Alberto M. Borobia

Trough tacrolimus concentrations in the first week after kidney transplantation are related to acute rejection.

There is evidence showing the importance of reaching immunosuppressant target concentrations as soon as possible. The aim of this study was to evaluate the relationship between tacrolimus trough concentrations within the first week after transplantation and the rate of acute rejection. In this descriptive-analytic study, we included 57 renal transplant patients receiving tacrolimus as the primary immunosuppressive drug. After univariate analysis, donor age, duration of hospital stay, and creatinine clearance (third month) showed significant differences between rejecters and nonrejecters. In addition, mean tacrolimus trough concentrations on day 5, day 7, mean of days 1-7, and mean of days 5-7 were found to be significantly lower in rejecters (P = 0.009, P = 0.012, P = 0.006, and P = 0.035, respectively). Receiver operating characteristic curve analysis with tacrolimus trough concentrations measured on days 5 and 7 was able to discriminate between patients with and without acute rejection (P = 0.028 and P = 0.048 after Bonferroni correction). The tacrolimus trough concentration with the best sensitivity-specificity balance was 9.3 ng/mL on day 5 and 8.7 ng/mL on day 7. In the Kaplan-Meier analysis, patients with tacrolimus trough concentrations below 9.3 mg/mL on day 5 showed a lower survival time without acute rejection (P = 0.048 after correction) in comparison with patients with tacrolimus trough concentrations above this concentration. After logistic regression, we obtained a model relating rejection with sex, donor age, and tacrolimus trough concentrations on day 5 (P = 0.004). No significant relationship between tacrolimus trough concentrations and delta creatinine clearance from week 1 to month 3 was obtained. These results confirm that tacrolimus trough concentrations during the first week are an important predictor of acute rejection. Therefore, it is critical to reach target blood concentrations of tacrolimus as soon as possible to improve allograft survival.

Acceptability and characteristics of 124 human bioequivalence studies with active substances classified according to the Biopharmaceutic Classification System

AIM The aim of this study was to evaluate the acceptability of 124 bioequivalence (BE) studies with 80 active substances categorized according to the Biopharmaceutics Classification System (BCS) in order to establish if there were different probabilities of proving BE between the different BCS classes. METHODS We evaluated the differences between pharmaceutical products with active substances from different BCS classes in terms of acceptability, number of subjects in the study (n), the point estimates, and intra- and inter-subject coefficients of variation data from BE studies with generic products. RESULTS Out of 124 BE studies 89 (71.77%) were performed with pharmaceutical products containing active substances classified by the BCS. In all BCS classes there were non-bioequivalent pharmaceutical products: 4 out of 26 (15.38%) in class 1, 14 out of 28 (50%) in class 2, 3 out of 22 (13.63%) in class 3 and 1 out of 13 (7.69%) in class 4. When we removed those pharmaceutical products in which intra-subject variability was higher than predicted (2 in class 1 active substances, 9 in class 2 and 2 in class 3) there were still non-BE pharmaceutical products in classes 1, 2 and 3. CONCLUSIONS Comparisons between pharmaceutical products with active substances from the four BCS classes have not allowed us to define differential characteristics of each class in terms of n, inter and intra-subject variability for C(max) or AUC. Despite the usually employed test dissolution methodology proposed as quality control, pharmaceutical products with active substances from the four classes of BCS showed non-BE studies.

An Acenocoumarol Dosing Algorithm Using Clinical and Pharmacogenetic Data in Spanish Patients with Thromboembolic Disease

Appropriate dosing of coumarins is difficult to establish, due to significant inter-individual variability in the dose required to obtain stable anticoagulation. Several genetic and other clinical factors have been associated with the coumarins dose, and some pharmacogenetic-guided dosing algorithms for warfarin and acenocoumarol have been developed for mixed populations. We recruited 147 patients with thromboembolic disease who were on stable doses and with an international normalized ratio (INR) between 2 and 3. We ascertained the influence of clinical and genetic variables on the stable acenocoumarol dose by multiple linear regression analysis in a derivation cohort (DC; n = 117) and developed an algorithm for dosing that included clinical factors (age, body mass index and concomitant drugs) and genetic variations of VKORC1, CYP2C9, CYP4F2 and APOE. For purposes of comparison, a model including only clinical data was created. The clinical factors explained 22% of the dose variability, which increased to 60.6% when pharmacogenetic information was included (p<0.001); CYP4F2 and APOE variants explained 4.9% of this variability. The mean absolute error of the predicted acenocoumarol dose (mg/week) obtained with the pharmacogenetic algorithm was 3.63 vs. 5.08 mg/week with the clinical algorithm (95% CI: 0.88 to 2.04). In the testing cohort (n = 30), clinical factors explained a mere 7% of the dose variability, compared to 39% explained by the pharmacogenetic algorithm. Considering a more clinically relevant parameter, the pharmacogenetic algorithm correctly predicted the real stable dose in 59.8% of the cases (DC) vs. only 37.6% predicted by the clinical algorithm (95% CI: 10 to 35). Therefore the number of patients needed to genotype to avoid one over- or under-dosing was estimated to be 5.

Overuse of PPIs in Patients at Admission, During Hospitalisation, and at Discharge in a Terciary Spanish Hospital

Background: The first generic PPI was introduced in Spain in 2001, and since then their prescriptions have increased steadily by about 200%. Aim: To evaluate the frequency of use and the appropriateness of indications of PPIs in hospitalised patients, and possible factors predicting their use. We also evaluated relevant PPI-drug interactions and serious adverse drug reactions (SADRs). Methods: This was a cross-sectional, prescription-indication drug-utilisation study in hospitalised patients with follow-up until discharge. Sampling was random and stratified by services, and was calculated to obtain an error in the precision of prescription of ±4% with a 95% confidence interval with maximum variability (50%). Results: 328 patients were included; 28.65% were prescribed a PPI at admission, 82.62% were prescribed a PPI during hospitalisation, and 54.75% at discharge, with inappropriate indications in 74.47%, 61.25% and 80.24% respectively. The OR of being discharged with PPIs was 3.01(95% CI:2.17 – 4.18, p=0.000). The inappropriate indication most frequently seen at admission and at discharge was antiplatelet therapy. During hospitalisation it was prophylaxis for stress ulcer in patients at low risk. PPI prescription at admission remained at discharge in 75.90% of cases, 73.02% without an acceptable indication. Being > 64 years old, taking > 4 drugs, co-medication (NSAIDs, antiaggregation and anticoagulation), certain hospital departments and length of stay > 15 days predicted 83.7% of prescriptions at discharge. Four relevant PPIdrug interactions were found, and 2 resulted in SADRs, thus the incidence per 1, 000 patients was 2.66 (Poisson 95% CI:0.62-7.23). Conclusions: There was a very high frequency of overuse of PPIs in inpatients and outpatients. Hospitalisation did not represent an opportunity for better prescription of PPIs.

A pharmacovigilance program from laboratory signals for the detection and reporting of serious adverse drug reactions in hospitalized patients.

The detection and reporting of serious adverse drug reactions (SADRs) have become important components of monitoring and evaluation activities performed in hospitals. We present the implementation of a prospective pharmacovigilance program based on automatic laboratory signals (ALSs) at a hospital. We also report the general findings after the first year of operation of the program, which involved ALSs that indicate various SADRs: agranulocytosis, aplastic anemia, liver injury, thrombocytopenia, hyponatremia, and rhabdomyolysis. The number of hospitalizations during the year was 54,525, and 1,732 patients experienced at least one ALS. The review of electronic medical records (EMRs) showed that no alternative cause (i.e., no non‐SADR explanation) for the ALS was identified in 520 (30%) of the patients. After the individual ALS–patient evaluation, a total of 110 SADRs (6.35% of those identified after reviewing EMRs and 21.15% of those requiring individual patient evaluations) were identified. In other words, in order to identify a single SADR, we had to review the electronic records of approximately 16 patients and personally visit 5 patients.

Use of prothrombin complex concentrates for urgent reversal of dabigatran in the Emergency Department

New oral anticoagulants (NOACs) are being implemented for use in daily clinical practice, anticoagulants that should theoretically replace the well-known vitamin K antagonists in the near future. Based on their inhibitory properties, NOACs can be classified into two main groups: direct thrombin

Evaluation of the influence of sex and CYP2C19 and CYP2D6 polymorphisms in the disposition of citalopram.

We investigate the impact of sex and genotype on citalopram disposition in 35 healthy volunteers who received an oral dose of 20mg citalopram within a single-dose bioequivalence study. CYP2C19*2 and *3, and CYP2D6*4 mutations were determined by Real-Time PCR. The influence of sex and genotype was analyzed by a linear mixed model for repeated measures, including formulation, period, sequence, sex, CYP2C19 and CYP2D6 as fixed effects and subject nested sequence*sex*CYP2C19*CYP2D6 as the random one. Pharmacokinetic parameters were log-transformed and AUC(infinity) and C(max) adjusted to the administered dose/weight. The model yields a statistical significance in AUC(infinity) and CL/F for CYP2C19 and CYP2D6. Gender, formulation, sequence or period effects were not statistically significant. AUC(infinity) of CYP2C19*1/*2 and CYP2C19*2/*2 carriers is 44% and 118% higher than wild type, respectively; CYP2D6 volunteers carrying 1/4 have an AUC 23% higher than wild type. Our data also suggest that the influence of CYP2D6 on AUC(infinity) is very low when it is in association with CYP2C19*1/*1 while its influence is more apparent in association with CYP2C19*1/*2. In conclusion, we demonstrate the influence of CYP2C19 and CYP2D6 in the disposition of citalopram, and we suggest that the influence of CYP2D6 is more probable in volunteers with at least one defective allele of CYP2C19.

Sublingual administration of tacrolimus in a renal transplant patient

Tacrolimus is used in renal and other organ transplantations for immunossupression therapy. Bioavailability of enterally administered tacrolimus is poor, and further reduced by gastrointestinal failure or enteral nutrition. In these situations, intravenous administration is necessary to prevent treatment failure. However, intravenous administration should be done in a continuous manner and it has been implicated in anaphylaxis, torsades de pointes, cardiac arrhythmia and other serious adverse events. Also it is more expensive than other routes of administration. Sublingual administration of tacrolimus has been used in some cases, and literature reports show that it provides therapeutic tacrolimus levels in lung and liver transplant recipients. Here, we report a first case of sublingual administration of tacrolimus in kidney transplantation.

Influence of sex and CYP2D6 genotype on mirtazapine disposition, evaluated in Spanish healthy volunteers

AIMS To evaluate the influence of sex and CYP2D6 genotype on mirtazapine disposition within two bioequivalence studies in healthy volunteers. METHODS Seventy-two healthy volunteers were included in two standard 2 x 2 crossover bioequivalence trials. Subjects received a single 30-mg oral dose of each mirtazapine formulation in each study period. Plasma concentrations were measured from 0 to 96 or 120 h by a HPLC with coupled mass spectrometry validated method. CYP2D6 genotyping was available for 68 subjects that were classified into three phenotypic groups depending on the number of active gene copies: extensive/ultrarapid metabolizers (UM-EM), intermediate (IM) and poor metabolizers (PM). To evaluate the influence of sex and genotype on mirtazapine disposition we performed a linear mixed model for repeated measures. Pharmacokinetic data were log-transformed and AUC and C(max) adjusted to the administered dose/weight. Factors included in the model were centre, formulation, period, sequence, sex and genotype as fixed effects, and subject nested sequence x sex x genotype as random one. A second model was also performed adding the interaction sex x genotype to the previous model. RESULTS Mirtazapine disposition evaluated as AUC(0-infinity) is influenced by sex (p=0.007) and CYP2D6 phenotype group (p=0.01). Attending to the theoretical figures provided by the model, mean (95% CI) dose/weight adjusted AUC(0-infinity) (ng h/ml)/(mg/kg) is 1516.62 (1411.27-1628.22) in EM/UM, 1613.63 (1482.14-1758.55) in IM and 2049.28 (1779.78-2357.24) in PM. In the case of C(max) these figures also show a trend to higher values in PM, but it did not reach statistical significance. Females show a lower dose/weight adjusted AUC(0-infinity): 1594.39 (1477.70-1720.28) vs. 1837.65 (1694.67-1992.70). On the contrary dose/weight adjusted C(max) is higher in females than in males: 38.33 (34.79-42.28) vs. 32.66 (29.44-36.21). CONCLUSIONS Both CYP2D6 genotype group and sex influence the disposition of mirtazapine in healthy volunteers and confirm reported data in the literature obtained by different methods. No sex-by-genotype interaction could be detected.

Symptomatic thromboembolic events in patients treated with intravenous-immunoglobulins: Results from a retrospective cohort study

AIMS To estimate the incidence and predictors of symptomatic arterial and venous thromboembolic events (TEE) from intravenous immunoglobulin (IVIg) therapy according to its indications. METHODS We performed a retrospective cohort study of patients seen at our institution and treated with IVIg over a 36-month period. Indications, comorbility and comedication associated with TEE were identified by a stepwise logistic regression analysis. RESULTS Of 303 patients included with at least one infusion of IVIg over three years, TEE were identified in a total of 50 patients treated with IVIg, for an incidence of 16.9% (CI 95%: 13.0-21.6); 27 (54%) arterial (9.1%;CI 95%: 6.3-13.0%) and 23 (46%) venous TEE (7.8%; CI95%: 5.2-11.4%), overall mortality was 32%. Per indication there were more patients with autoimmune conditions, secondary immunodeficiency, dysimmune neuropathies, acute rejection of solid organ transplantation and sepsis. Patients with TEE were significantly older, were more likely to be men, they had more comorbid conditions; the doses of IVIg were high (589.4mg/kg/day vs 387.0mg/kg/day, p<0.001) and differences in comedication were found. The stepwise logistic regression analysis retained high doses of IVIg (OR 3.03; CI 95%: 1.49-5.67) and diuretics therapy (OR 1.69; CI 95%: 1.06-3.97) when combined with the usual comorbid confounders. CONCLUSIONS The incidence of TEE from IVIg therapy remains high at one in six patients treated. The most remediable factor is a high daily IVIg load. Decreasing the daily IVIg dose together with carefully weighing diuretics therapy and comorbid risk factors may be the keys to saving lives.