Pain medications are also known as analgesics. Pain medications are used to treat the nociceptive and neuropathic pain.

Nociceptive Pain

Nociceptive pain is initiated by irritation or injuries of peripheral pain receptors and sensory nerve fibers. Sensory nerve fiber carries pain impulses or signals to spinal cord and brain. Peripheral pain receptors are spread over skin, subcutaneous tissue, muscles, bones, joints, ligaments and tendons. The pain receptors in spinal cord and brain are known as central pain receptors. Irritation of pain receptor is caused by injuries and stimulations by chemicals that is secreted during tissue inflammation.

Tissue inflammation is a physiological defense mechanism to fight and prevent further tissue injury. The tissue inflammation follows injury, infection and surgical incision. The chemicals secreted by inflamed tissue are bradykinin, serotonin and prostaglandin. Prostaglandin and several other chemicals which are secreted by inflamed tissue irritates the pain receptors resulting in acute pain. Acute pain lasts for less than 6 months and pain is considered chronic if pain continues for 6 months and longer. Skin diseases like boil, impetigo, carbuncle, furuncle, boil, cellulitis and abscess causes moderate to severe inflammation of skin and subcutaneous tissue. Tissue inflammation increases secretion of prostaglandin and bradykinin that irritates pain receptors and sensory nerve fibers results in moderate to severe nociceptive pain. Similarly, muscle tear, laceration and spasm also causes mild to severe muscle inflammation and increases secretion of prostaglandin that results in acute pain. The intensity of pain depends on severity of inflammation. Abundant amount of prostaglandin is secreted when inflammation and infection is widely spread within soft tissue. The cause of nociceptive pain if inadequately treated then long standing nociceptive pain become neuropathic pain.

Nociceptive pain is treated with NSAIDs for 2 to 3 weeks. Most nociceptive pain caused by trauma, infection and surgery last for 2 to 3 weeks. Nociceptive pain lasting 1 to 6 months may need adjuvant medications or alternative treatment. The alternative treatment is opioids for 1 to 3 weeks and should be discontinued once wound is healed and the pain subsides. Other treatments includes physical therapy and massage therapy.

Neuropathic Pain

Neuropathic pain is caused by abnormal physiological changes of peripheral and central (spinal cord) pain receptors as well as sensory nerve fibers. Such changes follow prolonged, severe, continuous or intermittent pain. The causes of neuropathic pain are neuropathy (diseases of central and peripheral receptors, sensory nerve fibers and spinal cord), spinal cord tumor and diseases of brain that affects pain centers. The most common cause of neuropathic pain is diabetic neuropathy that affects peripheral pain receptors and sensory nerve fibers. The interneuron are the cells that lies within spinal cord. Interneuron connects and transmits signal from peripheral tissue to brain. Damaged or abnormal interneuron often interprets and transmits signals like touch, temperature or pressure as a pain. Such impulses are then transmitted from spinal cord to brain as a pain impulse. These signals known as neuropathic pain are interpreted as severe intense electric shock like burning pain. The neuropathic impulses are generated within peripheral receptors or central receptors and carried to spinal cord and brain. Severe continuous neuropathic pain causes anxiety, depression, functional impairment and sleep deprivation. Most of the neuropathic pain do not respond to NSAIDs or opioids.

Neuropathic pain responds to selective antidepressants and antiepileptic medications. These analgesic are known as neuropathic analgesics or pain medication. Neuropathic pain resulting in anxiety disorder and depression need to be treated with neuropathic pain medications and alternative treatment. Alternative treatment may include massage therapy, physical therapy, mineral pill and homeopathic medications.

Classification of Pain Medications (Analgesics)