06 Pain, Inflammation, and Anesthesia Medications

How pain and anesthesia medicines differ

Pain medicines are grouped by how they reduce pain. Nonopioid analgesics often relieve mild to moderate pain and inflammation; opioids act on opioid receptors to reduce moderate to severe pain; and adjuvant analgesics help with particular pain types, such as neuropathic pain. Anesthetics temporarily reduce sensation or awareness for procedures.

Choosing a medicine depends on the cause and severity of pain, patient factors, and safety risks. Brand names can help with recognition, but products and formulations may vary.

Nonopioid pain and anti-inflammatory medicines

Acetaminophen (Tylenol) is an analgesic and antipyretic used for pain and fever, but it is not anti-inflammatory. Excessive total intake can cause severe liver injury, so combination products should be checked for hidden acetaminophen.

NSAIDs reduce prostaglandin production and can relieve both pain and inflammation. Common examples and uses include:

• Ibuprofen (Advil, Motrin): pain, fever, and inflammation, including musculoskeletal pain and menstrual cramps.

• Naproxen (Aleve, Naprosyn): pain and inflammation, including arthritis and menstrual cramps.

• Aspirin (Bayer): pain, fever, and inflammation. Low-dose aspirin is also associated with prevention of blood clots in selected patients, and it can increase bleeding risk because of its additional antiplatelet effects.

• Diclofenac (Voltaren): arthritis and localized musculoskeletal pain; available in oral and topical forms.

• Ketorolac (Toradol): short-term treatment of moderately severe acute pain. It is not intended for prolonged use because of serious gastrointestinal, kidney, and bleeding risks.

• Celecoxib (Celebrex): a selective COX-2 NSAID used for arthritis and other inflammatory pain; it still carries important cardiovascular and other NSAID risks.

Important NSAID risks include stomach ulcers or bleeding, kidney injury, fluid retention, and cardiovascular events. Taking multiple NSAIDs together can raise risk without necessarily improving relief. Acetaminophen is a useful alternative for some pain, but it does not treat inflammation.

Medicines for specific pain conditions

Some medicines are used for particular inflammatory or neuropathic pain conditions rather than as general-purpose pain relievers.

• Prednisone (Deltasone) and dexamethasone (Decadron) are glucocorticoids that suppress inflammation. They may be used for inflammatory conditions or flares, but are not routine substitutes for analgesics. Adverse effects increase with systemic exposure and prolonged use.

• Colchicine (Colcrys) is commonly used for acute gout flares and gout prevention. It is not a general-purpose pain reliever; gastrointestinal effects and drug interactions are important considerations.

• Gabapentin (Neurontin) and pregabalin (Lyrica) are gabapentinoids used for neuropathic pain, such as postherpetic neuralgia. They are not conventional anti-inflammatory drugs.

• Duloxetine (Cymbalta) is an SNRI antidepressant also used for certain chronic musculoskeletal and neuropathic pain conditions.

Opioids and overdose safety

Opioids activate opioid receptors and reduce pain perception. They may be used for selected cases of moderate to severe acute pain, postoperative pain, or cancer-related pain when appropriate.

Examples include:

• Morphine (MS Contin): an opioid agonist used for severe pain.

• Oxycodone (Roxicodone, OxyContin): an opioid agonist used for moderate to severe pain.

• Hydrocodone (Norco, Vicodin, including combination products): an opioid agonist used for pain and often supplied with acetaminophen.

• Hydromorphone (Dilaudid): an opioid agonist used for severe pain.

• Fentanyl (Duragesic, transdermal; Sublimaze, injectable): a potent opioid whose specialist-supervised uses vary by formulation and setting.

• Tramadol (Ultram): an opioid analgesic with additional monoamine effects; it is used for pain and has seizure and drug-interaction risks.

Opioids can cause sedation, constipation, nausea, dependence, and life-threatening respiratory depression. Risk increases when opioids are combined with alcohol, benzodiazepines, or other central nervous system depressants.

Naloxone (Narcan) is an opioid antagonist used to reverse a suspected overdose. Emergency services are still needed because naloxone's effect can wear off and repeat doses may be required.

Local and general anesthesia

Anesthesia is a temporary, medically controlled loss of sensation, with or without loss of awareness. Anesthetic medicines differ from everyday analgesics: some numb a limited area, while general anesthetics produce unconsciousness for procedures.

Local anesthetics block voltage-gated sodium channels in nerves, temporarily preventing pain signals from traveling. They can be given topically, by local injection, or as part of a regional block. Excessive systemic exposure can cause neurologic and cardiac toxicity, so dosing and monitoring matter.

Examples of local anesthetics include:

• Lidocaine (Xylocaine): an amide local anesthetic used topically or by injection for numbing during minor procedures; it is also used in some regional techniques.

• Bupivacaine (Marcaine): an amide local anesthetic used for longer-acting local or regional anesthesia, including nerve blocks and some neuraxial techniques.

• Ropivacaine (Naropin): an amide local anesthetic used for regional anesthesia and nerve blocks.

Examples of general anesthetics include:

• Propofol (Diprivan): an intravenous general anesthetic used for induction or maintenance of anesthesia and for procedural sedation under trained supervision. It does not provide reliable analgesia by itself.

• Ketamine (Ketalar): a dissociative general anesthetic and NMDA-receptor antagonist used for anesthesia or procedural sedation; it also has analgesic effects.

• Sevoflurane: an inhaled general anesthetic used for induction or maintenance of general anesthesia.

General anesthetics require specialized monitoring because they can impair consciousness, breathing, and circulation.

Combining approaches and remembering key distinctions

A multimodal approach combines medicines with different mechanisms. For appropriate postoperative pain, a conceptual example is combining an NSAID or acetaminophen with a local anesthetic. The goal is effective relief while limiting exposure to any one drug class, especially opioids.

This example is not a dosing recommendation. Individual risks and contraindications determine what is appropriate.

The main distinctions are that acetaminophen relieves pain and fever but is not anti-inflammatory; NSAIDs relieve pain and inflammation; opioids reduce pain but can suppress breathing; local anesthetics numb a region; and general anesthetics produce unconsciousness.

• Opioid analgesics