Influence of CYP3A5 polymorphism on tacrolimus blood concentrations in renal transplant patients

Objective Tacrolimus is an immunosuppressive drug with narrow therapeutic range and wide interindividual variation in its pharmacokinetics. Tacrolimus is a substrate of cytochrome P450(CYP)3A5. The aim of this study was to evaluate whether the A6986G polymorphism is associated with tacrolimus concentration /dose ratio. Methods Fifty-two Chinese renal transplant patients were enrolled in this study. Their body weight, dosage and concentration of tacrolimus were observed. CYP3A5 genotype was determined by polymerase chain reaction followed by restriction fragment length polymorphism analysis. Results A significant association was found between tacrolimus levels per dose/kg/d and CYP3A5 gene A6986G polymorphism (P<0.001). The CYP3A5 * 3 * 3 patients have a significantly higher tacrolimus level/dose than CYP3A5 * 1 * 1 and CYP3A5 * 1 * 3. Conclusions CYP3A5 gene A6986G polymorphism is associated with tacrolimus pharmacokinetics and dose requirements. Pharmacogenetic methods could be employed prospectively to help the dose selection and to individualize immunosuppressive therapy according to the result. Foundation item: Project (03GZ3072) supported by the Science and Technology Department of Hunan Province; project (2004035206) supported by the China Postdoctoral Foundation and project (30300383) supported by the National Natural Sciences Foundation of China     

Recent Developments in Drug Delivery to Prolong Allograft Survival in Lung Transplant Patients

Since the discovery of cyclosporine in 1971, calcineurin inhibitors have played a critical role in the therapeutic suppression of the immune response. Patients receiving solid organ transplants rely heavily on these medications to prevent the acute and chronic rejection of allografted tissue. These therapies can prove difficult because of potential toxicity, heightened risk of invasive infection, and erratic oral bioavailability, requiring frequent blood samples for monitoring of systemic levels. Added challenges are presented in immunosuppression of lung transplant patients owing to the increased susceptibility to invasive infection and extensive immune mechanisms inherent in lung tissue. With the introduction of tacrolimus, a more potent calcineurin inhibitor, clinical outcomes of transplants have continued to improve; however, little improvement has been noted in lung transplantation. While very effective upon arrival at the site of action, tacrolimus and cyclosporine present a variety of formulation challenges such as poor solubility, potential systemic toxicity, and extensive first pass metabolism. Initial attempts to improve solubility in both oral and intravenous formulations have resulted in variable drug absorption and increased systemic toxicity, respectfully, creating a need for formulation improvement. Through alternative routes of delivery and novel formulation techniques, researchers have addressed these issues and, in some cases, demonstrated improved clinical outcomes. Through enhanced solubilization, reduction in absorption variability, and more effective drug targeting with reduced systemic levels, improvements in outcomes and overall patient survival in lung and other solid organ transplantation can be expected.     

Development and Validation of HPTLC Method for Estimation of Tacrolimus in Formulations

A new, simple, and rapid high-performance thin-layer chromatographic method with a derivatization procedure was developed and validated for quantitative determination of tacrolimus. Tacrolimus was chromatographed on silica gel 60 F₂₅₄ TLC plate using toluene–acetonitrile–glacial acetic acid (6:4:0.1, by volume) as mobile phase. Tacrolimus was visualized using a derivatization reagent containing anisaldehyde–sulfuric acid in absolute alcohol and quantified by densitometric analysis in the reflectance mode at 675 nm. The method was found to give compact spots for the drug (R_f?=?0.40?±?0.03). The linear regression analysis data for the calibration plots showed good linear relationship with r²?=?.9989 in the concentration range 100–800 ng/spot. The method was validated for precision, recovery, repeatability, and robustness as per the International Conference on Harmonization guidelines. The minimum detectable amount was found to be 28.90 ng, whereas the limit of quantitation was found to be 97.04 ng. Statistical analysis of the data showed that the method is precise, accurate, reproducible, and selective for the analysis of tacrolimus. The method was successfully employed for the estimation of equilibrium solubility and quantification of tacrolimus as a bulk drug and in commercially available capsules and in-house developed self-microemulsifying formulations.     

Capability of Utilizing CYP3A5 Polymorphisms to Predict Therapeutic Dosage of Tacrolimus at Early Stage Post-Renal Transplantation

While CYP3A5 polymorphisms are used to predict the initial dosage of tacrolimus therapy, the predictive capability of genetic information for dosing at early stage post-renal transplantation is unknown. We investigated the influence of polymorphisms over time. An initial oral dose of modified-release once-daily tacrolimus formulation (0.20 mg/kg) was administered to 50 Japanese renal transplant patients every 24 h. Stepwise multiple linear regression analysis for tacrolimus dosing was performed each week to determine the effect of patient clinical characteristics. The dose-adjusted trough concentration was approximately 70% higher for patients with the CYP3A5*3/*3 than patients with the CYP3A5*1 allele before the second pre-transplantation tacrolimus dose (0.97 (0.78–1.17) vs. 0.59 (0.45–0.87) ng/mL/mg; p < 0.001). The contribution of genetic factors (CYP3A5*1 or *3) for tacrolimus dosing showed increased variation from Day 14 to Day 28 after transplantation: 7.2%, 18.4% and 19.5% on Days 14, 21 and 28, respectively. The influence of CYP3A5 polymorphisms on the tacrolimus maintenance dosage became evident after Day 14 post-transplantation, although the tacrolimus dosage was determined based only on patient body weight for the first three days after surgery. Tacrolimus dosage starting with the initial administration should be individualized using the CYP3A5 genotype information.     

Development and Characterization of Self-Microemulsifying Drug Delivery System of Tacrolimus for Intravenous Administration

Tacrolimus (FK 506), a poorly soluble immunosuppressant is currently formulated in nonaqueous vehicle containing hydrogenated castor oil derivative for intravenous administration. Hydrogenated castor oil derivatives are associated with acute anaphylactic reactions. This proposes to overcome the problems of poor aqueous solubility of the drug and the toxicity associated with currently used excipients by the development of a new parenterally acceptable formulation using self-microemulsifying drug delivery system (SMEDDS). Solubility of FK 506 in various oils, surfactants, and cosurfactants was determined to identify SMEDDS components. Phase diagrams were constructed at different ratios of surfactants: cosurfactant (K_m) to determine microemulsion existence area. Influence of oily phase content, K_m, aqueous phase composition, dilution, and incorporation of drug on mean globule size of microemulsions was studied. SMEDDSs were developed using ethyl oleate as oily phase and Solutol HS 15 as surfactant. Glycofurol was used successfully as a cosurfactant. Developed SMEDDS could solubilize 0.8% (wt/wt) FK 506 and on addition to aqueous phase could form spontaneous microemulsion with mean globule size < 30 nm. The resulting microemulsion was iso-osmotic, did not show any phase separation or drug precipitation even after 24 h, and exhibited negligible hemolytic potential to red blood cells.     

普乐可复联合护肝片治疗肝移植后轻、中度急性排斥反应的疗效分析

目的: 评价普乐可复(FK506) 联合护肝片治疗肝移植后轻、中度急性排斥反应的临床疗效。方法: 将47 例肝移植后出现轻、中度急性排斥反应的移植受者, 分为两组:对照组24 例, 试验组23例。试验组加用护肝片治疗, 3 片/次, 口服, 2 次/d(同FK506 一起服用) 。并于服药后第6 、14 天后复查FK506 血药浓度及肝、肾功能。结果: 试验组加用护肝片后患者的FK506 血药浓度明显提高(P <0.01), 与对照组比较有统计学差异(P <0.01) 。试验组FK506 联合护肝片治疗后的肝功能指标ALT 、AST 、TBIL 、DBIL 均较治疗前明显下降(P <0.01), 和对照组比较差异有统计学意义(P <0.05) 。其中, 试验组治疗后第6 天的显效率达47.83 %, 总有效率达91.30 %, 显著高于对照组(P <0.05) ;治疗后第14 天, 试验组的显效率较对照组提高23.91 %。FK506 联合护肝片治疗对肾功能指标无明显影响。结论: FK506 联合护肝片治疗肝移植后轻、中度急性排斥反应安全、有效。其中, 护肝片不仅可促进肝功能恢复, 还可明显提高FK506 血药浓度, 减少FK506 的用量。     

Therapeutic Potentials of Low-Dose Tacrolimus for Aberrant Endometrial Features in Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is a major anovulatory infertility affecting a great proportion of women of childbearing age and is associated with obesity, insulin resistance and chronic inflammation. Poor endometrial receptivity and recurrent implantation failure are major hurdles to the establishment of pregnancy in women with PCOS. The accumulating body of evidence obtained from experimental and clinical studies suggests a link between inherent adaptive and innate immune irregularities and aberrant endometrial features in PCOS. The use of conventional therapeutic interventions such as lifestyle modification, metformin and ovarian stimulation has achieved limited clinical success in restoring ovulation and endometrial receptivity in women with PCOS. Unlike other immunosuppressive drugs prescribed in the clinical management of autoimmune and inflammatory disorders that may have deleterious effects on fertility and fetal development, preclinical studies in mice and in women without PCOS but with repeated implantation failure revealed potential therapeutic benefits for the use of low-dose tacrolimus in treating female infertility. Improved systemic and ovarian immune functions, endometrial progesterone receptor and coreceptor expressions and uterine vascular adaptation to pregnancy were among features of enhanced progesterone-receptor sensitivity in the low-dose tacrolimus-treated mouse model of the disease. In this review, we have compiled available experimental and clinical data in literature on endometrial progesterone resistance and current therapeutic options, as well as mechanisms of actions and reported outcomes relevant to the potential therapeutic benefits for the use of low-dose tacrolimus in treating PCOS-associated female infertility.     

自身免疫疾病患者他克莫司稳态血药浓度影响因素的研究

目的：探讨年龄、性别、用药时长和合并用药对自身免疫疾病患者他克莫司稳态血药浓度的影响，并结合肝肾功能，初步建立他克莫司稳态血药浓度参考范围，为临床个体化用药提供理论依据。方法：纳入2017年8月至2021年6月107例我院风湿免疫科应用他克莫司治疗自身免疫疾病的患者，采用SPSS 22.0统计学软件对其性别、年龄、给药剂量、合并用药、用药时长及血药浓度，肝肾功能进行分析。结果：他克莫司治疗自身免疫疾病，不同性别间血药浓度差异有统计学意义（P<0.05），不同年龄段血药浓度差异无统计学意义（P>0.05），但服药剂量差异有统计学意义（P<0.05），患者用药时长不会影响有效剂量、目标血药浓度、肝肾功能。他克莫司剂量与血药浓度呈弱相关性（r=0.115，P=0.047），血药浓度范围在4.20～9.48 ng/mL时，患者谷草转氨酶（AST）、谷丙转氨酶（ALT）、尿素水平显著增高；血药浓度范围0.08～4.20 ng/mL时，患者血清肌酐、AST、ALT、白蛋白、总胆红素（TBIL）、直接胆红素（DBIL）、间接胆红素（IBIL）等关键临床指标差异无统计学意义。结论：他克莫司用于治疗自身免疫疾病，血药浓度个体间差异度大，建议临床医生将血药浓度控制在0.08～4.20 ng/mL，并结合患者性别、年龄、临床疗效，调整剂量、优化用药方案，避免肝、肾功能潜在损害风险。     

Influence of CYP3A5 polymorphism on tacrolimus blood concentrations in renal transplant patients

Objective Tacrolimus is an immunosuppressive drug with narrow therapeutic range and wide interindividual variation in its pharmacokinetics. Tacrolimus is a substrate of cytochrome P450(CYP)3A5. The aim of this study was to evaluate whether the A6986G polymorphism is associated with tacrolimus concentration/dose ratio.Methods Fifty-two Chinese renal transplant patients were enrolled in this study. Their body weight, dosage and concentration of tacrolimus were observed. CYP3A5 genotype was determined by polymerase chain reaction followed by restriction fragment length polymorphism analysis. Results A significant association was found between tacrolimus levels per dose/kg/d and CYP3A5 gene A6986G polymorphism(P＜0.001). The CYP3A5 * 3 * 3 patients have a significantly higher tacrolimus level/dose than CYP3A5 * 1 * 1 and CYP3A5 * 1 * 3. Conclusions CYP3A5 gene A6986G polymorphism is associated with tacrolimus pharmacokinetics and dose requirements. Pharmacogenetic methods could be employed prospectively to help the dose selection and to individualize immunosuppressive therapy according to the result.     

他克莫司治疗狼疮性肾炎(Ⅳ+Ⅴ型)1例的病理图像与用药分析

观察新型免疫抑制剂他克莫司对狼疮性肾炎(Ⅳ+Ⅴ)的疗效。1例在我院肾科临床诊断为肾病综合症、病理诊断为狼疮性肾炎(Ⅳ+Ⅴ)的女性患者,应用他克莫司(口服剂量为0.15～0.3mg/kg/d 2/日)进行治疗。对其血药浓度进行检测,根据血药浓度调整剂量。治疗2周后患者24小时尿蛋白转阴。新型免疫抑制剂他克莫司有望成为狼疮性肾炎治疗的安全、有效的方法之一。