Paracetamol -mechanism of action,pharmacokinetics,uses,adverse effect

              PARACETAMOL

• Analgesic ,anti-pyretic ,week anti inflammatory properties.
• Brain:Active cyclo-oxygenase -anti-pyretic action
• Gastric irritation mild

STUDENT CORNER:

HI!my dear stencildent family welcome back to our website ,if your knew to our site please do consider checking out our other posts to ,now moving on to our topic of discussion for today its about a very well and often used,and misused drug paracetamol it belongs to non -steroidal antiinflammatory drug click on this link to learn about NSAID CLASSIFICATION .

PHARMACOKINETICS:

• Orally well absorbed
• Thirty percent protein bound
• Metabolised by microsomal enzyme 

ADVERSE EFFECT:

• Nausea
• Rashes

Large dose: 

• Acute paracetamol poisoning 
• Hepatotoxic
• Jaundice
• Nephrotoxicity - renal failure

USES:

• Analgesic:tooth ache ,head ache 
• Antipyretic
• Chronic pulpitis,periodontal abscess,post extraction

MECHANISM OF ACTION:

• Small portion:

metabolised to -N-acetyl benzoquinone gets detoxified ,conjugation to glutathione

• large doses:

glutathione depleted ,toxic metabolites bind to sulphydryl group

chronic alcoholics,infants more prone to hepatotoxicity.

ACUTE PARACETAMOL POISONING :

• Occur in children ,low hepatic glucuronide conjugating ability

MECHANISM OF TOXICITY:

• N-acetyl -p -benzoquinoneimine  highly reactive arylating minor metabolite
• Detoxified by conjugation with glutathione

LARGE DOSE:

• Glucuronidation capacity saturated

In chronic alcoholics:

• Alcholism induced toxicity 

TREATMENT:

• Antidote N-acetylcysteine infused intra venously or orally