Oral oncolytic and antiretroviral therapy administration: dose adjustments, drug interactions, and other considerations for clinical use

Drug-drug interactions in HIV-infected patients receiving chemotherapy

INTRODUCTION

Coadministration of antiretrovirals and anti-cancer medications may present many complex clinical scenarios. This is characterized by the potential for drug-drug interactions (DDIs) and the challenges that arise in patient management. In this article, we investigate the potential for DDIs between antiretrovirals, including protease inhibitors (PIs), non-nucleoside reverse transcriptase inhibitors, nucleoside reverse transcriptase inhibitors (NRTIs), integrase strand transfer inhibitors (INSTIs), and anti-cancer medications.

AREAS COVERED

PubMed, Google Scholar, and Clinicaltrials.gov were searched for relevant articles in April 2024. Our review highlights PIs and NNRTIs as particularly prone to DDIs with anticancer agents, with implications for efficacy and toxicity of concomitant cancer therapy. We explain the mechanisms for interactions, emphasizing the significance of pharmacokinetic effects and enzyme induction or inhibition. We discuss clinical challenges encountered in the management of patients receiving combined ART and cancer therapy regimens.

EXPERT OPINION

Data are lacking for potential DDIs between antiretroviral and anti-cancer agents. While some interactions are documented, others are theoretical and based on the pharmacokinetic properties of the medications. Awareness of these interactions, inter-collaborative care between healthcare providers, and standardized treatment guidelines are all crucial for achieving optimal treatment outcomes and ensuring the well-being of patients with HIV/AIDS and cancer comorbidities.

The impact of HIV on non-adherence for tamoxifen among women with breast cancer in South Africa

PURPOSE

Women living with HIV (WLWH) and breast cancer (BC) have worse overall survival than HIV-negative women with BC, and poor adherence to prescribed tamoxifen is known to contribute to poor survival. We therefore investigated the association of HIV infection with adherence to adjuvant tamoxifen among women with localized hormone receptor (HR)-positive breast cancer in South Africa.

METHODS

Among 4,097 women diagnosed with breast cancer at six hospitals in the prospective South African Breast Cancer and HIV Outcomes (SABCHO) cohort study between July 2015 and December 2020, we focused on black women with stages I-III HR-positive breast cancer who were prescribed 20 mg of adjuvant tamoxifen daily. We collected venous blood once from each participant during a routine clinic visit, and analyzed concentrations of tamoxifen and its metabolites using a triple quadruple mass spectrometer. We defined non-adherence as a tamoxifen level < 60 ng/mL after 3 months of daily tamoxifen use. We compared tamoxifen-related side effects, and concurrent medication use among women with and without HIV and developed multivariable logistic regression models of tamoxifen non-adherence.

RESULTS

Among 369 subjects, 78 (21.1%) were WLWH and 291 (78.9%) were HIV-negative. After a median (interquartile range) time of 13.0 (6.2-25.2) months since tamoxifen initiation, the tamoxifen serum concentration ranged between 1.54 and 943.0 ng/mL and 208 (56.4%) women were non-adherent to tamoxifen. Women < 40 years of age were more likely to be non-adherent than women > 60 years (73.4% vs 52.6%, odds ratio (OR) = 2.49, 95% confidence interval (CI) = 1.26-4.94); likewise, WLWH (70.5% vs 52.6%, OR = 2.16, 95% CI = 1.26-3.70) than HIV-negative women. In an adjusted model WLWH had twice the odds of non-adherence to tamoxifen, compared to HIV-negative women (OR = 2.40, 95% CI = 1.11-5.20).

CONCLUSION

High rates of non-adherence to adjuvant tamoxifen may limit the overall survival of black South African women with HR-positive breast cancer, especially among WLWH.

Potential interactions between antineoplastic agents and medicines used to treat Covid-19

INTRODUCTION

Cancer patients with Covid-19 are exposed to treatment combinations that can potentially result in interactions that adversely affect patient outcomes. This study aimed to identify potential drug-drug interactions between antineoplastic agents and medicines used to treat Covid-19.

METHODS

We conducted a search for potential interactions between 201 antineoplastic agents and 26 medicines used to treat Covid-19 on the Lexicomp^® and Micromedex^® databases. The following data were extracted: interaction severity ("major" and "contraindicated") and interaction effects (pharmacokinetic and pharmacodynamic). We also sought to identify the therapeutic indication of the antineoplastic drugs involved in the potential drug-drug interactions.

RESULTS

A total of 388 "major" or "contraindicated" drug-drug interactions were detected. Eight drugs or combinations (baricitinib, lopinavir/ritonavir, atazanavir, darunavir, azithromycin, chloroquine, hydroxychloroquine, and sirolimus) accounted for 91.5% of these interactions. The class of antineoplastic agents with the greatest potential for interaction was tyrosine kinase inhibitors (accounting for 46.4% of all interactions). The findings show that atazanavir, baricitinib, and lopinavir/ritonavir can affect the treatment of all common types of cancer. The most common pharmacokinetic effect of the potential drug-drug interactions was increased plasma concentration of the antineoplastic medicine (39.4%).

CONCLUSIONS

Covid-19 is a recent disease and pharmacological interventions are undergoing constant modification. This study identified a considerable number of potential drug-drug interactions. In view of the vulnerability of patients with cancer, it is vital that health professionals carefully assess the risks and benefits of drug combinations.

Safety and efficacy of pharmacotherapy containing INSTIs and chemotherapy drugs in people living with HIV and concomitant colorectal cancer

BACKGROUND

Previous clinical data have shown that raltegravir-based antiretroviral therapy (ART) with fewer drug-drug interactions (DDIs) and adverse events (AEs) is a good regimen in patients with HIV infection who need cancer chemotherapy. There are currently few data on ART regimens that include Integrase inhibitors (INSTIs) other than RAL among this patient subgroup.

METHODS

We evaluated the safety and efficacy of different kinds of INSTI-based regimens among patients with HIV and concomitant colorectal cancer (CRC) who received antineoplastic agents.

RESULTS

From January 2020 to November 2021, 66 patients were enrolled. The patients were divided into three groups: 20 patients treated with dolutegravir (DTG)/lamivudine (3TC)/tenofovir (TDF) (group I), 24 patients treated with DTG/albuvirtide (ABT) (group II), and 22 patients treated with bictegravir (BIC)/tenofovir alafenamide (TAF)/emtricitabine (FTC) (group III). The majority of AEs during treatment were of grade 1-2. Treatment-related AEs of grade 3-4 occurred in 6 patients (9.09%), and no grade 5 AEs occurred. The most common AEs were nausea (100%) and neutrophils (84.85%) attributed to anticancer agents, and there was no significant difference in the incidence of these AEs among the three groups (P > 0.05). Viral load rebound was not observed among pretreated patients during chemotherapy. The viral load of untreated patients who started their ART concomitant with chemotherapy almost decreased to the lower limit of detection 6 months after ART initiation (only one patient in group III had a viral load of 102 copies/ml). At the 6th month, the CD4 count in group I decreased significantly from baseline (P < 0.05). However, the change in CD4 count was not significant in group II (P = 0.457) or group III (P = 0.748).

CONCLUSIONS

DTG- or BIC-containing regimens are good options for patients with HIV and concomitant CRC.

The Prevalence of Polypharmacy and Potential Drug-Drug Interactions among Iranian Cancer Patients: which Patients Were at Risk?

INTRODUCTION

Drug-Drug interactions (DDIs) are one of the considerable consequences of polypharmacy. Due to the influence of polypharmacy and drug interactions on cancer treatment and patients` health outcomes, the present study aimed to determine the prevalence of polypharmacy and potential DDIs among adult cancer patients in Kerman province, southeast of Iran.

METHODS

In this cross-sectional study, 315 cancer patients who referred to Kerman city oncology clinics were assessed in 2018. Data were collected through face-to-face interviews and medical charts were reviewed. Polypharmacy was defined as the use of at least five drugs simultaneously. Potential DDIs were checked using the "Drugs.com" online database. A bivariable and a multivariable logistic regression were used to determine the associated factors of outcome variables, polypharmacy status and potential DDI in SPSS software version 23.

RESULTS

Of 315 cancer patients, 191 patients (60.6%; 95% CI:54.9, 66) used at least five drugs during chemotherapy courses. The prevalence of potential DDIs was 59.6% (n = 140, 95% CI: 53.6-66.0. Experience co-morbid diseases (OR:6.60; 95%CI: 3.82, 11.42; P-value ≤0.0001), and positive metastatic status (OR:2.80; 95%CI: 1.62, 4.82; P-value ≤0.0001) could predict the polypharmacy during chemotherapy courses. Patients who suffered gastrointestinal cancers (OR:5.55; 95%CI: 2.26, 13.62; P-value ≤0.0001) and the number of prescribed or Over The Counter (OTC) drugs (OR:1.29; 95%CI: 1.12, 1.48; P-value <0.0001) predicted the occurrence of potential DDIs among cancer patients.

CONCLUSION

Regarding the high prevalence of polypharmacy and potential drug interactions among Iranian cancer patients during chemotherapy courses, it is advisable for physicians, nurses, and pharmacists to be vigilant to improve prescribing patterns. In addition, with intensive monitoring, alternative treatment strategies can be replaced.

The intersection of drug interactions and adverse reactions in contemporary antiretroviral therapy

PURPOSE OF REVIEW

Advances in antiretroviral therapy (ART) have transformed HIV infection into a chronic and manageable condition. The introduction of potent and more tolerable antiretrovirals (ARVs) with favorable pharmacokinetic profiles has changed the prevalence and nature of drug-drug interactions (DDIs). Here, we review the relevance of DDIs in the era of contemporary ART.

RECENT FINDINGS

Management of DDIs remains an important challenge with modern ART, primarily due to increased polypharmacy in older persons living with HIV. Significant DDIs exist between boosted ARVs or older nonnucleoside reverse transcriptase inhibitors and comedications for chronic comorbidities (e.g., anticoagulants, antiplatelets, statins) or complex conditions (e.g., anticancer agents, immunosuppressants). Newer ARVs such as unboosted integrase inhibitors, doravirine, and fostemsavir have reduced DDI potential, but there are clinically relevant DDIs that warrant consideration. Potential consequences of DDIs include increased toxicity and/or reduced efficacy of ARVs and/or comedications. Management approaches include switching to an ARV with less DDI potential, changing comedications, or altering medication dosage or dosing frequency. Deprescribing strategies can reduce DDIs and polypharmacy, improve adherence, minimize unnecessary adverse effects, and prevent medication-related errors.

SUMMARY

Management of DDIs requires close interdisciplinary collaboration from multiple healthcare disciplines (medicine, nursing, pharmacy) across a spectrum of care (community, outpatient, inpatient).

Novel Phenethylamines and Their Potential Interactions With Prescription Drugs: A Systematic Critical Review

BACKGROUND

The novel phenethylamines 4-fluoroamphetamine (4-FA) and 2,5-dimethoxy-4-bromophenethylamine (2C-B) fall in the top 10 most used new psychoactive substances (NPSs) among high-risk substance users. Various phenethylamines and NPS are also highly used in populations with mental disorders, depression, or attention deficit hyperactivity disorder (ADHD). Moreover, NPS use is highly prevalent among men and women with risky sexual behavior. Considering these specific populations and their frequent concurrent use of drugs, such as antidepressants, ADHD medication, and antiretrovirals, reports on potential interactions between these drugs, and phenethylamines 4-FA and 2C-B, were reviewed.

METHODS

The authors performed a systematic literature review on 4-FA and 2C-B interactions with antidepressants (citalopram, fluoxetine, fluvoxamine, paroxetine, sertraline, duloxetine, bupropion, venlafaxine, phenelzine, moclobemide, and tranylcypromine), ADHD medications (atomoxetine, dexamphetamine, methylphenidate, and modafinil), and antiretrovirals.

RESULTS

Limited literature exists on the pharmacokinetics and drug-drug interactions of 2C-B and 4-FA. Only one case report indicated a possible interaction between 4-FA and ADHD medication. Although pharmacokinetic interactions between 4-FA and prescription drugs remain speculative, their pharmacodynamic points toward interactions between 4-FA and ADHD medication and antidepressants. The pharmacokinetic and pharmacodynamic profile of 2C-B also points toward such interactions, between 2C-B and prescription drugs such as antidepressants and ADHD medication.

CONCLUSIONS

A drug-drug (phenethylamine-prescription drug) interaction potential is anticipated, mainly involving monoamine oxidases for 2C-B and 4-FA, with monoamine transporters being more specific to 4-FA.

Pharmacokinetic drug–drug interactions: an insight into recent US FDA-approved drugs for prostate cancer

Pharmacokinetic drug–drug interaction is a significant safety and efficiency concern as it results in considerable concentration changes. Drug–drug interactions are a substantial concern in anticancer drugs that possess a narrow therapeutic index. These interactions remain as the principal regulatory obstacle that can lead to termination in the preclinical stage, restrictions in the prescription, dosage adjustments or withdrawal of the drugs from the market. Drug metabolizing enzymes or transporters mediate the majority of clinically relevant drug interactions. Cancer diagnosed aged patients use multiple medications and are more prone to significant drug–drug interactions. This review provides detailed information on clinically relevant drug–drug interactions resulting from drug metabolism by enzymes and transporters with a particular emphasis on recent FDA approved antiprostate cancer drugs.

The effects of fasting on drug metabolism

Introduction: There is considerable variability in the rates and extent of drug metabolism between patients due to physiological, genetic, pharmacologic, environmental and nutritional factors such as fasting. This variability in drug metabolism may result in treatment failure or, conversely, in increased side effects or toxicity. Preclinical studies have shown that fasting alters drug metabolism by modulating the activity of drug metabolizing enzymes involved. However, until recently little was known about the effects of fasting on drug metabolism in humans.Areas covered: This review describes the effects of fasting on drug metabolism based on both preclinical studies and studies performed in humans.Expert opinion: A better understanding of the effects of fasting may improve the efficacy and safety of pharmacotherapy for individual patients. Fasting contributes to variability in human drug metabolism by differentially affecting drug metabolizing enzymes. Although the effects of fasting on drug metabolism appear to be small (between 10-20%), fasting may be relevant for drugs with a small therapeutic range and/or in combination with other factors that contribute to variability in drug metabolism such as physiological, genetic or pharmacological factors. Therefore, additional research on this topic is warranted.