mefenamic acid/paracetamol

Action and Spectrum

Actions and Spectrum: 

Action: 

Mefenamic acid has the action of inhibiting the release of prostaglandins,

Which is responsible for pain, inflammation, and fever.

Paracetamol act centrally in the brain and possess analgesic and antipyresis properties.

When both drugs are combined, they give synergistic effect.

Drug Interaction

Adverse Reaction

Frequency not defined

• Nausea
• Abdominal pain
• Dark coloured stool
• Flatulence
• Dyspepsia
• Vomiting
• Heartburn

Black Box Warning

Black Box Warning 

Liver toxicity

Contraindication / Caution

Contraindication/Caution: 

• Known allergy to NSAIDS
• Stomach ulcer history
• Active bleeding
• Liver impairment
• Kidney impairment

Pregnancy / Lactation

Pregnancy consideration:  

No data is available regarding the administration of the drug during pregnancy.

Breastfeeding warnings:

No data is available regarding the excretion of drugs in breast milk.

Pregnancy category: 

• Category A: well-controlled and satisfactory studies show no risk to the fetus in the first or later trimester.
• Category B: There was no evidence of risk to the fetus in animal studies, and there were not enough studies on pregnant women.
• Category C: There was evidence of risk of adverse effects in animal reproduction studies, and no adequate evidence in human studies must take care of potential risks in pregnant women.
• Category D: Adequate data with sufficient evidence of human fetal risk from various platforms, but despite the potential risk, and used only in emergency cases for potential benefits.
• Category X: Drugs listed in this category outweigh the risks over benefits. Hence, these categories of drugs need to be avoided by pregnant women.
• Category N: No data for the drug under this category is available.

Pharmacology

Pharmacology:

Mefenamic acid has the action of inhibiting the release of prostaglandins,

Which is responsible for pain, inflammation, and fever.

Paracetamols act centrally in the brain and possess analgesic and antipyresis properties.

When both drugs are combined, they give synergistic effect.

Pharmacokinetics: 

Absorption:

Mefenamic acid undergoes relatively rapid absorption through the gastrointestinal tract following oral administration, reaching highest plasma levels at 2-4 hours post administration.

Paracetamol is also quickly absorbed from the GI tract within a short time after oral administration as well. As a result, peak plasma is achieved between 30 and 60 minutes.

Distribution:

Mefenamic acid has a 90% binding strength to plasma proteins, especially albumin. It permeates tissues extensively.
Paracetamol permeates most bodily tissues.

Metabolism:

Mefenamic acid undergoes hepatic metabolism.

Paracetamol also undergoes hepatic metabolism.

Excretion and elimination

Mefenamic acid is mainly excreted in the urine in the form of glucuronide and as sulfate conjugates of its metabolites, while a small unchanged.

Paracetamol is mostly resulted in the excretion of the conjugates of the metabolites in urine, with a small part of it got unchanged.

Adminstartion

Administration: 

The drug is taken orally.

Patient Information Leaflet

Patient information leaflet 

Generic Name: mefenamic acid/paracetamol

Why do we use mefenamic acid/paracetamol? 

Both mefenamic acid and paracetamol suppress pain in the same manner (analgesics). Combining these drugs together covers more and performs better, in managing headaches, dental related pain, muscle pains, and menstrual cramps.

Mefenamic acid is useful for both easing of the inflammation in disorders of arthritis and joint pain. Mefenamic acid can be paired with paracetamol to give broader pain relief.