Define Acetaminophen
Acetaminophen, often known as paracetamol, is a pain reliever that is used to treat mild to moderate pain and fever. acetaminophen only marginally lowers body temperature at a typical dose; it is inferior to ibuprofen in this regard, and the benefits of its use for fever are uncertain. In acute migraine, acetaminophen greatly reduces pain, but only marginally in episodic tension headache.
The combination of aspirin, acetaminophen, and caffeine, on the other hand, is effective for both diseases and is suggested as a first-line treatment. Although acetaminophen is beneficial in the treatment of post-surgical pain, it is not as effective as ibuprofen.
This article will study Acetaminophen, acetaminophen uses, acetaminophen classification
and acetaminophen vs paracetamol in detail.
When Was Acetaminophen Invented?
In 1877, acetaminophen was created for the first time. In both the United States and Europe, it is the most widely prescribed pain and fever drug. It is listed as an essential medicine by the World Health Organization. acetaminophen is a generic drug that goes by the brand names Tylenol and Panadol, among others. With over 27 million prescriptions written in 2018, it was the sixteenth most widely prescribed drug in the United States.
Northrop, Harmon Morse in 1877, produced acetaminophen at Johns Hopkins University by reducing p-nitrophenol with tin in glacial acetic acid, but clinical pharmacologist Joseph von Mering did not test acetaminophen on humans until 1887.
Triagesic, a mix of acetaminophen, aspirin, and caffeine, was the first acetaminophen product to be introduced in the United States in 1950. It was taken off the market in 1951 when three users were diagnosed with the blood disorder agranulocytosis, and it took several years to figure out that the sickness was unrelated. Acetaminophen was reintroduced to the US market as a prescription medicine the following year, in 1952. In the United Kingdom, Sterling-Winthrop Co. began marketing acetaminophen as Panadol in 1956, and it was advertised as a better alternative to aspirin because it was safe for children and individuals with ulcers.
Dosage of Acetaminophen and Paracetamol
A maximum daily intake of three to four grammes is recommended for adults. Toxic effects, including liver failure, may occur at higher doses. In the United States, the United Kingdom, Australia, and New Zealand, acetaminophen poisoning is the leading cause of acute liver failure, accounting for the majority of drug overdoses.
Structure of Acetaminophen
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Synthesis of Acetaminophen and Paracetamol
Classical Method:
The acetylation of 4-aminophenol with acetic anhydride is the final step in traditional acetaminophen manufacturing processes. The way they make 4-aminophenol differs. In one approach, phenol is nitrated using nitric acid to produce 4-nitrophenol, which is then hydrogenated over Raney nickel to produce 4-aminophenol. Nitrobenzene is reduced electrolytically in another technique, yielding 4-aminophenol immediately.
Celanese synthesis
Direct acylation of phenol with acetic anhydride in the presence of hydrogen fluoride, conversion of the resultant ketone to a ketoxime with hydroxylamine, and the acid-catalyzed Beckmann rearrangement is all part of an alternative commercial synthesis discovered by Celanese.
Acetaminophen Uses
Acetaminophen uses in medical science.
1. Fever
When it comes to treating fever, acetaminophen is the medicine of choice. However, there hasn't been much research done on its antipyretic qualities, especially in adults. According to the most recent review on acetaminophen and fever management in general practice (2008), its advantages remain unclear. Furthermore, acetaminophen may cure a clogged or runny nose but no other cold symptoms such as sore throat, malaise, sneezing, or cough when used for the common cold; however, these data are of poor quality.
Acetaminophen had no effect in the treatment of dengue fever, and it was associated with a higher rate of liver enzyme increase, which could indicate liver damage. Overall, there is little evidence that antipyretic medications, such as acetaminophen, should be given to hospitalised patients with fever and illness on a regular basis.
2. Pain
Acetaminophen is used to treat mild to moderate pain, including headaches, muscle pains, minor arthritis pain, toothaches, and discomfort from colds, flu, sprains, and dysmenorrhea. Because there is inadequate evidence for the treatment of chronic pain, it is especially suggested for acute mild to severe pain.
3. Musculoskeletal Pain
The effectiveness of acetaminophen in musculoskeletal diseases like osteoarthritis and backache is unknown.
In osteoarthritis, it appears to produce only minor and clinically insignificant advantages. The American College of Rheumatology and the Arthritis Foundation's guideline for the therapy of osteoarthritis emphasises that acetaminophen's impact size in clinical trials has been relatively tiny, implying that it is useless for most people.
4. Headaches
For acute migraine, acetaminophen is effective: 39% of patients receive pain alleviation within one hour, compared to 20% in the control group. The combination of aspirin, acetaminophen, and caffeine "shows high evidence of effectiveness and can be used as a first-line treatment for migraine," according to the study. It is a better alternative to ibuprofen and sumatriptan. For self-medication of migraine, the German, Austrian, and Swiss headache organisations, as well as the German Society of Neurology, advocate the combination as a "highlighted" option, with acetaminophen alone as a first choice.
5. Dental and Other Post-Surgical Pain
Pain following dental surgery is a good model for how analgesics work on other types of acute pain. acetaminophen is not as effective as ibuprofen in relieving such pain. Non-steroidal anti-inflammatory medicines (NSAIDs) such as ibuprofen, naproxen, or diclofenac in full therapeutic dosage are demonstrably more effective than the acetaminophen/codeine combination commonly prescribed for dental pain. Combinations of acetaminophen with nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen or diclofenac are promising and may provide better pain relief than either acetaminophen or the NSAID alone. Furthermore, the combination of acetaminophen and ibuprofen may be preferable to acetaminophen/codeine and ibuprofen/codeine.
6. Other Pain
In newborn newborns, acetaminophen fails to reduce procedural discomfort. acetaminophen appears to be less effective than non-steroidal anti-inflammatory medicines for postpartum perineal pain (NSAIDs).
There isn't enough research to back up or reject the use of acetaminophen for cancer pain and neuropathic pain.
7. Patent Ductus Arteriosus
In patent ductus arteriosus, acetaminophen aids ductal closure. It is as effective as ibuprofen or indomethacin for this purpose, but it causes less gastrointestinal bleeding than ibuprofen.
Did You Know?
Acetaminophen is not better tolerated than ibuprofen for short-term pain relief. Nausea and abdominal pain are common gastrointestinal side effects, and their incidence is comparable to that of ibuprofen. It's probable that risk-taking behaviour will increase. The medicine may induce rare and potentially fatal skin responses such as Stevens-Johnson syndrome and toxic epidermal necrolysis, according to the US Food and Drug Administration, despite a review of the French Pharmacovigilance Database indicating no clear risk of these events.
The frequency of participants reporting side effects in clinical trials for osteoarthritis was identical for those taking acetaminophen and those taking a placebo. However, individuals using acetaminophen were approximately four times more likely to have abnormal liver function tests (indicating inflammation or injury to the liver), however, the clinical significance of this impact is unknown. A decline in haemoglobin level indicating gastrointestinal bleeding was found in 20% of individuals after 13 weeks of acetaminophen therapy for knee pain, a rate identical to the ibuprofen group.
FAQs on Acetaminophen
1. What exactly is Acetaminophen and how does it function in the body?
Acetaminophen, also widely known as paracetamol, is a common medication used as a pain reliever (analgesic) and a fever reducer (antipyretic). It is used to treat mild to moderate pain from headaches, muscle aches, and colds. Unlike NSAIDs such as ibuprofen, it has very weak anti-inflammatory effects. It is believed to work primarily in the central nervous system to inhibit the production of prostaglandins, which are chemicals that cause pain and fever.
2. Are Acetaminophen and Paracetamol the same chemical compound?
Yes, Acetaminophen and Paracetamol are two different names for the exact same chemical compound: N-acetyl-p-aminophenol. 'Acetaminophen' is the name commonly used in the United States, Canada, and Japan, while 'Paracetamol' is the standard name in many other parts of the world, including India and the UK. There is no chemical or medicinal difference between them.
3. What is the main difference between Acetaminophen and Ibuprofen?
The primary difference between Acetaminophen and Ibuprofen lies in their chemical class and mechanism of action.
- Class: Acetaminophen is in a class of its own as an analgesic, while Ibuprofen is a Non-Steroidal Anti-Inflammatory Drug (NSAID).
- Function: Both drugs relieve pain and reduce fever. However, Ibuprofen also possesses strong anti-inflammatory properties, making it effective for conditions involving swelling, like arthritis. Acetaminophen's anti-inflammatory action is very weak.
- Mechanism: Ibuprofen works by blocking COX-1 and COX-2 enzymes throughout the body, while Acetaminophen is thought to work more centrally in the brain and spinal cord.
4. What are some examples of the medical uses for Acetaminophen?
As per the NCERT curriculum context for drugs, Acetaminophen serves as a key example of a non-narcotic analgesic. Its primary uses include:
- Relief of mild to moderate pain, such as headaches, toothaches, and muscle aches.
- Reducing fever associated with illnesses like the common cold and flu.
- Managing pain where anti-inflammatory effects are not required, for example, in osteoarthritis.
5. How is Acetaminophen prepared commercially?
The most common industrial synthesis of Acetaminophen involves the acetylation of 4-aminophenol. The process typically starts with phenol, which is first nitrated to form p-nitrophenol. This intermediate is then reduced to create 4-aminophenol. In the final step, 4-aminophenol is treated with acetic anhydride, which adds an acetyl group to the amino group (-NH2), yielding the final product, Acetaminophen (N-acetyl-p-aminophenol).
6. Why can an overdose of Acetaminophen cause severe liver damage?
This is a critical example of drug metabolism. Under normal doses, the liver metabolises Acetaminophen into harmless compounds. However, during an overdose, this primary metabolic pathway becomes saturated. The body then uses a different pathway that produces a highly reactive and toxic byproduct called NAPQI (N-acetyl-p-benzoquinone imine). Normally, an antioxidant called glutathione neutralises NAPQI. But in an overdose, the liver's glutathione stores are quickly depleted, allowing NAPQI to accumulate and cause severe, potentially fatal, damage to liver cells.
7. Why is Acetaminophen classified as a non-narcotic analgesic?
Analgesics are broadly classified based on their mechanism and potential for addiction.
- Non-narcotic (or non-opioid) analgesics, like Acetaminophen and Aspirin, act to relieve pain without causing addiction, tolerance, or sedation. They are effective for mild to moderate pain.
- Narcotic analgesics, such as morphine, act on opioid receptors in the brain to block severe pain but have a high potential for causing addiction and drowsiness.
8. Do common medicines like Dolo 650 contain Acetaminophen?
Yes. Many well-known over-the-counter medications use Acetaminophen as their primary active ingredient, though they may use the name 'Paracetamol'. For example, Dolo 650 is a popular brand in India where the active ingredient is Paracetamol (the same chemical as Acetaminophen). The number '650' indicates the dosage of 650 mg. Other globally recognised brand names include Tylenol and Panadol.
