Drug-drug interactions of immunosuppressants and other drugs in kidney post-transplant recipients

Introduction: Immunosuppressants (ISS) are the most crucial tools used in the therapeutic regimens of transplant recipients. Nevertheless, these drugs are not the only ones adopted by patients; therefore, knowing the possible drug-drug interactions (DDIs) between immunosuppressants and other drugs commonly used in kidney transplant recipients is essential to ensure the effectiveness and safety of treatments. In this way, the objective is analyzing the DDIs between the immunosuppressants and other commonly used medications on kidney transplant adult recipients with active medical records undergoing post-transplant follow-up for 4.4 years (mean). Methods: First, we performed a cross-sectional study based on patients' records, in which the patient's profile and drugs used were examined, and after we analyzed DDIs by the Micromedex Drug Interactions® database. Results: We analyzed 176 patients with a mean age of 47.6(± 12.5); most were male (67.7%), and the majority received a kidney from a deceased donor (81.4%). Patients were exposed to 15.0 (± 5.4) different medicines after the transplantation, and 7.4 (± 4.0) of these medicines were simultaneous. After analyzing the DDIs according to the severity of interaction, documentation quality interaction effect, clinical management and probable interaction mechanism, the most frequent interaction was with tacrolimus, classified as moderate, and the 3 major causes of interaction occurred with azathioprine according to the Micromedex database. The primary medicines involved with immunosuppressant interactions were proton pump inhibitors, ranitidine, domperidone, amlodipine, enalapril, allopurinol, cyclobenzaprine, amitriptyline, fluoxetine, and ciprofloxacin. These DDIs' effects were related to, mainly, increase their immunosuppressant activity. Conclusion: Although the immunosuppressants analyzed lacked many clinical DDIs significance with other medicines, the healthcare team needs to monitor their DDIs' effects to prevent and minimize side effects in transplanted recipients.

Effects of cyclosporine on ischemia-reperfusion injuries in rat kidneys. An experimental model

Abstract Purpose To assess Cyclosporine A (CsA) therapy at an intraperitoneal dose of 15 mg.kg -1 in a rodent model of non-septic renal ischemia. Methods Twenty male Wistar rats were randomized to receive CsA therapy or none therapy before undergoing 30 minutes of renal ischemia followed by reperfusion. Additionally, 10 rats were randomized to undergo the same surgical procedure of the aforementioned animals with neither ischemia nor CsA therapy. Twelve hours after kidney ischemia, the left kidneys were evaluated for histological injury according to Park's criteria. Serum creatinine (Cr), urea nitrogen (Ur) and sodium levels were obtained at different times of the experimental protocol. Results Rodents in the CsA group showed negative results (p<0.05) in serum variables (Cr: 0.41±0.05mg/dL vs . 4.17±1.25mg/dL; Ur: 40.90±3.98mg/dL vs . 187.70±22.93mg/dL) even the non CsA or control group (Cr: 0.35±0.07mg/dL vs . 3.80±1.20mg/dL; Ur: 40.10±4.70mg/dL vs . 184.50±49.80mg/dL). The negative results were also verified in histological evaluation, CsA group had 50% in the very severe grade of lesion, 10% in the severe and 40% in the moderate to severe whereas the control group had 90% in the very severe grade. Conclusion CsA was incapable of preventing the deleterious effects of ischemia-reperfusion injury in rat kidneys.

Miocardiopatía hipertrófica en un recién nacido pretérmino con madre trasplantada renal / Hypertrophic cardiomyopathy in preterm newborn with kidney transplanted mother

La miocardiopatía hipertrófica en el recién nacido es una entidad poco frecuente y de etiología heterogénea. Se han descrito formas transitorias en hijos de madres con diabetes gestacional y en recién nacidos pretérminos expuestos a corticoides tanto prenatal como posnatalmente. Se presenta un caso de un recién nacido pretérmino, hijo de madre trasplantada renal al que se le detectó una miocardiopatía hipertrófica y que había estado expuesto prenatalmente a corticoides y tacrolimus que recibía la madre como tratamiento inmunosupresor. Ambos fármacos cruzan la barrera placentaria y, al llegar al feto, podrían haber favorecido su desarrollo. La miocardiopatía hipertrófica puede ser un efecto secundario poco común del tratamiento con tacrolimus en adultos y niños, y es reversible al retirarlo. En nuestro conocimiento, es el primer caso publicado de miocardiopatía hipertrófica transitoria tras la exposición fetal tanto a corticoides como a tacrolimus en un hijo de madre trasplantada renal.

Hypertrophic cardiomyopathy in the newborn is a rare entity with heterogeneous etiology. Transient forms have been described in children of mothers with gestational diabetes and in preterm infants exposed both to prenatal and postnatal corticosteroids. We report a case of a preterm infant son of a mother who received renal transplant in whom hypertrophic cardiomyopathy was detected. He had been prenatally exposed to corticosteroids and tacrolimus that received the mother as immunosuppressive therapy. Both drugs cross the placental barrier and, on reaching the fetus, could have favored its development. Hypertrophic cardiomyopathy may be an uncommon side effect of treatment with tacrolimus in adults and children and it is reversible upon withdrawal. To our knowledge, it is the first published case of transient hypertrophic cardiomyopathy after fetal exposure to both corticosteroids and tacrolimus in the son of a renal transplanted mother.

Impact of UGT1A9 polymorphism on mycophenolic acid pharmacokinetic parameters in stable renal transplant patients

There are wide individual differences in pharmacokinetic parameters of mycophenolate mofetil [MMF] among transplanted patients. Some studies have shown that single nucleotide polymorphisms [SNPs] of the Uridine Diphosphate Glucuronosyl Transferase1A9 [UGT1A9] are responsible for these differences in early days after transplantation. Therefore it was decided to evaluate the influence of UGT polymorphism on MMF pharmacokinetics among stable Iranian transplant patients. This was a cross sectional study from March 2008 through December 2008 in Imam Khomeini Hospital affiliated to the Tehran University of Medical Sciences in Iran. Blood samples were taken from 40 de novo stable Iranian renal transplant patients taking 2 g MMF daily with Sr[Cr]

Cytochrome P450 3A4[asterisk]1B as pharmacogenomic predictor of tacrolimus pharmacokinetics and clinical outcome in the liver transplant recipients

Tacrolimus is a macrolide immunosuppressant used for prevention of allograft rejection in organ transplantation and metabolized in the liver and intestine by cytochrome P450 3A4 [CYP3A4] enzyme. A single nucleotide polymorphism [SNP] in the CYP3A4 promoter region has been identified. It has been shown that the presence of CYP3A4[asterisk]1B allele [variant GG] is associated with a reduced catalytic activity of CYP3A4 in vivo. The aim of this study was to determine the role of CYP3A4[asterisk]1B on tacrolimus dosing and clinical outcome in liver transplant recipients. Forty-eight liver transplant recipients were stratified according to the genotype. There were 32 wild-type [AA] patients and 5 homozygous variant [GG] and 11 [AG] heterozygous. Tacrolimus doses and trough concentrations as well as phenotypic data were collected in the first 10 days of the transplant. The tacrolimus concentration was significantly higher in the wild [AA] group as compared to homozygous variant [GG] and heterozygous [AG] patients. Homozygous variant [GG] group had significantly lower dose requirements. However, no significant difference was observed in the concentration/dose ratio between all groups. Based on our results, it may be concluded that CYP3A4[asterisk]1B of recipient is an important factor influencing pharmacokinetic of tacrolimus, as patients with CYP3A4[asterisk]1B polymorphism may require lower tacrolimus doses to maintain therapeutic levels. The dose reduction may not affect clinical outcomes after liver transplant

Pharmacokinetics of cyclosporin: a microemulsion in children with idiopathic nephrotic syndrome

OBJECTIVE: We present a prospective study of a microemulsion of cyclosporin to treat idiopathic nephrotic syndrome in ten children with normal renal function who presented cyclosporin trough levels between 50 and 150 ng/ml and achieved complete remission with cyclosporin. To compare the pharmacokinetic parameters of cyclosporin in idiopathic nephrotic syndrome during remission and relapse of the nephrotic state. METHOD: The pharmacokinetic profile of cyclosporin was evaluated with the 12-hour area under the timeconcentration curve (auc0-12) using seven time-point samples. This procedure was performed on each patient during remission and relapse with the same cyclosporin dose in mg/kg/day. The 12-hour area under the timeconcentration curve was calculated using the trapezoidal rule. All of the pharmacokinetic parameters and the resumed 4-hour area under the time-concentration curve were correlated with the 12-hour area under the timeconcentration curve. ClinicalTrials.gov:NCT01616446. RESULTS: There were no significant differences in any parameters of the pharmacokinetic of cyclosporin during remission and relapse, even when the data were normalized by dose. The best correlation with the 12-hour area under the time-concentration curve was the 4-hour area under the time-concentration curve on remission and relapse of the disease, followed by the 2-hour level after cyclosporin (c2) dosing in both disease states. CONCLUSIONS: These data indicate that the same parameters used for cyclosporin therapeutic monitoring estimated during the nephrotic state can also be used during remission. Larger controlled studies are needed to confirm these findings.

Immunomodulatory effects of cardiotrophin-1 on in vitro cytokine production of monocytes & CD4+ T-lymphocytes.

Background & objectives: In congestive heart failure (CHF), increased concentrations of several cytokines including cardiotrophin-1 (CT-1) and immunactivation are found. This study was performed to evaluate whether CT-1 can induce in vitro cytokines in monocytes and CD4+ T-lymphocytes of healthy volunteers. Methods: The study was performed in vitro to see whether CT-1 can modulate monocyte or CD4+ T-lymphocyte interleukin (IL)-1β, -2, -4, -5, -10, interferon γ (IFNγ), and tumour necrosis factor α (TNFα) expression by flow cytometry following stimulation with CT-1 alone or together with lipopolysaccharide (LPS) or phorbol myristate acetate (PMA)/ionomycine (iono). Results: CT-1 increased the number of TNFα and IL-1β positive monocytes. LPS induced IL-10, TNFα, and IL-1β in monocytes but only IL-2 in CD4+ T-lymphocytes, whereas PMA/iono induced all cytokines besides IL-5 in monocytes and IL-1β in CD4+ T-lymphocytes. In LPS activated monocytes, CT-1 induced a concentration-dependent reduction in the number of TNFα positive monocytes. After LPS activation, CT-1 decreased the number of CD4+ lymphocytes positive for IL-2, IL-4, and IL-5. In addition, following PMA/iono stimulation, CT-1 initiated a concentration-dependent decrease of CD4+ T-lymphocytes positive for TNFα, IL-4, IL-5, and IL-10. Interpretation & conclusions: The present data show that in vitro CT-1 can activate monocytes and modulate cytokine production of activated CD4+ T-lymphocytes. We speculate that CT-1 may at least be partly responsible for immunactivation in CHF.

Estudio de biodisponibilidad relativa entre dos formulaciones orales de micofenolato mofetilo en voluntarios sanos / Relative bioavailability study of two oral formulations of mycophenolate mofetil in healthy volunteers

Background: The bioequivalence of different formulations of a same pharmaceutical product must be tested empirically. Aim: To evaluate the relative bioavailability for an oralformulation of mycophenolate mofetil (MMF) (Linfonex™) compared to the reference formulation (Cellcept™) to determine the bioequivalence between both formulations. Material and Methods: A randomized, crossover, double-blind trial in 22 healthy male volunteers, who received a single oral dose of 1000 mg of Linfonex and Cellcept with a washout period of 10 days. Plasma levels of the drug were determined by high performance liquid chr ornatography. Plasma concentrations were plotted and maximum concentration, area under the plasma concentration versus time between 0 and 12 hours after administration and área under plasma concentration curve versus time after administration between 0 and infinity, were calculated for both products. Results: The active compound, mycophenolic acid, was similarly absorbed in both formulations. No statistically significant differences were found in calculated pharmacokinetic parameters between both formulations. Conclusions: Linfonex™ 500 mg is bioequivalent to Cellcept™ 500 mg.

Low-dose cyclosporine treatment for sight-threatening uveitis: Efficacy, toxicity, and tolerance.

Aim: To ascertain the effectiveness, tolerability, and safety of low-dose cyclosporine in the management of sight-threatening uveitis. Materials and Methods: This was a retrospective clinical case series of patients using oral low-dose cyclosporine for the management of sight-threatening uveitis in the uvea clinic (UC). Patients receiving cyclosporine were identified from the clinic database. Main outcome measures were degree of intraocular inflammation, visual acuity and dose reduction of oral steroid for effectiveness and adverse symptoms, systemic hypertension, and raised serum creatinine for tolerability and safety. Results: Intraocular inflammation was improved or stable in 97% of patients, visual acuity was improved or stable in 91%, and oral steroid dosage was reduced in 73% (by half or more in 51%). Adverse symptoms were almost universal, the commonest being peripheral paresthesia/burning in 70% and fatigue in 67%. Significant systemic hypertension developed in 27% and raised creatinine in 30%, necessitating dose reduction. Cyclosporine was discontinued in 35%, being intolerable in 20% and ineffective in 15%. Conclusions: Cyclosporine was found to be effective in reducing inflammation and protecting vision in sight-threatening uveitis. It was safe with proper monitoring, including in children. It had a significant toxicity profile and a high incidence of adverse symptoms which required close supervision, and a prompt dose reduction or drug exchange.

Pharmacokinetic/pharmacodynamic relationships of FTY720 in kidney transplant recipients

FTY720 is a new and effective immunosuppressive agent, which produces peripheral blood lymphopenia through a lymphocyte homing effect. We investigated the relationship between the dose of FTY720 or blood concentration (pharmacokinetics, PK) and peripheral lymphopenia (pharmacodynamics, PD) in 23 kidney transplant recipients randomized to receive FTY720 (0.25-2.5 mg/day) or mofetil mycophenolate (2 mg/day) in combination with cyclosporine and steroids. FTY720 dose, blood concentrations and lymphocyte counts were determined weekly before and 4 to 12 weeks after transplantation. The effect of PD was calculated as the absolute lymphocyte count or its reductions. PK/PD modeling was used to find the best-fit model. Mean FTY720 concentrations were 0.36 ± 0.05 (0.25 mg), 0.73 ± 0.12 (0.5 mg), 3.26 ± 0.51 (1 mg), and 7.15 ± 1.41 ng/ml (2.5 mg) between 4 and 12 weeks after transplantation. FTY720 PK was linear with dose (r² = 0.98) and showed low inter- and intra-individual variability. FTY720 produced a dose-dependent increase in mean percent reduction of peripheral lymphocyte counts (38 vs 42 vs 56 vs 77, P < 0.01, respectively). The simple Emax model [E = (Emax * C)/(C + EC50)] was the best-fit PK/PD modeling for FTY720 dose (Emax = 87.8 ± 5.3 percent and ED50 = 0.48 ± 0.08 mg, r² = 0.94) or concentration (Emax = 78.3 ± 2.9 percent and EC50 = 0.59 ± 0.09 ng/ml, r² = 0.89) vs effect ( percent reduction in peripheral lymphocytes). FTY720 PK/PD is dose dependent and follows an Emax model (EC50 = 0.5 mg or 0.6 ng/ml). Using lymphopenia as an FTY720 PD surrogate marker, high percent reductions ( about 80 percent) in peripheral lymphocytes are required to achieve best efficacy to prevent acute allograft rejection.

A review of absorption characteristics of microemulsion cyclosporine products over the last 2 years in Indian subjects.

Microemulsion based cyclosporine has demonstrated better absorption with laser pharmacokinetic variability. For the clinical use of any new microemulsion based product, bioequivalence testing with existing formulation is necessary. Panimun Bioral (Test) and Sandimmun Neoral (Reference) were evaluated in different transplant centers using both volunteers as well as renal transplant patients. All these centres have reported that both products are bioequivalent. These reports offer the physician an option to convert the patients to the Test product for economic reasons.