SLCO1B1 and myopathy: Use caution/monitor. The results from an in vitro study with human liver tissue indicate that valsartan is a substrate of the hepatic uptake transporter OATP1B1; coadministration with OATP1B1 inhibitors may increase valsartan systemic exposure. Use caution/monitor. Comment: OATP1B1 inhibitors may increase risk of myopathy.