What Are Analgesic and Anti-Inflammatory Agents?
Analgesics, also known as pain relievers, are medicines used to reduce pain from conditions like headache, injury, and arthritis. Anti-inflammatory agents reduce swelling and help control fever. Although many of these drugs show similar actions, they differ in structure and side effects.
Classification of Analgesics
Analgesics are broadly classified into narcotic analgesics (opioids) and non-narcotic analgesics.
Morphine Analogues (Narcotic Analgesics)
These analgesics act on the brain and spinal cord to control severe pain. They include opioid agonists such as morphine, codeine, and diamorphine. They are useful for pain control but have addiction risks.
Morphine
Morphine is a strong opioid used as the standard drug for severe pain. It works directly on the central nervous system and is used in surgical pain, trauma, and cancer. It reduces the feeling of pain by altering pain perception in the brain.
Codeine
Codeine has weaker analgesic power compared to morphine because it is only partly converted to morphine in the body. It is used for moderate pain and cough relief. Its analgesic action is about one-sixth that of morphine.
Diamorphine (Heroin)
Diamorphine is a potent opioid analgesic used medically to treat severe pain due to surgery, heart attack, and end-stage diseases. It also reduces breathing distress caused by acute pulmonary edema.
Narcotic Antagonists
Narcotic antagonists block the effects of opioids. They have little action when taken alone but reverse opioid overdose or prevent dependence.
Naloxone
Naloxone is the first pure opioid antagonist. It quickly reverses respiratory depression caused by opioid overdose. It acts fast when given intravenously and may require repeated doses because its action lasts only a few hours.
Naltrexone
Naltrexone acts similar to naloxone but has a much longer action. It is useful in patients recovering from opioid addiction because it prevents the effect of opioids if taken again. It is also studied for use in alcoholism and septic shock.
Non-Steroidal Anti-Inflammatory Agents (NSAIDs)
NSAIDs relieve pain, reduce inflammation, and lower fever. They are commonly used for headaches, arthritis, menstrual pain, and sports injuries. Aspirin also prevents blood clotting in high-risk patients. NSAIDs may cause stomach irritation, ulcers, kidney issues, and fluid retention depending on dose and duration.
Classification of NSAIDs
- Non-Selective COX Inhibitors: Aspirin, Indomethacin, Ibuprofen, Piroxicam, Diclofenac
- Preferential COX-2 Inhibitors: Nimesulide, Meloxicam
- Selective COX-2 Inhibitors: Celecoxib, Rofecoxib
- Analgesic–Antipyretics With Weak Anti-Inflammatory Action: Paracetamol, Metamizol
Aspirin
Aspirin is a salicylate NSAID that blocks the COX-1 and COX-2 enzymes and prevents the formation of prostaglandins and thromboxanes. This reduces pain, swelling, fever, and blood clotting. It is used for pain relief and prevention of heart attack or stroke.
Diclofenac
Diclofenac reduces inflammation by blocking COX enzymes and decreasing leukocyte movement. It is commonly prescribed for arthritis, joint pain, menstrual cramps, and post-operative inflammation.
Ibuprofen
Ibuprofen is a widely used NSAID for arthritis, fever, menstrual pain, toothache, and muscle pain. It non-selectively inhibits COX enzymes, reducing prostaglandin levels. Compared to aspirin, its blood-thinning effect is weaker and shorter.
Piroxicam
Piroxicam blocks prostaglandin synthesis and reduces swelling, pain, and fever. It is mainly used for long-term management of rheumatoid arthritis and osteoarthritis.
Celecoxib
Celecoxib selectively blocks COX-2 without affecting COX-1, providing pain relief with lower risk of gastric irritation. It is used for arthritis, acute pain, and familial adenomatous polyposis to reduce intestinal polyps.
Mefenamic Acid
Mefenamic acid is used for short-term treatment of moderate pain, especially menstrual pain. It reduces blood loss during menstruation by inhibiting prostaglandin formation.
Paracetamol
Paracetamol provides pain relief and reduces fever, but has minimal anti-inflammatory action. It acts mainly in the brain by inhibiting COX-3 enzymes. It is considered safer on the stomach and is widely used in common cold and post-operative pain.
Aceclofenac
Aceclofenac reduces inflammatory mediators like prostaglandin E2, IL-1, and TNF. It is used for arthritis pain and has protective effects on cartilage. It decreases joint damage by blocking enzymes and reducing free radicals.
