Mefenamic Acid: Structure,Synthesis,SAR,Mechanism,Uses

Mefenamic Acid

Structure –

Here is the chemical structure of Mefenamic Acid:

Mefenamic Acid

Mefenamic Acid belongs to the group of nonsteroidal anti-inflammatory drugs (NSAIDs) and is commonly used to treat pain and inflammation in conditions such as menstrual cramps, headache, arthritis, and fever.

Synthesis –

Mefenamic Acid can be synthesized through a multistep reaction from 2,3-dimethylaniline. Here is a brief outline of the synthesis:

  1. Nitration: 2,3-dimethylaniline is nitrated using a mixture of concentrated nitric acid and sulfuric acid to yield 2,3-dimethyl-4-nitroaniline.
  2. Reduction: The nitro group of 2,3-dimethyl-4-nitroaniline is reduced to an amino group using a reducing agent such as iron and hydrochloric acid. This yields 2,3-dimethyl-4-aminobenzene.
  3. Diazotization: 2,3-dimethyl-4-aminobenzene is diazotized with nitrous acid to form the corresponding diazonium salt.
  4. Coupling: The diazonium salt is coupled with 2,3-dimethylphenol (also known as pyrocatechol dimethyl ether) in the presence of sodium hydroxide to form Mefenamic Acid.

Here is the chemical reaction for the last step:

Mefenamic Acid

Note that this synthesis is a simplified version and there may be additional steps and conditions required to obtain a high yield and purity of the final product.


The SAR (structure-activity relationship) of Mefenamic Acid is based on its ability to inhibit the enzyme cyclooxygenase (COX), which is responsible for the production of prostaglandins that cause pain and inflammation. Here are some key structural features that are important for its activity:

  1. Carboxylic acid group: The carboxylic acid group (-COOH) is important for binding to the COX enzyme and inhibiting its activity. This group is also essential for the solubility of the compound in water.
  2. Aromatic ring: The aromatic ring of Mefenamic Acid is important for hydrophobic interactions with the COX enzyme, which contributes to its binding affinity.
  3. Methyl groups: The two methyl groups on the aromatic ring of Mefenamic Acid contribute to its lipophilicity and enhance its ability to cross cell membranes and reach its target site.
  4. Conformation: Mefenamic Acid has a non-planar conformation due to the steric hindrance between the carboxylic acid group and the methyl groups on the aromatic ring. This conformation allows it to interact with different regions of the COX enzyme, enhancing its binding affinity.

Overall, the SAR of it highlights the importance of the carboxylic acid group, the aromatic ring, and the conformation of the molecule for its ability to inhibit COX activity and reduce pain and inflammation.

Mechanism –

The mechanism of action of it involves inhibition of the enzyme cyclooxygenase (COX), which is responsible for the production of prostaglandins that cause pain and inflammation. Here is the mechanism of action of Mefenamic Acid:

  1. it enters the cell and reaches the site of action, which is the COX enzyme.
  2. Mefenamic Acid binds to the active site of COX, which inhibits the conversion of arachidonic acid to prostaglandins.
  3. By inhibiting the production of prostaglandins, Mefenamic Acid reduces pain, inflammation, and fever.
  4. Mefenamic Acid also inhibits the production of thromboxane A2, which is involved in platelet aggregation and blood clotting.
  5. The inhibition of COX by Mefenamic Acid is reversible and the enzyme activity can recover after the drug is eliminated from the body.

Overall, the mechanism of action of Mefenamic Acid is similar to other nonsteroidal anti-inflammatory drugs (NSAIDs) and involves inhibition of COX activity, which leads to reduced production of prostaglandins and other inflammatory mediators.

Uses –

it  is a nonsteroidal anti-inflammatory drug (NSAID) that is primarily used for the treatment of pain and inflammation associated with various conditions. Here are some of the common uses of Mefenamic Acid:

  1. Menstrual pain: it  is often used to relieve menstrual pain (dysmenorrhea), which is caused by the release of prostaglandins during the menstrual cycle.
  2. Headache: it is also used to relieve headaches, including tension headaches and migraines.
  3. Arthritis: it can be used to reduce pain and inflammation in various forms of arthritis, including rheumatoid arthritis and osteoarthritis.
  4. Fever: it can be used to reduce fever, which is often associated with infections or other inflammatory conditions.
  5. Dental pain: it can be used to relieve dental pain, including pain associated with tooth extraction or other dental procedures.

It is important to note that it should be used only under the supervision of a healthcare provider and according to the prescribed dosage and duration. Like other NSAIDs, it may have side effects and interactions with other medications, and should not be used in certain conditions such as pregnancy or bleeding disorders.

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