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JEE Chemistry
Analgesics Types

Analgesics types

Analgesics are medications primarily used to alleviate pain. The term "analgesic" originates from the Greek words "an" (meaning "without") and "algein" (meaning "to cause pain"), implying a state without pain. These drugs are categorized into two main types: non-opioid analgesics and opioid analgesics. Common non-opioid pain relievers include acetaminophen, ibuprofen, and aspirin, often available over the counter. Many of these medications work by reducing inflammation and blocking pain signals to the brain.

Opioid analgesics are the most potent pain relievers and are only available with a doctor's prescription. Examples include morphine and oxycodone, which act directly on the central nervous system to reduce pain perception. Due to their effectiveness in pain management, but also their significant potential for dependence or addiction, their use requires careful oversight by healthcare professionals. Understanding their mechanisms and effective application is crucial for proper pain management and minimizing side effects.

1.0Classification of analgesics

Pain-relieving medications that act on the central nervous system are called analgesics and are divided into two types:

Narcotic (addictive) drugs

These are primarily opioid alkaloids and their derivatives, such as morphine, codeine, marijuana, and heroin. They induce pain relief and sleep, and in high doses, can cause unconsciousness, convulsions, and even death. Also known as opiates, they are derived from the opium poppy. These are highly potent drugs with a strong potential for addiction with chronic use.

These are milder pain relievers that do not cause dependence and are typically available over the counter. They are widely used to treat mild to moderate pain, reduce inflammation, and lower fever.

Common examples include:

  • Paracetamol (Acetaminophen)
  • Aspirin
  • Ibuprofen
  • Naproxen
  • Analgin
  • Novalgin
  • Butazolidine
  • Brufen

Characteristic:

  • Effective in relieving headaches, muscle pain, joint pain, toothaches, and fever.
  • Often have antipyretic (fever-reducing) and anti-inflammatory properties.
  • Aspirin also acts as a blood thinner, making it helpful in preventing heart attacks and managing angina by reducing blood clot formation.

Non-narcotic (non-addictive) drugs: 

These medications are less potent and do not cause addiction. Common examples include aspirin, analgin, paracetamol, novalgin, butazolidine, brufen, and naproxen. These drugs also possess antipyretic (fever-reducing) properties. Aspirin, novalgin, and phenacetin act as both fever reducers and pain relievers. They are effective in providing quick relief from pain and fever. Additionally, aspirin is now used to prevent heart attacks and relieve angina due to its anti-blood clotting action.

Also known as opioid analgesics, these are powerful pain-relieving drugs used for managing severe pain, such as after major surgery, injury, or in cancer patients. Due to their strength and high potential for addiction, these medications are available only by prescription and are used under strict medical supervision.

Examples include:

  • Morphine
  • Codeine
  • Oxycodone
  • Heroin (illegal)
  • Marijuana (in certain medical contexts)

Characteristic:

  • Act directly on the central nervous system (CNS) to block pain signals and alter pain perception.
  • Can induce sleep and feelings of euphoria.
  • In high doses, it may lead to unconsciousness, respiratory depression, convulsions, or even death.
  • Prolonged use can cause physical dependence, requiring careful monitoring.

Compound Analgesics

Compound analgesics are medications that combine two or more active ingredients to enhance pain relief. A common example is the combination of acetaminophen with codeine, which provides stronger pain relief than either component alone. These are often prescribed when non-opioid analgesics alone are not sufficient, such as in:

  • Post-operative pain
  • Moderate musculoskeletal pain
  • Dental pain

By combining drugs with different mechanisms, compound analgesics can offer greater effectiveness while sometimes reducing the dosage of individual components.

2.0Mechanism of Action

  • Non-narcotic analgesics typically work by inhibiting the synthesis of prostaglandins, a class of chemicals that play a role in transmitting pain and causing inflammation.
  • Narcotic analgesics bind to opioid receptors in the brain and spinal cord, effectively blocking pain signals from reaching the brain.

Chemistry of Action of Aspirin and Similar Drugs

Significant advances have been made in understanding how aspirin-like drugs (such as NSAIDs) work. Although these medications may appear chemically different from one another, they often show similar therapeutic effects—such as reducing pain, fever, and inflammation—as well as similar side effects.

This is because most of these effects stem from a common mechanism of action:
They work by inhibiting a specific biochemical pathway involved in the production of prostaglandins—natural chemical messengers in the body that are responsible for causing pain, inflammation, and fever.

Prostaglandins are synthesized through a process that involves the cyclooxygenase (COX) enzymes. Drugs like aspirin block these enzymes (COX-1 and COX-2), which in turn reduces prostaglandin production, thereby relieving symptoms.

3.0Side Effects of Analgesics

Analgesics, or painkillers, are among the most widely used medications. While they offer essential relief from pain, it is crucial to use them cautiously and responsibly, as improper use can lead to serious health risks.

Before taking any pain-relieving medication, it is always recommended to consult a doctor. The type of analgesic and the correct dosage depend on factors such as the individual’s health condition, age, and the severity of pain. Misuse or overuse can lead to side effects, dependency, or even life-threatening complications.

For example, sleeping pills—which are sometimes used to relieve pain-related insomnia—can be helpful when taken under medical supervision and in prescribed doses. However, exceeding the recommended dosage can be extremely dangerous and may lead to overdose, organ failure, or even death.

In general, some common side effects of analgesics include:

  • Gastrointestinal issues (nausea, ulcers, stomach bleeding — especially with NSAIDs)
  • Liver or kidney damage (with long-term use of paracetamol or NSAIDs)
  • Drowsiness, confusion, and dizziness (more common with opioid analgesics)
  • Constipation and respiratory depression (associated with opioids)
  • Addiction or dependency, particularly with opioids or sedative combinations

Table of Contents


  • 1.0Classification of analgesics
  • 1.1Narcotic (addictive) drugs
  • 1.2Non-narcotic (non-addictive) drugs:
  • 1.3Compound Analgesics
  • 2.0Mechanism of Action
  • 2.1Chemistry of Action of Aspirin and Similar Drugs
  • 3.0Side Effects of Analgesics

Frequently Asked Questions

Most NSAIDs work similarly by inhibiting COX enzymes, but some are selective COX-2 inhibitors (like celecoxib), which aim to reduce inflammation with fewer gastrointestinal side effects.

At low doses, aspirin selectively inhibits thromboxane A2, a compound that promotes platelet aggregation (clotting). This makes it effective in preventing heart attacks and strokes.

Analgesics are medicines used to relieve pain without causing loss of consciousness. They are commonly known as painkillers.

Non-opioid analgesics are used for mild to moderate pain and are usually available over the counter. Opioid analgesics are stronger, used for severe pain, and require a prescription due to their risk of addiction.

NSAIDs (Non-Steroidal Anti-Inflammatory Drugs), such as ibuprofen, naproxen, and aspirin, reduce inflammation and pain.

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