaprine.
  • Mechanism: Reduce muscle spasms and associated pain through central nervous system actions.
  • Uses: Musculoskeletal pain, spasticity.
  • Side Effects: Drowsiness, dizziness, dry mouth, potential sedation.


  • Examples: Prednisone, dexamethasone.
  • Mechanism: Anti-inflammatory action by suppressing immune responses and reducing inflammation.
  • Uses: Acute inflammatory pain, joint pain, nerve compression syndromes.
  • Side Effects: Increased risk of infection, bone density loss, and gastrointestinal issues.


The spectrum of analgesics—ranging from opioids to non-opioids—and co-analgesics offers versatile options for pain management. Each medication class possesses distinct mechanisms, uses, and potential side effects, allowing healthcare providers to tailor treatment plans based on individual needs while weighing the risks and benefits for effective pain relief. Collaboration between healthcare professionals and patients is crucial in selecting the most suitable medications while optimizing pain management strategies.