Inhibition of CYP3A7 DHEA-S Oxidation by Lopinavir and Ritonavir: An Alternative Mechanism for Adrenal Impairment in HIV Antiretroviral-Treated Neonates.
Chem Res Toxicol
; 34(4): 1150-1160, 2021 04 19.
Article
in En
| MEDLINE
| ID: mdl-33821626
ABSTRACT
Prophylactic antiretroviral therapy (ART) in HIV infected pregnant mothers and their newborns can dramatically reduce mother-to-child viral transmission and seroconversion in the neonate. The ritonavir-boosted lopinavir regimen, known as Kaletra, has been associated with premature birth and transient adrenal insufficiency in newborns, accompanied by increases in plasma dehydroepiandrosterone 3-sulfate (DHEA-S). In the fetus and neonates, cytochrome P450 CYP3A7 is responsible for the metabolism of DHEA-S into 16α-hydroxy DHEA-S, which plays a critical role in growth and development. In order to determine if CYP3A7 inhibition could lead to the adverse outcomes associated with Kaletra therapy, we conducted in vitro metabolic studies to determine the extent and mechanism of CYP3A7 inhibition by both ritonavir and lopinavir and the relative intrinsic clearance of lopinavir with and without ritonavir in both neonatal and adult human liver microsomes (HLMs). We identified ritonavir as a potent inhibitor of CYP3A7 oxidation of DHEA-S (IC50 = 0.0514 µM), while lopinavir is a much weaker inhibitor (IC50 = 5.88 µM). Furthermore, ritonavir is a time-dependent inhibitor of CYP3A7 with a KI of 0.392 µM and a kinact of 0.119 min-1, illustrating the potential for CYP3A mediated drug-drug interactions with Kaletra. The clearance rate of lopinavir in neonatal HLMs was much slower and comparable to the rate observed in adult HLMs in the presence of ritonavir, suggesting that the addition of ritonavir in the cocktail therapy may not be necessary to maintain effective concentrations of lopinavir in neonates. Our results suggest that several of the observed adverse outcomes of Kaletra therapy may be due to the direct inhibition of CYP3A7 by ritonavir and that the necessity for the inclusion of this drug in the therapy may be obviated by the lower rate of lopinavir clearance in the neonatal liver. These results may lead to a reconsideration of the use of ritonavir in neonatal antiretroviral therapy.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Ritonavir
/
Dehydroepiandrosterone Sulfate
/
Anti-Retroviral Agents
/
Cytochrome P-450 CYP3A
/
Lopinavir
/
Cytochrome P-450 CYP3A Inhibitors
Limits:
Adult
/
Humans
/
Newborn
Language:
En
Journal:
Chem Res Toxicol
Journal subject:
TOXICOLOGIA
Year:
2021
Document type:
Article
Affiliation country:
United States