In vitro assessment of antiretroviral drugs demonstrates potential for ototoxicity

Assessment of the toxicity of different antiretroviral drugs and their combinations on Sertoli and Leydig cells

The human immunodeficiency virus continues to pose a significant global public health challenge, affecting millions of individuals. The current treatment strategy has incorporated the utilization of combinations of antiretroviral drugs. The administration of these drugs is associated with many deleterious consequences on several physiological systems, notably the reproductive system. This study aimed to assess the toxic effects of abacavir sulfate, ritonavir, nevirapine, and zidovudine, as well as their combinations, on TM3 Leydig and TM4 Sertoli cells. The cell viability was gauged using 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) and neutral red uptake (NRU) assays. Reactive oxygen species (ROS) production was assessed via the 2',7'-dichlorofluorescein diacetate (DCFDA) test, and DNA damage was determined using the comet assay. Results indicated cytotoxic effects at low drug concentrations, both individually and combined. The administration of drugs, individually and in combination, resulted in the production of ROS and caused damage to the DNA at the tested concentrations. In conclusion, the results of this study suggest that the administration of antiretroviral drugs can lead to testicular toxicity by promoting the generation of ROS and DNA damage. Furthermore, it should be noted that the toxicity of antiretroviral drug combinations was shown to be higher compared to that of individual drugs.

Anti-CD4 antibody and dendrimeric peptide based targeted nano-liposomal dual drug formulation for the treatment of HIV infection

AIMS

Development and characterization of LAM and DTG loaded liposomes conjugated anti-CD4 antibody and peptide dendrimer (PD2) to improve the therapeutic efficacy and to achieve targeted treatment for HIV infection.

MAIN METHODS

A 2-level full factorial design was used to optimize the preparation of dual drug loaded liposomes. Optimized dual drug loaded ligand conjugated liposomes were assessed for their cytotoxicity and cell internalization on TZM-bl cells. Anti-HIV efficiency of the dual drug loaded liposomes were screened for their inhibitory potential in TZM-bl cells and the activities were confirmed using Peripheral Blood Mononuclear Cells (PBMCs).

KEY FINDINGS

The particle size of the optimized dual drug-loaded liposomes was 133.7 ± 4.04 nm, and the spherical morphology of the liposomes was confirmed by TEM analysis. The entrapment efficiency was 34 ± 4.9 % and 54 ± 1.8 % for LAM and DTG, respectively, and a slower in vitro release of LAM and DTG was observed when entrapped into liposomes. The cytotoxicity of the dual drug loaded liposomes was similar to the cytotoxicity of free drug solutions. Conjugation of anti-CD4 antibody and PD2 did not significantly influence the cytotoxicity but it enhanced the uptake of liposomes into the cells. Conjugated dual drug loaded liposomes exhibited better HIV inhibition with lower IC50 values (0.0003 ± 0.0002 μg/mL) compared to their free drug solutions (0.002 ± 0.001 μg/mL). The liposomal formulations have shown similar activities in both screening and confirmatory cell-based assays.

SIGNIFICANCE

The results demonstrated the cell targeting ability of dual drug loaded liposomes conjugated with anti-CD4 antibody and peptide dendrimer. Conjugated liposomes also improved anti-HIV efficiency of LAM and DTG.

Phytosterols reverse antiretroviral-induced hearing loss, with potential implications for cochlear aging

Cholesterol contributes to neuronal membrane integrity, supports membrane protein clustering and function, and facilitates proper signal transduction. Extensive evidence has shown that cholesterol imbalances in the central nervous system occur in aging and in the development of neurodegenerative diseases. In this work, we characterize cholesterol homeostasis in the inner ear of young and aged mice as a new unexplored possibility for the prevention and treatment of hearing loss. Our results show that cholesterol levels in the inner ear are reduced during aging, an effect that is associated with an increased expression of the cholesterol 24-hydroxylase (CYP46A1), the main enzyme responsible for cholesterol turnover in the brain. In addition, we show that pharmacological activation of CYP46A1 with the antiretroviral drug efavirenz reduces the cholesterol content in outer hair cells (OHCs), leading to a decrease in prestin immunolabeling and resulting in an increase in the distortion product otoacoustic emissions (DPOAEs) thresholds. Moreover, dietary supplementation with phytosterols, plant sterols with structure and function similar to cholesterol, was able to rescue the effect of efavirenz administration on the auditory function. Altogether, our findings point towards the importance of cholesterol homeostasis in the inner ear as an innovative therapeutic strategy in preventing and/or delaying hearing loss.

Ototoxicity prognostic models in adult and pediatric cancer patients: a rapid review

PURPOSE

A cornerstone of treatment for many cancers is the administration of platinum-based chemotherapies and/or ionizing radiation, which can be ototoxic. An accurate ototoxicity risk assessment would be useful for counseling, treatment planning, and survivorship follow-up in patients with cancer.

METHODS

This systematic review evaluated the literature on predictive models for estimating a patient's risk for chemotherapy-related auditory injury to accelerate development of computational approaches for the clinical management of ototoxicity in cancer patients. Of the 1195 articles identified in a PubMed search from 2010 forward, 15 studies met inclusion for the review.

CONCLUSIONS

All but 1 study used an abstraction of the audiogram as a modeled outcome; however, specific outcome measures varied. Consistently used predictors were age, baseline hearing, cumulative cisplatin dose, and radiation dose to the cochlea. Just 5 studies were judged to have an overall low risk of bias. Future studies should attempt to minimize bias by following statistical best practices including not selecting multivariate predictors based on univariate analysis, validation in independent cohorts, and clearly reporting the management of missing and censored data. Future modeling efforts should adopt a transdisciplinary approach to define a unified set of clinical, treatment, and/or genetic risk factors. Creating a flexible model that uses a common set of predictors to forecast the full post-treatment audiogram may accelerate work in this area. Such a model could be adapted for use in counseling, treatment planning, and follow-up by audiologists and oncologists and could be incorporated into ototoxicity genetic association studies as well as clinical trials investigating otoprotective agents.

IMPLICATIONS FOR CANCER SURVIVORS

Improvements in the ability to model post-treatment hearing loss can help to improve patient quality of life following cancer care. The improvements advocated for in this review should allow for the acceleration of advancements in modeling the auditory impact of these treatments to support treatment planning and patient counseling during and after care.

Exploring the effects and mechanisms of organophosphorus pesticide exposure and hearing loss

Many environmental factors, such as noise, chemicals, and heavy metals, are mostly produced by human activities and easily induce acquired hearing loss. Organophosphorus pesticides (OPs) constitute a large variety of chemicals and have high usage with potentiate damage to human health. Moreover, their metabolites also show a serious potential contamination of soil, water, and air, leading to a serious impact on people's health. Hearing loss affects 430 million people (5.5% of the global population), bringing a heavy burden to individual patients and their families and society. However, the potential risk of hearing damage by OPs has not been taken seriously. In this study, we summarized the effects of OPs on hearing loss from epidemiological population studies and animal experiments. Furthermore, the possible mechanisms of OP-induced hearing loss are elucidated from oxidative stress, DNA damage, and inflammatory response. Overall, this review provides an overview of OP exposure alone or with noise that leads to hearing loss in human and experimental animals.

Putative COVID-19 therapies imatinib, lopinavir, ritonavir, and ivermectin cause hair cell damage: A targeted screen in the zebrafish lateral line

The biomedical community is rapidly developing COVID-19 drugs to bring much-need therapies to market, with over 900 drugs and drug combinations currently in clinical trials. While this pace of drug development is necessary, the risk of producing therapies with significant side-effects is also increased. One likely side-effect of some COVID-19 drugs is hearing loss, yet hearing is not assessed during preclinical development or clinical trials. We used the zebrafish lateral line, an established model for drug-induced sensory hair cell damage, to assess the ototoxic potential of seven drugs in clinical trials for treatment of COVID-19. We found that ivermectin, lopinavir, imatinib, and ritonavir were significantly toxic to lateral line hair cells. By contrast, the approved COVID-19 therapies dexamethasone and remdesivir did not cause damage. We also did not observe damage from the antibiotic azithromycin. Neither lopinavir nor ritonavir altered the number of pre-synaptic ribbons per surviving hair cell, while there was an increase in ribbons following imatinib or ivermectin exposure. Damage from lopinavir, imatinib, and ivermectin was specific to hair cells, with no overall cytotoxicity noted following TUNEL labeling. Ritonavir may be generally cytotoxic, as determined by an increase in the number of TUNEL-positive non-hair cells following ritonavir exposure. Pharmacological inhibition of the mechanotransduction (MET) channel attenuated damage caused by lopinavir and ritonavir but did not alter imatinib or ivermectin toxicity. These results suggest that lopinavir and ritonavir may enter hair cells through the MET channel, similar to known ototoxins such as aminoglycoside antibiotics. Finally, we asked if ivermectin was ototoxic to rats in vivo. While ivermectin is not recommended by the FDA for treating COVID-19, many people have chosen to take ivermectin without a doctor’s guidance, often with serious side-effects. Rats received daily subcutaneous injections for 10 days with a clinically relevant ivermectin dose (0.2 mg/kg). In contrast to our zebrafish assays, ivermectin did not cause ototoxicity in rats. Our research suggests that some drugs in clinical trials for COVID-19 may be ototoxic. This work can help identify drugs with the fewest side-effects and determine which therapies warrant audiometric monitoring.

Hearing Loss in Offspring Exposed to Antiretrovirals During Pregnancy and Breastfeeding

Over 27 million people worldwide currently receive daily antiretroviral therapy for the management of HIV/AIDS. In order to prevent the continued spread of HIV, the World Health Organization (WHO) recommends the use of highly active antiretroviral therapy by pregnant and nursing women. There is currently little research into the auditory effects of this therapy on children exposed during pregnancy and breastfeeding, and research to date on the direct effects of antiretroviral exposure on the auditory system is inconclusive. The current study examined the effects of WHO-recommended first-line antiretrovirals in a well-controlled animal model to evaluate the potential for auditory damage and dysfunction following these exposures. Female breeding mice were each exposed to one of four antiretroviral cocktails or a vehicle control once daily during pregnancy and breastfeeding. Offspring of these mice had their auditory status evaluated after weaning using auditory brainstem responses and distortion-product otoacoustic emissions (DPOAEs). Auditory brainstem response thresholds following antiretroviral exposure during gestation and breastfeeding showed elevated thresholds and increased wave latencies in offspring of exposed mice when compared to unexposed controls, but no corresponding decrease in DPOAE amplitude. These differences in threshold were small and so may explain the lack of identified hearing loss in antiretroviral-exposed children during hearing screenings at birth. Minimal degrees of hearing impairment in children have been correlated with decreased academic performance and impaired auditory processing, and so these findings, if also seen in human children, suggest significant implications for children exposed to antiretrovirals during development despite passing hearing screenings at birth.

Vestibular Cochlear Manifestations in COVID-19 Cases

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a high transmissible infectious disease that primarily impacts the respiratory system and leads to death as it worsens. Ever since the World Health Organization declared the disease as a global pandemic, the pathophysiology, clinical manifestations, and disease prognosis has been discussed in various literature. In addition to impaired respiratory health, the symptoms also indicated the involvement of the cardiovascular and neurological system after SARS-CoV-2 infection. Despite the pulmonary, cardiovascular, and neurological complications, many reports also revealed the prevalence of vestibulocochlear symptoms like dizziness, vertigo, vestibular neuritis, sudden sensorineural hearing loss, and tinnitus. Though many clinical reports and scientific reviews reported the vestibular and cochlear impairments associated with coronavirus disease 2019 (COVID-19) infection, the underlying pathological mechanisms are still unclear and unexplored. In this review, we discussed the published clinical reports, research articles, and literature reviews related to vestibulocochlear manifestations following SARS-CoV-2 infections. We also summarized the current knowledge about the prevalence, epidemiological and clinical features, and potential pathological mechanisms related to vestibular and cochlear manifestations resulting from COVID-19 infections.

Detecting Novel Ototoxins and Potentiation of Ototoxicity by Disease Settings

Over 100 drugs and chemicals are associated with permanent hearing loss, tinnitus, and vestibular deficits, collectively known as ototoxicity. The ototoxic potential of drugs is rarely assessed in pre-clinical drug development or during clinical trials, so this debilitating side-effect is often discovered as patients begin to report hearing loss. Furthermore, drug-induced ototoxicity in adults, and particularly in elderly patients, may go unrecognized due to hearing loss from a variety of etiologies because of a lack of baseline assessments immediately prior to novel therapeutic treatment. During the current pandemic, there is an intense effort to identify new drugs or repurpose FDA-approved drugs to treat COVID-19. Several potential COVID-19 therapeutics are known ototoxins, including chloroquine (CQ) and lopinavir-ritonavir, demonstrating the necessity to identify ototoxic potential in existing and novel medicines. Furthermore, several factors are emerging as potentiators of ototoxicity, such as inflammation (a hallmark of COVID-19), genetic polymorphisms, and ototoxic synergy with co-therapeutics, increasing the necessity to evaluate a drug's potential to induce ototoxicity under varying conditions. Here, we review the potential of COVID-19 therapies to induce ototoxicity and factors that may compound their ototoxic effects. We then discuss two models for rapidly detecting the potential for ototoxicity: mammalian auditory cell lines and the larval zebrafish lateral line. These models offer considerable value for pre-clinical drug development, including development of COVID-19 therapies. Finally, we show the validity of in silico screening for ototoxic potential using a computational model that compares structural similarity of compounds of interest with a database of known ototoxins and non-ototoxins. Preclinical screening at in silico, in vitro, and in vivo levels can provide an earlier indication of the potential for ototoxicity and identify the subset of candidate therapeutics for treating COVID-19 that need to be monitored for ototoxicity as for other widely-used clinical therapeutics, like aminoglycosides and cisplatin.

Cerebral Vascular Toxicity of Antiretroviral Therapy

HIV infection is associated with comorbidities that are likely to be driven not only by HIV itself, but also by the toxicity of long-term use of antiretroviral therapy (ART). Indeed, increasing evidence demonstrates that the antiretroviral drugs used for HIV treatment have toxic effects resulting in various cellular and tissue pathologies. The blood-brain barrier (BBB) is a modulated anatomophysiological interface which separates and controls substance exchange between the blood and the brain parenchyma; therefore, it is particularly exposed to ART-induced toxicity. Balancing the health risks and gains of ART has to be considered in order to maximize the positive effects of therapy. The current review discusses the cerebrovascular toxicity of ART, with the focus on mitochondrial dysfunction. Graphical Abstract Graphical representation of the interactions between HIV, antiretroviral therapy (ART), and the blood-brain barrier (BBB).

A Narrative Review of Pharmacologic Treatments for COVID-19: Safety Considerations and Ototoxicity

OBJECTIVE/HYPOTHESIS

The purpose of this review is to summarize evidence-based data regarding the ototoxic effects of potential COVID-19 therapeutics to treat patients suffering from SARS-CoV-2.

METHODS

Medications under investigation as novel therapeutics to treat COVID-19 were identified using the search term coronavirus therapeutics, COVID therapeutics, and SARS-CoV-2 therapeutics on ClinicalTrials.gov and the PubMed Database. A literature review was performed using the PubMed Database for each proposed COVID-19 therapeutic to identify relevant articles. Search criteria included Medical Subject Headings (MeSH) and key word search terms for ototoxicity, vestibulotoxicity, hearing disorders, and vertigo.

RESULTS

Six proposed COVID-19 therapeutics were identified as possessing ototoxic side effects including chloroquine and hydroxychloroquine, azithromycin, lopinavir-ritonavir, interferon, ribavirin, and ivermectin.

CONCLUSIONS

Available evidence suggests that ototoxic effects may be improved or mitigated by stopping the offending agent. Recognition of hearing loss, tinnitus, or imbalance/vertigo is therefore crucial to facilitate early intervention and prevent long-term damage. Hospitals should consider the inclusion of audiologic monitoring protocols for patients receiving COVID-19 therapeutics with known ototoxicity, especially in high-risk patient groups such as the elderly and hearing impaired. Laryngoscope, 131:1626-1632, 2021.

Don't forget ototoxicity during the SARS-CoV-2 (Covid-19) pandemic!

Aim of this communication is to remind clinical professionals to be aware of ototoxic side effects of several specific drugs proposed for the treatment of the new virus SARS-CoV-2 (Covid-19). In particular, chloroquine and hydroxychloroquine, azithromycin, as well as antiviral drugs such as remdesivir, favipiravir and lopinavir can all present potential ototoxic side effects. The data in the literature do not offer specific information on their potential synergetic effects nor on their interactions.

Nevirapine Biotransformation Insights: An Integrated In Vitro Approach Unveils the Biocompetence and Glutathiolomic Profile of a Human Hepatocyte-Like Cell 3D Model

The need for competent in vitro liver models for toxicological assessment persists. The differentiation of stem cells into hepatocyte-like cells (HLC) has been adopted due to its human origin and availability. Our aim was to study the usefulness of an in vitro 3D model of mesenchymal stem cell-derived HLCs. 3D spheroids (3D-HLC) or monolayer (2D-HLC) cultures of HLCs were treated with the hepatotoxic drug nevirapine (NVP) for 3 and 10 days followed by analyses of Phase I and II metabolites, biotransformation enzymes and drug transporters involved in NVP disposition. To ascertain the toxic effects of NVP and its major metabolites, the changes in the glutathione net flux were also investigated. Phase I enzymes were induced in both systems yielding all known correspondent NVP metabolites. However, 3D-HLCs showed higher biocompetence in producing Phase II NVP metabolites and upregulating Phase II enzymes and MRP7. Accordingly, NVP-exposure led to decreased glutathione availability and alterations in the intracellular dynamics disfavoring free reduced glutathione and glutathionylated protein pools. Overall, these results demonstrate the adequacy of the 3D-HLC model for studying the bioactivation/metabolism of NVP representing a further step to unveil toxicity mechanisms associated with glutathione net flux changes.

Drug-induced hearing loss: a case/non-case study in the French pharmacovigilance database

Hearing loss is defined as a decrease in the ability to perceive sounds which can occur suddenly or gradually and affects one ear or both. It is related to various etiologies, in particular drugs. The identification of all drugs that could be associated with hearing loss is essential for the patients' life quality. The objective of our study was to identify signals of hearing loss involving drugs approved in the last 20 years. The occurrence in association with drugs known for their ototoxicity was also analyzed. We used a case/non-case method in the French Pharmacovigilance Database (FPVD). The cases were reports of hearing loss in the FPVD between January 2007 and August 2017. Non-cases were all reports over the same period. We calculated the reporting odds ratio (ROR) with 95% confidence intervals. Among the 555 reports of hearing loss, significant RORs were found for 68 drugs. The main therapeutic classes implicated were antineoplastic agents (n = 240), systemic anti-infective agents (n = 182), immunosuppressants (n = 42) loop diuretics (n = 26), and salicylate analgesics (n = 26). We found signals of hearing loss with azacitidine, vaccines and nevirapine, immunosuppressants such as leflunomide, and biotherapies such as panitumumab and vandetanib. Prescribers should be informed about the potential associations with all these drugs. The role of the pathology itself and the known ototoxic drugs that can be associated do not allow to conclude definitively. Audiograms for the early detection of hearing loss induced by drugs known to be ototoxic are rarely carried out. Preventive treatments exist and must be considered.

An Evidence-Based Practical Approach to Pediatric Otolaryngology in the Developing World

Despite humanitarian otolaryngology groups traveling in record numbers to resource-limited areas treating pediatric otolaryngology disease processes and training local providers, there remains a large burden of unmet needs. There is a meager amount of published information that comes from the developing world from an otolaryngology standpoint. As would be expected, the little information that does comes involves some of the most common pediatric otolaryngology diseases and surgical burdens including childhood hearing loss, otitis media, adenotonsillectomies, airway obstructions requiring tracheostomies, foreign body aspirations, and craniomaxillofacial surgeries, including cleft lip and palate.

HIV status and hearing loss among children between 6 and 12 years of age at a large urban health facility in south western Uganda

INTRODUCTION

Pediatric HIV infection and treatment may increase the risk for hearing loss (HL), both sensorineural (SNHL) and conductive hearing loss (CHL). There is limited data on this subject, especially from sub Saharan Africa. The aim of this study was therefore to compare the prevalence of hearing loss among HIV positive and negative children, to determine the types of hearing loss and whether Nevirapine (NVP) based antiretroviral therapy (ART) is associated with HL.

METHODS

We conducted a cross sectional study at two tertiary health facilities in south western Uganda. We consecutively enrolled 79 HIV negative and 148 HIV positive children aged between 6 and 12 years. Inclusion criteria were completion of written consent, ability to follow instructions to perform an audiogram and absence of congenital HL. We conducted hearing screening using the iPad Shoebox® audiometer, and confirmatory assessments were conducted using pure tone audiometry. Hearing was classified as either normal hearing, CHL, SNHL or mixed.

RESULTS

Of the 227 children enrolled, 115 (50.7%) were female. The mean age was 9.2 years (median = 9). Based on self-report, frequency of HL among HIV positive children was 6.8% and 20.3% among HIV negative children (p=<0.01). Using objective measures, prevalence of HL among the HIV positive children was 8.8% compared to 10.1% among the HIV negative children (p = 0.74). CHL was generally more frequent than SNHL but SNHL occurred more frequently among HIV positive (7.4%) compared to HIV negative children (3.8%). No association was found between NVP based ART and HL (p = 0.41). Logistic regression showed that older age of the child (p = 0.01), previous ear infection (p=<0.01), tuberculosis (TB) treatment (p=<0.01) and long term duration on ART (p=<0.01) were significantly associated with HL. Age (p = 0.02), previous ear infection (p = 0.01) and TB treatment (p = 0.005) remained significant in the multiple regression model.

CONCLUSION

Prevalence of HL is similar among HIV positive and negative children. Older age of the child, previous ear infection, use of TB drugs and long duration on ART among the HIV positive children increase the odds of having hearing loss among children. However, use of NVP was not associated with HL.

Audiological and electrophysiological alterations in HIV-infected individuals subjected or not to antiretroviral therapy

Introduction

The Human Immunodeficiency Virus (HIV) and infections related to it can affect multiple sites in the hearing system. The use of High Activity Anti-Retroviral Therapy (HAART) can cause side effects such as ototoxicity. Thus, no consistent patterns of hearing impairment in adults with Human Immunodeficiency Virus / Acquired Immune Deficiency Syndrome have been established, and the problems that affect the hearing system of this population warrant further research.

Objectives

This study aimed to compare the audiological and electrophysiological data of Human Immunodeficiency Virus-positive patients with and without Acquired Immune Deficiency Syndrome, who were receiving High Activity Anti-Retroviral Therapy, to healthy individuals.

Methods

It was a cross-sectional study conducted with 71 subjects (30–48 years old), divided into groups: Research Group I: 16 Human Immunodeficiency Virus-positive individuals without Acquired Immunodeficiency Syndrome (not receiving antiretroviral treatment); Research Group II: 25 Human Immunodeficiency Virus-positive individuals with Acquired Immunodeficiency Syndrome (receiving antiretroviral treatment); Control Group: 30 healthy subjects. All individuals were tested by pure-tone air conduction thresholds at 0.25–8 kHz, extended high frequencies at 9–20 kHz, electrophysiological tests (Auditory Brainstem Response, Middle Latency Responses, Cognitive Potential).

Results

Research Group I and Research Group II had higher hearing thresholds in both conventional and high frequency audiometry when compared to the control group, prolonged latency of waves I, III, V and interpeak I–V in Auditory Brainstem Response and prolonged latency of P300 Cognitive Potential. Regarding Middle Latency Responses, there was a decrease in the amplitude of the Pa wave of Research Group II compared to the Research Group I.

Conclusions

Both groups with Human Immunodeficiency Virus had higher hearing thresholds when compared to healthy individuals (group exposed to antiretroviral treatment showed the worst hearing threshold) and seemed to have lower neuroelectric transmission speed along the auditory pathway in the brainstem, subcortical and cortical regions.

Nevirapine modulation of paraoxonase-1 in the liver: An in vitro three-model approach

INTRODUCTION

Nevirapine is associated with severe hepatotoxicity, through the formation of reactive metabolites. Paraoxonase-1 (PON-1) is a promiscuous enzyme involved in the metabolism of xeno- and endobiotics and proposed as a biomarker of hepatotoxicity. The aim of this work was to explore the effects of nevirapine and its phase I metabolites, 2-hydroxy-nevirapine and 12-hydroxy-nevirapine, on PON-1 activities.

MATERIAL AND METHODS

2D and 3D primary cultures of rat hepatocytes, and also HepG2 2D cell cultures, were exposed to nevirapine, 2-hydroxy-nevirapine, and 12-hydroxy-nevirapine. The paraoxonase (POase), arylesterase (AREase) and lactonase (LACase) activities of PON-1 were quantified.

RESULTS

Effects of nevirapine and its metabolites were only observed in the 3D cell model. Both nevirapine and 12-hydroxy-nevirapine increased POase (p<0.05, p<0.01) and LACase activities (p<0.05, p<0.001). The AREase activity was increased only upon 12-hydroxy-nevirapine exposure (p<0.01). These modulatory effects were observed at 300μM concentrations of nevirapine and 12-hydroxy-nevirapine.

CONCLUSIONS

The formation of 12-hydroxy-nevirapine seems to be the main factor responsible for the increase of PON-1 activities induced by nevirapine exposure. This effect was only observed in the 3D model, suggesting that an in vivo-like system is necessary for this modulation to occur. The present data suggest that the 3D model is a more suitable in vitro model than the conventional ones to explore drug effects on PON-1.

Amikacin Concentrations Predictive of Ototoxicity in Multidrug-Resistant Tuberculosis Patients

Aminoglycosides, such as amikacin, are used to treat multidrug-resistant tuberculosis. However, ototoxicity is a common problem and is monitored using peak and trough amikacin concentrations based on World Health Organization recommendations. Our objective was to identify clinical factors predictive of ototoxicity using an agnostic machine learning method. We used classification and regression tree (CART) analyses to identify clinical factors, including amikacin concentration thresholds that predicted audiometry-confirmed ototoxicity among 28 multidrug-resistant pulmonary tuberculosis patients in Botswana. Amikacin concentrations were measured for all patients. The quantitative relationship between predictive factors and the probability of ototoxicity were then identified using probit analyses. The primary predictors of ototoxicity on CART analyses were cumulative days of therapy, followed by cumulative area under the concentration-time curve (AUC), which improved on the primary predictor by 87%. The area under the receiver operating curve was 0.97 on the test set. Peak and trough were not predictors in any tree. When algorithms were forced to pick peak and trough as primary predictors, the area under the receiver operating curve fell to 0.46. Probit analysis revealed that the probability of ototoxicity increased sharply starting after 6 months of therapy to near maximum at 9 months. A 10% probability of ototoxicity occurred with a threshold cumulative AUC of 87,232 days · mg · h/liter, while that of 20% occurred at 120,000 days · mg · h/liter. Thus, cumulative amikacin AUC and duration of therapy, and not peak and trough concentrations, should be used as the primary decision-making parameters to minimize the likelihood of ototoxicity in multidrug-resistant tuberculosis.