Panadol/Panadol Optizorb Mechanism of Action

Pharmacology: Pharmacodynamics: Mechanism of Action: Paracetamol is an analgesic and antipyretic. Its mechanism of action is believed to include inhibition of prostaglandin synthesis, primarily within the central nervous system.
Pharmacodynamic Effects: The lack of peripheral prostaglandin inhibition confers important pharmacological properties such as the maintenance of the protective prostaglandins within the gastrointestinal tract.
Paracetamol is, therefore, particularly suitable for: patients with a history of disease or patients taking concomitant medication, where peripheral prostaglandin inhibition would be undesirable (such as, for example, those with a history of gastrointestinal bleeding or the elderly).
In two dental pain studies conducted in patients following surgical removal of third molars, pain relief was observed at a median time of 15 minutes following administration of the 1000mg dose of Panadol Tablets with Optizorb.
Panadol Tablets with Optizorb demonstrated superior pain relief at 1000 mg dose compared to placebo and to Panadol Tablets with Optizorb at 500mg dose. Panadol Tablets with Optizorb at the 500 mg dose also demonstrated superior efficacy compared to placebo.
Pharmacokinetics: Absorption: Paracetamol is rapidly and almost completely absorbed from the gastrointestinal tract.
Distribution: Binding to the plasma proteins is minimal at therapeutic concentrations.
Metabolism: Paracetamol is metabolised in the liver and excreted in the urine mainly as glucuronide and sulphate conjugates.
Elimination: Less than 5% is excreted as unmodified paracetamol.
Paracetamol is rapidly absorbed from the gastrointestinal tract and is distributed into most body tissues. Binding to plasma proteins is minimal at therapeutic concentrations. Paracetamol is metabolised in the liver and excreted in the urine mainly as glucuronide and sulphate metabolites - less than 5% is excreted as unmodified paracetamol. The mean plasma half life is about 2.3 hours.
Paracetamol Tablets with Optizorb contain a disintegrant system which optimises tablet dissolution compared to standard paracetamol tablets.
Human scintigraphy data demonstrate that Paracetamol Tablets with Optizorb generally start to disintegrate by 5 minutes post dose. Human pharmacokinetic data demonstrate that paracetamol can generally be detected in plasma by 10 minutes. Human pharmacokinetic data demonstrate that early absorption of paracetamol (fraction of dose over the first 60 minutes) is 32% greater from Paracetamol Tablets with Optizorb compared to standard paracetamol tablets (p<0.0001). There is also less between-subject and less within- subject variability (p<0.0001) in early absorption of paracetamol from Paracetamol Tablets with Optizorb compared to standard paracetamol tablets.
Human pharmacokinetic data demonstrate that maximum plasma concentration of paracetamol is reached at least 25% faster for Paracetamol Tablets with Optizorb compared to standard paracetamol tablets in fasted and fed states (p < 0.01). Total extent of absorption of paracetamol from Paracetamol Tablets with Optizorb is equivalent to that from standard paracetamol tablets.