Drug therapy in the heart transplant recipient: part IV: drug-drug interactions

Prevention and rehabilitation after heart transplantation: A clinical consensus statement of the European Association of Preventive Cardiology, Heart Failure Association of the ESC, and the European Cardio Thoracic Transplant Association, a section of ESOT

Little is known either about either physical activity patterns, or other lifestyle-related prevention measures in heart transplantation (HTx) recipients. The history of HTx started more than 50 years ago but there are still no guidelines or position papers highlighting the features of prevention and rehabilitation after HTx. The aims of this scientific statement are (i) to explain the importance of prevention and rehabilitation after HTx, and (ii) to promote the factors (modifiable/non-modifiable) that should be addressed after HTx to improve patients' physical capacity, quality of life and survival. All HTx team members have their role to play in the care of these patients and multidisciplinary prevention and rehabilitation programmes designed for transplant recipients. HTx recipients are clearly not healthy disease-free subjects yet they also significantly differ from heart failure patients or those who are supported with mechanical circulatory support. Therefore, prevention and rehabilitation after HTx both need to be specifically tailored to this patient population and be multidisciplinary in nature. Prevention and rehabilitation programmes should be initiated early after HTx and continued during the entire post-transplant journey. This clinical consensus.

Metabolic Disorders in Liver Transplant Recipients: The State of the Art

Liver transplantation represents a chief therapeutic approach for acute liver failure, end-stage liver disease and hepatocellular carcinoma. Despite witnessing advancements in short- and medium-term survival over recent decades, attributed to refinements in surgical techniques and immunosuppressive protocols, long-term mortality remains impervious to modification. Notably, cardiovascular disease emerges as a predominant cause of mortality among liver transplant recipients. This trend is accentuated by the increasing prominence of non-alcoholic steatohepatitis-related cirrhosis as an indication for liver transplantation. Moreover, the administration of immunosuppressive agents is intricately linked to the degradation of the metabolic profile in liver transplant recipients, thereby contributing to the initiation or exacerbation of cardiovascular risk factors, such as hypertension, diabetes, and dyslipidaemia. In addition, the post-liver transplantation period is marked by a decline in lifestyle quality and a failure to acknowledge the psychological distress experienced by patients throughout the transplant process. These factors can precipitate a deterioration in the patient's metabolic profile, exacerbated by suboptimal therapeutic compliance. This narrative review aims to comprehensively address the principal metabolic disorders intricately associated with liver transplantation.

Management of Atrial Arrhythmias After Lung Transplant

The overall survival in patients undergoing lung transplantation is poor. Although postsurgical atrial arrhythmias seem to play a major role in the morbidity and mortality of this population, data regarding the clinical and interventional management of this complication are still controversial. Through a review of the literature in the field, we observed that not only the surgical technique is clearly arrhythmogenic, but the new administration of peri-procedure beta-blockers and amiodarone for arrhythmia prevention and treatment, respectively, seems harmful in these postsurgical patients. However, low-dose beta-blockers administered after surgery seem feasible in arrhythmia prevention in specific patient subgroups, and, aside from amiodarone, alternative antiarrhythmic agents can be safely and effectively used to treat symptomatic patients on top of adequate rate control. Finally, as to complex atrial arrhythmias occurring late after lung transplant surgery, radiofrequency catheter ablation seems a feasible treatment option. In light of this evidence and considering the absence of clear recommendations in the field, we suggest a practical approach that may help the clinician in the management of this postsurgical complication. However, as most of these considerations are drawn from small-sized and retrospective studies, more evidence is needed in the future to clarify which medical and interventional strategies may best treat these postsurgical arrhythmias and thus potentially improve the outcome of these frail patients.

Outcomes among heart transplant recipients following acute coronary syndrome: A nationwide population based study

BACKGROUND

For patients with refractory heart failure despite optimal medical therapy, orthotopic heart transplantation (OHT) remains the treatment of choice. Since transplanted hearts have variable cardiac denervation and acute coronary syndrome often presents as a silent myocardial infarction or with atypical symptoms, the true impact of ACS on outcomes within this population needs more study. The aim of this study is to evaluate in-hospital mortality in post-transplant patients with ACS.

METHODS

Utilizing data from the 2002-15 Nationwide Inpatient Sample database, patients with a primary diagnosis of acute coronary syndrome among those with prior heart transplantation were included. A risk adjusted regression analysis was performed to assess if ACS post-OHT had an independent impact on the risk of in-hospital mortality. A 2:1 propensity matching was used to match ACS patients with and without OHT, respectively to assess differences in mortality.

RESULTS

A total of 3,224,073 patients with a primary diagnosis of acute coronary syndrome were included, of which 842 (0.03%) were heart-transplant recipients. The type of ACS: NSTEMI (76.0% vs 74.5%; p = 0.32) and STEMI (24.8% vs 26.7%; p = 0.21) between heart transplant and non-heart transplant patients was similar in both groups. Following ACS, patients with heart transplant were more likely to have accompanying shock of any etiology (15.6% vs 3.8%; p < 0.001) and cardiogenic shock (11.2% vs 2.6%; p < 0.001) compared to those with native hearts. OHT patients also had significantly higher in-hospital mortality (14.3% vs. 3.7%; p < 0.001) that remain significant following regression analysis (aOR 3.6, 95% CI 2.8-4.5; p < 0.001) irrespective of the presence of cardiogenic shock compared to native hearts. This relationship remained consistent following propensity matching where patients with OHT had significantly higher in-hospital mortality (13.5% vs. 7%; p < 0.001).

CONCLUSIONS

ACS following OHT was more likely to have accompanying cardiogenic shock. ACS in the setting of prior OHT remained a strong independent predictor of higher mortality as compared to native hearts.

Clinical conundrums involving statin drug-drug interactions

Statins are the cornerstone of pharmacologic therapy for the prevention and treatment of atherosclerotic cardiovascular disease. While they are generally considered safe, statins can be affected by drug-drug interactions (DDIs) that increase their systemic exposure increasing the risk for statin-associated muscle symptoms. These interactions are primarily mediated through metabolizing enzymes such as cytochrome P450 isoenzymes and membrane-bound drug transporting proteins including P-glycoprotein and organic ion transporting polypeptide. Recognition and avoidance of clinically significant statin DDIs is important to ensure their safe use. Conversely, concern over statin DDIs that are not clinically significant may lead to inappropriate underutilization or avoidance of statins in patients who would benefit from them. While many statin DDIs are well-characterized, we present several others that are less-well-established which may warrant clinical attention.

Dyslipidemia in Transplant Patients: Which Therapy?

Cardiovascular disease is the most important cause of death worldwide in recent years; an increasing trend is also shown in organ transplant patients subjected to immunosuppressive therapies, in which cardiovascular diseases represent one of the most frequent causes of long-term mortality. This is also linked to immunosuppressant-induced dyslipidemia, which occurs in 27 to 71% of organ transplant recipients. The aim of this review is to clarify the pathophysiological mechanisms underlying dyslipidemia in patients treated with immunosuppressants to identify immunosuppressive therapies which do not cause dyslipidemia or therapeutic pathways effective in reducing hypercholesterolemia, hypertriglyceridemia, or both, without further adverse events.

Proprotein Convertase Subtilisin/Kexin Type 9 Inhibitors Use for Atherogenic Dyslipidemia in Solid Organ Transplant Patients

Dyslipidemia is a widespread risk factor in solid organ transplant patients, due to many reasons, such as the use of immunosuppressive drugs, with a consequent increase in cardiovascular diseases in this population. PCSK9 is an enzyme mainly known for its role in altering LDL levels, consequently increasing cardiovascular risk. Monoclonal antibody PCSK9 inhibitors demonstrated remarkable efficacy in the general population in reducing LDL cholesterol levels and preventing cardiovascular disease. In transplant patients, these drugs are still poorly used, despite having comparable efficacy to the general population and giving fewer drug interactions with immunosuppressants. Furthermore, there is enough evidence that PCSK9 also plays a role in other pathways, such as inflammation, which is particularly dangerous for graft survival. In this review, the current evidence on the function of PCSK9 and the use of its inhibitors will be discussed, particularly in transplant patients, in which they may provide additional benefits.

Preventing alloimmune rejection using circular RNA FSCN1-silenced dendritic cells in heart transplantation

BACKGROUND

While heart transplantation is used as a standard treatment for heart failure, transplant rejection continues to pose a challenge. Recent evidence has shown that circular RNA (circRNA) is a new type of gene regulator in cell development. Our aim was to demonstrate that treatment with tolerogenic dendritic cells (Tol-DCs) generated by circular RNA FSCN1 (circFSCN1) silencing could prevent alloimmune rejection and prolong heart graft survival in heart transplantation.

METHODS

Bone marrow-derived DCs were transfected with circFSCN1 siRNA in vitro. The circFSCN1 level was measured by qRT-PCR. DC maturation was determined by flow cytometry. Mixed lymphocyte reactions (MLRs) were conducted to assess the function of DCs to activate T cells and to generate regulatory T cells (Tregs). In situ RNA hybridization and fluorescent microscopy were performed to detect the distribution of circFSCN1 in DCs. A heterotopic allogeneic murine heart transplantation was conducted where recipients were pre-treated with donor derived circFSCN1-silenced Tol-DCs. Heartbeat was monitored to assess immune rejection.

RESULTS

Exonic circFSCN1 was highly expressed in the cytoplasm of mature DCs. Knockdown of circFSCN1 using siRNA arrested DCs at an immature state, impaired DC's ability to activate T cells and enhanced Treg generation. Treatment with circFSCN1-silenced Tol-DCs prevented alloimmune rejection, prolonged allograft survival, reduced fibrosis, and induced Tregs in vivo.

CONCLUSIONS

Knockdown of circFSCN1 induces Tol-DCs and treatment with these Tol-DCs prevents alloimmune rejection and prolongs allograft survival. This is a promising therapeutic target to combat transplant rejection in heart transplantation and increases our understanding of circRNA in the immune system.

Statin intolerance: new data and further options for treatment

PURPOSE OF REVIEW

Hypercholesterolemia is a major risk factor for cardiovascular diseases. Administration of statins represents the cornerstone of the prevention and treatment of cardiovascular disease, with demonstrated long-term safety and efficacy. This review aims to revisit statin intolerance mechanisms, as well as to discuss new data and therapeutic options.

RECENT FINDINGS

Although statins are well tolerated, myopathy and other adverse effects are a challenging problem, being the main reason for poor adherence to treatment and failure in lowering cardiovascular risk. Statin intolerance is the subject of ongoing research, as these drugs are widely used. There are alternative options of treatment if statin intolerance emerges, that is, lowering the dose, intermittent dosages, and/or combining a statin with other drugs, such as ezetimibe, proprotein convertase subtilisin-kexin type 9 inhibitors, bempedoic acid, angiopoietin-like 3 protein inhibitors, and nutraceuticals. If even the lowest statin dose cannot be tolerated, a nonstatin regimen is recommended to reduce LDL cholesterol levels.

SUMMARY

Treatment options in statin intolerance include combinations of a lower dose of statin with other lipid-lowering regimens or only nonstatin drugs in the presence of complete intolerance. New hypolipidemic therapies that address gene editing are emerging, and may prove useful in the future.

Management of Arrhythmias After Heart Transplant: Current State and Considerations for Future Research

Orthotropic heart transplantation remains the most effective therapy for patients with end-stage heart failure, with a median survival of ≈13 years. Yet, a number of complications are observed after orthotropic heart transplantation, including atrial and ventricular arrhythmias. Several factors contribute to arrhythmias, such as autonomic denervation, effect of the surgical technique, acute and chronic rejection, and transplant vasculopathy among others. To minimize risk of future arrhythmias, the bicaval technique and minimizing ischemic time are current surgical standards. Sinus node dysfunction is the most common indication for early (within 30 days) pacemaker implantation, whereas atrioventricular block incidence increases as time from transplant increases. Atrial fibrillation can occur in the first few weeks following transplantation but is uncommon in the long term unless secondary to a precipitant such as acute rejection. The most common atrial arrhythmias are atrial flutters, which are mainly typical, but atypical circuits can be observed such as those that involve the remnant donor atrium in regions immediately adjacent to the atrioatrial anastomosis suture line. Choosing the appropriate pharmacological therapy requires careful consideration due to the potential interaction with immunosuppressive agents. Despite historical concerns, adenosine is effective and safe at reduced doses if administered under cardiac monitoring. Catheter ablation has emerged as an effective treatment strategy for symptomatic supraventricular tachycardias, including ablation of atypical flutter circuits. Cardiac allograft vasculopathy is an important risk factor for sudden cardiac death, yet the role of prophylactic implantable cardioverter-defibrillator implant for sudden death prevention is unclear. Current indications for implantable cardioverter-defibrillator implantation are as in the nontransplant population. A number of questions for future research are posed.

The impact of depression on heart transplant outcomes: A retrospective single-center cohort study

BACKGROUND

Depression is prevalent in patients with heart failure and after heart transplant. We identified the prevalence of pre- and post-transplant depression and its association with clinical characteristics and post-transplant outcomes.

METHODS

We reviewed 114 adults transplanted 1/1/2015 to 12/31/2015 and identified patients with pre- and post-transplant depression. Clinical characteristics and outcomes were compared.

RESULTS

Of 114 patients, 35.1% had pre-transplant depression and 26.3% had post-transplant depression. Patients with post-transplant depression within the first year were significantly more likely to have acute rejection (10% vs 0%), longer intensive care unit (11.7 days vs 7.8 days) and hospital stay (31.7 days vs 16.3 days), and discharge to inpatient rehabilitation (26.7% vs 8.3%). Patients with post-transplant depression within the first year had significantly higher 5-year mortality (30% vs 9.5%, p = .009). However, after adjustment for total artificial heart/biventricular assist device, acute rejection, intensive care unit, and hospital length of stay, this relationship was no longer significant (HR 2.11; 95% CI 0.18-25.27; p = .556).

CONCLUSIONS

Depression is common among heart transplant candidates and recipients. While pre-transplant depression did not impact outcomes, patients with post-transplant depression were more likely to have had a complicated course, suggesting the need for increased vigilance regarding depression in such patients.

NAFLD and liver transplantation: Disease burden, current management and future challenges

Non-alcoholic fatty liver disease (NAFLD), specifically its progressive form non-alcoholic steatohepatitis (NASH), represents the fastest growing indication for liver transplantation in Western countries. Diabetes mellitus, morbid obesity and cardiovascular disease are frequently present in patients with NAFLD who are candidates for liver transplantation. These factors require specific evaluation, including a detailed pre-surgical risk stratification, in order to improve outcomes after liver transplantation. Moreover, in the post-transplantation setting, the incidence of cardiovascular events and metabolic complications can be amplified by immunosuppressive therapy, which is a well-known driver of metabolic alterations. Indeed, patients with NASH are more prone to developing early post-transplant complications and, in the long-term, de novo malignancy and cardiovascular events, corresponding to higher mortality rates. Therefore, a tailored multidisciplinary approach is required for these patients, both before and after liver transplantation. Appropriate candidate selection, lifestyle modifications and specific assessment in the pre-transplant setting, as well as pharmacological strategies, adjustment of immunosuppression and a healthy lifestyle in the post-transplant setting, play a key role in correct management.

Post-Transplantation Diabetes Mellitus

Solid organ transplantation (SOT) is an established therapeutic option for chronic disease resulting from end-stage organ dysfunction. Long-term use of immunosuppression is associated with post-transplantation diabetes mellitus (PTDM), placing patients at increased risk of infections, cardiovascular disease and mortality. The incidence rates for PTDM have varied from 10 to 40% between different studies. Diagnostic criteria have evolved over the years, as a greater understating of PTDM has been reached. There are differences in pathophysiology and clinical course of type 2 diabetes and PTDM. Hence, managing this condition can be a challenge for a diabetes physician, as there are several factors to consider when tailoring therapy for post-transplant patients to achieve better glycaemic as well as long-term transplant outcomes. This article is a detailed review of PTDM, examining the pathogenesis, diagnostic criteria and management in light of the current evidence. The therapeutic options are discussed in the context of their safety and potential drug-drug interactions with immunosuppressive agents.

Predisposing factors for late mortality in heart transplant patients

BACKGROUND

Because of the growing prevalence of terminal heart failure on the one hand and organ shortage on the other hand, an optimal care of heart transplant recipients based on the knowledge of potential risk factors not only early, but also in a long-term course after heart transplantation is of great importance. Therefore, the aim of the present study was to identify predisposing factors for late mortality in this patient collective.

METHODS

Data from long-term heart transplant patients collected during follow-up visits in the current center were retrospectively analyzed. Clinical, laboratory, including immune monitoring and apparative examination results were studied with regard to all-cause mortality.

RESULTS

One hundred and seventy-two patients after heart transplantation (mean: 13.2 ± 6.4 years) were divided into two groups: survivors (n = 133) and non-survivors (n = 39). In comparison with survivors, non-survivors were characterized by significantly more pronounced renal insufficiency with more frequent dialysis, anemia and worse functional status. Additionally, non-survivors obtained hearts from relevantly more obese donors. In a multivariate Cox regression analysis the following parameters were shown to be independent risk factors for increased mortality: CD4 percentage < 42%, C-reactive protein ≥ 0.5 mg/dL, presence of rejections requiring therapies in the past, onset of cardiac allograft vasculopathy < 5 years following heart transplantation and no use of beta-blockers.

CONCLUSIONS

Low CD4+ cell percentages, sustained inflammation, relevant organ rejections, early onset of transplant vasculopathy and no use of beta-blockers are risk factors for higher mortality in a long-term follow-up after heart transplantation.

Management of dyslipidemia in adult solid organ transplant recipients

Solid organ transplantation (SOT) has revolutionized treatment of end-stage disease. Improvements in the SOT continuum of care have unmasked a significant burden of cardiovascular disease, manifesting as a leading cause of morbidity and mortality. Although several risk factors for development of post-transplant cardiovascular disease exist, dyslipidemia remains one of the most frequent and modifiable risks. An important contributor to dyslipidemia in SOT recipients is the off-target metabolic effects of immunosuppressive medications, which may alter lipoproteins and their metabolism. Dyslipidemia management is paramount as lipid-lowering therapy with statins has demonstrated reductions in graft vasculopathy, decreased rejection rates, and improved survival. Several nonstatin medication options are available, but data supporting their benefit in the SOT population are minimal, typically extrapolated from studies in the general population. Further compounding dyslipidemia management is the complex interplay of drug interactions between lipid-lowering and immunosuppressant medications, which can result in serious toxicity and/or therapeutic failure.

Perioperative Management of the Cardiac Transplant Recipient

Management of the cardiac transplant recipient includes careful titration of inotropes and vasopressors. Recipient pulmonary hypertension and ventilatory status must be optimized to prevent allograft right ventricular failure. Vasoplegia, coagulopathy, arrhythmias, and renal dysfunction also require careful management to achieve an optimal outcome. Primary graft dysfunction (PGD) can be an ominous problem after cardiac transplantation. Although mild degrees of PGD may be managed medically, mechanical circulatory support with extracorporeal membrane oxygenation or temporary ventricular assist devices may be required. Retransplantation may be necessary in some cases.

Pharmacokinetic Drug-Drug Interactions Between Immunosuppressant and Anti-Infective Agents: Antimetabolites and Corticosteroids

Infections account for 15–20% of deaths in transplant recipients, requiring rapid and appropriate therapeutic interventions. Many anti-infective agents interact with immunosuppressive regimens used in transplantation, placing patients at increased risk for adverse drug reactions and prolonged hospitalizations. There is established data regarding the level of evidence and magnitude of interactions between calcineurin inhibitors and mammalian target of rapamycin inhibitors with anti-infective agents. Less is known about the interactions with anti-proliferative agents and corticosteroids, with gaps in knowledge on the appropriate management of these interactions. The objective of this review was to highlight the pharmacokinetic drug–drug interactions between antimetabolites and corticosteroids with commonly used anti-infective agents.

Honoring 50 Years of Clinical Heart Transplantation in Circulation

Heart transplantation has become a standard therapy option for advanced heart failure. The translation of heart transplantation from innovative experiments to long-term clinical success has married prescient insights with discipline and organization in the domains of surgical techniques, organ preservation, immunosuppression, organ donation and transplantation logistics, infection control, and long-term graft surveillance. This review explores the key milestones of the past 50 years of heart transplantation and discusses current challenges and promising innovations on the clinical horizon.

Amiodarone use in patients listed for heart transplant is associated with increased 1-year post-transplant mortality

BACKGROUND

Pre-transplant amiodarone use has been postulated as a risk factor for morbidity and mortality after orthotopic heart transplantation (OHT). We assessed pre-OHT amiodarone use and tested the hypothesis that it is associated with impaired post-OHT outcomes.

METHODS

We performed a retrospective cohort analysis of adult OHT recipients from the registry of the International Society for Heart and Lung Transplantation (ISHLT). All patients had been transplanted between 2005 and 2013 and were stratified by pre-OHT amiodarone use. We derived propensity scores using logistic regression with amiodarone use as the dependent variable, and assessed the associations between amiodarone use and outcomes with Kaplan-Meier analysis after matching patients 1:1 based on propensity score, and with Cox regression with adjustment for propensity score.

RESULTS

Of the 14,944 OHT patients in the study cohort, 32% (N = 4,752) received pre-OHT amiodarone. Amiodarone use was higher in recent years (29% in 2005 to 2007, 32% in 2008 to 2010, 35% in 2011 to 2013). Amiodarone-treated patients were older and more frequently had a history of sudden cardiac death (27% vs 13%) and pre-OHT mechanical circulatory support. Key donor characteristics and allograft ischemia times were similar between groups. In propensity-matched analyses, amiodarone-treated patients had higher rates of cardiac reoperation (15% vs 13%) and permanent pacemaker (5% vs 3%) after OHT and before discharge. Amiodarone-treated patients also had higher 1-year mortality (hazard ratio 1.15, 95% confidence interval 1.02 to 1.30), but the risks of early graft failure, retransplantation and rehospitalization were similar between groups.

CONCLUSIONS

Amiodarone use before OHT was independently associated with increased 1-year mortality. The need for amiodarone therapy should be carefully and continuously assessed in patients awaiting OHT.

Post-cardiac transplant recipient: Implications for anaesthesia

The annual heart transplant rate is gradually increasing worldwide. A proportion of this patient population present for an elective or emergency surgery which may or may not be related to the transplanted heart. A MEDLINE search for heart transplant, anaesthesia, adult, paediatric and surgery was conducted to review anaesthetic management for heart transplant recipients. Anaesthesia and perioperative management are different in these cases. A thorough understanding of the physiology of denervated heart, post-transplant morbidities and pharmacology of immunosuppressants is essential for best perioperative management and improved post-operative outcome.

Clopidogrel-Precipitated Rhabdomyolysis in a Stable Heart Transplant Patient

Objective:

To report the case of an orthotopic heart transplant recipient who developed rhabdomyolysis precipitated by the addition of clopidogrel to the existing regimen of cyclosporine and atorvastatin, which had been tolerated for more than 3 years without adverse effects or laboratory evidence of myositis.

Case Summary:

Fourteen years after cardiac transplantation, a 58-year-old woman began a planned 4 week course of clopidogrel 75 mg/day following coronary angioplasty and placement of a stent in the left circumflex coronary artery. Almost 4 weeks later, she presented with severe muscle pain and weakness and laboratory evidence of rhabdomyolysis, with marked elevations of plasma creatine kinase (96 000 U/L) and urine myoglobin (332 872 μg/L.) as well as early acute renal failure (serum creatinine 2.9 mg/dL). Symptoms and laboratory abnormalities resolved with cessation of cyclosporine, atorvastatin, and clopidogrel. Clopidogrel was not restarted, while atorvastatin and cyclosporine were; the patient had no recurrence of symptoms up to 15 months later.

Discussion:

Both atorvastatin and cyclosporine, as well as clopidogrel's active thiol derivative, are metabolized by the cytochrome P450 3A4 isoenzyme. Cyclosporine is also a moderate inhibitor of this isoenzyme. We postulate that competition between atorvastatin and clopidogrel for CYP3A4 receptors, already partially inhibited by cyclosporine, led to increased atorvastatin concentrations, resulting in the acute onset of rhabdomyolysis. This theory is further supported by the patient's continued ability to tolerate the combination of atorvastatin and cyclosporine, without clopidogrel, on rechallenge. Use of the Naranjo probability scale revealed that rhabdomyolysis was probably precipitated by the addition of clopidogrel to the stable baseline regimen of cyclosporine and atorvastatin.

Conclusions:

Practitioners must be conscious of the potential for adverse effects when prescribing clopidogrel to heart transplant patients who are concomitantly receiving cyclosporine and a statin. If concomitant administration is required, careful clinical and laboratory monitoring of the patient is necessary.

A clinician's guide to drug-drug interactions with direct-acting antiviral agents for the treatment of hepatitis C viral infection

The US Food and Drug Administration has recently approved a number of new direct-acting antiviral agents for the treatment of chronic hepatitis C virus that have significantly increased the likelihood of a virological cure. These agents are highly effective but present a substantial risk for a host of clinically relevant drug-drug interactions. These interactions must be considered both when starting and stopping any medication, including over-the-counter medications and herbal supplements. These drug-drug interactions can increase the risk of toxicity or decrease the likelihood of treatment response. Knowledge of these interactions is paramount in optimizing the success of antiviral therapy.

CONCLUSION

In this review we summarize the available data regarding drug-drug interactions for direct-acting antiviral agents, the interactions being the most clinically relevant that are currently known; this review is intended to serve as a clinician's guide to understanding and managing these complex interactions. (Hepatology 2016;63:634-643).

Advanced therapies for end-stage heart failure

Management of the advanced heart failure patient can be complex. Therapies include cardiac transplantation and mechanical circulatory support, as well inotropic agents for the short-term. Despite a growing armamentarium of resources, the clinician must carefully weigh the risks and benefits of each therapy to develop an optimal treatment strategy. While cardiac transplantation remains the only true “cure” for end-stage disease, this resource is limited and the demand continues to far outpace the supply. For patients who are transplant-ineligible or likely to succumb to their illness prior to transplant, ventricular assist device therapy has now become a viable option for improving morbidity and mortality. Particularly for the non-operative pa-tient, intravenous inotropes can be utilized for symptom control. Regardless of the treatments considered, care of the heart failure patient requires thoughtful dialogue, multidisciplinary collaboration, and individualized care. While survival is important, most patients covet quality of life above all outcomes. An often overlooked component is the patient’s control over the dying process. It is vital that clinicians make goals-of-care discussions a priority when seeing patients with advanced heart failure. The use of palliative care consultation is well-validated and facilitates these difficult conversations to ensure that all patient needs are ultimately met.

An observational study of ezetimibe in cardiac transplant recipients receiving calcineurin inhibitors

BACKGROUND

Cardiac transplant patients are at risk for developing cardiac allograft vasculopathy, and dyslipidemia in this patient population has been associated with increased risk. Data evaluating the efficacy and safety of ezetimibe in this population are minimal.

OBJECTIVES

The purpose of this study was to assess the effects of ezetimibe, alone or in combination with other lipid-lowering agents, in cardiac transplant recipients receiving calcineurin inhibitors (CNIs).

METHODS

This study was a single-center retrospective chart review. Data on demographics, medications prescribed for dyslipidemia and prevention of transplant rejection, results of lipid panels, CNI blood concentrations, and adverse effects were extracted from medical records of cardiac transplant recipients who were prescribed ezetimibe, either alone or in combination with other lipid-lowering agents, and seen at least once in a 12-month period at a cardiac transplantation clinic of an 800-bed teaching hospital.

RESULTS

There were 71 patients prescribed ezetimibe in whom a safety analysis was performed. Approximately 49% (n = 35) were included in the analysis for lipid lowering. Ezetimibe significantly decreased low-density lipoprotein cholesterol (LDL-C; 129 mg/dL vs 94 mg/dL, P < .0001), non-high-density lipoprotein cholesterol (non-HDL-C; 170 mg/dL vs 127.5 mg/dL, P = .0058), and total cholesterol (236 mg/dL vs 200 mg/dL, P < .0001). There was no significant change in HDL-C and triglycerides as compared with baseline. The proportion of patients achieving goal LDL-C < 100 mg/dL significantly increased from 11.5% at baseline to 60.5% after the addition of ezetimibe (P < .0001). Ezetimibe had no measurable effect on blood CNI concentrations or doses. Adverse effects were reported by 15.5% of patients (n = 11), with 4% (n = 3) of patients discontinuing therapy. The most common complaints were gastrointestinal intolerance and myalgia.

CONCLUSIONS

Ezetimibe was associated with lower LDL-C in cardiac transplant recipients either as combination therapy in patients with elevated LDL-C or as monotherapy, with a low frequency of adverse effects.

Managing depression in patients with advanced heart failure awaiting transplantation

PURPOSE

The relative merits of various forms of antidepressant therapy in patients with heart failure (HF) are discussed, including disease-specific pharmacokinetic changes and drug-interaction challenges in current or likely future candidates for heart transplantation.

SUMMARY

There is a growing emphasis on the use of antidepressants in patients with chronic HF, as depression can have a negative impact on HF progression and morbidity and mortality after heart transplants or other invasive cardiac surgery. Evidence from one small study of patients with concomitant end-stage HF and major depression indicated a reduced risk of cardiovascular death in those receiving β-blockers in combination with selective serotonin-reuptake inhibitor (SSRI) therapy. In addition to pharmacokinetic changes caused by HF itself, which can decrease medication absorption and distribution, other issues to consider in the drug selection process include the potential for antidepressants to interact with posttransplant immunosuppressive therapy and the possible effects of antidepressant use on surgical transfusion requirements. The SSRIs are generally recommended as first-line therapies for depressed patients with HF; however, fluvoxamine and fluoxetine should be avoided due to interactions with immunosuppressant agents. If SSRI therapy is not well tolerated or adjunctive therapy is required, bupropion, mirtazapine, venlafaxine, and duloxetine may be suitable alternatives for certain patients.

CONCLUSION

Key considerations in antidepressant selection in the context of advanced HF include HF-related changes in drug pharmacokinetics that may affect initial dosing or dosage adjustment, possible drug interactions, adverse effects that may potentiate those induced by immunosuppressants added after transplantation, and tolerability issues.

Genetics or environment in drug transport: the case of organic anion transporting polypeptides and adverse drug reactions

INTRODUCTION

Organic anion transporting polypeptide (OATP) uptake transporters are important for the disposition of many drugs and perturbed OATP activity can contribute to adverse drug reactions (ADRs). It is well documented that both genetic and environmental factors can alter OATP expression and activity. Genetic factors include single nucleotide polymorphisms (SNPs) that change OATP activity and epigenetic regulation that modify OATP expression levels. SNPs in OATPs contribute to ADRs. Environmental factors include the pharmacological context of drug-drug interactions and the physiological context of liver diseases. Liver diseases such as non-alcoholic fatty liver disease, cholestasis and hepatocellular carcinoma change the expression of multiple OATP isoforms. The role of liver diseases in the occurrence of ADRs is unknown.

AREAS COVERED

This article covers the roles OATPs play in ADRs when considered in the context of genetic or environmental factors. The reader will gain a greater appreciation for the current evidence regarding the salience and importance of each factor in OATP-mediated ADRs.

EXPERT OPINION

A SNP in a single OATP transporter can cause changes in drug pharmacokinetics and contribute to ADRs but, because of overlap in substrate specificities, there is potential for compensatory transport by other OATP isoforms. By contrast, the expression of multiple OATP isoforms is decreased in liver diseases, reducing compensatory transport and thereby increasing the probability of ADRs. To date, most research has focused on the genetic factors in OATP-mediated ADRs while the impact of environmental factors has largely been ignored.

Low-dose Gabapentin for Intractable Hiccups in a Heart Transplant Recipient

Intractable hiccups can be a serious complication in transplant recipients. Unfortunately, many of the pharmacotherapies used to stop hiccups are associated with severe side effects as well as drug-drug interactions with immunosuppressants. We report a case of a heart transplant recipient who had had intractable hiccups for 2 months, resulting in severe insomnia, diminished appetite, and weight loss. To treat the hiccups, treatment with oral baclofen (5–10 mg 3 times daily) was started. After 6 weeks of therapy, the baclofen was titrated down and discontinued because it had not stopped the hiccups and was causing severe central nervous system side effects. Gabapentin (100 mg twice daily) was then prescribed and within 24 hours of the start of that treatment, the hiccups had resolved completely. After 3 weeks of therapy, the patient had no side effects and the gabapentin was subsequently discontinued. One year after stopping the gabapentin, the patient remains free of hiccups. Gabapentin appears to be a promising medication for the treatment of intractable hiccups in thoracic transplant recipients because of its lack of serious side effects at low doses, rapid onset of action, and lack of drug-drug interactions with transplant medications.

Cytochrome P450-mediated cardiovascular drug interactions

INTRODUCTION

There are numerous drug-drug interactions (DDIs) related to cardiovascular medications and many of these are mediated via the cytochrome P450 (CYP) system. Some of these may lead to serious adverse events and it is, therefore, essential that clinicians are aware of the important interactions that occur.

AREAS COVERED

An extensive literature search was performed to analyze the CYP-mediated cardiovascular DDIs that lead to a loss of efficacy or potential toxicity. Cardiovascular drugs may be victims or act as perpetrators of DDIs. The paper analyzes CYP-mediated drug interactions concerning anticoagulants, antiplatelet agents, antiarrhythmics, β-blockers, calcium antagonists, antihypertensive medications, lipid-lowering drugs and oral antidiabetic agents.

EXPERT OPINION

Cardiovascular DDIs involving the CYP system are numerous. Additionally, the spectrum of drugs prescribed is constantly changing, particularly with cardiovascular diseases and it is not necessarily the case that drugs that had shown safety earlier will always show safety. Clinicians are encouraged to develop their knowledge of CYP-mediated DDIs so that they can choose safe drug combination regimens, adjust drug dosages appropriately and conduct therapeutic drug monitoring for drugs with narrow therapeutic indices.