Neoral-to-Gengraf conversion in renal transplant recipients

[The use of generics in transplantation: Towards rational and safe solutions!]

Generic immunosuppressive drugs are available in Europe Canada and the United States. Between countries, there are large differences in penetration of generic drugs in general, and for immunosuppressive drugs in particular. The registration for generic immunosuppressive drugs are slightly different, but the criteria for registration of narrow therapeutic index drugs and bioequivalence studies, performed only in healthy volunteers, will remain in the medical landscape. About 50 studies compare the clinical efficacy and bioequivalence of the generic immunosuppressive drugs in patients with solid organ transplants. To allow for safe substitution, a number of criteria need to be fulfilled. Consensus statements were made by most transplant organizations. Authorities and payers should refrain from forcing pharmacists to dispense generic drugs in patients on maintenance immunosuppressive treatment. Generic substitution could be safe if realized by the treating physician, for a well-informed patient. Substitution must be followed by control visits to check if the patient is taking the medication correctly and if the drug exposure, through a close monitoring, remains stable. Substitution from one generic to another generic should be avoided, in all cases.

Generic immunosuppression in solid organ transplantation: systematic review and meta-analysis

OBJECTIVE

To compare the clinical efficacy and bioequivalence of generic immunosuppressive drugs in patients with solid organ transplants.

DESIGN

Systematic review and meta-analysis of all studies comparing generic with innovator immunosuppressive drugs.

DATA SOURCES

Medline and Embase from 1980 to September 2014.

REVIEW METHODS

A literature search was performed for all studies comparing a generic to an innovator immunosuppressive drug in solid organ transplantation. Two reviewers independently extracted data and assessed quality of studies. Meta-analyses of prespecified outcomes were performed when deemed appropriate. Outcomes included patient survival, allograft survival, acute rejection, adverse events and bioequivalence.

RESULTS

1679 citations were screened, of which 50 studies met eligibility criteria (17 randomized trials, 15 non-randomized interventional studies, and 18 observational studies). Generics were compared with Neoral (cyclosporine) (32 studies), Prograf (tacrolimus) (12 studies), and Cellcept (mycophenolate mofetil) (six studies). Pooled analysis of randomized controlled trials in patients with kidney transplants that reported bioequivalence criteria showed that Neoral (two studies) and Prograf (three studies) were not bioequivalent with generic preparations according to criteria of the European Medicines Agency. The single Cellcept trial also did not meet bioequivalence. Acute rejection was rare but did not differ between groups. For Neoral, the pooled Peto odds ratio was 1.23 (95% confidence interval 0.64 to 2.36) for kidney randomized controlled trials and 0.66 (0.40 to 1.08) for observational studies. For kidney observational studies, the pooled Peto odds ratios were 0.98 (0.37 to 2.60) for Prograf and 0.49 (0.09 to 2.56) for Cellcept. Meta-analyses for non-renal solid organ transplants were not performed because of a lack of data.There were insufficient data reported on patient or graft survival. Pooling of results was limited by inconsistent study methods and reporting of outcomes. Many studies did not report standard criteria used to determine bioequivalence. While rates of acute rejection seemed similar and were relatively rare, few studies were designed to properly compare clinical outcomes. Most studies had short follow-up times and included stable patients without a history of rejection.

CONCLUSIONS

High quality data showing bioequivalence and clinical efficacy of generic immunosuppressive drugs in patients with transplants are lacking. Given the serious consequences of rejection and allograft failure, well designed studies on bioequivalence and safety of generic immunosuppression in transplant recipients are needed.

[Special considerations in generic substitution of immunosuppressive drugs in transplantation]

Long-term success in solid organ transplantation strongly depends on the optimal use of maintenance immunosuppressive treatment. Cyclosporin and tacrolimus are the most frequently administered immunosuppressants and they are designed to narrow therapeutic index drugs. The substitution of the branded formulation by their generic counterparts may lead to economic benefit only if equivalent clinical outcomes can be achieved. There is no published evidence to date on the guarantee of their long-term therapeutic equivalence and cases of therapeutic failures have been reported due to inadvertent drug conversion. The disadvantageous clinical consequences of a non medical, mechanistic forced switch from the original to generic formulation of tacrolimus and the estimated loss of the payer's presumed savings are presented in a kidney transplant recipient population. Special problems related to pediatric patients, drug interactions with concurrent medications and the burden of additional therapeutic drug monitoring and follow up visits are also discussed. The authors are convinced that the implementation of the European Society of Organ Transplantation guidelines on generic substitution may provide a safe way for patients and healthcare payers.

Generic immunosuppression in solid organ transplantation: a Canadian perspective

The introduction of generic immunosuppressant medications may present an opportunity for cost savings in solid organ transplantation if equivalent clinical outcomes to the branded counterparts can be achieved. An interprofessional working group of the Canadian Society of Transplantation was established to develop recommendations on the use of generic immunosuppression in solid organ transplant recipients (SOTR) based on a review of the available data. Under current Health Canada licensing requirements, a demonstration of bioequivalence with the branded formulation in healthy volunteers allows for bridging of clinical data. Cyclosporine, tacrolimus, and sirolimus are designated as "critical dose drugs" and are held to stricter criteria. However, whether this provides sufficient guarantee of therapeutic equivalence in SOTR remains controversial, and failure to maintain an appropriate balance of immunosuppression may have serious consequences, including rejection, graft loss, and death. Published evidence supporting therapeutic equivalence of generic formulations in SOTR is lacking. Moreover, in the setting of multiple generic formulations the potential for uncontrolled product switching is a major concern, since generic preparations are not required to demonstrate bioequivalence with each other. Although close monitoring is recommended with any change in formulation, drug product switches are likely to occur without prescriber knowledge and may pose a significant patient safety risk. The advent of generic immunosuppression will require new practices including more frequent therapeutic drug and clinical monitoring, and increased patient education. The additional workload placed on transplant centers without additional funding will create challenges and could ultimately jeopardize patient outcomes. Until more robust clinical data are available and adequate regulatory safeguards are instituted, caution in the use of generic immunosuppressive drugs in solid organ transplantation is warranted.

Cyclosporine: A Commentary on Brand versus Generic Formulation Exchange

The evidence for conversion from brand name to generic equivalent cyclosporine is conflicting. Cyclosporine is a narrow therapeutic-range drug for which small variations in exposure may have severe clinical consequences for transplant patients. There is currently a lack of comparative outcome data relating to the pharmacokinetics of the reference formulation, Neoral, and generic formulations in transplant recipients. A major common concern is the potential inability to attain similar trough levels, an issue that can be easily corrected by ongoing therapeutic drug monitoring to ensure that the new steady state falls within an intended target range. Prospective clinical studies investigating the efficacy and safety of generic formulations in both de novo and long-term transplant patients are also awaited. Until further evidence is available on the conversion of transplant patients to or between generic formulations of cyclosporine, any transfer to a different cyclosporine formulation should be undertaken with close supervision. The best available information to date, however, does not support the frequently held but unsubstantiated belief that generic preparations of immunosuppressive drugs are not as effective as brand names or that conversion from brand to generic is associated with significant danger. This paper attempts to initiate a discussion of these issues.

Clinical evaluation of efficacy and safety of cyclosporine (Imusporin) in renal transplant patients with stable graft function maintained on neoral or bioral

Objective:

Previous pharmacokinetic studies have demonstrated bioequivalence of Imusporin (microemulsion preparation of cyclosporine, Cipla) to the innovator product Neoral (Novartis, Switzerland). This study was done to evaluate the clinical efficacy and safety of Imusporin in patients who have already undergone renal transplant and have stable graft function maintained on cyclosporine preparation other than Imusporin.

Materials and Methods:

Twenty-two renal allograft recipients (mean age of 31.77 years, range 18-53 years), with stable graft function, previously on Neoral or Bioral were switched over to Imusporin after recording their relevant baseline clinical and biochemical parameters. These were repeated on 1, 4, 7, 15, 30 and 90 days after the start of therapy. Change in dosage required to maintain C2 levels at each visit were analyzed by paired sample t-test. Safety of the drug was assessed by the type and severity of adverse events developed during the therapy. Cost analysis was done assuming an average maintenance immunosuppression dose of 150 mg/day of cyclosporine.

Results:

Twenty-one patients completed the study. One patient was lost to follow-up. Mean C2 value before switchover was 894 ± 208 ng/ml, which was not significantly different from the mean values of C2 after switchover therapy (P>0.30). Change in dosage required to maintain C2 levels was not significantly different from the baseline dose of 2.34 mg/ kg body weight (P>0.1). No patient developed graft rejection after switchover therapy at a median follow-up of 16 months (14-18 months). Mean baseline SCr was similar to SCr at day 90 (1.38 vs. 1.37 mg/dl, P=0.930). No severe adverse events were reported. Mild side-effects included headache (4), somnolence (2), dry mouth (5) and generalized fatigue (6). Use of Imusporin (Cipla, India) results in an annual savings of Rs. 19892 over Neoral (Novartis, Switzerland) and Rs. 2263 over Bioral (Panacea Biotech, India).

Conclusions:

Imusporin is clinically as safe and efficacious as other cyclosporine preparations available while significantly reducing the cost of treatment.

The clinical impact of 1:1 conversion from Neoral to a generic cyclosporine (Gengraf) in renal transplant recipients with stable graft function

The introduction of cyclosporine (CYA) to the immunosuppressive armamentarium has had a significant effect on graft survival. An improvement in the formulation from the oil-based to a microemulsion-based form has resulted in better absorption and more predictable CYA bioavailability. Since the introduction of the first microemulsion form (Neoral), several bioequivalent formulations are now available and are switched in a 1:1 fashion at pharmacies to curtail costs. The purpose of our study was to study the effect of a 1:1 switch from Neoral to Gengraf on CYA trough levels and serum creatinine (SRC) in renal transplant recipients with stable graft function. Eighty-two renal transplant recipients with stable graft function were enrolled in the study, and of these, 73 were switched to Gengraf, whereas nine remained on Neoral. The 13 patients switched to Gengraf required a dosage change after the mean CYA trough levels changed from 234 +/- 96 ng/mL at baseline to 289 +/- 102 ng/mL (p < 0.05) at 2 wk. With the adjustments in dosage, the levels approached the baseline trough concentrations (239 +/- 151 ng/dL). The nine patients who remained on Neoral had no change in the CYA levels or SCR. Nearly 20% of patients who switched to a bioequivalent CYA preparation required a dose adjustment to return to pre-conversion CYA trough levels. Our study raises serious concerns regarding the switchability of generic CYA for Neoral without careful follow-up therapeutic drug monitoring.

Altered Cytochrome P450 Metabolism of Calcineurin Inhibitors: Case Report and Review of the Literature

A 19-year-old woman was admitted to receive a kidney transplant from a nonliving donor. At the time of transplantation, she was taking oral phenytoin 300 mg every morning, 100 mg at noon, and 300 mg every evening (total of 700 mg/day) to treat seizures secondary to hemodialysis. Immediately after the transplantation, phenytoin treatment was resumed, and immunosuppressive therapy consisting of antithymocyte globulin, cyclosporine, mycophenolate mofetil, and corticosteroids was started. Her cyclosporine blood levels varied over the first 10 days after transplantation. Cyclosporine was discontinued, and tacrolimus was begun after acute rejection was discovered. The rejection was treated with antithymocyte globulin, plasmapheresis, and intravenous immunoglobulin, and subsequently resolved; however, the patient's blood concentrations of tacrolimus varied widely. Phenytoin is an antiepileptic drug that induces hepatic enzymes, affecting the cytochrome P450 3A family. These enzymes metabolize approximately 50% of all prescribed drugs, including cyclosporine and tacrolimus. According to the Naranjo adverse drug reaction probability scale, this patient's adverse drug reaction probably occurred from altered metabolism of cyclosporine and tacrolimus due to phenytoin therapy. Clinicians must identify drug interactions between metabolic enzyme inducers or inhibitors and drug substrates with narrow therapeutic ranges, closely monitor drug concentrations, and observe patients for clinical signs and symptoms of therapeutic failure or toxicity. In daily practice, clinicians should explore the metabolic characteristics of drugs and their biotransformation pathways to identify patients who require alternative therapy.

Generic cyclosporine formulations: more open questions than answers

The introduction of cyclosporine (CsA) in clinical practice has significantly improved patient and allograft survival after organ transplantation. The new microemulsion CsA formulation, Neoral, has been associated with a more reproducible absorption and a better patient outcome as compared to the old formulation Sandimmune. Recently, several generic CsA formulations have been tested as bioequivalent to Neoral. Bioequivalence tests have been performed in selected groups of young, healthy male volunteers usually in single-dose studies, and then extended to completely different population, such as transplant recipients. However, growing body of evidence shows that CsA pharmacokinetics in healthy subjects is different from that of transplant patients, treated chronically with CsA. Therefore, converting patients from Neoral to the new generic formulations could be detrimental, exposing patients to increased risk of graft function deterioration and graft loss. Thus, more research and more accurate bioequivalence tests are required to address the unanswered problems dealing with the generic CsA formulations.