Toxicokinetic interaction between quetiapine and antiretroviral therapy following quetiapine overdose

Clinically Relevant Interactions between Atypical Antipsychotics and Anti-Infective Agents

This is a comprehensive review of the literature on drug interactions (DIs) between atypical antipsychotics and anti-infective agents that focuses on those DIs with the potential to be clinically relevant and classifies them as pharmacokinetic (PK) or pharmacodynamic (PD) DIs. PubMed searches were conducted for each of the atypical antipsychotics and most commonly used anti-infective agents (13 atypical antipsychotics by 61 anti-infective agents/classes leading to 793 individual searches). Additional relevant articles were obtained from citations and from prior review articles written by the authors. Based on prior DI articles and our current understanding of PK and PD mechanism, we developed tables with practical recommendations for clinicians for: antibiotic DIs, antitubercular DIs, antifungal DIs, antiviral DIs, and other anti-infective DIs. Another table reflects that in clinical practice, DIs between atypical antipsychotics and anti-infective agents occur in patients also suffering an infection that may also influence the PK and PD mechanisms of both drugs (the atypical antipsychotic and the anti-infective agent(s)). These tables reflect the currently available literature and our current knowledge of the field and will need to be updated as new DI information becomes available.

Interactions of cobicistat and ritonavir in patients with HIV and its clinical consequences

INTRODUCTION

The prescription of antiretroviral treatment (ART) that contains pharmacokinetic enhancers such as ritonavir and cobicistat is frequent. The objective of this stdy was to analyze the potential interactions of ART that include these molecules in their formulation with the patient's home medication, as well as the clinical management of those potentially serious.

METHODS

Prospective study conducted in the pharmacy care clinic of a third level hospital between January and December of 2018. Those HIV+patients with an ART containing cobicistat or ritonavir were included in the study. Potential interactions between ART and concomitant medication were analysed in three databases (Micromedex®, Drugs.com and Liverpool), the interventions carried out were detailed, and adverse drug reactions analysed.

RESULTS

968 patients were included with a total of 2,148 prescriptions (274 different medications). A total of 86 interventions were performed regarding potential interactions in patients. The most frequent were substitutions of corticoid treatments, treatment suspensions and closer monitoring of treatments. A total of possible adverse drug reactions were analysed. The degree of agreement in the severity classification of the interactions for cobicistat and ritonavir was good among the three databases. It was remarkable Micromedex® as the most complete because it has more registered medications.

CONCLUSION

The interactions between ART with pharmacokinetic enhancers in its composition and concomitant medication is frequent and requires a significant variety of interventions. The check of interactions in different databases is recommended since they can cause adverse drug reactions.

Drug-drug interactions and clinical considerations with co-administration of antiretrovirals and psychotropic drugs

Psychotropic medications are frequently co-prescribed with antiretroviral therapy (ART), owing to a high prevalence of psychiatric illness within the population living with HIV, as well as a 7-fold increased risk of HIV infection among patients with psychiatric illness. While ART has been notoriously associated with a multitude of pharmacokinetic drug interactions involving the cytochrome P450 enzyme system, the magnitude and clinical impact of these interactions with psychotropics may range from negligible effects on plasma concentrations to life-threatening torsades de pointes or respiratory depression. This comprehensive review summarizes the currently available information regarding drug-drug interactions between antiretrovirals and pharmacologic agents utilized in the treatment of psychiatric disorders-antidepressants, stimulants, antipsychotics, anxiolytics, mood stabilizers, and treatments for opioid use disorder and alcohol use disorder-and provides recommendations for their management. Additionally, overlapping toxicities between antiretrovirals and the psychotropic classes are highlighted. Knowledge of the interaction and adverse effect potential of specific antiretrovirals and psychotropics will allow clinicians to make informed prescribing decisions to better promote the health and wellness of this high-risk population.

Older HIV-infected adults. Complex patients (III): Polypharmacy

Polypharmacy is a well-described problem in the geriatric population. It is a relatively new problem for people living with HIV (PLWH), as this group now has a life expectancy approaching that of the general population. Defining polypharmacy for PLWH is difficult, since the most common traditional definition of at least five medications would encompass a large percentage of PLWH who are on antiretrovirals (ARVs) and medications for other medical comorbidities. Even when excluding ARVs, the prevalence of polypharmacy in PLWH is higher than the general population, and not just in resource-rich countries. Using a more nuanced approach with "appropriate" or "safer" polypharmacy allows for a better framework for discussing how to mitigate the associated risks. Some of the consequences of polypharmacy include adverse effects of medications including the risk of geriatric syndromes, drug-drug interactions, decreased adherence, and over- and undertreatment of medical comorbidities. Interventions to combat polypharmacy include decreasing pill burden-specifically with fixed-dose combination (FDC) tablets- and medication reconciliation/deprescription using established criteria. The goal of these interventions is to decrease drug interactions and improve quality of life and outcomes. Some special populations of interest within the community of PLWH include those with chronic pain, substance abuse, or requiring end of life care. A final look into the future of antiretroviral therapy (ART) shows the promise of possible two-drug regimens, which can help reduce the above risks of polypharmacy.

Clinically significant drug interactions with atypical antipsychotics

Atypical antipsychotics [also known as second-generation antipsychotics (SGAs)] have become a mainstay therapeutic treatment intervention for patients with schizophrenia, bipolar disorders and other psychotic conditions. These agents are commonly used with other medications--most notably, antidepressants and antiepileptic drugs. Drug interactions can take place by various pharmacokinetic, pharmacodynamic and pharmaceutical mechanisms. The pharmacokinetic profile of each SGA, especially with phase I and phase II metabolism, can allow for potentially significant drug interactions. Pharmacodynamic interactions arise when agents have comparable receptor site activity, which can lead to additive or competitive effects without alterations in measured plasma drug concentrations. Additionally, the role of drug transporters in drug interactions continues to evolve and may effect both pharmacokinetic and pharmacodynamic interactions. Pharmaceutical interactions occur when physical incompatibilities take place between agents prior to drug absorption. Approximate therapeutic plasma concentration ranges have been suggested for a number of SGAs. Drug interactions that markedly increase or decrease the concentrations of these agents beyond their ranges can lead to adverse events or diminished clinical efficacy. Most clinically significant drug interactions with SGAs occur via the cytochrome P450 (CYP) system. Many but not all drug interactions with SGAs are identified during drug discovery and pre-clinical development by employing a series of standardized in vitro and in vivo studies with known CYP inducers and inhibitors. Later therapeutic drug monitoring programmes, clinical studies and case reports offer methods to identify additional clinically significant drug interactions. Some commonly co-administered drugs with a significant potential for drug-drug interactions with selected SGAs include some SSRIs. Antiepileptic mood stabilizers such as carbamazepine and valproate, as well as other antiepileptic drugs such as phenobarbital and phenytoin, may decrease plasma SGA concentrations. Some anti-infective agents such as protease inhibitors and fluoroquinolones are of concern as well. Two additional important factors that influence drug interactions with SGAs are dose and time dependence. Smoking is very common among psychiatric patients and can induce CYP1A2 enzymes, thereby lowering expected plasma levels of certain SGAs. It is recommended that ziprasidone and lurasidone are taken with food to promote drug absorption, otherwise their bioavailability can be reduced. Clinicians must be aware of the variety of factors that can increase the likelihood of clinically significant drug interactions with SGAs, and must carefully monitor patients to maximize treatment efficacy while minimizing adverse events.

Important Drug-Drug Interactions in HIV-Infected Persons on Antiretroviral Therapy: An Update on New Interactions Between HIV and Non-HIV Drugs

Advances in antiretroviral therapy have turned HIV into a chronic, manageable disease. Patients often require treatment for co-morbid conditions as well as HIV, and consequently, pharmacokinetic interactions between antiretrovirals (ARVs) and other drug classes are an increasing concern. Protease inhibitors and non-nucleoside reverse transcriptase inhibitors are involved in the CYP450 or other transporter systems, and may be associated with higher risk of clinically significant drug interactions. One reverse transcriptase inhibitor, abacavir, has demonstrated weak inhibition of CYP3A4, 2D6 and 2C9 in vitro, but is not associated with any clinically significant interactions involving the CYP450 system. The integrase inhibitor raltegravir is not involved in the CYP450 system, and may be a suitable option to use when trying to minimize interactions with other drug classes. This review summarizes recently published data on clinically significant drug interactions between ARVs and other drug classes including antineoplastics, immunosuppressant transplant drugs, directly acting antivirals for hepatitis C, antifungals, antimalarials, corticosteroids, psychotropics, hormonal contraceptives, anticoagulants, drugs for pulmonary hypertension, and herbal products. In situations of suspected or potential interactions, close monitoring is warranted, and dose adjustments or substitutions may be required.