Pentosan polysulfate

The hypothetic mechanism of action of pentosan polysulfate sodium includes a local effect in the bladder after systemic administration and excretion into the urine by binding of glycosaminoglycans to the deficient mucous of the bladder. This binding of glycosaminoglycans to the bladder mucous reduces bacterial adherence to the inner surface of the bladder and in consequence the incidence of infections is reduced as well. It is hypothesized, that a potential barrier function of pentosan polysulfate sodium instead of the damaged urothelial mucus might play a role as well the antiinflammatory activity of pentosan polysulfate sodium.

Absorption

Less than 10% of orally administered pentosan polysulfate sodium are slowly absorbed from the gastrointestinal tract and are available in systemic circulation in the form of unchanged pentosan polysulfate sodium or it’s metabolites. All studies describe very low systemic availability of unchanged pentosan polysulfate sodium after oral administration. Overall, the reported systemic bioavailability after oral administration of pentosan polysulfate sodium is below 1%.

Distribution

In healthy volunteers, a single parenteral administration of radioactively labelled pentosan polysulfate sodium leads to a progressive up-take of total radioactivity by the liver, spleen, and kidney (50 min after 1 mg/kg i.v.: 60% of the dose in the liver, 7.7% in the spleen; 3 h post dosing: 60% in the liver plus spleen, and 13% in the bladder).

Biotransformation

Pentosan polysulfate sodium is metabolised extensively by desulfation in liver and spleen and depolymerisation in the kidney.

Elimination

The apparent plasma half-life of pentosan polysulfate sodium depends on the route of administration. While pentosan polysulfate sodium is rapidly cleared from circulation of i.v. administration, the apparent plasma half-life after oral administration is in the range of 24-34 hours. Accordingly, oral administration of pentosan polysulfate sodium 3-times daily is expected to lead to accumulation of pentosan polysulfate sodium over the first 7 days of administration (accumulation factor 5-6.7). After oral administration unabsorbed pentosan polysulfate sodium is excreted predominantly unchanged in the faeces. About 6% of the administered dose of pentosan polysulfate sodium were excreted via urine after desulfation and depolymerisation.