SLC22A6 and pulmonary arterial hypertension: Next, a DDI trial between PAH and probenecid (administered as a 1 g oral dose) was simulated using the default Ki value within Simcyp for probenecid against OAT1 (4 μM), which is in line with the IC50 value that we observed for the PAH uptake inhibition following a 10 min incubation (5.1 μM).