Many parents know acetaminophen: In the form of suppositories or juice, it helps with fever and pain. But not only children benefit from this well-tolerated drug. At the end of the 19th century, English and German chemists in particular were researching alternatives to natural painkillers used to date, such as willow bark. The 1886 newly developed substances acetanilide and phenacetin proved to be pain-relieving and even fever-reducing.
Research on paracetamol
Paracetamol was synthesized for the first time in 1893, but it was not until 1948 that Brodie and Axelrod discovered that this white, odorless powder with a bitter taste is responsible for the breakdown of the two substances mentioned and for their action. In 1956, acetaminophen was introduced as a painkiller in the market.
Effect of paracetamol
In addition to acetylsalicylic acid and ibuprofen, acetaminophen is one of the most commonly used analgesics worldwide. Paracetamol is used for mild to moderately severe pain and is included in the group of so-called cyclooxygenase inhibitors (non-opioid analgesics). Since paracetamol simultaneously reduces fever (antipyretic) and is particularly well tolerated, it is mainly used in children.
However, unlike the other two active ingredients, acetaminophen does not work well with pain caused by inflammation, such as rheumatic diseases.
Function of paracetamol
Paracetamol is also referred to chemically as N-acetyl-para-aminophenol (abbreviated to: APAP), 4'-hydroxyacetanilide or 4-acetamidophenol. Although paracetamol has been used for decades, the exact mechanism of action was - as with many other drugs - unknown for a long time. Even today, not every detail is unraveled. Although it is now known that paracetamol inhibits the cyclooxygenase Cox-2 - an endogenous substance that is activated in cell damage and stimulates the production of pro-inflammatory and pain-enhancing prostaglandins.
But since the inhibitory effect of paracetamol is only comparatively weak, other mechanisms must be involved in its effectiveness. These are not yet decrypted. Paracetamol is often offered in combination with caffeine. This is intended to increase the analgesic effect of paracetamol.
Dosage of paracetamol
Paracetamol is available in various dosage forms. In children, suppositories or juices or syrups are usually used, in adults more tablets and capsules. Also infusions are available. Paracetamol can be taken once or in three to four single doses per day. Between taking the single doses should be at least six to eight hours.
It is important in the dosage of acetaminophen not to exceed the recommended maximum amount, as it can lead to life-threatening liver damage in an overdose.
- Adults should not take more than eight tablets of 500 milligrams, that is, four grams per day.
- In children, the dose of paracetamol - depending on the age - is lower. It is recommended to use 10 to 15 milligrams of paracetamol per kg of body weight per single dose with a daily upper limit of 50 milligrams per kilogram of body weight.
Paracetamol: side effects
In the range of the recommended dosage paracetamol is poor in possible side effects and well tolerated. Rarely, or very rarely, are disorders of blood formation, allergic reactions, abdominal pain, nausea, an increase in liver function or a cramping of the respiratory tract with shortness of breath.
However, overdose with acetaminophen can cause serious side effects. In particular, the liver can be severely damaged if one adult takes more than ten to twelve grams or over a longer period daily more than 7.5 grams (in children correspondingly smaller amounts).
For this reason, Paracetamol has been subject to a prescription in Germany since July 2008 in larger packs (from ten grams of the active substance). Lower quantities can still be purchased over the counter in the pharmacy. Also critical for the liver is the concomitant use of potentially liver-damaging substances (for example anticonvulsant medicines) or alcohol abuse.
Paracetamol may interfere with the elimination of other liver metabolised drugs such as the antibiotic chloramphenicol. It should also be noted that the onset of action by drugs that affect gastric emptying can be accelerated or slowed down.
For blood tests, the doctor should be informed about the use of acetaminophen, as this may affect certain laboratory values (for example, blood sugar, uric acid). During pregnancy and lactation paracetamol should be taken at short notice and only after consultation with the doctor.