The influence of antiretroviral medications on the pharmacokinetics of prednisolone (a CYP3A4 substrate) was investigated in three groups of ten HIV-infected subjects receiving either lopinavir/ritonavir or efavirenz or no antiretrovirals. Each subject received a single prednisone dose (20 mg) followed by serial blood sampling for determining prednisolone pharmacokinetics. Prednisolone AUC was 20% lower in the presence of efavirenz than in subjects on no antiretrovirals. Prednisolone AUC was significantly lower in the presence of efavirenz versus lopinavir/ritonavir (GMR=0.60, p=0.01) and was higher in the subjects taking lopinavir/ritonavir than in subjects on no antiretrovirals, but this was not significant (p>0.05). The authors conclude that prednisolone concentrations may fluctuate widely when patients on efavirenz switch to lopinavir/ritonavir or vice versa.
Influence of antiretroviral drugs on the pharmacokinetics of prednisolone in HIV-infected individuals. Busse KH, Formentini E, Alfaro RM, Kovacs JA, Penzak SR. J Acquir Immune Defic Syndr, 2008, 48(5): 561-566.