NAPA Extend Mechanism of Action

Pharmacology: Pharmacodynamics: Paracetamol is a para-aminophenol derivative that exhibits analgesic and antipyretic activity. The mechanism of action of paracetamol is believed to include the inhibition of prostaglandin synthesis, primarily within the central nervous system. It does not possess anti-inflammatory activity. It provides relief from mild to moderate pain and fever. The combination of immediate release and sustained release paracetamol provides pain relief, which may last up to 8 hours.
Pharmacokinetics: Absorption: Napa Extend are bilayer tablets incorporating an immediate release and a sustained release dose of paracetamol.
The sustained release layer is formulated in such a manner that it rapidly hydrates to form a gel layer at the matrix periphery; the drug is then released from the matrix by a combination of diffusion and erosion of the gel layer.
Napa Extend releases drug at a rate which ensures that therapeutically active plasma paracetamol concentrations are rapidly attained and maintained until up to 8 hours after administration.
Distribution: Paracetamol is distributed into most body tissues. Binding to the plasma proteins is minimal at therapeutic concentrations but increases with increasing doses.
Metabolism: Paracetamol is metabolised extensively in the liver and excreted in the urine mainly as inactive glucuronide and sulfate conjugates. The metabolites of paracetamol include a minor hydroxylated intermediate which has hepatotoxic activity. This intermediate metabolite is detoxified by conjugation with glutathione, however, it can accumulate following paracetamol overdosage (more than 150 mg/kg or 10 g total paracetamol ingested) and if left untreated can cause irreversible liver damage.
Paracetamol is metabolised differently by premature infants, newborns, infants and young children compared to adults, the sulfate conjugate being predominant.
Excretion: Paracetamol is excreted in the urine mainly as the glucuronide and sulphate conjugates. Less than 5% is excreted unchanged.
Approximately 85% of a dose of paracetamol is excreted in urine as free and conjugated paracetamol within 24 hours of ingestion. Administration of paracetamol to patients with moderate to severe renal impairment may result in accumulation of paracetamol conjugates. The elimination half-life varies from one to three hours.