Abstract
Tanshinol has desirable antianginal and pharmacokinetic properties and is a key compound of Salvia miltiorrhiza roots (Danshen). It is extensively cleared by renal excretion. This study was designed to elucidate the mechanism underlying renal tubular secretion of tanshinol and to compare different ways to manipulate systemic exposure to the compound. Cellular uptake of tanshinol was mediated by human OAT1 (Km, 121 μM), OAT2 (859 μM), OAT3 (1888 μM), and OAT4 (1880 μM) and rat Oat1 (117 μM), Oat2 (1207 μM), and Oat3 (1498 μM). Other renal transporters (human OATP4C1, OCT2, OCTN1, MATE1, MATE2-K, MRP2, MRP4, and BCRP and rat Oct1, Oct2, Octn1, Octn2, Mate1, Mrp2, Mrp4, and Bcrp) showed either ambiguous ability to transport tanshinol or no transport activity. Rats may be a useful model, to investigate the contribution of the renal transporters on the systemic and renal exposure to tanshinol. Probenecid-induced impairment of tubular secretion resulted in a 3 - 5-fold increase in rat plasma AUC0-∞ of tanshinol. Tanshinol exhibited linear plasma PK properties over a large intravenous dose range (2 - 200 mg/kg) in rats; the dosage adjustment could result in increases, in plasma AUC0-∞ of tanshinol, of about 100-fold. Tanshinol exhibited very little dose-related nephrotoxicity. In summary, renal tubular secretion of tanshinol consists of uptake from blood, primarily by OAT1/Oat1, and the subsequent luminal efflux into urine mainly by passive diffusion. Dosage adjustment appears to be an efficient and safe way to manipulate systemic exposure to tanshinol. Tanshinol shows low propensity to cause renal transporter-mediated herb-drug interactions.
- drug-drug interactions
- natural products
- pharmacokinetics
- Transporter-mediated drug/metabolite disposition
- Uptake transporters (OATP, OAT, OCT, PEPT, MCT, NTCP, ASBT, etc.)
- The American Society for Pharmacology and Experimental Therapeutics