A pharmacokinetic and clinical review of the potential clinical impact of using different formulations of cyclosporin A. Berlin, Germany, November 19, 2001

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.

Oral drug delivery strategies for development of poorly water soluble drugs in paediatric patient population

Selecting the appropriate formulation and solubility-enabling technology for poorly water soluble drugs is an essential element in the development of formulations for paediatric patients. Different methodologies and structured strategies are available to select a suitable approach and guide formulation scientists for development of adult formulations. However, there is paucity of available literature for selection of technology and overcoming the challenges in paediatric formulation development. The need for flexible dosing, and the limited knowledge of the safety of many formulation excipients in paediatric subjects, impose significant constraints and in some instances require adaptation of the approaches taken to formulating these drugs for the adult population. Selection of the best drug delivery system for paediatrics requires an efficient, systematic approach that considers a drug's physical and chemical properties and the targeted patient population's requirements. This review is a step towards development of a strategy for the design of solubility enhancing paediatric formulations of highly insoluble drugs. The aim of this review is to provide an overview of different approaches and strategies to consider in order to assist development of paediatric formulation for poorly water-soluble drugs with the provision of examples of some marketed products. In addition, it provides recommendations to overcome the range of challenges posed by these strategies and adaptations of the adult approach/product presentation required to enable paediatric drug development and administration.

Meeting Regulatory Requirements for Drugs with a Narrow Therapeutic Index: Bioequivalence Studies of Generic Once-Daily Tacrolimus

Despite growing clinical confidence in generics and their potential to reduce long-term healthcare costs, the transplant community have had real concerns about the use of generic immunosuppressants. One such immunosuppressant is tacrolimus, a cornerstone of lifelong treatment for patients who have undergone a solid organ transplant. Tacrolimus has a narrow therapeutic index (NTI), giving rise to questions about the potential for clinically relevant altered drug exposure. Its use in transplant patients also gives rise to questions about the most discriminative subject population for bioequivalence studies. The recognised need for stringent criteria to support approval of generic drugs with an NTI led the European Medicines Association and Health Canada to provide detailed information on requirements for bioequivalence studies and introduce tighter bioequivalence limits for these drugs, including tacrolimus. The aim of this article is to illustrate how regulatory guidance is implemented during the clinical development of generic immunosuppressants, using a generic, once-daily prolonged-release formulation of tacrolimus as an example.

Adsorption and Leachable Contamination of Flucloxacillin, Cyclosporin and Amiodarone Following Delivery Through an Intravenous Administration Set

PURPOSE

Interactions between a pharmaceutical drug and its delivery device can result in changes in drug concentration and leachable contamination. Flucloxacillin, amiodarone and cyclosporin were investigated for drug concentration changes and leachable contamination after delivery through an intravenous administration set.

METHODS

Flucloxacillin, amiodarone and cyclosporin were delivered through an intravenous administration set and the eluate analysed by HPLC-UV and HPLC-MS.

RESULTS

The average recovery of flucloxacillin was 99.7% and no leachable compounds were identified. The average recovery of cyclosporin was 96.1%, which contrasts previous findings that have reported up to 50% loss of cyclosporin. This is likely due to the use of DEHP-free administration sets in this study, as adsorption of cyclosporin is linearly related to DEHP content. The average recovery of amiodarone was 91.5%. 5-hydroxymethylfurfural was identified in the amiodarone solution following delivery through the administration set as well as the 5% glucose solution used for delivery.

CONCLUSIONS

Drug/administration set interactions may modify pharmaceuticals during delivery. In this study, only 90% of the amiodarone was delivered through a generic administration set. Given the growing use of generic administration sets in hospital settings, validation of the suitability of their use is required to ensure patient safety and expected levels of efficacy.

Comparison of clinical effects, trough and peak levels between branded and generic formulation of Cyclosporine in stable psoriatic patients

BACKGROUND

Cyclosporine A (CyA) is a drug for moderate-to-severe psoriasis. Recently, a generic formulation has been approved as bioequivalent to the branded one. The guidelines for the bioequivalence for critical-dose drugs with a narrow therapeutic range, such as CyA, are questionable. Therefore, it is important to assess the clinical outcome and the pharmacokinetics of different formulations in various patient groups. The current literature lacks of this information in dermatology. The primary objective of this prospective study is to investigate the clinical equivalence (in terms of maintenance of clinical effect) between the generic formulation of CyA and its branded one in patients with psoriasis. A secondary objective is to analyze their trough (C<inf>0</inf>) and peak levels (C<inf>2</inf>).

METHODS

Twenty patients with stable psoriasis under treatment with the branded CyA were monitored in terms of clinical efficacy (psoriasis area severity index, PASI), safety (laboratory values), and their pharmacokinetics utilizing trough (C<inf>0</inf>) and peak plasma concentration (C<inf>2</inf>). The same patients were subsequently shifted to the generic formulation for comparison.

RESULTS

In our sample the efficacy of the two formulations was equal in most cases (P=0.863). A non-significant difference between the C<inf>0</inf> and C<inf>2</inf> of the branded CyA compared to the generic one emerged (respectively P=0.738 and P=0.695).

CONCLUSIONS

The branded and the generic formulations of CyA seem to be not only bioequivalent, but also comparable in terms of clinical efficacy in patients with psoriasis. However, larger samples are required to confirm these findings.

Bioequivalence between innovator and generic tacrolimus in liver and kidney transplant recipients: A randomized, crossover clinical trial

BACKGROUND

Although the generic drug approval process has a long-term successful track record, concerns remain for approval of narrow therapeutic index generic immunosuppressants, such as tacrolimus, in transplant recipients. Several professional transplant societies and publications have generated skepticism of the generic approval process. Three major areas of concern are that the pharmacokinetic properties of generic products and the innovator (that is, "brand") product in healthy volunteers may not reflect those in transplant recipients, bioequivalence between generic and innovator may not ensure bioequivalence between generics, and high-risk patients may have specific bioequivalence concerns. Such concerns have been fueled by anecdotal observations and retrospective and uncontrolled published studies, while well-designed, controlled prospective studies testing the validity of the regulatory bioequivalence testing approach for narrow therapeutic index immunosuppressants in transplant recipients have been lacking. Thus, the present study prospectively assesses bioequivalence between innovator tacrolimus and 2 generics in individuals with a kidney or liver transplant.

METHODS AND FINDINGS

From December 2013 through October 2014, a prospective, replicate dosing, partially blinded, randomized, 3-treatment, 6-period crossover bioequivalence study was conducted at the University of Cincinnati in individuals with a kidney (n = 35) or liver transplant (n = 36). Abbreviated New Drug Applications (ANDA) data that included manufacturing and healthy individual pharmacokinetic data for all generics were evaluated to select the 2 most disparate generics from innovator, and these were named Generic Hi and Generic Lo. During the 8-week study period, pharmacokinetic studies assessed the bioequivalence of Generic Hi and Generic Lo with the Innovator tacrolimus and with each other. Bioequivalence of the major tacrolimus metabolite was also assessed. All products fell within the US Food and Drug Administration (FDA) average bioequivalence (ABE) acceptance criteria of a 90% confidence interval contained within the confidence limits of 80.00% and 125.00%. Within-subject variability was similar for the area under the curve (AUC) (range 12.11-15.81) and the concentration maximum (Cmax) (range 17.96-24.72) for all products. The within-subject variability was utilized to calculate the scaled average bioequivalence (SCABE) 90% confidence interval. The calculated SCABE 90% confidence interval was 84.65%-118.13% and 80.00%-125.00% for AUC and Cmax, respectively. The more stringent SCABE acceptance criteria were met for all product comparisons for AUC and Cmax in both individuals with a kidney transplant and those with a liver transplant. European Medicines Agency (EMA) acceptance criteria for narrow therapeutic index drugs were also met, with the only exception being in the case of Brand versus Generic Lo, in which the upper limits of the 90% confidence intervals were 111.30% (kidney) and 112.12% (liver). These were only slightly above the upper EMA acceptance criteria limit for an AUC of 111.11%. SCABE criteria were also met for the major tacrolimus metabolite 13-O-desmethyl tacrolimus for AUC, but it failed the EMA criterion. No acute rejections, no differences in renal function in all individuals, and no differences in liver function were observed in individuals with a liver transplant using the Tukey honest significant difference (HSD) test for multiple comparisons. Fifty-two percent and 65% of all individuals with a kidney or liver transplant, respectively, reported an adverse event. The Exact McNemar test for paired categorical data with adjustments for multiple comparisons was used to compare adverse event rates among the products. No statistically significant differences among any pairs of products were found for any adverse event code or for adverse events overall. Limitations of this study include that the observations were made under strictly controlled conditions that did not allow for the impact of nonadherence or feeding on the possible pharmacokinetic differences. Generic Hi and Lo were selected based upon bioequivalence data in healthy volunteers because no pharmacokinetic data in recipients were available for all products. The safety data should be interpreted in light of the small number of participants and the short observation periods. Lastly, only the 1 mg tacrolimus strength was utilized in this study.

CONCLUSIONS

Using an innovative, controlled bioequivalence study design, we observed equivalence between tacrolimus innovator and 2 generic products as well as between 2 generic products in individuals after kidney or liver transplantation following current FDA bioequivalence metrics. These results support the position that bioequivalence for the narrow therapeutic index drug tacrolimus translates from healthy volunteers to individuals receiving a kidney or liver transplant and provides evidence that generic products that are bioequivalent with the innovator product are also bioequivalent to each other.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01889758.

A Systematic Literature Review Approach to Estimate the Therapeutic Index of Selected Immunosuppressant Drugs After Renal Transplantation

BACKGROUND

Drugs that exhibit close margins between therapeutic and toxic blood concentrations are considered to have a narrow therapeutic index (NTI). The Food and Drug Administration has proposed that NTI drugs should have more stringent bioequivalence standards for approval of generic formulations. However, many immunosuppressant drugs do not have a well-defined therapeutic index (TI).

METHODS

We sought to determine whether safety, efficacy, and pharmacokinetic data obtained from the medical literature through a comprehensive literature search could be used to estimate the TI of cyclosporine, tacrolimus, and sirolimus. In this analysis, we considered TI ≤2 as a criterion to define a drug as having an NTI.

RESULTS

Published literature indicates that cyclosporine has a TI of 2-3, which falls just short of our criteria to be classified as having an NTI. We found sirolimus and tacrolimus to have a therapeutic range of 5-12 ng/mL and of 5-20 ng/mL, respectively, but were unable to calculate the TI.

CONCLUSIONS

Although the current literature does not provide a clear indication that these drugs have an NTI, the routine use of therapeutic drug monitoring in clinical practice suggests that more stringent testing of their pharmacokinetic and pharmacodynamic properties should be performed before the approval of generic formulations.

Pilot study on the efficacy and safety of generic mycophenolate mofetil (Mycept) compared with Cellcept among incident low-risk primary kidney transplant recipients

AIM

The aim of this study was to establish the efficacy and safety of generic mycophenolate mofetil (Mycept) and determine the bioequivalence with Cellcept. This will provide patients an alternative cost-effective option that may improve compliance and long-term outcome.

METHODS

This was a comparative study between 2 nonconcurrent matched groups on Mycept and Cellcept. A total of 56 patients were included based on criteria (20 incidental patients on Mycept, matched to 20 historical patients on Cellcept, and 16 additional incidental patients on Cellcept). Patient and graft survival and safety parameters were reviewed at 6 months. Bioequivalence of Mycept with Cellcept was done by measuring area under the curve (AUC) of mycophenolic acid (MPA), maximum concentration, and time to maximum concentration for 16 patients in each group.

RESULTS

Twenty incidental Mycept patients completed 6 months of follow-up. No significant difference was observed in survival (P = 1.0), graft function (P = .2320), and rejection episodes (P = .6250) between groups. The most common side effect of Mycept was hematologic and infectious. The MPA AUC of Mycept (37.38 ng/mL) was within the recommended MPA of 30-60 ng/mL. The maximum concentration (6.06 ng/mL) and time to maximum concentration (1.19 hours) of the 10 Mycept patients were not significantly different from the 10 Cellcept patients.

CONCLUSION

There was no proven statistically significant difference between Mycept and Cellcept in efficacy and graft survival at 6 months after kidney transplantation. Hematologic side effects were noted more frequently among patients on Mycept and monitoring regularly is recommended.

Conversion to generic cyclosporine A in stable chronic patients after heart transplantation

Background

Cyclosporine A (CSA) is a narrow therapeutic index drug. Available CSA products differ in the constitution of their emulsion. To compare intra-individual differences after a conversion to a generic CSA, a retrospective single-center study was initiated.

Methods

Twenty adult stable chronic (>24 months post heart transplant) recipients were included in the present retrospective study. These patients were previously switched from Sandimmune Neoral® to the generic CSA (Equoral®) according to the patients’ preference during the clinical routine. Dose-normalized trough levels (DNL) and trough levels (C0) at 8 months, 4 months, and 2 weeks before the switch were retrospectively compared with the corresponding values at 2 weeks, 4 months, and 8 months after the switch to the generic CSA. Additionally, changes in the routine laboratory parameters, the number of treated rejection episodes, and the adherence to the CSA target levels were compared.

Results

The mean DNL (adapted to the daily CSA dose in mg) was 0.71±0.26 (ng/mL)/mg on Neoral therapy; on Equoral it was 0.68±0.23 (ng/mL)/mg, (P=0.38). In comparison to the CSA daily dose prior to the conversion, at postconversion, no significant changes of CSA daily dose were observed (Neoral 140.67±39.81 mg versus Equoral 134.58±41.61 mg; P=0.13). No rejection episodes requiring therapy occurred prior to or postconversion (P=0.99). Additionally, no statistically significant changes of routine laboratory parameters regarding the Modification of Diet in Renal Disease or hematological parameters were seen (all P=not significant). No adverse events after the conversion were observed.

Conclusion

This study in chronic and stable HTx patients demonstrated no statistically significant differences in the CSA DNL after a conversion to generic CSA (Equoral). The generic CSA was generally well-tolerated. We concluded that a conversion from Neoral to Equoral is safe and clinically feasible in this distinct patient population. However, multiple switches between different generic immunosuppressants must especially be avoided in the interest of patient safety, and close follow-up examinations must be warranted.

Equivalence and interchangeability of narrow therapeutic index drugs in organ transplantation

The calcineurin inhibitors (CNIs), ciclosporin and tacrolimus, are the mainstay of immunosuppression in solid organ transplantation. Generic formulations of these drugs are now available. With increasing pressure on healthcare budgets and the consequent need to match health expectations to available resources, substitution with a generic product appears an attractive option to reduce costs. Approval of generic products differs from innovator drugs, and narrow therapeutic index drugs (NTIs; including CNIs) bring their own particular considerations. With NTIs, small variations in drug exposure could result in reduced immunosuppression or drug toxicity with potentially adverse effects on patient outcomes. NTIs are subject to stricter regulatory approval versus many other generic drugs. However, different generic formulations may still not necessarily be therapeutically equivalent in individuals, raising the possibility of significant differences in exposure between products. Although regional recommendations vary, many guidelines emphasise the need for NTI drug substitution to be initiated by the transplant physician, thus ensuring careful therapeutic monitoring and reduced negative patient impact. The need for therapeutic monitoring during generic substitution has important implications for the overall costs of generic treatment as these costs have to be factored in to the potential savings made from using generic formulations. The reduced acquisition costs of generic products may not necessarily translate into lower overall healthcare costs. This article examines the issue of equivalence and interchangeability of NTI drugs used in organ transplantation, the implications of the approval process for generic drugs on treatment efficacy and safety, and the effective management of substitutions between products.

PEGylated single-walled carbon nanotubes as nanocarriers for cyclosporin A delivery

Single-walled carbon nanotubes (SWCNTs) have attracted the attention of many researchers due to their remarkable physicochemical features and have been found to be a new family of nanovectors for the delivery of therapeutic molecules. The ability of these nanostructures to load large amounts of drug molecules on their outer surface has been considered as the main advantage by many investigators. Here, we report the development of a PEGylated SWCNT-mediated delivery system for cyclosporin A (CsA) as a potent immunosuppressive agent. The available OH group in the CsA structure was first linked to a bi-functional linker (i.e., succinic anhydride) in order to provide a COOH terminal group. CsA succinylation process was optimized by using the modified simplex method. The resulting compound, CsA-CO-(CH(2))(2)-COOH, was then grafted onto the exterior surface of SWCNTs, previously PEGylated with phospholipid-PEG(5000)-NH(2) conjugates, through the formation of an amide bond with the free amine group of PEGylated SWCNTs. Drug loading, stability of the PEGylated SWCNT-CsA complex, and in vitro release of the drug were evaluated. Loading efficiencies of almost 72% and 68% were achieved by UV spectrophotometry and elemental analysis methods, respectively. It was observed that 57.3% of cyclosporine was released from CsA-Pl-PEG(5000)-SWCNTs after 3 days. In this investigation, we conjugated CsA to an amine-terminated phospholipid-polyethylene glycol chain attached on SWCNTs via a cleavable ester bond and demonstrated the possible potential of PEGylated SWCNT-based systems for CsA delivery.

Safety and efficacy of generic cyclosporine arpimune in Filipino low-risk primary kidney transplant recipients

BACKGROUND

In the Philippines, maintenance of immunosuppression may not always be affordable, leading to acute rejection and graft loss. The availability of the generic cyclosporine Arpimune could be economically beneficial, but its safety and efficacy should be established.

METHODS

This prospective cohort study enrolled 30 renal transplant patients who received Arpimune with mycophenolate/prednisone. Their results were compared up to 6 months with 30 matched control patients who received Neoral during the same period. Areas under the receiver operating characteristic curves (AUC) after intake of Arpimune and therapeutic drug monitoring using cyclosporine levels 2 hours after each dose were done. Pearson correlation was performed to determine linearity of relationship between the generic cyclosporine concentrations and AUC 0-4. Chi-square test was used in obtaining cyclosporine Arpimune concentrations.

RESULTS

The abbreviated concentration AUC of Arpimune was similar to that of Neoral, and the 2-hour sampling point (r = 0.813; P < .001) showed the best correlation. Calculated creatinine clearance (mL/min) versus Neoral was 71.36 ± 13 versus 68.03 ± 16.6 (P = .61) at 1 month, 70.4 ± 14.8 versus 64.2 ± 11.4 (P = .12) at 3 months, and 74.02 ± 15.8 versus 62.03 ± 12.1 (P = .002) at 6 months. Two Arpimune versus 4 Neoral patients (P = .67) developed biopsy-proven acute rejection. One septic death occurred in the Arpimune group. Graft survival was 100% in both groups. Hyperlipidemia was the most frequent side effect for both.

CONCLUSIONS

The AUC of Arpimune was similar to that of Neoral. Use of the generic cyclosporine Arpimune provided effective immunosuppression in the 6 months after transplantation. Renal allograft function was similar to that of Neoral, with minimal rates of acute rejection and adverse events.

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.

The use of cyclosporine in dermatology: part II

Cyclosporine is highly effective in the treatment of a multitude of dermatoses. Concern over its side effect profile has limited its use in dermatology. Adverse effects are, for the most part, dose dependent and related to duration of therapy. Using the recommended monitoring protocols results in a significant decrease in the incidence of cyclosporine-related toxicities. This article provides a comprehensive review of the pharmacokinetics of cyclosporine, potential drug interactions, adverse effects, and recommendations for monitoring in patients treated with cyclosporine. The use of cyclosporine in pregnancy and in the pediatric population is also addressed.

LEARNING OBJECTIVES

After completing this learning activity, participants should be familiar with the monitoring guidelines of cyclosporine, its contraindications, its possible drug interactions, its adverse effect profile, and its use in pregnancy and the childhood and adolescent populations.

Interchangeability of ciclosporin formulations in stable adult renal transplant recipients: comparison of Equoral and Neoral capsules in an international, multicenter, randomized, open-label trial

The cost of immunosuppression following transplantation can be reduced by using generic ciclosporin (for example, Equoral) rather than innovator ciclosporin drugs such as Neoral. Thus, this study aims to evaluate the interchangeability, safety, and tolerability of Equoral, a generic ciclosporin, with Neoral in stable adult renal transplant recipients. This was a multicenter, randomized, open-label, parallel-group clinical trial in stable renal transplant patients, comparing 6 months of treatment with Equoral with the same treatment period on Neoral. The primary end point was the between-treatment comparison of the total daily ciclosporin dose at the end of the study. A total of 99 patients were enrolled and constituted the full analysis/safety population, and 78 patients forming the per-protocol population were assessed for efficacy. Equoral was found to be equivalent to Neoral with regard to the primary end point of daily dose at the end of the study. This was supported by comparable serum ciclosporin levels at the end of the study. There were no renal transplant rejection incidents, but there was one death (in the Neoral group). Drug tolerability and incidence of adverse events were comparable between the treatment groups. In conclusion, Equoral and Neoral are interchangeable in stable renal transplant patients, and both drugs are associated with a similar safety and tolerability profile.

Influence of purple grape juice in cyclosporine bioavailability

OBJECTIVE

The present study was designed to investigate the effect of a single purple grape juice administration on cyclosporin A (CyA) oral bioavailability in healthy volunteers.

DESIGN

The study followed a two-period crossover design, where the volunteers were randomly assigned to receive 200-mg CyA soft-gelatin capsules with 200 mL of either purple grape juice or water in the first day of the experiment.

SETTING AND PATIENTS

Volunteers were kept at the clinical research unit during the blood sampling period and fasted from 10 p.m. until 4 hours after dosing. A washout period of 1 week was observed before the second treatment was administered.

MAIN OUTCOME MEASURE

Blood samples were taken before and at 0.5, 1, 1.5, 2, 2.5, 3, 4, 6, 8, 10, and 12 hours after CyA dosing. All meals received during the study day were standardized. Whole blood was assayed to determined CyA concentration using the Emit 2000 Cyclosporine specific immunoassay (Dade Behring Limited, Syva Company, Dade Behring Inc. Cupertino, CA). Pharmacokinetic parameters were determined by noncompartmental analysis from the individual whole blood concentration-time curves after each treatment using Excel 2003 software. Statistical analysis was performed using paired Student t-test (a 5 .05) with the aid of SAS software.

RESULTS

Twelve healthy male volunteers were enrolled in the study, with a mean age of 20.6 years (range 19 -23 years). Purple grape juice significantly decreased cyclosporine AUC by 30% and Cmax by 28%. The time to peak blood level and elimination half-life of the drug, however, were not affected. The clearance determined increased around 50%, with purple grape juice. CyA half-life was not affected, indicating that the change observed in clearance (CL/F) was probably due to a change in the absorption (bioavailability) rather than in the elimination process after administration with purple grape juice.

CONCLUSION

Purple grape juice decreased AUC and Cmax, whereas half-life was not changed, suggesting that juice affects the absorption and not drug elimination. The above findings are similar to previous data on the effects on CyA pharmacokinetics caused by the ingestion of red wine. Our findings are potentially relevant in the clinic. The intake of CyA with purple grape juice should be discouraged, as drug bioavailability can be decrease by 30%, leading to blood levels below the drug therapeutic window. A free interval of at least 2 hours between CyA intake and purple juice drinking is recommended.

Healthcare costs in renal transplant recipients using branded versus generic ciclosporin

BACKGROUND

Generic ciclosporin A modified (CsA) does not have an equivalent pharmacokinetic profile to branded CsA in some transplant populations, potentially leading to negative clinical consequences and increased long-term costs.

OBJECTIVE

To assess direct healthcare costs for de novo renal transplant recipients in the US receiving branded versus generic CsA in the first month after transplantation.

METHODS

Administrative claims data from eight private US health plans were linked to the Organ Procurement and Transplantation Network data. A total of 227 renal transplant cases between 1996 and 2004 were included: 183 were dispensed branded CsA and 44 received generic CsA. Log transformed multiple linear regression was used to model total first-year healthcare costs after the initial CsA claim, controlling for both patient demographics and clinical characteristics and clustering at the transplant centre level.

RESULTS

After controlling for patient factors and pre-CsA costs, total healthcare costs were significantly higher (p = 0.04) for patients receiving generic CsA versus branded CsA. The main driver for the difference was the cost associated with immunosuppressants other than CsA (p = 0.01).

CONCLUSION

Despite initial perceived cost savings associated with generic CsA, de novo renal transplant recipients incurred greater total healthcare costs than those treated with branded CsA. Patients receiving generic CsA may need higher doses or other immunosuppressants to maintain the transplanted kidney than patients receiving branded CsA. Providers and payers need to be aware of potential differences in total healthcare costs between formulations of bioequivalent critical-dose drugs to make the best choice for patient care.

Oral cyclosporine A--the current picture of its liposomal and other delivery systems

The discovery of cyclosporine A was a milestone in organ transplantation and the treatment of autoimmune diseases. However, developing an efficient oral delivery system for this drug is complicated by its poor biopharmaceutical characteristics (low solubility and permeability) and the need to carefully monitor its levels in the blood. Current research is exploring various approaches, including those based on emulsions, microspheres, nanoparticles, and liposomes. Although progress has been made, none of the formulations is flawless. This review is a brief description of the main pharmaceutical systems and devices that have been described for the oral delivery of cyclosporine A in the context of the physicochemical properties of the drug and the character of its interactions with lipid membranes.

Therapeutic equivalence and mg:mg switch ability of a generic cyclosporine microemulsion formulation (Sigmasporin Microral) in stable renal transplant patients maintained on Sandimmun Neoral

We tested a hypothesized pharmacokinetic difference between the reference (Sandimmun Neoral) and test (Sigmasporin Microral) products to prove therapeutic equivalence in an open, multiple fixed dose, one-way crossover, multicenter, and multinational study over a period of 29 days. Forty two stable renal transplant recipients maintained on Sandimmun Neoral were enrolled. Whole blood was collected at day 14 of the study at 0, 0.5, 1.0, 1.5, 2, 3, 4, 5, 6, 8, 10, and 12 hours after reference dosing and the same schedule was repeated at day 29 after switching on an mg:mg basis to the test product at day 15 of the study. Analysis of variance was performed for the pharmacokinetic parameters (area under the curve [AUC]0-12, maximum concentration [Cmax]) of cyclosporine using log-transformed values. Tolerability was assessed by vital signs, adverse events, and laboratory investigations. The 90% confidence interval (CI) test for the Ln-transformed, pharmacokinetic parameters was all within the US Food and Drug Administration acceptable range of 80% to 125%, as Ln area under the steady-state curve (AUCss) was within the range of 92.56 to 103.55 and Ln Cmax was within the range of 85.73 to 103.58; the same also applied for AUC0-4, which may be considered the area of greatest inter- and intra-patient variability. Furthermore, in line with the newly adopted recommendations of the Expert Advisory Committee on Bioavailability and Bioequivalence of Health Canada, the 90% CI for AUCss was within the narrow range of 90% to 112%. No significant difference in tolerability was recorded between the two products. Sigmasporin Microral (Julphar) was found to be bioequivalent and clinically interchangeable on an mg:mg basis with Sandimmun Neoral (Novartis).

Developing early formulations: Practice and perspective

Early formulations are prepared mostly for drug compounds at both discovery and preclinical stages and are used to animals via various routes such as oral and intravenous dosing. They serve the purpose of evaluating these compounds on a broad range of pharmaceutical interests, notably pharmacology (activity/efficacy), pharmacokinetics (PK), and toxicology. It is estimated that approx. 40% of all drug compounds discovered have certain delivery limitations due to poor solubility or poor bioavailability. This brings tremendous challenges to the scientists working in the field of early formulations. This study intends to cover a broad spectrum of early formulations including basic aspect and development aspect. On basic aspect, it summarized early formulation study purpose, objectives, dosing route, animal species, etc. It then evaluated a variety of dosage forms and solubility enhancement approaches including various solutions, suspensions, lipid-based formulations, solid dispersions, etc. On development aspect, this study broadly reviewed literatures and current practice in the field, the issues and challenges. It offered authors' own approaches and strategies including general development schemes for oral and for i.v., recommended excipient use range for oral and for i.v., experimental procedures for vitro serial dilution method, for kinetic solubility, etc. The study also discussed a number of case analyses and emphasized scientific rationales and experimental approaches in each of them. The study concluded with authors' summary and some comments on early formulation practice, thoughts and perspectives on its future trend. The study is a mixture of literature review and investigational research. It provides many useful information, practical procedures, and recommendations. It is expected that the study will fill the void of literature of such kind, and provide direct benefit to everyday practitioners in the field.

Bioavailability of a New Generic Formulation of Mycophenolate Mofetil MMF 500 Versus CellCept in Healthy Adult Volunteers

Several studies have revealed a decreased incidence of early graft rejection with the use of mycophenate mofetil (MMF). The cost of the drug is, however, prohibitive especially in developing countries with limited resources. We compared the pharmacokinetic profile of a new MMF generic formulation (MMF 500 batch number: 06T3001; Medis Tunis) with those of Cellcept, (batch number: M1427; Hoffmann La Roche, Switzerland) in healthy volunteers. The study was double-blinded to investigator and volunteers. It had a balanced randomized, two-treatment, two-period, two-sequence, single-dose, crossover, comparative oral bioavailability design in adult healthy human volunteers. The study was designed, performed, and monitored by CRO Transmedical s.a.l International (Beirut, Lebanon) in accordance with the Basic Principals defined in the US 21 CFR Part 312.20, and the principals enunciated in the World Medical Association Declaration of Helsinki. We included nonsmoking healthy volunteers between the ages of 22 and 45 years. The subjects were admitted to the hospital one night prior to blood sampling. After volunteers received the same dinner, they were fasted overnight and for 2 hours postdosing. At 8 am each person received a single oral dose of 500 mg of either formulation. Blood samples were collected to construct the pharmacokinetic profiles as follows: 0, 0.15, 0.30, 0.45 minutes and 1, 1.15, 1.30, 2, 4, 6, 10, 12, and 24 hours. Water and food intake were the same for all volunteers during the whole study period. Following an 8-day washout period, the subjects were crossed over. Plasma mycophenolic acid concentrations were determined using a high-performance liquid chromatography validated enzyme-linked immunosorbent assay-based method (TransMedical, Beirut Lebanon). Physical examinations, hematology, urinanalysis, serum chemistry tests, and liver enzymes were performed at screening and at the end of each period. Subjects were monitored for safety and adverse events throughout the study by two physicians (one from the hospital and one from TransMedical). The Cmax, Tmax, and AUC for MMF 500 were 10.14 ng/mL, 51.82 minutes, and 18.33 ng/mL/h vs 10.94 ng/mL, 49.09 minutes, and 17.46 ng/mL/h for CellCept, respectively. The 90% confidence intervals (LSM) of Cmax, Tmax, and AUC for MMF 500 were 92.7%, 105.6%, and 105%, respectively, which is within the Food and Drug Administration (FDA)-assigned range for immunosuppressive drugs (90% to 111%). These results indicated that the products are equivalent and switchable according to FDA rulings.

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.

Bioequivalence of enteric-coated mycophenolate sodium and mycophenolate mofetil: a meta-analysis of three studies in stable renal transplant recipients

BACKGROUND

Mycophenolic acid (MPA) is an inhibitor of lymphocyte proliferation and is well established as an immunosuppressive agent in solid organ transplantation. The initial formulation of the drug was a prodrug formulation, mycophenolate mofetil (MMF, Cellcept), which is well absorbed and rapidly converted to mycophenolate in plasma. However, the use of MMF is associated with adverse gastrointestinal events, which can lead to withdrawal of therapy. In an effort to reduce the gastrointestinal effects of MMF, an enteric-coated formulation of the drug was developed, based on the sodium salt of MPA (EC-MPS, Myfortic).

METHODS

Although bioequivalence has been demonstrated in an individual study in maintenance kidney transplant patients, this manuscript documents bioequivalence in a much larger data set of 82 patients by a meta-analysis of data from clinical trials.

RESULTS

The results confirm the bioequivalence of EC-MPS and MMF for both mycophenolate and metabolite exposure, and for maximum plasma mycophenolate concentrations, across three studies. The 90% confidence interval of the ratio of EC-MPS to MMF for mycophenolate plasma AUC in the 82 patients was 101.1 to 114.5% and for Cmax was 83.0% to 112.7%.

CONCLUSION

These findings provide reassurance to transplant professionals and patients that, when choosing between EC-MPS and MMF, they are choosing between formulations that give equivalent mycophenolate exposure.

Update on the use of ciclosporin in immune-mediated dermatoses

Immune-mediated dermatoses, such as psoriasis and atopic dermatitis, affect a significant proportion of the population. Although most cases are not life threatening, these diseases can have a profound effect on the sufferer's quality of life and that of their family. Systemic therapy, such as ciclosporin, is often indicated for severe or recalcitrant disease. The efficacy of ciclosporin in the treatment of psoriasis and atopic dermatitis has been established and clinical data also demonstrate its efficacy in treating less common but equally challenging conditions such as pyoderma gangrenosum, lichen planus, autoimmune bullous disease, recalcitrant chronic idiopathic urticaria and chronic dermatitis of the hands and feet. The risk of potential adverse events associated with ciclosporin is greatly reduced if current treatment and monitoring guidelines are followed.

Three generations of cyclosporine a formulations: an in vitro comparison

When the microemulsion formulation of the critical dose drug cyclosporine A (CsA) (Sandimmun Optoral) was introduced in the mid-1990s, it became clear that this new formulation improves the oral bioavailability of CsA and has a positive influence on its pharmacokinetic variability. Previous studies with the original CsA formulation (Sandimmun) showed that the size of the emulsion droplets and concomitant food intake has an effect on the absorption of CsA from the small intestine when orally administered. It was suggested that these effects might have an influence on the drugs' pharmacokinetic parameters. In this study, we focused on the two above-mentioned aspects and compared the first and second generations of CsA products (Sandimmun, Sandimmun Optoral) to generic CsA formulations by analyzing the contents of cyclosporine A gel capsules with respect to their emulsion droplet and micelle sizes using photon correlation spectroscopy (PCS). We tried to discern any differences in droplet size between different generations of CsA formulations, primarily the second and third generation, through simple physical tests. Because a high fat content food may influence the absorption of CsA, we also determined the distribution of CsA between hydrophilic and lipophilic phases using high-performance liquid chromatography analysis. It became clear that when compared under simple physical conditions, established cyclosporine formulations and new generic products show significant differences in droplet size and distribution between an aqueous phase and a high fat content food. Whether these differences are of clinical relevance remains to be investigated.

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.

Assessment of the bioequivalence of a generic cyclosporine A by a randomized controlled trial in stable renal recipients

BACKGROUND

The aim of this study was to determine the bioequivalence of Cysporin, a generic cyclosporine A, compared with Neoral in stable renal transplant recipients.

METHODS

Study design consisted of an open label, two-way crossover, randomized controlled trial of Cysporin versus Neoral in stable renal transplant recipients. In all, 33 patients were enrolled; 31 were randomized and 28 were evaluable. AUCs(0-12) were done on day 14 and 28; C(0) and C(2) were done on days 0, 7, 21 and 35. Dose conversion was 1:1. Outcome measures for serum cyclosporin A concentrations expressed as the mean+/-SD were AUC(0-12) (microg x hr/L), C(max) (microg/L), C(2) (microg/L), T(max) (hr) and T(1/2) (hr). Mean and 90% CI of the ratio Cysporin/Neoral of log-transformed data were calculated using a general linear model.

RESULTS

The main pharmacokinetic features were: AUC(0-12): Cysporin 3495+/-1319, Neoral 3853+/-1378 (P<0.05); C(max): Cysporin 755+/-301, Neoral 881+/-368 (P<0.05); C(2): Cysporin 613+/-235, Neoral 672+/-255 (P>0.05); T(max): Cysporin 1.9+/-0.8, Neoral 1.4+/-0.6 (P<0.005); and T1/2: Cysporin 8.8+/-4.3, Neoral 8.7+/-6.2 (P>0.05). Estimated ratios of Cysporin/Neoral were: AUC 0.93 (90% CI 0.88-0.98; P<0.05); C(max) 0.88 (90% CI 0.80-0.97; P<0.05); and T(max) 1.32 (90% CI 1.14-1.53; P<0.005).

CONCLUSIONS

Both the extent and rate of absorption of Cysporin are significantly less than those of Neoral. The 90% CI for the ratios of Cysporin/Neoral for AUC and C(max) lie within 0.80-1.25. Hence in this clinical context Cysporin is pharmacologically bioequivalent with Neoral. This study illustrates the importance of testing bioequivalence of generic cyclosporine A products in transplant recipients not healthy volunteers.

Differentiation of innovator versus generic cyclosporine via a drug interaction on sirolimus

OBJECTIVE

Both sirolimus and cyclosporine are immunosuppressants used in a combined regimen after organ transplantation. When coadministered with the innovator formulation of cyclosporine, sirolimus blood levels increase 3.3-fold due to a pharmacokinetic interaction. We assessed this drug interaction for potential differences when the innovator formulation is replaced by a generic cyclosporine.

METHODS

In this randomized single-dose crossover study, 28 healthy subjects received 5 mg sirolimus oral solution with 250 mg cyclosporine soft gelatin capsules given as the innovator formulation (reference treatment) versus a generic formulation (test treatment). Sirolimus peak blood concentration (Cmax) and area under the concentration-time curve (AUC) were compared between test and reference treatments by standard bioequivalence testing.

RESULTS

Sirolimus Cmax was significantly lower by 17% in the presence of generic versus innovator cyclosporine (p=0.0003) and failed bioequivalence criteria with a test/reference ratio of 0.83 (90% confidence interval, 0.77-0.90). Nearly half of the subjects (46%) had sirolimus Cmax changes which fell outside the bioequivalence window with individual Cmax decreases up to 52% and increases up to 39%. Sirolimus AUC was significantly lower by 11% in the presence of generic versus innovator cyclosporine (p=0.041) but satisfied average bioequivalence criteria with a test/reference ratio of 0.89 (0.83-0.95). Nonetheless, over a third of the subjects (43%) had sirolimus AUC changes outside the standard bioequivalence window with individual AUC decreases up to 39% and increases up to 42%.

CONCLUSIONS

Switching between innovator and generic cyclosporine may have a clinically-relevant impact on coadministered sirolimus pharmacokinetics. If such a switch is initiated by the prescriber, follow-up therapeutic monitoring of both cyclosporine and sirolimus blood levels should be performed to guide dose adjustments as necessary. If the switch is made without consulting the prescriber, potentially significant changes in sirolimus exposure could go unnoticed by the clinician and patient.

Switchability of neoral and equoral according to Food and Drug Administration rules and regulations

According to the US Food and Drug Administration (FDA), if a drug product contains a drug substance that is chemically identical and is delivered to the site of action at the same rate and extent as another drug product, then it is equivalent and can be substituted (switchable) for that drug product. Methods used to define bioequivalence as stated by the FDA rules (FDA 21 CFR 320, 24) are (1) pharmacokinetic (PK) studies in healthy volunteers, (2) comparative clinical trials, and (3) pharmacodynamic (PD) studies (bioactivity). We evaluated the switchability of Equoral (IVAX-USA) with Neoral (Novartis Switzerland using all FDA rules. In a single oral dose, we undertook a comparative bioavailability study of Equoral (IVAX, USA) Neoral (Novartis, USA), and Neoral (Novartis UK). The pharmacokinetics of Equoral and Neoral were determined with blood levels at 0, 0.25, 0.5, 0.75, 1, 1.25, 1.5, 1.75, 2, 2.5, 3, 3.5, 4, 5, 6, 8, 10, 12, 16, 24, 30, 36, 42, and 48 hours. The area under curve (AUC), AUC extrapolated to infinity (AUC0-inf), rate of absorption (Tmax), extent of absorption (Cmax), half time (t1/2) of Equoral and Neoral were all within the 90% confidence interval of 80% to 125% boundaries. A comparative multinational multicenter clinical trial in stable renal transplant patients included 70 patients (22 women and 48 men) of mean age of 33 years (range, 26 to 43) was performed in Turkey, Lebanon, and Pakistan. In this study the ratios of LSM and the 90% confidence intervals for the Nontransformed/Parameters (AUC0-t, AUCinf, Tmax, and Cmax) of Equoral and Neoral SGC were 98% and 95%, respectively, which are within the 80% to 125% FDA acceptance range. For immunosuppressive drugs, the site of action is the lymphocyte and the measurable response is the decrease in lymphocyte count caused by the relative concentration of the drug in the lymphocyte. In a controlled switch, fixed-dose study, both Equoral and Neoral achieved the same concentration in the lymphocytes and caused the same degree of lymphocyte count reduction. The results of the testing (bioavailability-bioequivalence, clinical studies, and pharmacodynamic-bioactivity) required by FDA for interchangeability ("switchability") of immunosuppressive agents suggests that Neoral and Equoral are switchable.

Comparison of different cyclosporine immunoassays to monitor C0 and C2 blood levels from kidney transplant recipients: Not simply overestimation

BACKGROUND

Immunoassays used for the measurement of cyclosporine (CsA) usually show cross-reactivity for CsA metabolites, usually resulting in unacceptable bias.

METHODS

To assess the performance of different immunoassays, CsA concentrations were analyzed in 132 samples using ACMIA, EMIT-VIVA, CEDIA-PLUS, and HPLC. Samples were collected from kidney transplant patients monitored with the traditional blood CsA trough level (C0, n=73) and the new sampling at 2-h post CsA dosing (C2, n=59).

RESULTS

Overall, the correlations between HPLC and other methods were good (r values ranging from 0.85 to 0.97). The use of C2 concentrations to monitor CsA exposure were associated with an overall better performance of all the immunoassays as compared with C0 values. However, none of the immunoassays agreed with the guidelines proposed in the Lake Louis Consensus Conference. Of note, the CEDIA-PLUS was the only that provided a linear relationship with HPLC for both sampling times. A false positive case associated with ACMIA was also documented in blood samples from a patient withdrawn from CsA for 1 month.

CONCLUSION

These data suggest that the performance of some of the most used immunoassays is not satisfactory, eventually leading to incorrect therapeutic decision guided by erroneous CsA monitoring.

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.

Use of cyclosporine in thoracic transplantation

The use of cyclosporine (CyA) in clinical thoracic transplantation has markedly improved the survival and quality of life of patients in the past 2 decades. In the mid-1990s a significant advance in formulation design took place with the introduction of Neoral. This new microemulsion formulation of CyA demonstrates reduced intersubject and intrasubject variability in absorption and improved oral bioavailability compared with the oil-based CyA formulation. Moreover, C2 measurements of CyA could result in an even better method to avoid overimmunosuppression. On the other hand, generic alternatives of CyA could potentially reduce costs to transplant recipients as well as to the general community. Since the initiation of tacrolimus, mycophenolate mofetil, and rapamycin, slow but expanding variations of immunosuppressive protocols have taken place. Transplantation medicine is thus becoming an increasingly exciting and innovative field, in which CyA continues to play a central role as the core immunosuppressant of choice for the majority of patients.

Bioequivalence of a new cyclosporine a formulation to Neoral

New cyclosporine A (CsA) formulations must prove their bioequivalence to Neoral, the reference CsA formulation, to allow free prescription for the patients. The aim of this study was to compare the pharmacokinetics (PK) of a new CsA formulation (Zinograf-ME), produced by Strides-Arcolab, to Neoral and to demonstrate their interchangeability in stable renal transplant recipients. Twelve-hour PK studies were obtained from 18 (13 M/5 F) adult patients (mean age 44.7 +/- 12 years). They received their renal allografts from 13 cadaver and 5 living donors. Before enrollment, all patients were receiving a third generic CsA for a mean of 48 months. Nine patients were also under azathioprine and 9 under mycophenolate mofetil; 17 received prednisone. A single oral dose of either Zinograf or Neoral was administered. The first PK study was performed with one formulation, and 1 week later, a second PK was done with the other formulation. During the washout period, patients continued taking the third CsA formulation. The drug substitution was done milligram-for-milligram. The CsA whole-blood level was measured by TDx immunoassay. Mean +/- SD of area under the curve (AUC), maximum concentration (C(max)), and concentration at the second hour (C2) of Zinograf were not statistically different from those with Neoral (4019 +/- 1466 vs 3971 +/- 1325 ng x h/mL, 998 +/- 376 vs 1021 +/- 356 ng/mL, and 707 +/- 254 vs 734 +/- 229 ng/mL, respectively). In the same way, the Zinograf 90% confidence interval for either C(max) (-123, +77 ng/mL) or AUC (-214, +311 ng.mL/h) were within the Neoral bioequivalence interval for the same parameters (+/-204 ng/mL and +/-794 ng x mL/h, respectively). These data demonstrate that the ZinografME CsA formulation is bioequivalent to Neoral.

Ciclosporin in psoriasis clinical practice: an international consensus statement

The main recommendations for the use of ciclosporin in the management of psoriasis are: (i) intermittent short courses (average of 12 weeks duration) of ciclosporin are preferable; (ii) ciclosporin should be given in the dose range 2.5-5.0 mg kg(-1) day(-1) (doses greater than 5.0 mg kg(-1) day(-1) should only be given in exceptional circumstances); (iii) treatment regimens should be tailored to the needs of each patient; (iv) selection of patients should take into account psychosocial disability, as well as clinical extent of disease and failure of previous treatment; (v) each patient's renal function (as measured by serum creatinine) should be thoroughly assessed before and during treatment; (vi) each patient's blood pressure should be carefully monitored before and during treatment; (vii) adherence to treatment guidelines substantially reduces the risk of adverse events; (viii) long-term continuous ciclosporin therapy may be appropriate in a subgroup of patients; however, duration of treatment should be kept below 2 years whenever possible; and (ix) when long-term continuous ciclosporin therapy is necessary, annual evaluation of glomerular filtration rate may be useful to accurately monitor renal function.

Therapeutic drug monitoring of cyclosporine: 20 years of progress

Since its introduction 20 years ago, cyclosporine (CyA), a powerful immunosuppressant with a narrow therapeutic window, remains the cornerstone of many drug regimens in renal transplantation. However, attempts to balance its therapeutic value with its pleiotropic side effects continue to challenge clinicians. To address the wide intraindividual and interindividual differences in absorption, distribution, metabolism, and elimination of the oil-based formulation of CyA (Sandimmune), a microemulsion (Neoral) was introduced; it displayed better absorption and lower intraindividual variability. Neoral also improves the utility of therapeutic monitoring of CyA to estimate exposure to the drug and predict patient outcomes. Drug monitoring techniques are undergoing continual refinement: today, a limited sampling strategy--C2 monitoring--shows great promise as a comparatively simple, safe, and effective method to optimize patient outcomes during both short-term and maintenance CyA therapy. However, it is not clear whether this method is useful for treatment optimization with generic formulations of CyA. Although generic substitutes meet federal bioequivalence criteria, they may not display the same pharmacokinetic properties. Further, preliminary data have shown a 10% lower 1-year graft survival rate among patients treated with generic versus Neoral CyA. Current challenges in optimizing CyA therapy include determining pretransplant patient characteristics relevant to selection of the appropriate exposure or the development of a Bayesian forecasting technique that predicts dose adjustments necessary to achieve the optimal drug regimen during the critical period immediately posttransplant.

Experience with cyclosporine

The introduction of cyclosporine (CyA) was a landmark in transplantation, and in the two decades that have followed, enormous experience has been acquired in its use. This has led to both an understanding of its mechanism, pharmacokinetics and toxicity, and the continued evolution of its clinical application. Many of the initial complexities related to the hydrophobic nature of the molecule, and its variable absorption were addressed by the introduction of the microemulsion formulation Neoral. Despite this, the therapeutic window for CyA remains narrow, and therapeutic drug monitoring, recognized early after its introduction, is essential. However, this too has been redefined with single-point, 2-hour, postdose monitoring being demonstrated to correlate better with dose and outcome than the traditional 12-hour trough level. Implementation of such techniques may impact on efficacy and the long-term effects of nephrotoxicity. The need to gain experience with new facets of CyA is likely to continue. In particular, the use of reduced doses to minimize nephrotoxicity during long-term management has produced favorable early results. Furthermore, in the near future the availability of generic CyA formulations will increase. It cannot be assumed that these will be bioequivalent to the current preparations, and modifications of therapy, outside of current experience, may be required. However, if 20 years of CyA usage has taught us anything, it is that different formulations may have very different biological behavior, and at least this situation can be approached with a caution gained from long experience.

Inhibitors of Calcineurin

Before the early 1980s, patient and allograft survival for solid organ transplant recipients was dismal. By 1983, the first calcineurin blocker, cyclosporine (Sandimmun), had been introduced, and outcomes were dramatically improved. However, cyclosporine macroemulsion had suboptimal pharmacokinetics, significant drug interactions, and several adverse effects, including nephrotoxicity, neurotoxicity, hyperlipidemia, and hypertension. Recent advances with cyclosporine include the introduction of modified dosage formulations: Neoral, a microemulsion, and several generic microemulsion products. The potent second-generation calcineurin blocker tacrolimus (Prograf) was introduced in 1994 and has become the drug of choice for several types of transplant recipients. Although tacrolimus has improved pharmacokinetics and therapeutic drugmonitoring parameters, it has adverse effects such as nephrotoxicity, neurotoxicity, and diabetes. Thus, current immunosuppressive regimens implementing calcineurin blockers often involve additional immunosuppressive agents to “spare” the use of these agents, minimizing their adverse effects. This article reviews the mechanisms of action, pharmacokinetics, clinical use, therapeutic drug monitoring, drug interactions, adverse effects, and dosing of cyclosporine and tacrolimus in solid organ transplant recipients.