Drug-drug interactions when treating HIV-related metabolic disorders

Introduction: Drug-drug interactions (DDI) between antiretroviral drugs and drugs for the treatment of metabolic disturbances in people living with human immunodeficiency virus (HIV) (PLWH) have represented a problem of paramount importance in the recent times. The problem has been mainly driven by sharing common metabolizing pathways. This problem has classically been worsened by the frequent use of pharmacokinetic boosters to enhance protease inhibitors and some integrase inhibitors plasma levels. Areas covered: This article focuses on the interactions between antiretroviral drugs and those drugs used to treat metabolic disturbances which frequently appear in PLWH. These include dyslipidemia, diabetes mellitus, hyperuricemia, and finally, drugs for the treatment of overweight and clinical obesity. References from PubMed, Embase, or Web of Science, among others, were reviewed. Expert opinion: The advent of safer drugs, in terms of DDI, in the antiretroviral and the metabolic field,such as non-boosted antiretrovirals and drugs with divergent metabolizing paths. Besides, learning by the caregivers on how to decrease and manage DDI, together with the extensive use of online updated DDI databases, has undoubtedly minimized the problem. The foreseeable increase in the burden of HIV-associated comorbidities and their associated treatments anticipates further complexities in the management of DDI in PLWH.

Tolerability of Current Antiretroviral Single-Tablet Regimens

The advent of protease inhibitors (PI) in the mid-nineties and its use as part of triple combinations revolutionized the management of HIV infection. Since then, progression to AIDS and AIDS-related deaths can be prevented. However, antiretroviral therapy based on PI has been discouraged for a while given its lower tolerability compared to alternative options; and only recent improvements in pharmacotherapy have renewed the interest for the newest agents within this class. First, the tolerability of the latest PI darunavir (DRV) and atazanavir is much better than for older PI, such as indinavir or lopinavir. Second, metabolic abnormalities and/or drug interactions associated to ritonavir boosting have been ameliorated using cobicistat. Third, adding safer accompanying nucleos(t)ides, such as tenofovir alafenamide (TAF), have minimized further toxicity concerns of PI. Finally, the unique barrier to resistance and new single-tablet regimen (STR) presentation makes DRV, especially attractive for long-term therapy. The recent coformulation of DRV, cobicistat, TAF, and emtricitabine (DRV/c/TAF/FTC) within a single pill to be given once daily (Symtuza^®) has positioned PI again at the frontline of HIV therapeutics. In this review, we discuss the results of studies that have assessed the efficacy and safety of the newest STR. In view of the current data, it seems worthy expanding the consideration of Symtuza® for a wider range of clinical scenarios, beyond the treatment of antiretroviral failures including first-line therapy and switching of otherwise virologically suppressed patients. The good tolerability and robust resistance profile should reward Symtuza^® and position it among the preferred contemporary STRs.

Differences between HIV-infected and uninfected adults in the contributions of smoking, diabetes and hypertension to acute coronary syndrome: two parallel case-control studies

OBJECTIVES

The aim of the study was to assess the separate contributions of smoking, diabetes and hypertension to acute coronary syndrome (ACS) in HIV-infected adults relative to uninfected adults.

METHODS

Two parallel case-control studies were carried out. In the first study, HIV-positive adults diagnosed with ACS between 1997 and 2009 (HIV+/ACS) were matched for age, gender and known duration of HIV infection with HIV-positive adults without ACS (HIV+/noACS), each individual in the HIV+/ACS group being matched with three individuals in the HIV+/noACS group. In the second study, each individual in the HIV+/ACS group in the first study was matched for age, gender and calendar date of ACS diagnosis with three HIV-negative individuals diagnosed with ACS between 1997 and 2009 (HIV-/ACS). Each individual in the HIV-/ACS group was then matched for age and gender with an HIV-negative adult without ACS (HIV-/noACS). After matching, the ratio of numbers of individuals in the HIV+/ACS, HIV+/noACS, HIV-/ACS and HIV-/noACS groups was therefore 1 : 3 : 3 : 3, respectively. We performed logistic regression analyses to identify risk factors for ACS in each case-control study and calculated population attributable risks (PARs) for smoking, diabetes and hypertension in HIV-positive and HIV-negative individuals.

RESULTS

There were 57 subjects in the HIV+/ACS group, 173 in the HIV+/noACS group, 168 in the HIV-/ACS group, and 171 in the HIV-/noACS group. Independent risk factors for ACS were smoking [odds ratio (OR) 4.091; 95% confidence interval (CI) 2.086-8.438; P < 0.0001] and a family history of cardiovascular disease (OR 7.676; 95% CI 1.976-32.168; P = 0.0003) in HIV-positive subjects, and smoking (OR 4.310; 95% CI 2.425-7.853; P < 0.0001), diabetes (OR 5.778; 95% CI 2.393-15.422; P = 0.0002) and hypertension (OR 6.589; 95% CI 3.554-12.700; P < 0.0001) in HIV-negative subjects. PARs for smoking, diabetes and hypertension were 54.35 and 30.58, 6.57 and 17.24, and 9.07 and 38.81% in HIV-positive and HIV-negative individuals, respectively.

CONCLUSIONS

The contribution of smoking to ACS in HIV-positive adults was generally greater than the contributions of diabetes and hypertension, and was almost twice as high as that in HIV-negative adults. Development of effective smoking cessation strategies should be prioritized to prevent cardiovascular disease in HIV-positive adults.

The toxicogenetics of antiretroviral therapy: the evil inside

The most important factor limiting the success of an antiretroviral therapy regimes is toxicity. Toxicity can depend on a number of factors; some of these are intrinsic to the host and may not only affect the latter's outward appearance, but also determine the intensity these toxic effects may reach. The former is exemplified by idiosyncratic or hypersensitivity reactions, whereas the latter is usually appreciated in metabolic disturbances or fat redistribution syndromes. Some of the determinants of antiretroviral toxicity are genetic in origin and have been the subject of intense study in recent years. Some of these are linked to a single nucleotide polymorphism (SNP), whereas others depend on a complex interaction between multiple genes variations. One of these tests (HLA B*5701) is now being applied in clinical practice and widely used to prevent the risk of hypersensitivity reactions to abacavir. Many other genetic determinants of antiretroviral drug toxicity have been suggested as an explanation for nucleoside analogue toxicity; these include lactic acidosis, peripheral neuropathy and pancreatitis, and have also been suggested as a potential basis for the non-nucleoside toxicity derived from immunogenetic factors involved in nevirapine hypersensitivity to SNPs in efavirenz enzyme metabolism, amongst other things. Metabolic toxicity, mainly due to protease inhibitors (PIs) is far more complex and depends on the interaction of various genes. The same seems to be true for fat redistribution syndromes and atherosclerosis, although a clear picture of the genetic factors operating in these syndromes is yet to emerge. The ultimate goal of pharmacogenetics is to customize antiretroviral therapy by identifying the genes that can maximize efficacy whilst helping avoid known side effects of antiretroviral drugs.