What is the acetaminophen mechanism of action? | Detailed Explanation

Do you know the acetaminophen mechanism of action? Maybe this is a deep medical question. Before discussing this problem, we will introduce what acetaminophen is. Acetaminophen, a cyclooxygenase inhibitor, is an antipyretic analgesic and non-steroidal anti-inflammatory drug with an odorless, slightly bitter taste. Its common dosage forms are tablets, granules, capsules, etc. It is easily soluble in hot water or ethanol, dissolved in acetone, and slightly soluble in water. Besides, it is unstable to acid, base and oxygen in aqueous solution, most stable at pH 6. 

The applications of acetaminophen 

In clinical practices, acetaminophen is used for cold fever, joint pain, headache, neuralgia, and muscle pain. This product is suitable for headache fever patients who should not use aspirin, such as aspirin allergy, peptic ulcer disease, or aspirin-induced asthma because there is no obvious gastrointestinal irritation. Acetaminophen injection is a kind of intravenous acetaminophen preparation, which has the characteristics of strong antipyretic and analgesic effects, reducing opioid consumption and improving patient satisfaction. It is a safe and effective intravenous drug, so it has been widely used in clinical antipyretic, analgesic.

Traditional statements of acetaminophen mechanism of action 

Acetaminophen can reduce the synthesis and release of prostaglandins by inhibiting the hypothalamic thermoregulatory center, leading to peripheral vascular dilation and sweating, and achieving antipyretic effect. By inhibiting the synthesis and release of prostaglandin, bradykinin and histamine, it can increase the pain threshold and play an analgesic effect.

Two new statements of acetaminophen mechanism of action

1. By inhibiting Cycoperoxidase COX-3 

So far, the exact mechanism of how acetaminophen works is not fully understood. However, some studies show that the mechanism of action of acetaminophen is different from that of non-steroidal anti-inflammatory drugs, and it does not work by inhibiting the activity of COX enzymes in inflammatory tissues, but the position it appears to exist in the central nervous system. Further studies have also stated that the role of acetaminophen in the brain may be central analgesic by inhibiting COX-3, an enzyme derived from tissue type COX-1.

2. Maybe N-Acylphentolamine is a new inhibitor

Most people currently believe that acetaminophen works by inhibiting cycoperoxidase and, ultimately, prostaglandin synthesis. While other scientists, including Zygmunt of Sweden, have suggested that acetaminophen may also act on molecular targets other than the cyclooxygenase enzyme, and its mechanism of action is not as simple as inhibiting the cyclooxygenase enzyme.

Studies have shown that N-Acylphentolamine, a metabolite of acetaminophen in the nervous system, has certain effects on several important molecular targets in pain and thermoregulation pathways. The study by Swedish scientists has suggested a new hypothesis on the mechanism of acetaminophen's antipyretic and analgesic action, but Zygmunt believes that whether this new hypothesis can solve the mystery of the pharmacological mechanism of acetaminophen needs to be verified by further research.

Adverse reaction when using acetaminophen

After talking about the acetaminophen mechanism of action, we want to introduce some notices when different people take it.

1. This product causes few adverse reactions, including nausea, vomiting, sweating, abdominal pain and pallor. Occasionally platelets and leukocytes are reduced. The symptoms of hemolytic anemia, allergic reactions, rash urticaria, dermatitis, and bronchospasm also occasionally happen when the patients take acetaminophen.

2. Excessive misuse can cause acute toxic manifestations mainly liver damage. Loss of appetite, nausea, vomiting, tenderness in the right upper abdomen, jaundice, and elevated blood bilirubin will occur when taking too much acetaminophen. In severe cases, liver function abnormalities, liver coma, hepatic encephalopathy, and confusion also will happen. 

Acetaminophen is a prescription drug, we should follow the doctor's advice when using it and must use it reasonably. That is to say, it can not be used blindly. In addition, people who are allergic to any component of the drug should not use it, and if they have uncomfortable symptoms after use, they should seek medical attention in time.

Conclusion: 

Finally, we want to give a conclusion on the topic of “acetaminophen mechanism of action”. It has the function of allaying a fever and relieving pain by inhibiting the hypothalamic thermoregulatory center, reducing synthesis and release of prostaglandin, bradykinin, and histamine. But now an in-depth acetaminophen mechanism of action has been studied, such as by inhibiting Cycoperoxidase COX-3 and N-Acylphentolamine to achieve its effects.