ANALGESICS

• Analgesics


  Pain relievers; given in order to manage pain
• Pain


  An unpleasant sensation that can be either acute or chronic and is a consequence of complex neurochemical processes in the peripheral and central nervous systems (CNS)
• Pain is subjective, and the clinician must rely on the patient's perception and description of pain
• Nociceptive pain


  Pain from physical damage or potential damage to the body
• Nociceptive pain


  • Sports injury
  • Dental procedure
  • Arthritis
• Nociceptive pain is the most common type of pain people experience
• Neuropathic pain


  Pain that develops when the nervous system is damaged or not working properly due to disease or injury
• Neuropathic pain does not develop in response to any specific circumstance or outside stimulus
• People can suffer from neuropathic pain even when the aching or injured body part is not actually there
• Conditions that can result in neuropathy

  • Alcoholism
  • Shingles
  • Unmanaged diabetes
  • Stroke
  • Multiple sclerosis
  • Cancer treatments

  
• Nonopioid analgesics

  Nonsteroidal anti-inflammatory agents (NSAIDs) that are often effective for mild to moderate arthritic pain (nociceptive pain)

  
• Neuropathic pain


  Can be treated with opioids (some situations require higher doses) but responds best to anticonvulsants, tricyclic antidepressants, or serotonin/norepinephrine reuptake inhibitors
• For severe or chronic malignant or nonmalignant pain, opioids are considered part of the treatment plan in select patients
• Opioids


  Natural, semisynthetic, or synthetic compounds that produce morphine-like effects
• Chemical classes of opioid agonists

  • Natural: Morphine, Codeine
  • Semisynthetic: Hydromorphone, Hydrocodone, Oxycodone, Oxymorphone
  • Synthetic: Fentanyl, Meperidine, Methadone, Tapentadol, Tramadol

  
• All opioids act by binding to specific opioid receptors in the CNS to produce effects that mimic the action of endogenous peptide neurotransmitters (for example, endorphins, enkephalins, and dynorphins)
• Our bodies produce these neurotransmitters in order to produce analgesic effect
• Widespread availability of opioids has led to abuse of those agents with euphoric properties (which is why morphine is a controlled substance)
• Opioid receptor subtypes, their functions, and their endogenous peptide affinities

  • μ (mu): Supraspinal and spinal analgesia; sedation; inhibition of respiration; slowed gastrointestinal transit; modulation of hormone and neurotransmitter release. Endorphins > Enkephalins > Dynorphins
  • δ (delta): Supraspinal and spinal analgesia; modulation of hormone and neurotransmitter release. Enkephalins > Endorphins and Dynorphins
  • κ (kappa): Supraspinal and spinal analgesia; psychotomimetic effects; slowed gastrointestinal transit. Dynorphins >> Endorphins and enkephalins

  
• Non-narcotic (Non-opioid) analgesics


  They can remove pain but they do not produce the effects of morphine or narcotic effects. Generally safer; most of them can be bought OTC.

  
• NSAIDs


  Act by inhibiting the synthesis of prostaglandins, which are created from arachidonic acid and are the major mediator of pain and cause inflammation

  
• Do not give aspirin to patients with dengue because dengue fever or virus may affect platelet count. Aspirin is non-selective therefore it would also affect COX-1, which is important in platelet aggregation.
• Acetaminophen


  Inhibits prostaglandin synthesis in the CNS, which explains its antipyretic and analgesic properties. It has less effect on cyclooxygenase in peripheral tissues, which accounts for its weak anti-inflammatory activity. It is inactivated in our periphery.