Beneficial effects of Wuzhi Capsule on tacrolimus blood concentrations in liver transplant patients with different donor-recipient CYP3A5 genotypes.

WHAT IS KNOWN AND OBJECTIVE: Tacrolimus (Tac) is an immunosuppressant that is widely used to prevent allograft rejection in patients after liver transplantation. Its metabolism mainly depends on the cytochrome P450 3A5 (CYP3A5), which has genetic polymorphisms. Recently, a Chinese herbal medicine known as Wuzhi Capsule (WZC) was shown to increase Tac blood concentrations by inhibiting the activity of CYP3A in animal studies in rats. To date, it remains unexplored whether WZC can be efficiently used to enhance the blood concentration of Tac in liver transplant patients with different donor-recipient CYP3A5 genotypes. METHODS: A total of 185 liver transplant patients were enrolled and two-way ANOVA was carried out, then they were divided into four groups according to the combinations of donor-recipient CYP3A5 phenotypes. WZC was given to patients when the dose of Tac was ≥4 mg, and the dose-adjusted C0 (C0 /D) of Tac measured twice in succession was ≤1 ng/ml/mg. The blood trough concentration of Tac (C0 ), C0 /D, and dose- and body weight-adjusted C0 (C0 /D/W) was analysed on days 7 and 14 after liver transplantation. RESULTS: The genotypes of donor and recipient or WZC had significant effects on C0, C0/D and C0/D/W. There were significant differences in the Tac blood concentrations between the groups. The recipient expression (*1)/donor expression (*1) (R+/D+) group had the lowest C0 , C0 /D and C0 /D/W among the four groups. Furthermore, a larger proportion of patients in the CYP3A5 expression groups required Tac dose adjustment to achieve a therapeutic effect and were given Tac with WZC. Notably, the use of WZC significantly increased the blood concentrations of Tac in the CYP3A5 expression groups and greater increases in the C0 /D and C0 /D/W were significantly associated with higher doses of WZC in the CYP3A5 expression groups. What is more, WZC reduced the hospitalization cost of patients to a certain extent. WHAT IS NEW AND CONCLUSION: WZC significantly increased the C0 , C0 /D and C0 /D/W in the CYP3A5 expression groups and reduced the hospitalization expenses of patients to a certain extent. What is more, greater increases in the C0 /D and C0 /D/W were significantly associated with higher doses of WZC.

Estimation of drug exposure by machine learning based on simulations from published pharmacokinetic models: The example of tacrolimus.

We previously demonstrated that Machine learning (ML) algorithms can accurately estimate drug area under the curve (AUC) of tacrolimus or mycophenolate mofetil (MMF) based on limited information, as well as or even better than maximum a posteriori Bayesian estimation (MAP-BE). However, the major limitation in the development of such ML algorithms is the limited availability of large databases of concentration vs. time profiles for such drugs. The objectives of this study were: (i) to develop a Xgboost model to estimate tacrolimus inter-dose AUC based on concentration-time profiles obtained from a literature population pharmacokinetic (POPPK) model using Monte Carlo simulation; and (ii) to compare its performance with that of MAP-BE in external datasets of rich concentration-time profiles. The population parameters of a previously published PK model were used in the mrgsolve R package to simulate 9000 rich interdose tacrolimus profiles (one concentration simulated every 30 min) at steady-state. Data splitting was performed to obtain a training set (75%) and a test set (25%). Xgboost algorithms able to estimate tacrolimus AUC based on 2 or 3 concentrations were developed in the training set and the model with the lowest RMSE in a ten-fold cross-validation experiment was evaluated in the test set, as well as in 4 independent, rich PK datasets from transplant patients. ML algorithms based on 2 or 3 concentrations and a few covariates yielded excellent AUC estimation in the external validation datasets (relative bias < 5% and relative RMSE < 10%), comparable to those obtained with MAP-BE. In conclusion, Xgboost machine learning models trained on concentration-time profiles simulated using literature POPPK models allow accurate tacrolimus AUC estimation based on sparse concentration data. This study paves the way to the development of artificial intelligence at the service of precision therapeutic drug monitoring in different therapeutic areas.

Appropriateness of tacrolimus therapeutic drug monitoring timing in the emergency department.

PURPOSE: Evaluate the appropriateness of the timing of serum samples collected in the emergency department (ED) for tacrolimus (TAC) measurement. METHODS: Single-center, retrospective review of TAC samples collected in the ED from September 1 to October 31, 2017. The primary evaluation was incidence of inappropriate sample collection for TAC measurement, defined as samples not collected 12 h (±2 h; 10-14 h) after the last dose, or within 2 h of the next dose if last known dose time was not documented. Incidence of repeat TAC measurements obtained within 24 h of ED presentation (if initial sample collection inappropriate), inappropriate TAC regimen adjustments, and healthcare costs of inappropriate TAC measurements was evaluated. Data collection included patient demographics, ED visit information, TAC measurement and timing related to last or next dose, changes to TAC regimen, and ED disposition. Descriptive data are reported. RESULTS: Sixty-two patients were included. Forty-one (66%) initial TAC measurements were collected inappropriately in the ED. No patients had a regimen adjustment as a result of inappropriate concentration collection, but 32 patients (78%) did require a repeat measurement within 24 h of ED presentation due to initial inappropriate collection. Costs associated with incorrectly collected TAC measurements were $2,647.78 for the two-month time period and this is extrapolated to an estimated $15,886.68 annual expense for patients. CONCLUSIONS: Inappropriate sample collection for TAC measurements was common in the ED, resulting in frequent repeat laboratory draws and increased healthcare costs.

Assessment of tacrolimus and creatinine concentration collected using Mitra microsampling devices.

BACKGROUND: Current practice requires regular venous blood samples for monitoring of tacrolimus concentrations post renal transplant requiring regular hospital visits. Mitra devices use volumetric absorptive microsampling technology and absorb a fixed amount of blood (10 µL) from a capillary blood sample. They are a viable volumetric alternative to dried blood spots and are able to be posted to the laboratory for analysis. OBJECTIVE: The aim was to develop and validate liquid chromatography-tandem mass spectrometry (LC-MS/MS) assays for tacrolimus and creatinine analysis using Mitra devices. The usefulness of this approach was assessed in renal transplant patients routinely monitored for tacrolimus and creatinine. METHOD: Routine tacrolimus samples were used to assess the utility and reliability of Mitra sampling. Shared sample preparation for both tacrolimus and creatinine was carried out in a 96-deep well plate; mass spectrometric analysis was then undertaken for tacrolimus followed by re-injection for creatinine analysis. RESULTS: Comparison of 131 Mitra samples with a routine LC-MS/MS assay for tacrolimus showed a minimal bias -5.6% (95% CI -8.5 to -2.7%). Comparison of 135 serum and Mitra samples for creatinine using a fully validated LC-MS/MS assay showed a bias -6.5% (95% CI -8.5 to -4.5%). DISCUSSION: We have developed assays for tacrolimus and creatinine on fingerprick blood using the Mitra device and believe this approach provides a viable alternative to repeated venepuncture for therapeutic drug monitoring. This method could open up the opportunity for patients to perform tacrolimus and kidney function monitoring at home.

Paritaprevir, ritonavir, ombitasvir, and dasabuvir treatment in renal transplant patients with hepatitis C virus infection.

BACKGROUND/AIMS: The Social Security System of our country reimburses only paritaprevir, ritonavir, ombitasvir, and dasabuvir (PrOD) regime in treatment-naive patients with hepatitis C regardless of kidney disease. Most of our renal transplant (RT) recipients were treated with PrOD. The aim of the present study was to investigate the efficacy and safety of PrOD in RT patients with hepatitis C virus (HCV) infection in a single center real-life experience. MATERIALS AND METHODS: RT recipients with a post-transplant follow-up of at least 1 year were included in the study. The patients were treated and monitored according to the guidelines. Blood levels of immunosuppressive patients were closely followed up and adjusted. RESULTS: A total of 21 (12 male and nine female) patients were assessed. The age of the patients was 50.8±8.5 years. Ten patients were infected with G1a, 10 patients with G1b, and one patient with G4 HCV. Two patients had compensated cirrhosis. Eighteen patients were treatment-naive, and three were peginterferon+ribavirin-experienced. Sustained virologic response (SVR12) was achieved in all patients. None of the patients discontinued the treatment. Cyclosporine (Csa) and tacrolimus (Tac) doses were reduced to once a day to once a week to maintain the blood level within normal range. The most common adverse effect was anemia in patients receiving ribavirin. Renal functions did not change during the treatment period. CONCLUSION: In this real-life experience, all of the 21 PrOD-treated RT recipients reached SVR12. Tac or Csa serum levels were maintained within the normal range with close monitoring. PrOD regime can be successfully and safely used in RT recipients with HCV infection with close follow-up.

Large-Scale Variability of Inpatient Tacrolimus Therapeutic Drug Monitoring at an Academic Transplant Center: A Retrospective Study.

BACKGROUND: Inpatient tacrolimus therapeutic drug monitoring (TDM) lacks standardized guidelines. In this study, the authors analyzed variability in the preanalytical phase of the inpatient tacrolimus TDM process at their institution. METHODS: Patients receiving tacrolimus (twice-daily formulation) and tacrolimus laboratory analysis were included in the study. Times of tacrolimus administration and laboratory study collection were extracted, and time distribution plots for each step in the inpatient TDM process were generated. RESULTS: Trough levels were drawn appropriately in 25.9% of the cases. Timing between doses was consistent, with 91.9% of the following dose administrations occurring 12 ± 2 hours after the previous dose. Only 38.1% of the drug administrations occurred within 1 hour of laboratory study collection. Tacrolimus-related patient safety events were reported at a rate of 1.9 events per month while incorrect timing of TDM sample collection occurred approximately 200 times per month. Root cause analysis identified a TDM process marked by a lack of communication and coordination of drug administration and TDM sample collection. Extrapolating findings nationwide, we estimate $22 million in laboratory costs wasted annually. CONCLUSIONS: Based on this large single-center study, the authors concluded that the inpatient TDM process is prone to timing errors, thus is financially wasteful, and at its worst harmful to patients due to clinical decisions being made on the basis of unreliable data. Further work is needed on systems solutions to better align the laboratory study collection and drug administration processes.

Comparison of the long-term efficacy and safety of generic tacrolimus, Tacrobell, with Prograf in liver transplant recipients.

INTRODUCTION: The purpose of this study was to compare the safety and efficacy of generic tacrolimus (Tacrobell [TCB]) and a reference tacrolimus (Prograf [PGF]) in liver transplant recipients. PATIENTS AND METHODS: We retrospectively analyzed 167 patients who used TCB or PGF between January 2009 and March 2016 for >1 year (TCB group, n=86; PGF group, n=81). To assess the efficacy and safety of TCB, we evaluated the relationship between drug dose and trough level, survival, rejection, infection, kidney function, and side effects. RESULTS: There was no difference in the preoperative demographics between the two groups. Moreover, there was no difference in the drug dose and trough level between the groups at 1 week after surgery. Coefficient of variation (CV) values were obtained at the drug trough level for each patient and no differences in CV values were identified within 1 year (p=0.587) and up to 5 years (p=0.824) in both groups. Rehospitalization (p=0.1) and total rejection (p=0.915) did not differ between the two groups, but the rejection severity, recorded as the rejection activity index value, was worse in the PGF group (p=0.039). No difference was found in the infection rate (p=0.818), and with regard to nephrotoxicity, there was no difference in the rate of patients with chronic kidney disease stage 3 and above during the follow-up period. No differences were found between the two groups in terms of drug side effects and adverse events. CONCLUSION: The generic tacrolimus, TCB, is a comparable alternative to the original tacrolimus, PGF, as a main immunosuppressive drug for liver transplantation.

Rapid determination of immunosuppressive drug concentrations in whole blood by coated blade spray-tandem mass spectrometry (CBS-MS/MS).

Coated Blade Spray (CBS) is a technology that efficiently integrates sample preparation and direct coupling to mass spectrometry (MS) on a single device. In this article, we present CBS-tandem mass spectrometry (CBS-MS/MS) as a novel tool for the rapid and simultaneous determination of four commonly used immunosuppressive drugs (ISDs) in whole blood: tacrolimus (TAC) and cyclosporine-A (CycA), which are calcineurin inhibitors; and sirolimus (SIR) and everolimus (EVR), which are both mTOR (mechanistic target of rapamycin) inhibitors. Given that CBS extracts via free concentration, analytes that are largely bound to plasma proteins or red blood cells provide considerably lower extraction recovery rates. Therefore, we defy the solventless philosophy of SPME-based techniques, like CBS, by performing the analyte-enrichment step via direct immersion in a solvent-modified matrix. The assay was linear within the evaluated range of concentrations (between 1 and 100 ng/mL for EVR/SIR/TAC and 10-1000 ng/mL for CycA), and the limits of quantification were determined to be 10 ng/mL for CycA and 1 ng/mL for EVR/SIR/TAC. Good accuracy (87-119%) and linearity (r2 ≥ 0.99) were attained over the evaluated range for all ISDs. Interassay imprecision (CV) determined from incurred sample reanalysis was ≤10% for all ISDs. Our method was validated using Liquichek™ whole blood immunosuppressant quality control (QC) standards purchased from Bio-Rad. Concentrations determined by CBS-MS/MS were inside the range specified by Bio-Rad and within 15% of the expected mean value for all ISDs at all QC levels. Furthermore, the effect of different hematocrit levels (20, 45, and 70%) in the entire calibration range was carefully studied. No statistical differences (RSD ≤ 7%) in the calibration curve slopes of ISDs in blood were observed. CBS offers a simpler workflow than that of traditional methods; it eliminates the need for chromatographic separation and provides a clean extract that allows for long-term MS instrumental operation with minimal maintenance. Additionally, because CBS integrates all analytical steps into one device, it eliminates the risk of instrumental carry-over and can be used as a low-cost disposable device for sample preparation and analysis. Fully-automated sample preparation simplifies the method and allows for total analysis times as short as 3 min with turn-around times of less than 90 min.

Pharmacokinetics and Clinical Outcomes of Generic Tacrolimus (Hexal) Versus Branded Tacrolimus in De Novo Kidney Transplant Patients: A Multicenter, Randomized Trial.

BACKGROUND: Scrupulous comparison of the pharmacokinetic and clinical characteristics of generic tacrolimus formulations versus the reference drug (Prograf) is essential. The pharmacokinetics of the Tacrolimus Hexal (TacHexal) formulation is similar to Prograf in stable renal transplant patients, but data in de novo patients are lacking. METHODS: De novo kidney transplant patients were randomized to generic tacrolimus (TacHexal) or Prograf in a 6-month open-label study. RESULTS: The primary end point, the dose-normalized area under the curve0-12h at month 1 posttransplant, was similar with TacHexal or Prograf; back-transformed geometric means of adjusted log-transformed values (analysis of variance) were 18.99 ng·h·L (TacHexal) and 20.48 ng·h·L (Prograf) (ratio, 1.08; 90% confidence interval, 0.84-1.38; P = 0.605). The dose-normalized peak concentration geometric means at month 1 was also comparable between treatments (ratio, 1.16; 90% confidence interval, 0.88-1.54; P = 0.377). There were no relevant differences in other pharmacokinetic parameters at month 1 or in area under the curve0-4h and trough concentration when measured at months 3 and 6. The adjusted change in mean estimated glomerular filtration rate from baseline to month 6 (Nankivell) was noninferior for TacHexal versus Prograf using observed values (47.7 vs 38.6 mL/min per 1.73 m, P < 0.001) and was superior based on observed values (P = 0.044) but not using last observation-carried forward method. Rates of biopsy-proven acute rejection (5.7% vs 7.9%), adverse events, and serious adverse events were similar with TacHexal or Prograf. CONCLUSION: Tacrolimus pharmacokinetics is similar with TacHexal and Prograf early after kidney transplantation. Efficacy and safety in this limited data set were comparable, with at least equivalent graft function under TacHexal.

Comprehensive risk assessment for early neurologic complications after liver transplantation.

AIM: To determine risk factors for early neurologic complications (NCs) after liver transplantation from perspective of recipient, donor, and surgeon. METHODS: In all, 295 adult recipients were enrolled consecutively between August 2001 and February 2014 from a single medical center in Taiwan. Any NC in the first 30 d post-liver transplantation, and perioperative variables from multiple perspectives were collected and analyzed. The main outcome was a 30-d NC. Generalized additive models were used to detect the non-linear effect of continuous variables on outcome, and to determine cut-off values for categorizing risk. Risk factors were identified using multiple logistic regression analysis. RESULTS: In all, 288 recipients were included, of whom 142 (49.3%) experienced at least one NC, with encephalopathy being the most common 106 (73%). NCs prolonged hospital stay (35.15 ± 43.80 d vs 20.88 ± 13.58 d, P < 0.001). Liver recipients' age < 29 or ≥ 60 years, body mass index < 21.6 or > 27.6 kg/m(2), Child-Pugh class C, history of preoperative hepatoencephalopathy or mental disorders, day 7 tacrolimus level > 8.9 ng/mL, and postoperative intra-abdominal infection were more likely associated with NCs. Novel risk factors for NCs were donor age < 22 or ≥ 40 years, male-to-male gender matching, graft-recipient weight ratio 0.9%-1.9%, and sequence of transplantation between 31 and 174. CONCLUSION: NCs post- liver transplantation occurs because of factors related to recipient, donor, and surgeon. Our results provide a basis of risk stratification for surgeon to minimize neurotoxic factors during transplantation.

Sublingual administration improves systemic exposure of tacrolimus in kidney transplant recipients: comparison with oral administration.

BACKGROUND: Tacrolimus (TCR) is an immunosuppressive drug used by oral administration. Intravenous (IV) TCR administration is required under conditions of gastrointestinal diseases or abdominal surgery at the onset of paralytic ileus. The infusion formulation needs a large dilution and therefore a careful technical management during continuous infusion by 24 h and may determine anaphylaxis, cardiac arrhythmia, QT prolongation and torsades de pointes. Sublingual (SL) TCR administration was suggested as an alternative route. DESIGN: The aim of this study was to compare in the same kidney transplanted patients the TCR pharmacokinetic profiles by both the routes coupled with the pharmacoeconomic analysis. The study enrolled eight subjects undergoing renal transplantation and treated with TCR and methylprednisolone. TCR was administered by oral route at the scheduled dosage while the 50% of oral dosage was used by SL route, taking into account the absence of liver first pass. RESULTS: Except for AUC, which resulted significantly increased after oral administration, all exposure parameters were not significantly different between the two routes of administration. Analysis of dose-adjusted exposure parameters showed significant increases in AUC and Cmin after SL administration confirming a better bioavailability of the SL route compared with oral route. Cost saving was obtained using the SL rather than the IV route of TCR delivery. CONCLUSION: When oral administration of TCR is not advised, SL delivery represents an attractive option to IV administration.

Transition from brand to generic tacrolimus is associated with a decrease in trough blood concentration in pediatric heart transplant recipients.

There are limited data available on the bioequivalence of generic and brand-name tacrolimus in pediatric and heart transplant patients. We characterized changes in 12-hour trough concentrations and clinical outcomes after transition from brand to generic tacrolimus in pediatric thoracic organ transplant recipients. Patients with a pharmacy-confirmed date of switch between generic and brand tacrolimus were identified, as well as a matched control group that did not switch for comparison. We identified 18 patients with a confirmed date of switch, and in 12 patients that remained on the same dose, trough concentrations were 14% less than when they were on brand (p = 0.037). The average change was -1.15 ± 1.76 ng/mL (p = 0.045). The control group did not experience a change in trough concentration and was different than the switched group (p = 0.005). There were no differences in dosage changes or kidney or liver function. In the year after switch, 24% of patients who were switched to generic experienced a rejection event vs. 18% in the patients on brand. We suggest a strategy of monitoring around the time of transition, and education of the patient/family to notify the care team when changes from brand to generic or between generics occur.

Assessment of four methodologies (microparticle enzyme immunoassay, chemiluminescent enzyme immunoassay, affinity column-mediated immunoassay, and flow injection assay-tandem mass spectrometry) for measuring tacrolimus blood concentration in Japanese liver transplant recipients.

Therapeutic drug monitoring (TDM) and subsequent dosage adjustment for individual patients in the treatment with tacrolimus are required after liver transplantation to prevent rejection and over-immunosuppression, which leads to severe infection and adverse reactions including nephrotoxicity. The purpose of this study was to evaluate the analytical performance among commercially available immunoassay methods, which were microparticle enzyme immunoassay (MEIA), chemiluminescent enzyme immunoassay (CLIA), and affinity column-mediated immunoassay (ACMIA), compared with an assay using liquid chromatography-tandem mass spectrometry (LC-MS/MS). In addition, the flow injection assay (FIA-MS/MS) was also evaluated to determine whether it could be available as a new method of analysis in tacrolimus therapy. The blood tacrolimus concentrations in samples from liver transplant recipients (n = 102) were measured using MEIA, CLIA, ACMIA, and LC-MS/MS. Additional blood samples from liver transplant recipients (n = 54) were analyzed using both FIA-MS/MS and LC-MS/MS. Because the assay performance and characteristics of MEIA, CLIA, ACMIA, and FIA-MS/MS are relatively different, the measured data should be carefully considered depending on the methodology.

Metabolic status of 1088 patients after renal transplantation: assessment of twelve years monitoring in Algiers Mustapha Hospital.

Since the introduction of monitoring levels of immunosuppressive medications in our service in July 2000, 1088 kidney transplant patients were received for therapeutic drug monitoring and regular follow-up. The aim of this study was to retrospectively analyze the data on these renal graft patients in Algeria and correlate with our 12 years' experience with calcineurin inhibitor (CNI) measurements. In addition, during this period, we also examined other bioche-mical parameters. The analysis was focused on the difference of effect of cyclosporin A (CsA; 623 patients) and Tacrolimus (Tac; 465 patients) on lipid and glucose metabolism and their side-effects, if any, on the renal function. The mean age at the time of transplantation was 36.1 years. A great majority of the transplanted kidneys had been taken from living related donors (88.6%). Three-quarters of all grafts were transplanted in our country (79.5%). Dyslipidemia and renal dysfunction were the most common adverse effects of CsA and Tac exposure, with a frequency of 21.4% and 10.3%, respectively. Both the CNIs had a similar effect on the lipid levels. The highest incidence occurred at 3-12 months after renal graft. Tac seemed to have more side-effects on glycemia, causing the onset of diabetes mellitus more than two-fold than CsA (6.9% vs. 3.1%). A significant difference was observed during 12-24 months after transplantation. However, Tac was associated with the most favorable effects on renal function estimated with the Modification of Diet in Renal Disease (MDRD) formula.

Prograf five milligrams versus Tacrolimus medis in healthy volunteers: a bioequivalence study.

For FDA approval, bioequivalence of a generic version of Tacrolimus must be demonstrated in a randomized, two-treatments, two-periods, two-sequences, single-dose crossover study in healthy adult volunteers. Currently there are at least 3 differents generic equivalent for Tacrolimus, that are approved by the EMA and the FDA, with a USA market share of nearly 50%. However, the market share of generic immunosuppressive drugs in the Middle East region is still very low due to the reluctance of the physician to accept Tacrolimus generics, considered to be a narrow therapeutic window drug, that are approved using the standard bioequivalence criteria of 80% to 125%. Herein we present a bioequivalence study of a new Tacrolimus generic, Tacrolimus Medis 5 mg developed by Medis Tunisia batch number 12G3003 compared with Prograf® 5 mg batch number 7202 manufactured by Astellas Toyama Co., Ltd. Japan and HIKMA Pharmaceuticals, Amman-Jordan in healthy adult volunteers using the 90%-111% criteria recommended for drugs with narrow therapeutic window. The study was, balanced, randomized, two-treatments, two-periods, two-sequences, single dose, crossover, comparative oral bioavailability study in healthy adult human volunteers. The study was carried out in accordance with the Basic Principles defined in the U.S. 21 CFR Part 312.20, the principles enunciated in the Declaration of Helsinki (World Medical Association Declaration of Helsinki). Thirty six non-smoking healthy, as determined by medical history, volunteers, 18 years and older, were included. Following randomization using a computer software (pharma solution) the volunteers were given a single oral dose of 5 milligrams following a 12 hour fast with a wash out period of 7 days. Pharmacokinetics profile with blood levels at: 0, 0.5, 1, 1.5, 2, 2.5, 3, 4, 6, 8, 10, 12, and 24 hours were performed following each dose. Tacrolimus plasma level was determined using an HPLC validated method (Transmedical For Life S.A.R.L. Beirut Lebanon), for accuracy, suitability, reproducibility, precision , long-term stability and robustness. Physical examinations, hematology, urine analysis and serum chemistry tests were performed at screening and before dosing in each period and at end of the study. Volunteers were monitored for safety and adverse events throughout the study. Both products were bioequivalent at the entire pharmacokinetic parameters tested. The LSM were 95.31%-101.21% for AUC, 94.65%-101.11% for AUC0-inf, 97.15%-100.02% for Cmax and 91.54%-103.75% for Half-life. Respectively all of which are within the EU and FDA approval limits (90-111%) indicating that the 2 products are equivalent and switchable.

A Markov chain model to evaluate the effect of CYP3A5 and ABCB1 polymorphisms on adverse events associated with tacrolimus in pediatric renal transplantation.

The SNP A6986G of the CYP3A5 gene (*3) results in a non-functional protein due to a splicing defect whereas the C3435T was associated with variable expression of the ABCB1 gene, due to protein instability. Part of the large interindividual variability in tacrolimus efficacy and toxicity can be accounted for by these genetic factors. Seventy-two individuals were examined for A6986G and C3435T polymorphism using a PCR-RFLP-based technique to estimate genotype and allele frequencies in the Jordanian population. The association of age, hematocrit, platelet count, CYP3A5, and ABCB1 polymorphisms with tacrolimus dose- and body-weight-normalized levels in the subset of 38 pediatric renal transplant patients was evaluated. A Markov model was used to evaluate the time-dependent probability of an adverse event occurrence by CYP3A5 phenotypes and ABCB1 genotypes. The time-dependent probability of adverse event was about double in CYP3A5 non-expressors compared to the expressors for the first 12 months of therapy. The CYP3A5 non-expressors had higher corresponding normalized tacrolimus levels compared to the expressors in the first 3 months. The correlation trend between probability of adverse events and normalized tacrolimus concentrations for the two CYP3A5 phenotypes persisted for the first 9 months of therapy. The differences among ABCB1 genotypes in terms of adverse events and normalized tacrolimus levels were only observed in the first 3 months of therapy. The information on CYP3A5 genotypes and tacrolimus dose requirement is important in designing effective programs toward management of tacrolimus side effects particularly for the initial dose when tacrolimus blood levels are not available for therapeutic drug monitoring.

System for integrated adherence monitoring: real-time non-adherence risk assessment in pediatric kidney transplantation.

This study reports initial results of the development of the SIAM, a non-adherence risk assessment system for tacrolimus and sirolimus for the pediatric kidney transplant population. Forty-eight youths between 10 and 25 yr of age diagnosed with chronic kidney disease or a kidney transplant used an electronic pill bottle (EM; time stamps each bottle opening) to dispense their medication for at least 30 days or until their next clinic appointment. Youth also completed a self-report adherence measure, and standard deviations were calculated for the last four medication serum trough levels obtained for each patient. Estimation models were developed for each medication (i.e., SIAM(TACRO) and SIAM(SIRO) ) to assign weights to these clinically available adherence measures (self-report and trough levels) for the calculation of a non-adherence risk composite score. SIAM(TACRO) models included both self-report and tacrolimus trough levels and significantly predicted EM. For sirolimus, the model predictive of adherence as measured by EM consisted of the standard deviation of sirolimus trough levels only (SIAM(SIRO) ). Non-adherence risk can be effectively assessed using clinically available assessment tools. However, the best methods for using self-report and trough levels to predict non-adherence likely differ based on the medication for which adherence is being assessed.

Successful and cost-efficient replacement of immunoassays by tandem mass spectrometry for the quantification of immunosuppressants in the clinical laboratory.

The purpose of this paper is to describe the implantation of mass spectrometry in replacement of immunoassays for the measurement of immunosuppressant drugs in the clinical setting, from scientific and financial perspectives. A straightforward, rapid, and economical method was developed for the simultaneous quantification of tacrolimus, sirolimus, and cyclosporine. Following a simple protein precipitation step, supernatants are injected on a small C(18) guard cartridge and gradient elution of the immunosuppressants is performed in a total chromatographic run time of 2.25 min. Sodium adducts of the compounds and internal standards are quantified by electrospray tandem mass spectrometry. The method shows inter-assay impression of less than 10-15% for all compounds with good extraction efficiency (89-104%) and minimal matrix effects, except for sirolimus where ion suppression is more pronounced. The method correlates well with chemiluminescent microparticle immunoassays (on the Abbott Architect analyzer), although the immunoassay results are significantly higher than those obtained by HPLC-MS/MS. The transition from immunoassays to mass spectrometry was well received by the laboratory staff, and significant reductions in reagent costs have been realized (>$250,000 CAD per year). With these savings, the purchase and installation of two complete HPLC-MS/MS systems was completely financed in less than three years.

Validation on the simplified medication adherence questionnaire (SMAQ) in renal transplant patients on tacrolimus.

BACKGROUND: Non-adherence to immunosuppressive medication is associated with graft loss and death. The simplified medication adherence questionnaire (SMAQ) is a short and reliable instrument for assessing adherence to medication. OBJECTIVE: Validation of a version of the SMAQ instrument adapted for use in transplant patients in a sample of kidney graft recipients. METHODS: Observational, longitudinal prospective study in 150 renal transplant patients on tacrolimus, over 18 years old, who had received a graft at least one year before. Basic sociodemographic and clinical data were recorded; patients completed the SMAQ twice (administered by doctor/nurse) and self-administered the Morisky-Green scale. The analysis database included 144 patients that met selection criteria and that provided the required data. Descriptive characteristics for all recorded parameters and psychometric characteristics of the questionnaire (reliability and validity) were studied. RESULTS: Mean age in the sample was 50.63 (12.44) years, 60.42% were men. Some 20.14% of patients had sub-target tacrolimus levels (<5 ng/ml), and unjustified variations in immunosuppressive drug levels were reported for 13.48%. Regarding SMAQ results, 39.01%/41.84% of patients were non-adherent (doctor/nurse administration); 22.38% according to the Morisky-Green scale. Interobserver agreement (kappa) was 0.821 (P<.001). The Cramer's-V statistic for convergent validity was 0.516 (P<.001). SMAQ scores were associated with unjustified variations in tacrolimus levels. In the prediction of tacrolimus levels (target vs subtarget), SMAQ compared to Morisky-Green provided a better classification of patients, with greater sensitivity and lower specificity. CONCLUSION: The questionnaire provides good levels of validity and interobserver agreement. An enhanced sensitivity is advantageous to better detect non-adherent patients for a better follow-up.