Converting to a Generic Formulation of Mycophenolate Mofetil in Stable Kidney Transplant Recipients: 1 Year of Drug Surveillance and Outcome

Generic Medicinal Products in Immunosuppressive Therapy-Should It be a Challenge for Therapeutic Drug Monitoring?

ABSTRACT

Immunosuppressants have a narrow therapeutic index (NTIDs). Indisputably cyclosporine, tacrolimus, everolimus, and sirolimus have NTIDs, and only in the case of mycophenolic acid, a scientific discussion has not been yet concluded. Their specificities highlight the implications for generics introduced into the drug market, more precisely, with bioequivalence testing. In the European Union, the European Medicines Agency (EMA) released the "Guideline on the Investigation of Bioequivalence." The bioequivalence (BE) of the generic (tested, T) versus original (reference, R) product should be confirmed by obtaining a 90% confidence interval (CI) for the T:R ratio of each of the 2 decisive pharmacokinetic parameters, namely, the area under the curve (AUC) between 90.00% and 111.11%. A similar approach (90.00%-112.00%) for AUC was adopted by the Canadian Agency for Drugs and Technologies in Health (CADTH) for NTIDs; however, the US Food and Drug Administration is still based on classic acceptance criteria: 90% CI between 80.00% and 125.00% but with special requirements of BE testing. A discussion about long-expected global consensus was performed in this study based on the literature concerning BE testing in the case of NTIDs. The narrow acceptance criteria reduce the potential mean difference in bioavailability between generic and original products by a few percent. To identify this problem, special attention has been paid to switching drugs (generic-generic, original-generic) and therapeutic drug monitoring after conversion (TDM). There is no global consensus on the acceptance criteria for the BE of generic drugs; therefore, consensus and harmonization are strictly necessary. This study presents a review of the generic drug market and its classification by manufacturers, drug agencies, and dates of marketing authorization. Guidelines for TDM optimization (during switching/conversion) have been proposed. Physicians and clinical pharmacists should pay special attention to switching immunosuppressive drugs between original versus generic formulations, and generic versus generic formulations. Patients and their families should be educated on the risks associated with uncontrolled conversion.

Is There Evidence to Support Brand to Generic Interchange of the Mycophenolic Acid Products?

The uptake of generic immunosuppressants lags comparatively to other drug classes, despite that the Food and Drug Administration (FDA) uses identical bioequivalence standards for all drugs. Transplant societies acknowledge the cost savings associated with generic immunosuppressants and support their use following heart, lung, kidney, or bone marrow transplantation. Seven studies of the pharmacokinetics or clinical efficacy of generic mycophenolate mofetil compared to the innovator product are published; all studies and products were ex-United States. Three studies did not demonstrate any pharmacokinetic differences between generic and innovator products in healthy subjects, achieving FDA bioequivalence requirements. Two studies in renal allograft recipients demonstrated no difference in area under the curves between generic and innovator products, and in one, the maximum concentration (Cmax) fell outside the FDA regulatory range. Two studies revealed no difference in acute organ rejection or graft function in renal allograft recipients. Patient surveys indicate that cost is a barrier to immunosuppressant adherence. Generics present a viable method to reduce costs to payers, patients, and health care systems. Adherence to immunosuppressants is crucial to prevent graft failure. An affordable regimen potentially confers greater adherence. Concerns regarding the presumed inferiority of generic immunosuppressants should be assuaged by regulatory requirements for bioequivalency testing, transplant society position statements, and pharmacokinetic and clinical studies.

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.

Safety and efficacy of the switch to generic mycophenolate mofetil and tacrolimus in heart transplant patients

BACKGROUND

Generic immunosuppressants may offer economic advantages, but their use is still controversial. At our center, 55 heart transplant patients were switched from CellCept(®) to Myfenax Teva(®) (MT) (n = 51, 18% female, 8.1 ± 6.6 yr post-transplantation) and/or Prograf(®) to Tacrolimus Sandoz(®) (TS) (n = 17, 41% female, 6.6 ± 5.8 yr post-transplantation).

METHODS

We conducted an acute monitoring and a retrospective follow-up with regard to safety and efficacy. Acute cellular rejections (ACRs) on endomyocardial biopsies (EMBs) four wk after the MT switch were specifically compared to a matched retrospective control group.

RESULTS

Tacrolimus C0 levels (TS switch) as well as hemoglobin, leukocytes, and thrombocytes (MT switch) did not change (p = NS) during the three wk after each respective switch (8.7 ± 2.9 vs. 8.4 ± 1.9 μg/L, 129.1 ± 12.6 vs. 130.1 ± 12.8 g/L, 6.3 vs. 6.2 × 10(9) /L, and 217.4 ± 56.6 vs. 219.3 ± 61.8 × 10(9) /L, respectively). 0% of the EMBs in the MT switch vs. 3% of the EMBs in the control group showed ACR>grade 1R (p = NS). After six months, survival was 96% (MT switch) and 100% (TS switch), and the frequency of severe ACR was low. Safety parameters measured at the next annual follow-up were also stable following each switch.

CONCLUSION

Switching to MT and/or TS several years after heart transplantation appeared safe in the short-term perspective, showing no detectable changes in tacrolimus C0 levels, safety or efficacy, during an average follow-up of six months.

A pilot study on the safety and efficacy of generic mycophenolate agent as conversion maintenance therapy in stable liver transplant recipients

PURPOSE

The patent covering mycophenolate mofetil (MMF) in Korea has expired and, thus, several generic MMF agents are now commercially available. The supply of Cellcept (Roche Korea) was interrupted at the end of 2011, so it was inevitable that a generic MMF would be used instead. During this period, we performed a prospective pilot study to examine the safety and efficacy of a generic mycophenolate agent (Myconol: Hanmi Pharmaceutical, Seoul Korea) for use as conversion maintenance therapy in stable liver transplantation (OLT) recipients.

METHODS

OLT recipients, who were treated with MMF on an outpatient basis from January 2012 to March 2012, attended follow-up interviews conducted. The patients had undergone OLT ≥ 2 years before the study, had tolerated Cellcept, and showed stable liver function. Fifty-three patients were followed up for more than 3 months after conversion to the same dose of Myconol.

RESULTS

After conversion to Myconol, 6 patients (11.3%) experienced new side effects, which disappeared when they reverted to Cellcept (n = 5) or stopped taking Myconol medication (n = 1). The side effects associated with Myconol included gastrointestinal symptoms (indigestion and diarrhea; n = 3), skin eruptions (n = 1), pruritus (n = 1), and insomnia (n = 1). The mean mycophenolic acid levels were 1.71 ± 0.88 μg/mL for Cellcept and 1.83 ± 0.91 μg/mL for Myconol, which showed a strong correlation (r(2) = 0.92, P < .001).

CONCLUSIONS

Myconol showed similar pharmacokinetics to those of Celcept, but a small proportion of patients experienced agent-specific side effects; therefore, patients should be closely monitored when taking Myconol. Also, further studies, with a greater number of patients, are required to identify the full spectrum of drug-associated side effects.

Transplant coordinators' perceived impact of availability of multiple generic immunosuppression therapies on patients, workload, and posttransplant maintenance therapy

Background. No studies have evaluated the impact of multiple generic immunosuppression medications on transplant coordinators (TCs) and patients. Methods. A cross-sectional, multicenter online survey of TCs managing transplant recipients' outpatient immunosuppression was undertaken to assess TCs' perceptions of the impact of multiple generic immunosuppression therapies on patients and workload. Results. Forty-six of 106 transplant centers contacted (43%) completed the survey, with usable information from 34 TCs (53% in centers performing >100 solid organ transplants annually, 82% registered nurses, and 68% with >5-year experience working with transplant patients). TCs indicated that “change in strength,” “switching from branded to generics,” “heavy pill burden,” and “switching from one generic to another” were the four most frequent reasons for patient confusion regarding immunosuppression. TCs reported increased patient confusion over the previous year for patients on generic immunosuppression therapy: 44% answered ≥3 patient calls/day regarding confusion over immunosuppression therapy. Most TCs indicated increased workload since the introduction of generic immunosuppression therapy. TCs perceived “acute rejection rates,” “rate of graft loss,” and “poor patient adherence” as the three most likely consequences of multiple generic immunosuppression therapy. Conclusion. TCs associated availability of multiple generic immunosuppression therapy with increased patient confusion and time spent addressing patient concerns.

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.

Next level of immunosuppression: drug/immune monitoring

1. Current immunological monitoring relies heavily on clinical judgment and therapeutic drug levels and does not adequately assess the functional or donor-specific immunosuppression (IS) status of recipients of liver transplantation (LT). 2. Trough levels of drugs are arbitrary and are more clinically relevant for preventing supratherapeutic or subtherapeutic dosing and blood concentrations and for more closely monitoring at-risk populations (children, the elderly, and patients with organ dysfunction). The AUC or the post-dose levels may be more precise, but they have not been used extensively by transplant centers. 3. Data on drug/immune monitoring specific to LT are fairly limited; therefore, clinical practice is often borrowed from experiences with nonhepatic transplantation (mainly renal transplantation). 4. The monitoring of drug levels in patients taking generic immunosuppressants is challenging because the formulations may change with each prescription. The monitoring of drug or antibody levels is not yet clinically available for biological therapies (induction, lymphocyte-depleting, and maintenance agents). 5. Polymorphisms in drug metabolism (cytochrome P450 and P-glycoprotein) may be useful in selecting the initial and maintenance dosages of immunosuppressants and in preventing complications from over or underimmunosuppression. 6. Future immune monitoring assays should be focused on genomic or immunological predispositions and on specific reactivities to donor antigens to guide the appropriate dosing and minimization of IS after LT.

Generics: need for clinical concern?

The market of generic drugs is in continuous development in all countries, including Belgium. Their low cost explains their success in western and developed countries. However, clinical concerns have been raised when generics are used. Indeed, various studies suggest that generic substitution can be associated with reduced efficacy or (and) increased side-effects, particularly with drugs used in severe diseases or pathological states such as epilepsy, cardiac arrhythmia, prevention of graft-rejection, ... The generic drugs must have systemic bioavailability similar to that of the original drug. Thus, they have supposed similar therapeutic bioequivalence. However, similar pharmacokinetics does not imply identical therapeutic activity, particularly with drugs having narrow therapeutic indices such as anti-epileptics, anti-arrythmics ... In this case, switchability rather than prescribability may cause problems. Low pharmaceutical quality is more frequent when drugs are produced in certain countries, in some cases causing a real concern when activity and safety are considered.