Cassia angustifolia and tacrolimus interaction in a liver transplant patient, a case report

Cassia angustifolia is a species of plant from the Senna family that has traditionally been used as a laxative in different herbal products and commercial medicines. Even though there are few documented drug-plant interactions, the use of C. angustifolia with different drugs may have additive effects, such as with other laxatives or potassium-depleting diuretics. Its use also increases peristalsis which, may reduce drug absorption. The combination with digoxin has been associated with an increased risk of digoxin toxicity, probably due to an increase in plasma digoxin concentrations and hypokalaemia. We present a case with supratherapeutic trough concentration of tacrolimus, an immunosuppressive agent, and a herbal product in a liver transplant patient after concomitant intake of tacrolimus and a herbal product based on C. angustifolia, suggesting a possible drug-lant interaction through by P-glycoprotein. We observed an increase in the patient's blood concentration 2.8-fold and the area under the curve at steady state 2.1-fold. This interaction could be of clinical relevance, given the dose-dependent side effects of tacrolimus, such as nephrotoxicity, neurotoxicity, hypertension, hyperglycaemia, or electrolyte alterations.

Population Pharmacokinetic Model of Adalimumab Based on Prior Information Using Real World Data

Adalimumab is a fully human monoclonal antibody used for the treatment of inflammatory bowel disease (IBD). Due to its considerably variable pharmacokinetics and the risk of developing antibodies against adalimumab, it is highly recommended to use a model-informed precision dosing approach. The aim of this study is to develop a population pharmacokinetic (PopPK) model of adalimumab for patients with IBD based on a literature model (reference model) to be used in the clinical setting. A retrospective observational study with 54 IBD patients was used to develop two different PopPK models based on the reference model. One of the developed models estimated the pharmacokinetic population parameters (estimated model), and the other model incorporated informative priors (prior model). The models were evaluated with bias and imprecision. Clinical impact was also assessed, evaluating the differences in dose interventions. The developed models included the albumin as a continuous covariate on apparent clearance. The prior model was superior to the estimated model in terms of bias, imprecision and clinical impact on the target population. In conclusion, the prior model adequately characterized adalimumab PK in the studied population and was better than the reference model in terms of predictive performance and clinical impact.

Efficacy and safety of high-flow nasal cannula therapy in elderly patients with acute respiratory failure

INTRODUCTION

To assess the efficacy and safety of high-flow nasal cannula (HFNC) in elderly patients with acute respiratory failure (ARF) not due to COVID-19, refractory to treatment with conventional oxygen therapy and/or intolerant to noninvasive ventilation (NIV) or continuous positive airway pressure (CPAP) and without criteria for admission to intensive care units (ICU).

METHODS

Prospective observational study of patients with ARF treated with HFNC who presented clinical and arterial blood gas deterioration after 24 h of medical treatment and oxygenation by conventional systems. The degree of dyspnoea, gas exchange parameters (arterial O2 pressure/inspired O2 fraction ratio (PaO2/FiO2); oxygen saturation measured by oximetry/ inspired fraction of oxygen (Sp02/Fi02), ROX index), degree of patient tolerance and mortality were evaluated. These were measured at discharge from the emergency department (ED), 24 h after treatment with conventional oxygenation and 60, 120 min and 24 h after initiation of HFNC. The results were analyzed for all patients as a whole and for patients with hypercapnia (arterial carbon dioxide tension (PaCO2) < 45 mmHg) separately.

RESULTS

200 patients were included in the study between November 2019 and November 2020, with a mean age of 83 years, predominantly women (61.9%), obese (Body Mass Index (BMI) 31.1), with high comorbidity (Charlson index 4) and mild-moderate degree of dependence (Barthel 60). A number of 128 patients (64%) were hypercapnic. None had respiratory acidosis (pH 7.39). Evaluation at 60 min, 120 min and 24 h showed significant improvement in all patients and in the subgroup of hypercapnic patients with respect to baseline parameters in respiratory rate (RR), dyspnoea, ROX index, PaO2/FiO2, SpO2/FiO2 and patient comfort. No changes in PaCO2 or level of consciousness were observed. HFNC was well tolerated. Ten patients (5%) died due to progression of the disease causing ARF.

CONCLUSIONS

HFNC is an effective and safe alternative in elderly patients with ARF not due to COVID-19, refractory to treatment with conventional oxygen therapy and/or intolerant to NIV or CPAP and without criteria for admission to ICU.

Population pharmacokinetics models of sirolimus in renal transplant patients: A systematic review

OBJECTIVE

Sirolimus is used in the immunosuppressive therapeutic treatment  of kidney transplant patients. The high pharmacokinetic variability of sirolimus  makes pharmacokinetic monitoring and dosage individualization of  mmunosuppressive therapy a key process to achieve better efficacy results.  The availability of a population pharmacokinetic model can be used to provide  better pharmacokinetic adjustment of plasma concentrations of sirolimus and  thus achieve greater clinical benefit.

METHOD

We conducted a systematic review of the literature available in the  Medline, Embase, and Scopus databases to identify and subsequently analyze  population pharmacokinetic models of orally administered sirolimus in adult  patients after kidney transplant. The descriptors used MeSH were kidney  transplantation, pharmacokinetics, and sirolimus. The following variables from  the selected studies were assessed: study population, immunosuppressive  treatment, blood sampling times, covariates analyzed, type of pharmacokinetic  model, computer software used, estimated pharmacokinetic  parameters, interindividual variability of pharmacokinetic parameters, residual  variability and mathematical equations of the pharmacokinetic model.

RESULTS

A total of 548 results were obtained, excluding 175 records that were  identified in more than one database. Finally, seven articles that  et  the inclusion criteria were selected. Most of the pharmacokinetic models found fit a two-compartment model. The interindividual variability of sirolimus  was explained by covariates such as age, weight, liver function, cyclosporine exposure and dose, sirolimus doses, CYP3A5 genetic  olymorphisms, serum creatinine, and concomitant treatment.

CONCLUSIONS

The two-compartment model was the pharmacokinetic model of  choice in most of the selected studies. The interindividual variability of the  pharmacokinetic parameters of sirolimus is explained by demographic, clinical,  genetic, and biochemical variables. The availability of pharmacokinetic models  of sirolimus can assist in optimizing therapy in patients after kidney transplant.

Evaluation of the Predictive Performance of Population Pharmacokinetic Models of Adalimumab in Patients with Inflammatory Bowel Disease

Adalimumab is a monoclonal antibody used for inflammatory bowel disease. Due to its considerably variable pharmacokinetics, the loss of response and the development of anti-antibodies, it is highly recommended to use a model-informed precision dosing approach. The aim of this study is to evaluate the predictive performance of different population-pharmacokinetic models of adalimumab for inflammatory bowel disease to determine the pharmacokinetic model(s) that best suit our population to use in the clinical routine. A retrospective observational study with 134 patients was conducted at the General University Hospital of Alicante between 2014 and 2019. Model adequacy of each model was evaluated by the distribution of the individual pharmacokinetic parameters and the NPDE plots whereas predictive performance was assessed by calculating bias and precision. Moreover, stochastic simulations were performed to optimize the maintenance doses in the clinical protocols, to reach the target of 8 mg/L in at least 75% of the population. Two population-pharmacokinetic models were selected out of the six found in the literature which performed better in terms of adequacy and predictive performance. The stochastic simulations suggested the benefits of increasing the maintenance dose in protocol to reach the 8 mg/L target.

Fast-Track Liver Transplantation: Six-year Prospective Cohort Study with an Enhanced Recovery After Surgery (ERAS) Protocol

Introduction

Enhanced recovery after surgery (ERAS) has been shown to facilitate discharge, decrease length of stay, improve outcomes and reduce costs. We used this concept to design a comprehensive fast-track pathway (OR-to-discharge) before starting our liver transplant activity and then applied this protocol prospectively to every patient undergoing liver transplantation at our institution, monitoring the results periodically. We now report our first six years results.

Patients and methods

Prospective cohort study of all the liver transplants performed at our institution for the first six years. Balanced general anesthesia, fluid restriction, thromboelastometry, inferior vena cava preservation and temporary portocaval shunt were strategies common to all cases. Standard immunosuppression administered included steroids, tacrolimus (delayed in the setting of renal impairment, with basiliximab induction added) and mycophenolate mofetil. Tacrolimus dosing was adjusted using a Bayesian estimation methodology. Oral intake and ambulation were started early.

Results

A total of 240 transplants were performed in 236 patients (191♂/45♀) over 74 months, mean age 56.3±9.6 years, raw MELD score 15.5±7.7. Predominant etiologies were alcohol (n = 136) and HCV (n = 82), with hepatocellular carcinoma present in 129 (54.7%). Nine patients received combined liver and kidney transplants. The mean operating time was 315±64 min with cold ischemia times of 279±88 min. Thirty-one patients (13.1%) were transfused in the OR (2.4±1.2 units of PRBC). Extubation was immediate (< 30 min) in all but four patients. Median ICU length of stay was 12.7 hours, and median post-transplant hospital stay was 4 days (2-76) with 30 patients (13.8%) going home by day 2, 87 (39.9%) by day 3, and 133 (61%) by day 4, defining our fast-track group. Thirty-day-readmission rate (34.9%) was significantly lower (28.6% vs. 44.7% p=0.015) in the fast-track group. Patient survival was 86.8% at 1 year and 78.6% at five years.

Conclusion

Fast-Tracking of Liver Transplant patients is feasible and can be applied as the standard of care

Pre-emptive deceased-donor kidney transplant: A matched cohort study

INTRODUCTION

Currently, kidney transplantation is the treatment of choice for patients with kidney disease who require replacement therapy. Dialysis is a necessary step, but not mandatory prior to transplantation. There is the possibility of pre-emptive transplantation or transplantation in pre-dialysis, that is, without previous dialysis. The aim of the present study is to evaluate the result of our experience with a pre-emptive kidney transplant from a deceased donor.

MATERIALS AND METHODS

Retrospective, observational, matched cohort study. We compared 66 pre-emptive with 66 non pre-emptive recipients, who received a first renal graft performed at our centre, matched by age and gender of donors and recipients, time of transplant, immunological risk, immunosuppression and cold ischaemia time. Early graft loss, incidence of acute rejection, delayed graft function, renal function at 12 and 36 months and graft and recipient survival were assessed in this period.

RESULTS

The percentage of recipients who presented early graft loss, delayed graft function and acute rejection was similar in both groups. No differences were observed in their renal function at 12 and 36 months after transplantation, as well as the actuarial survival of patients (P=0.801) and grafts (P=0.693) in the studied period. The total calculated cost of the period on dialysis for the control group was 8,033,893.16 euros.

CONCLUSIONS

Pre-emptive transplantation can yield comparable outcomes to those for post-dialysis kidney transplantation, and results in better quality of life for patients with end-stage kidney disease, as well as a reduced cost.

Efficacy and safety of high-flow nasal cannula oxygen therapy in patients with acute heart failure

OBJECTIVES

To evaluate the efficacy and safety of high-flow nasal cannula (HFNC) oxygen therapy in patients in acute respiratory failure due to acute heart failure (AHF) refractory to conventional oxygen therapy or noninvasive ventilation.

METHODS

Prospective observational study of patients with AHF and respiratory failure attended in an emergency department whose condition worsened after they were admitted to a short-stay unit, leading to use of HFNCs. Efficacy was assessed using a modified Borg dyspnea scale and oxygenation variables on discharge from the emergency department. Data were recorded after 24 hours on conventional oxygen therapy and after 60 and 120 minutes and 24 hours of HFNC therapy. Safety outcomes were the degree of patient comfort and the frequency of adverse events.

RESULTS

Prospective observational study of patients with AHF and respiratory failure attended in an emergency department whose condition worsened after they were admitted to a short-stay unit, leading to use of HFNCs. Efficacy was assessed using a modified Borg dyspnea scale and oxygenation variables on discharge from the emergency department. Data were recorded after 24 hours on conventional oxygen therapy and after 60 and 120 minutes and 24 hours of HFNC therapy. Safety outcomes were the degree of patient comfort and the frequency of adverse events.

CONCLUSION

HFNC oxygen therapy offers a treatment alternative for patients with acute respiratory failure due to AHF.

Envarsus, a novelty for transplant nephrologists: Observational retrospective study

The aim of this study was to evaluate the trough concentrations (Cp_trough) and the tacrolimus dosage regimen after the conversion of Prograf or Advagraf to Envarsus (new pharmaceutical form with MeltDose technology that improves the absorption of fat-soluble drugs) in patients with stable renal transplantation, and their renal function. We selected stable renal transplant patients who were converted to Envarsus. Two periods were defined: Baseline and Conversion (Envarsus) and they were stratified according to the pharmaceutical form used in the Baseline period. Sixty-one patients were included (24 with Advagraf and 37 with Prograf), with an average age of 52years. The mean post-transplant time at the time of conversion to Envarsus was 76.3months and the mean follow-up in the Baseline and Conversion period was 10.1months and 11.6months, respectively. In the Prograf and Envarsus group, the Cp_trough medians were 6.6 vs 6.4 ng/mL (P=.636), with a mean daily dose that decreased significantly from 3mg to 2mg (P<.001), respectively, maintaining the filtration rate. The median Cp_trough values in the Advagraf and Envarsus groups were 5.7ng/mL and 6.3ng/mL (P=.07), with a median daily dose of 7mg and 4mg (P<.001), respectively, and the same renal function. In stable renal transplant patients, the conversion from Advagraf to Envarsus has allowed the dose of tacrolimus to be reduced by 42.9% and, in the case of Prograf, by 33.3%, maintaining similar Cp_trough values, without renal function being altered.

Population pharmacokinetics of oxaliplatin after intraperitoneal administration with hyperthermia in Wistar rats

BACKGROUND

The evaluation of the efficacy and toxicity of hyperthermic intraoperative peritoneal chemotherapy presents some difficulties, due in part to the lack of information about the pharmacokinetic behavior of the drugs administered in this procedure. The aim of this study was to characterize the population pharmacokinetics of hyperthermic intraoperative peritoneal oxaliplatin in Wistar rats and to evaluate the effect of treatment-related covariates dose, instillation time and temperature on the pharmacokinetic parameters.

METHODS

Oxaliplatin peritoneal and plasma concentrations from 37 rats treated by either intravenous or intraperitoneal oxaliplatin administrations under different instillation times, temperatures and doses were analyzed according to a population pharmacokinetic approach using the software NONMEM V7.3®.

RESULTS

Intraperitoneal (n = 115) and plasma (n = 263) concentrations were successfully described according to a two-compartment model with first order absorption. No significant effect of dose, temperature and instillation time on pharmacokinetic parameters was found. However, an abrupt decrease in the elimination process was observed, reflected in the structural pharmacokinetic model through a modification in clearance. The typical parameters values and the interindividual variability (CV %) in clearance, central and peripheral volume of distribution were 3.25 mL/min (39.1%), 53.6 mL (37.8%) and 54.1 mL (77.3%), respectively. Clearance decreased to 0.151 mL/min (39.1%) when the instillation was still ongoing, at 31.4 min. One of the possible reasons behind the clearance decrease would be an alteration of renal function due to surgery and/or hyperthermia.

CONCLUSIONS

This study described the deterioration of the drug elimination process due to the procedure, and estimated the time at which this deterioration is most likely to occur. In addition, dose, instillation time and temperature had no influence in the PK parameters.

Suitability of the AUC Ratio as an Indicator of the Pharmacokinetic Advantage in HIPEC

The purpose of this study was to evaluate the area under the concentration-time curve (AUC) ratio as an optimal indicator of the pharmacokinetic advantage during hyperthermic intraperitoneal perioperative chemotherapy. The impact on the AUC ratio on the variables related to the calculation of systemic drug exposure, instillation time, and peripheral drug distribution was evaluated through simulations as well as through a retrospective analysis of studies published in the literature. Both model simulations and the retrospective analysis showed that the 3 variables evaluated had an impact on the AUC ratio value if the complete systemic exposure was not fully considered. However, when that complete systemic exposure was considered, none of these variables affected the AUC ratio value. AUC ratio is not a characteristic parameter of a drug if the calculated systemic drug exposure is not complete. Thus, AUC ratio is not valid for comparing the pharmacokinetic advantage of 2 drugs, and it should not be employed to prove whether a drug can be used in hyperthermic intraperitoneal perioperative chemotherapy safely with regard to toxicity. As an alternative, the study of the absorption rate constant and the bioavailability are proposed as the true and independent parameters that reflect the amount of drug absorbed.

Impact of Laparotomy and Intraperitoneal Hyperthermic Instillation (LIHI) on the oxaliplatin pharmacokinetics after intravenous administration in Wistar rats

PURPOSE

In peritoneal metastasis condition, the fact that most of the disease is limited to the peritoneal cavity laid the foundations for a surgical treatment, including intraperitoneal hyperthermic chemotherapy (HIPEC). The aim of this study was to evaluate the impact of the surgical procedures implied in open HIPEC technique, referred to laparotomy procedures followed by an intraperitoneal hyperthermic instillation (LIHI) on oxaliplatin tissue distribution and elimination. To delimit the influence of this procedure alone, oxaliplatin was administered as an intravenous (iv) bolus in both groups.

METHODS

An experimental model in Wistar rats was employed, and LIHI was evaluated as a dichotomous covariate by using a population pharmacokinetic (PK) approach. Rats were randomized in two groups receiving 1.5 mg iv oxaliplatin alone or 1.5 mg iv oxaliplatin under LIHI conditions, carrying out a hyperthermic 5% dextrose instillation. The oxaliplatin plasma concentrations were characterized by an open two-compartment PK model.

RESULTS

Results concluded that surgical conditions affect the oxaliplatin elimination and distribution from blood to peripheral tissues, increasing the systemic drug exposure. Concretely, oxaliplatin peripheral volume of distribution, and clearance decreased by 48.6% and 55.3%, respectively, compared to the control group that resulted in a two-fold increase of the area under the concentration time curve.

CONCLUSIONS

Comparison in clinical practice of oxaliplatin PK parameters obtained after iv administrations with those obtained after HIPEC interventions must be done carefully. This would limit the use of iv PK parameters to simulate new scenarios for oxaliplatin in HIPEC.

Mammalian Target of Rapamycin Inhibitor Monotherapy: Efficacy in Renal Transplantation

BACKGROUND

Calcineurin inhibitors (CNI) have failed to improve long-term outcomes in renal transplantation. Anti-proliferative and anti-angiogenic effects of mammalian target of rapamycin inhibitors (m-TOR) without nephrotoxicity could improve long-term survival in selected transplant recipients.

METHODS

We examined the evolution of 98 low-immunological risk renal transplant recipients on m-TOR monotherapy: 7 patients had induction without CNI and 91 were switched to m-TOR at 12 (p25-p75: 4-36) months after transplant.

RESULTS

Median follow-up time was 46 (p25-p75: 28.5-72.0) months. Fifteen recipients dropped out of the study (15.3%): 8 patients (8.2%) had to change their immunosuppressive treatment because of complications and 7 (7.1%) lost their grafts as a result of chronic rejection (4 cases) or death with a functioning graft (3 cases). At the end of follow-up, 83 of 98 (84.6%) recipients remained on monotherapy. The rates of recipient and graft survivals were 100% and 98.8% at 2 years and 96.9% and 93.5% at 4 years; the percentages of patients on monotherapy after 2 and 4 years were 95.2% and 85.2%, respectively. Renal function improved significantly and proteinuria decreased but not significantly. Those patients switched to m-TOR significantly received more erythropoietin, angiotensin-converting enzyme inhibitors/angiotensin receptor blockers, and hypotensive agents than before starting m-TOR, whereas there were no significant changes related to the use of statins, body weight, or percentage of diabetic patients. No case of non-compliance was reported.

CONCLUSIONS

This study supports the safety and efficacy of monotherapy with m-TOR in selected renal transplant recipients.

PEG-Interferon-α ribavirin-induced HCV viral clearance: a pharmacogenetic multicenter Spanish study

OBJECTIVE

Dual PEGylated interferon-α (PEG-IFN) and ribavirin therapy has been the main hepatitis C virus (HCV) treatment of the last decade. Current direct-acting antiviral agents have improved the outcome of therapy but also have increased the cost and management complexity of treatment. The current study analyzes host genetics, viral and clinical predictors of sustained viral response (SVR) to dual PEG-IFN and ribavirin therapy in a representative Spanish population.

METHODS

Observational prospective multicentre pharmacogenetic cohort study conducted in 12 different hospitals of 12 different Spanish regions. A total of 98 patients with SVR and 106 with non-SVR in response to PEG-IFN and ribavirin therapy were included. 33 single nucleotide polymorphisms located in 24 different genes related with inflammatory, immune and virus response were selected. Clinical and viral data were also analyzed as candidate of SVR predictors.

RESULTS

IL-28B (rs12979860, rs7248668, rs8105790, rs8099917) and TNFRSF1B (rs1061622) genotypes, as well as TNFRSF1B/IL-10/TNFα (-308) non-TTG and TNFRSF1B/IL- 10/IL-4 non-TTC haplotypes together with lower age, lower basal HCV RNA load, higher basal serum LDL cholesterol values, VHC genotypes 2 and 3 and basal low grade fibrosis 0-2 were associated with a SVR in the univariate analysis. Independent predictors of SVR in the multivariate analysis were IL-28B rs12979860 CC, TNFRSF1B/IL-10/IL-4 non-TTC along with low baseline HCV RNA load and HCV genotypes 2 and 3.

CONCLUSIONS

IL-28B rs12979860 CC, TNFRSF1B/ IL-10/ IL-4 non-TTC haplotype, low baseline HCV RNA load and HCV genotypes 2 and 3 may help to predict successful outcome to PEG-IFN/ribavirin therapy in Spanish population.

Kinetic study of acamprosate absorption in rat small intestine

Acamprosate (calcium bis acetyl-homotaurine), a homotaurine derivative, a structural analogue of gamma-aminobutyric acid (GABA) and an upper homologue of taurine, is a relatively new drug used to prevent relapse in weaned alcoholics. When administered orally as enteric-coated tablets at relatively high doses, this drug has a bioavailability of about 11%; however, the intestinal absorption mechanism has not been studied in depth. The present study was therefore planned to characterize the intestinal transport of acamprosate in the rat and the effect of chronic alcohol treatment on this process, quantifying its kinetic parameters and investigating possible inhibitors. Using an in vitro technique, acamprosate absorption was measured in the rat intestine from three different groups: alcohol group [fed a liquid diet containing 5% (w/v) ethanol for 4 weeks], isocaloric pair-fed control, and a solid diet group. Intestinal acamprosate absorption was found to occur mainly by passive diffusion with a diffusive permeability of 0.213+/-0.004 cm/h in control pair-fed animals, 0.206+/-0.001 cm/h in animals receiving chronic alcohol treatment, and 0.193+/-0.001 cm/h in the solid diet group. Inhibition studies showed that at a 10(-3) M acamprosate concentration, some compounds such as GABA, taurine, proline, and glycine at 40 mM each did not affect acamprosate transport. Nevertheless, when a lower concentration of the drug (10(-4) M) was assayed, a significant reduction of acamprosate transport in the presence of taurine or GABA 40 mM was found. These results suggest that acamprosate in the rat jejunum, could be transported, in part, by a carrier system. Further experiments using different concentrations of taurine (10, 20, and 80 mM) showed that the maximum inhibition (32%) is achieved at 20 mM of taurine. These latter results suggest that acamprosate and taurine share, at least, an intestinal carrier system in rat jejunum. From the above results, it can be concluded that there are probably two pathways involved in the intestinal absorption of acamprosate: passive diffusion and mediated transport, with the former being predominant. Moreover, neither chronic ethanol intake nor the type of diet seems to alter the intestinal absorption of the drug.