Steady-State Pharmacokinetics of Darunavir/Ritonavir and Pitavastatin when Co-administered to Healthy Adult Volunteers

Background The treatment of hyperlipidaemia in human immunodeficiency virus (HIV)-infected patients has become increasingly important. However, treatment options are limited because of the drug-drug interaction between certain statins and HIV medications metabolized by cytochrome P450 (CYP) enzymes. Objectives The primary objective was to investigate the steady-state pharmacokinetics of pitavastatin when co-administered with darunavir/ritonavir. The secondary objective was to investigate the steady-state pharmacokinetics of both darunavir and ritonavir when co-administered with pitavastatin. Methods This was a single-centre, open-label, multidose, fixed-sequence study in HIV seronegative healthy volunteers. Pitavastatin 4 mg was administered once daily on days 1-5 and on days 12-16, and darunavir 800 mg/ritonavir 100 mg once daily on days 6-16. Pharmacokinetic blood sampling was performed on days 5, 11 and 16. No significant interaction was concluded if the 90 % confidence intervals (CIs) of the geometric mean ratios (GMRs) for total exposure [i.e. the area under the plasma concentration-time curve over a dosing interval at steady state (AUC(0-tau))] and for peak exposure [i.e. the maximum plasma concentration (C-max)] of the two treatments were within the 80-125 % range. Results Twenty-eight subjects (mean age 30.5 years) were enrolled, and pharmacokinetic data were available for 27 subjects. For pitavastatin, the GMRs and 90 % CIs for the AUC(0-tau) and C-max ratios with co-administration were 0.74 (0.69-0.80) and 0.96 (0.84-1.09), respectively. For both darunavir and ritonavir, the 90 % CIs for the AUC(0-tau) and C-max ratios were within 80-125 % with pitavastatin co-administration. No significant safety issues were reported. Conclusion Darunavir/ritonavir decreased total exposure to pitavastatin by 26 %, while peak exposures were similar. Pitavastatin did not influence the pharmacokinetics of darunavir or ritonavir. There is limited interaction between pitavastatin and darunavir/ritonavir.