Boceprevir and Antiretroviral Pharmacokinetic Interactions in HIV/HCV Co-infected Persons: AIDS Clinical Trials Group Study A5309s

Combined Oral Contraceptives As Victims of Drug Interactions

Combined oral contraceptives (COCs) are widely used in women of reproductive age in the United States. Metabolism plays an important role in the elimination of estrogens and progestins contained in COCs. It is unavoidable that a woman using COCs may need to take another drug to treat a disease. If the concurrently used drug induces enzymes responsible for the metabolism of progestins and/or estrogens, unintended pregnancy or irregular bleeding may occur. If the concurrent drug inhibits the metabolism of these exogenous hormones, there may be an increased safety risk such as thrombosis. Therefore, for an investigational drug intended to be used in women with reproductive potential, evaluating its effects on the pharmacokinetics of COCs is important to determine if additional labeling is necessary for managing drug-drug interactions (DDIs) between the concomitant product and the COCs. It is challenging to determine when this clinical drug interaction study is needed, whether an observed exposure change of progestin/estrogen is clinically meaningful, and if the results of a clinical drug interaction study with one COC can predict exposure changes of unstudied COCs to inform labeling. In this review, we summarize the current understanding of metabolic pathways of estrogens and progestins contained in commonly used COCs and known interactions of these COCs as victim drugs and we discuss possible mechanisms of interactions for unexpected results. We also discuss recent advances, knowledge gaps, and future perspectives on this important topic. The review will enhance the understanding of DDIs with COCs and improve the safe and effective use of COCs. SIGNIFICANCE STATEMENT: This minireview provides an overview of the metabolic pathways of ethinyl estradiol and progestins contained in commonly used combined oral contraceptives (COCs) and significant drug interactions of these COCs as victims. It also discusses recent advances, knowledge gaps, future perspectives, and potential mechanisms for unexpected results of clinical drug interaction studies of COCs. This minireview will help the reader understand considerations when evaluating the drug interaction potential with COCs for drugs that are expected to be used concurrently.

HIV-1 viremia not suppressible by antiretroviral therapy can originate from large T cell clones producing infectious virus

BACKGROUNDHIV-1 viremia that is not suppressed by combination antiretroviral therapy (ART) is generally attributed to incomplete medication adherence and/or drug resistance. We evaluated individuals referred by clinicians for nonsuppressible viremia (plasma HIV-1 RNA above 40 copies/mL) despite reported adherence to ART and the absence of drug resistance to the current ART regimen.METHODSSamples were collected from at least 2 time points from 8 donors who had nonsuppressible viremia for more than 6 months. Single templates of HIV-1 RNA obtained from plasma and viral outgrowth of cultured cells and from proviral DNA were amplified by PCR and sequenced for evidence of clones of cells that produced infectious viruses. Clones were confirmed by host-proviral integration site analysis.RESULTSHIV-1 genomic RNA with identical sequences were identified in plasma samples from all 8 donors. The identical viral RNA sequences did not change over time and did not evolve resistance to the ART regimen. In 4 of the donors, viral RNA sequences obtained from plasma matched those sequences from viral outgrowth cultures, indicating that the viruses were replication competent. Integration sites for infectious proviruses from those 4 donors were mapped to the introns of the MATR3, ZNF268, ZNF721/ABCA11P, and ABCA11P genes. The sizes of the clones were estimated to be from 50 million to 350 million cells.CONCLUSIONThese findings show that clones of HIV-1-infected cells producing virus can cause failure of ART to suppress viremia. The mechanisms involved in clonal expansion and persistence need to be defined to effectively target viremia and the HIV-1 reservoir.FUNDINGNational Cancer Institute, NIH; Howard Hughes Medical Research Fellows Program, Howard Hughes Medical Institute; Bill and Melinda Gates Foundation; Office of AIDS Research; American Cancer Society; National Cancer Institute through a Leidos subcontract; National Institute for Allergy and Infectious Diseases, NIH, to the I4C Martin Delaney Collaboratory; University of Rochester Center for AIDS Research and University of Rochester HIV/AIDS Clinical Trials Unit.

Clinical pharmacology profile of boceprevir, a hepatitis C virus NS3 protease inhibitor: focus on drug-drug interactions

Boceprevir is a potent, orally administered ketoamide inhibitor that targets the active site of the hepatitis C virus (HCV) non-structural (NS) 3 protease. The addition of boceprevir to peginterferon plus ribavirin resulted in higher rates of sustained virologic response (SVR) than for peginterferon plus ribavirin alone in phase III studies in both previously treated and untreated patients with HCV infection. Because boceprevir is metabolized by metabolic routes common to many other drugs, and is an inhibitor of cytochrome P450 (CYP) 3A4/5, there is a high potential for drug-drug interactions when boceprevir is administered with other therapies, particularly when treating patients with chronic HCV infection who are often receiving other medications concomitantly. Boceprevir is no longer widely used in the US or EU due to the introduction of second-generation treatments for HCV infection. However, in many other geographic regions, first-generation protease inhibitors such as boceprevir continue to form an important treatment option for patients with HCV infection. This review summarizes the interactions between boceprevir and other therapeutic agents commonly used in this patient population, indicating dose adjustment requirements where needed. Most drug interactions do not affect boceprevir plasma concentrations to a clinically meaningful extent, and thus efficacy is likely to be maintained when boceprevir is coadministered with the majority of other therapeutics. Overall, the drug-drug interaction profile of boceprevir suggests that this agent is suitable for use in a wide range of HCV-infected patients receiving concomitant therapies.