Zolterol SR Mechanism of Action

Pharmacology: Prostaglandins are known to contribute significantly in the pathogenesis of inflammation, pain and fever. The formation of precursors of prostaglandins and thromboxanes from arachidonic acid is reduced in the presence of diclofenac as it inhibits the activity of the enzyme cyclo-oxygenase.
As an antirheumatic and anti-inflammatory drug, diclofenac may act peripherally in inflamed tissues and block pain impulse generation possibly by reducing prostaglandin activities and inhibition of synthesis and actions of the local mediators involved in such responses.
Diclofenac also works as an antipyretic by acting centrally on the hypothalamic heat-regulating centre to increase peripheral vasodilation which then increases blood flow through the skin, sweating and heat loss. This central action in the hypothalamus may be due to the reduction of prostaglandin activity.
Pharmacokinetics: Diclofenac is almost completely absorbed from the SR tablet. The peak plasma concentration of Zolterol SR tablet is lower than the conventional tablet as it is released more slowly. Absorption of Zolterol SR tablet is slower when taken with or after meal than when taken in an empty stomach. However, the amount of diclofenac absorbed is not affected by food.
No accumulation in plasma happens after repeated oral administration if the recommended dosage intervals are adhered to. More than 99% of diclofenac is bound to plasma proteins at therapeutic level. Diclofenac also penetrates synovial fluid where its concentration might persist even when plasma concentrations fall.
Only about 50% of diclofenac reaches the systemic circulation in the unchanged form due to first-pass metabolism through the liver. Diclofenac is metabolised mainly by glucuronidation after hydroxylation. For patients suffering from impaired hepatic function (chronic hepatitis, non-decompensated liver cirrhosis), the pharmacokinetics and metabolism of diclofenac are similar in patients without liver disease.
The terminal half-life of diclofenac is 1-2 hours. Most of the dose (65%) is eliminated in the forms of glucuronide and sulphate conjugates in the urine and the rest in the form of metabolites through the bile (about 35%) in the faeces. Less than 1% is excreted as unchanged. In patients with impaired renal function, no accumulation of diclofenac has been reported.