A review of the clinical pharmacology of maraviroc. Introduction

P2X7-deficiency improves plasticity and cognitive abilities in a mouse model of Tauopathy

Alzheimer's disease is the most common form of dementia characterized by intracellular aggregates of hyperphosphorylated Tau protein and extracellular accumulation of amyloid β (Aβ) peptides. We previously demonstrated that the purinergic receptor P2X7 (P2X7) plays a major role in Aβ-mediated neurodegeneration but the relationship between P2X7 and Tau remained overlooked. Such a link was supported by cortical upregulation of P2X7 in patients with various type of frontotemporal lobar degeneration, including mutation in the Tau-coding gene, MAPT, as well as in the brain of a Tauopathy mouse model (THY-Tau22). Subsequent phenotype analysis of P2X7-deficient Tau mice revealed the instrumental impact of this purinergic receptor. Indeed, while P2X7-deficiency had a moderate effect on Tau pathology itself, we observed a significant reduction of microglia activation and of Tau-related inflammatory mediators, particularly CCL4. Importantly, P2X7 deletion ultimately rescued synaptic plasticity and memory impairments of Tau mice. Altogether, the present data support a contributory role of P2X7 dysregulation on processes governing Tau-induced brain anomalies. Due to the convergent role of P2X7 blockade in both Aβ and Tau background, P2X7 inhibitors might prove to be ideal candidate drugs to curb the devastating cognitive decline in Alzheimer's disease and Tauopathies.

The challenge of polypharmacy in an aging population and implications for future antiretroviral therapy development

: It is estimated that by 2030 nearly three-quarters of persons living with HIV will be 50 years and older. The aging HIV population presents a new clinical concern for HIV providers: adverse effects from polypharmacy. An aging population means more comorbidities and potentially more drug-drug interactions for providers to manage. This review discusses major comorbidities including cardiovascular disease, anticoagulation, hypertension, diabetes mellitus and malignancy and considerations for drug-interactions with antiretrovirals.

Cytochrome P450 3A5 plays a prominent role in the oxidative metabolism of the anti-human immunodeficiency virus drug maraviroc

Maraviroc is an anti-human immunodeficiency virus drug that acts by blocking viral entry into target cells. With use of ultra-performance liquid chromatography-mass spectrometry several monooxygenated, dioxygenated, and glucuronidated metabolites of maraviroc were identified both in vitro and in vivo. Characterization of the enzymes involved in the production of these metabolites determined that cytochrome P450 3A5 was the principal enzyme responsible for the formation of an abundant metabolite of maraviroc that resulted from oxygenation of the dichlorocyclohexane ring. For the formation of this metabolite, the V(max) values for CYP3A4 and CYP3A5 were 0.04 and 0.93 pmol · min⁻¹ · pmol P450⁻¹, and the K(m) values were 11.1 and 48.9 μM, respectively. Furthermore, human liver microsomes isolated from donors homozygous for the loss-of-function CYP3A5*3 allele exhibited a 79% decrease in formation of this metabolite compared with those homozygous for the wild-type CYP3A5*1 allele. To probe which divergent residues between CYP3A4 and CYP3A5 might play a role in the differential activities of these enzymes toward maraviroc, mutations were introduced into both enzymes and metabolism of maraviroc was measured. A CYP3A5 L57F mutant exhibited a 61% decrease in the formation of this metabolite, whereas formation by a CYP3A4 F57L mutant was increased by 337% compared with that of the wild type. Taken together, these data provide novel insights into the biotransformation of maraviroc as well as the potential role of CYP3A4 and CYP3A5 divergent residues in the enzymatic activities of these two highly homologous enzymes.

Use of antineoplastic agents in patients with cancer who have HIV/AIDS

Highly active antiretroviral therapy (HAART) has substantially reduced morbidity and mortality of AIDS-related complications in patients with HIV; however, the prevalence of AIDS-defining cancers and non-AIDS-defining cancers has increased. In this Review we discuss the management of HAART pharmacotherapy in relation to cytotoxic chemotherapy or targeted antineoplastic agents. We will review potential pharmacological interactions between antiretroviral and antineoplastic therapies and consider how to combine antiretroviral and antineoplastic agents in patients with HIV who are receiving HAART therapy.