Pharmacokinetics and pharmacodynamics of warfarin when coadministered with pentosan polysulfate sodium

Modi NB, Kell S, Simon M, Vargas R · Journal of Clinical Pharmacology

The specific interaction test behind the label: oral PPS at the licensed dose left R- and S-warfarin concentrations, half-lives, prothrombin time, partial thromboplastin time and INR unchanged. Adverse events were mild and mostly attributable to the warfarin titration.

Population

Healthy subjects titrated on warfarin to an INR of 1.4–1.8

Intervention

Oral PPS 100 mg every 8 hours for 7 days on top of the titrated warfarin dose

Comparator

Placebo on top of the titrated warfarin dose

Limitations

Oral PPS only — the route with negligible systemic absorption — so the absence of an interaction cannot be carried across to injected PPS, which measurably prolongs clotting times on its own; healthy volunteers at a low target INR over one week.