Oral-intravenous crossover study of fingolimod pharmacokinetics, lymphocyte responses and cardiac effects

OBJECTIVE: The pharmacokinetics and lymphocyte responses to the immunomodulator fingolimod (FTY720) were characterized after oral and intravenous administration. METHODS: In this randomized, two-period crossover study 11 evaluable healthy subjects received single doses of fingolimod 1.25 mg orally and 1 mg intravenously infused over 2 h. The pharmacokinetics of fingolimod, blood lymphocyte counts and heart rate were characterized for 28 days after each dose. RESULTS: After oral administration, Cmax was 1.1+/-0.2 ng/ml occurring at 12 h postdose and the AUC was 201+/-31 ng.h/ml. After intravenous infusion, Cmax was 4.9+/-0.8 ng/ml, AUC was 175+/-50 ng. h/ml, clearance was 6.3+/-2.3 l/h and distribution volume was 1199+/-260 l. The oral/intravenous ratio of dose-normalized AUCs was 0.94 (95%CI: 0.78-1.12). The pharmacologically active metabolite fingolimod-phosphate was quantifiable near its peak after oral administration but not after intravenous administration. The mean lymphocyte nadir occurred on day 1 and was 35% lower after oral (0.74x10(9)/l) than after intravenous (1.15x10(9)/l) administration. Lymphocytes recovered to the normal range by day 15 for both treatments. The mean heart rate nadir occurred 3-4 h postdose and was 11% lower after oral administration (47 bpm) versus intravenous administration (53 bpm). CONCLUSIONS: Average systemic exposure to fingolimod was similar after oral and intravenous administration. However, the acute decrease in lymphocyte counts was weaker after intravenous administration, likely because of lower blood levels of the active metabolite fingolimod-phosphate compared with oral administration.     

Hepatitis viruses under immunosuppressive agents

Clinical and experimental studies have shown that T cell-mediated immune mechanisms are involved in the pathogenesis of hepatitis B virus (HBV) and hepatitis C virus infection. Immunosuppressants may impair T cell function and thereby reduce immune-mediated hepatocytolysis and virus clearance. In addition, corticosteroid may activate the glucocorticoid responsive element in the HBV genome to enhance HBV replication and gene expression. These combined effects result in an increase of viraemia in association with a decrease of serum aminotransferase and hepatic necroinflammation. In acute infection, use of immunosuppressants will increase the incidence of chronic evolution. In chronic infection, withdrawal of immunosuppressants will be followed by a clinical flare due to a rebound of immune attack to hepatocytes with increased viral load. This may lead to a subsequent decrease of the viraemia. Therefore, short-term use of immunosuppressant before antiviral therapy may be beneficial in the treatment of chronic viral hepatitis. However, the clinical rebound may be extremely severe and lead to hepatitis failure; thus, the patients should be monitored closely upon tapering and after the withdrawal of immunosuppressants. Long-term use of immunosuppressants in patients with hepatitis virus infection is usually deleterious, particularly in patients after organ transplantation. These findings suggest that clinicians should be cautious in the use of immunosuppressants in patients with hepatitis virus infection.     

血栓性血小板减少性紫癜治疗的研究进展

血栓性血小板减少性紫癜(TTP)是一种血栓性微血管病,患者因严重缺乏血管性血友病因子裂解酶导致大量富血小板血栓堵塞血管,最终引发终末器官衰竭。血浆置换作为TTP治疗的基石,极大程度提高了患者的生存率。随着对TTP病理生理机制的进一步探索,逐渐涌现了其它类型的替代疗法、新型免疫抑制剂、靶向拮抗剂、基因治疗等新兴手段,有望进一步降低该病患者的死亡率和复发率。本文就TTP治疗的最新研究进展作一综述。     

Pre-transplant gingival hyperplasia predicts severe cyclosporin-induced gingival overgrowth in renal transplant patients

Abstract. The relationship between the pre-transplant periodontal status and the development of post-transplant gingival overgrowth was investigated in a longitudinal study. The periodontal condition of 35 patients was examined on 2 occasions while they were on the transplant waiting list and then at 4–6, 10–12, 16 and 20 weeks post-transplant. At each visit the plaque index, the bleeding index and a pocket index (CPITN) were measured. Dental impressions were taken of the pre- and post-transplant gingival condition and used to make stone models which were used to score the gingival overgrowth index (GOI). The patients divided into 3 distinct groups having severe ( n = 13), mild ( n = 16) or no post-transplant gingival overgrowth ( n =6). Only 1 of the patients had taken cyclosporin prior to inclusion into the study. All the patients who developed severe overgrowth had evidence of gingival hyperplasia before the transplant. There was no difference in the serum cyclosporin levels between the three groups (χ²<2.28, p >0.319). Furthermore, there was no statistical difference for any of the periodontal indices. This study indicates that the hyperplastic gingival inflammatory response of some individuals appears to be potentiated by cyclosporin resulting in severe post-transplant overgrowth. In other patients the same reaction may allow the fibroblastic activity to occur to an extent where it produces a mild clinically apparent overgrowth.     

Factors influencing the magnitude and clinical significance of drug interactions between azole antifungals and select immunosuppressants

The magnitude of drug interactions between azole antifungals and immunosuppressants is drug and patient specific and depends on the potency of the azole inhibitor involved, the resulting plasma concentrations of each drug, the drug formulation, and interpatient variability. Many factors contribute to variability in the magnitude and clinical significance of drug interactions between an immunosuppressant such as cyclosporine, tacrolimus, or sirolimus and an antifungal agent such as ketoconazole, fluconazole, itraconazole, voriconazole, or posaconazole. By bringing similarities and differences among these agents and their potential interactions to clinicians' attention, they can appreciate and apply these findings in a individualized patient approach rather than follow only the one-size-fits-all dosing recommendations suggested in many tertiary references. Differences in metabolism and in the inhibitory potency of cytochrome P450 3A4 and P-glycoprotein influence the onset, magnitude, and resolution of drug interactions and their potential effect on clinical outcomes. Important issues are the route of administration and the decision to preemptively adjust dosages versus intensive monitoring with subsequent dosage adjustments. We provide recommendations for the concomitant use of these agents, including suggestions regarding contraindicated combinations, those best avoided, and those requiring close monitoring of drug dosages and plasma concentrations.     

Multi-drug resistance gene-1 (MDR-1) haplotypes and the CYP3A5*1 genotype have no influence on ciclosporin dose requirements as assessed by C0 or C2 measurements

The intestinal efflux pump P-glycoprotein (P-gp), the product of the multi-drug resistance-1 (MDR-1) gene, significantly influences the pharmacokinetics of several drugs. Ciclosporin is a substrate for P-gp and is metabolized by cytochrome P450 (CYP) 3A enzymes. P-gp activity is affected by several known single nucleotide polymorphisms (SNPs) and haplotypes. MDR-1 genotypes of SNPs C1236T, G2677T/A and C3435T, as well as haplotypes C-G-C and T-T-T and CYP3A5*1 genotype (predictive of CYP3A5 expression), were related to ciclosporin blood concentrations measured at both 0 and 2 h after drug dosing in 197 stable renal transplant patients. Significant differences (of a magnitude unlikely to be relevant clinically) in dose-normalized blood ciclosporin concentrations were found only between MDR-1 genotypes of the C1236T SNP and between haplotype groups C-G-C and T-T-T in patients that were expressers of CYP3A5. MDR-1 SNPs and haplotypes and also CYP3A5*1 genotype, do not appear to have a major influence on ciclosporin pharmacokinetics.     

Immunosuppressant therapy of thyroid eye disease

Summary Thyroid eye disease is attributed to an autoimmune process where both cellular and humoral immunity play a role. In this report, after a short introduction dealing with immunopathogenesis of the disease, immunosuppressant therapy is discussed. Treatment with glucocorticoids (as the standard substance), nonsteroid immunosuppressants (azathioprine, cyclophosphamide, lately cyclosporin) and with the immunomodulatory substance ciamexone is reviewed. Retroorbital irradiation as a local immunosuppressive method and plasmapheresis are also discussed. While systemic glucocorticoids and to a lesser extent orbital radiotherapy are routinely administered for severe Graves' ophthalmopathy, nonsteroid immunosuppressants and plasmapheresis are not yet part of the established treatment of thyroid eye disease. Their use should currently remain confined to controlled studies.Abbreviations ATA American Thyroid Association - EO Endocrine ophthalmopathy (thyroid eye disease) - Cy Cyclosporin - LATS Long-acting thyroid stimulator - CT Computed tomography - Tg Thyroglobulin     

Novel gastroretentive sustained-release tablet of tacrolimus based on self-microemulsifying mixture: in vitro evaluation and in vivo bioavailability test

Aim:

To develop a novel gastroretentive drug delivery system based on a self-microemulsifying (SME) lipid mixture for improving the oral absorption of the immunosuppressant tacrolimus.

Methods:

Liquid SME mixture, composed of Cremophor RH40 and monocaprylin glycerate, was blended with polyethylene oxide, chitosan, polyvinylpyrrolidone and mannitol, and then transformed into tablets via granulation, with ethanol as the wetting agent. The tablets were characterized in respect of swelling, bioadhesive and SME properties. In vitro dissolution was conducted using an HCl buffer at pH 1.2. Oral bioavailability of the tablets was examined in fasted beagle dogs.

Results:

The tablet could expand to 13.5 mm in diameter and 15 mm in thickness during the initial 20 min of contact with the HCl buffer at pH 1.2. The bioadhesive strength was as high as 0.98±0.06 N/cm². The SME gastroretentive sustained-release tablets preserved the SME capability of the liquid SME formations under transmission electron microscope. The drug-release curve was fit to the zero-order release model, which was helpful in reducing fluctuations in blood concentration. Compared with the commercially available capsules of tacrolimus, the relative bioavailability of the SME gastroretentive sustained-release tablets was 553.4%±353.8%.

Conclusion:

SME gastroretentive sustained-release tablets can enhance the oral bioavailability of tacrolimus with poor solubility and a narrow absorption window.