Bioequivalence requirements for generic products

Post-market quality assessment of 22 ciprofloxacin brands by HPLC available in Bangladesh market

Antibiotic resistance has been recognized as a public health threat in recent years, and mortality due to resistance is increasing alarmingly every year. Antibiotic resistance, among many factors, may arise due to the consumption of substandard antibiotic brands that provide subnormal levels of the drug in the blood. Post-market evaluation can provide important information in assessing pharmaceutical products in terms of quality, purity, and therapeutic aspects. Ciprofloxacin, a broad-spectrum antibiotic, has been used against a wide range of infectious diseases in Bangladesh. The present study aimed to determine the quality attributes of twenty-two commonly prescribed brands of ciprofloxacin 500 mg tablet collected from Dhaka city and the rural regions of Jessore. RP-HPLC coupled with UV-visible spectrophotometry was used to determine the potency of ciprofloxacin in tablets, and the zone of inhibition was determined using Kirby-Bauer's disc diffusion method to assess the antimicrobial efficacy against different strains of microorganisms. We found that 95.45% of brands (21 out of 22 brands) of ciprofloxacin tablets met United States Pharmacopoeia (USP) and British Pharmacopoeia (BP) specified potency, whereas one brand failed. From dissolution studies, we observed that 68.2% of brands (15 out of 22 brands) followed USP/NF dissolution test specifications, whereas 31.8% (7 out of 22 brands) failed to release 80% of the labeled amount of drug within 30 min. Drug release kinetics data showed that most brands followed the Weibull drug release kinetic model. Fit factor analysis exhibited that 8 brands out of 22 (36.4%) failed to comply similar dissolution profiles with the reference product. Minimum inhibitory concentrations, assessed against five bacterial strains, further showed good antimicrobial sensitivity by all brands.

Health professionals' perceptions on local production and bioequivalence study of generic medicines: A cross-sectional survey of physicians and pharmacy professionals in Addis Ababa, Ethiopia

Local production of generic medicines in developing countries has a critical role to meet public health needs by ensuring the availability of essential medicines and providing patients' relief from the burden of unaffordable medical bills. Compliance with bioequivalence (BE) requirements increase the quality and competitiveness of generic drugs regardless of the source. In this regard, a regional BE center has been established in Addis Ababa, Ethiopia to serve the needs of Ethiopia and neighbouring countries. The present study aimed to assess the knowledge and perceptions of health professionals working in Addis Ababa regarding local production and BE studies of generic medicines. A cross-sectional survey was employed and physician participants working at public hospitals and pharmacists from various practice settings were selected using convenient sampling technique. Data was collected using self-administered structured questionnaire. Descriptive statistics was used to summarize the data and multinomial logistic regression analyses was used to assess predictors of health professionals' perception towards the source of drugs. Statistically significant association was declared at p-value < 0.05. A total of 416 participants responded and 272 (65.4%) of them were male. Nearly half of the study participants (n = 194) preferred the imported products. Compared to physicians, participants with diploma (AOR = 0.40; 95%CI: 0.18-0.91, p = 0.028) and bachelor degree and above holders (AOR = 0.32; 95%CI: 0.15-0.68, p = 0.003) in pharmacy were more likely to prefer locally produced products. Participants who practiced in pharmaceutical industries (AOR = 0.40, 95%CI: 0.22-0.77, p = 0.006) preferred locally manufactured products as compared to those practicing in the hospital. While a majority (321, 77.2%) believed in the advantages of doing BE studies locally, only 106 (25.5%) recognized that local pharmaceutical manufacturers did not implement BE studies for their generic products and lack of enforcement by the national regulatory body was raised as a reason for not conducting BE studies by most of the participants (67.9%). The present study revealed a modest preference by physicians and pharmacy professionals towards locally produced products. Majority of participants supported the idea of doing BE studies locally. However, manufacturers and regulators should devise ways to increase health professionals' confidence in local products. Strengthening local BE study capacity is also highly recommended.

Biosimilarity Assessment of 2 Filgrastim Therapeutics in Healthy Volunteers

This study aimed to compare the pharmacokinetic, pharmacodynamic, and safety profiles of a proposed biosimilar and innovator filgrastim therapeutics in healthy volunteers. In a crossover design, 23 subjects received a single subcutaneous injection of 300-µg filgrastim, followed by a 7-day washout period. Assessed pharmacokinetic parameters were the maximum observed filgrastim serum concentration (C_max ), time to reach C_max (t_max ), the area under the concentration-time curve (AUC), and elimination half-life. Pharmacodynamics were assessed by the maximum observed absolute neutrophil count effect (E_max ), t_max,E (time to reach E_max ), and the area under the effect of the absolute neutrophil count -time curve. The test/reference ratio (90% confidence intervals) of C_max of 0.992 (0.860-1.143), AUC_0-inf of 0.995 (0.891-1.111), E_max of 0.952 (0.841, 1.078), and area under the effect of the absolute neutrophil count -time curve from time zero to 96 hours of 0.939 (0.854-1.032), were all well within the predefined equivalence boundaries of 80% and 125%. Obtained values for t_max (∼4 hours), t_max,E (∼15 hours), and elimination half-life (∼3.5 hours) were comparable between 2 treatment groups. The local tolerability and incidence of adverse events were comparable, with no clinically meaningful difference between biosimilar and innovator products. Altogether, the results suggested a high similarity of the proposed biosimilar to the innovator filgrastim in healthy volunteers.

Importance of medicine quality in achieving universal health coverage

OBJECTIVE

To assess the importance of ensuring medicine quality in order to achieve universal health coverage (UHC).

METHODS

We developed a systems map connecting medicines quality assurance systems with UHC goals to illustrate the ensuing impact of quality-assured medicines in the implementation of UHC. The association between UHC and medicine quality was further examined in the context of essential medicines in low- and middle-income countries (LMICs) by analyzing data on reported prevalence of substandard and falsified essential medicines and established indicators for UHC. Finally, we examined the health and economic savings of improving antimalarial quality in four countries in sub-Saharan Africa: the Democratic Republic of the Congo (DRC), Nigeria, Uganda, and Zambia.

FINDINGS

A systems perspective demonstrates how quality assurance of medicines supports dimensions of UHC. Across 63 LMICs, the reported prevalence of substandard and falsified essential medicines was found to be negatively associated with both an indicator for coverage of essential services (p = 0.05) and with an indicator for government effectiveness (p = 0.04). We estimated that investing in improving the quality of antimalarials by 10% would result in annual savings of $8.3 million in Zambia, $14 million in Uganda, $79 million in two DRC regions, and $598 million in Nigeria, and was more impactful compared to other potential investments we examined. Costs of substandard and falsified antimalarials per malaria case ranged from $7 to $86, while costs per death due to poor-quality antimalarials ranged from $14,000 to $72,000.

CONCLUSION

Medicines quality assurance systems play a critical role in reaching UHC goals. By ensuring the quality of essential medicines, they help deliver effective treatments that lead to less illness and result in health care savings that can be reinvested towards UHC.

Policy of Multisource Drug Products in Latin America: Opportunities and Challenges on the Application of Bioequivalence In Vitro Assays

BACKGROUND

The replacement of traditional in vivo bioequivalence studies by in vitro dissolution assays, based on the biopharmaceutical classification system (BCS), has emerged as an important tool for demonstrating the interchangeability of multisource products. This paper summarizes the current implementation of the BCS-based biowaiver for the development of multisource products in Latin America, and identifies several challenges and opportunities for greater convergence and application of BCS regulatory requirements.

METHODS

Differences and similarities between the current BCS-based biowaivers' guidelines proposed by two relevant regulatory agencies for the Latin American region (FDA and WHO) and the new ICH harmonization guideline were identified and compared. An update of the BCS-based biowaiver guideline for Latin American countries was also considered, based on the respective regulatory information on bioequivalence studies, which is publicly available.

RESULTS

About 50% of the Latin American countries analyzed have no information on the implementation of any bioequivalence standards, while in the countries where bioequivalence studies are considered, the acceptance and application of BCS-based biowaiver requirements is quite heterogeneous. This situation contrasts with the international trend of global harmonization for BCS-based biowaiver guidance, suggesting the need in Latin America to identify opportunities and overcome challenges to improve the development of BCS-based biowaivers to avoid costly and time-consuming in vivo bioequivalence studies.

CONCLUSIONS

The study shows that the region is in a position to improve access to safe and effective medicines at a reasonable cost by applying BCS-based biowaiver guidance.

Predicting Cost-Effectiveness of Generic vs. Brand Dabigatran Using Pharmacometric Estimates Among Patients with Atrial Fibrillation in the United States

Generic entry of newer anticoagulants is expected to decrease the costs of atrial fibrillation management. However, when making switches between brand and generic medications, bioequivalence concerns are possible. The objectives of this study were to predict and compare the lifetime cost‐effectiveness of brand dabigatran with hypothetical future generics. Markov microsimulations were modified to predict the lifetime costs and quality‐adjusted life years of patients on either brand or generic dabigatran from a US private payer perspective. Event rates for generics were predicted using previously developed pharmacokinetic‐pharmacodynamic models. The analyses showed that generic dabigatran with lower‐than‐brand systemic exposure were dominant. Meanwhile, generic dabigatran with extremely high systemic exposure was not cost‐effective compared with the brand reference. Cost‐effectiveness of generic medications cannot always be assumed as shown in this example. Combined use of pharmacometric and pharmacoeconomic models can assist in decision making between brand and generic pharmacotherapies.

Switching medication products during the treatment of psychiatric illness

BACKGROUND

The common practice of switching between branded (reference) medications and their corresponding generic products, between generic products, or even from a generic product to a branded medication during the treatment of central nervous system (CNS) disorders may compromise efficacy and/or tolerability.

METHODS

We assessed the published literature from March 1, 2010 through June 30, 2017 via PubMed using the MeSH term 'generics, drugs' alone and in combination with class-specific terms (e.g., 'anticonvulsants', 'mood stabilisers'), for studies detailing outcomes following product switches.

RESULTS

Although some studies comparing the initiation of reference versus generic drugs suggest equivalence between products, several studies detailing a switch between reference and generic products describe reductions in efficacy, reduced medication adherence and persistence, and increased overall health care resource utilization and costs associated with generic substitution.

CONCLUSION

When product switches are considered, they should only proceed with the full knowledge of both patient and provider.

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.

Biosimilar: what it is not

A biosimilar is a high quality biological medicine shown to be in essence the same as an original product. The European Medicines Agency (EMA) paved the way in the regulatory arena by creating a safeguarding framework for the development of biosimilars. Biosimilar is thus a regulatory term that alludes to the evidence-based studies required to demonstrate such very high similarity. They are therefore not innovative products but the pathway laid down by the EMA for their approval represented a new paradigm. This has brought some confusion and has cast doubts among healthcare professionals about the scientific evidence behind their authorization. Many papers have been published to clarify the concept, and to reassure those professionals, but misconceptions frequently still arise. Unfortunately, this prevents biosimilars from deploying their full therapeutic added value. This paper is intended to approach those misconceptions from a new angle, by explaining what a biosimilar is not…and why. A biosimilar is neither a generic, nor an original product. It is not a biobetter or a 'stand-alone'. Therefore, it should not be managed as such therapeutically, commercially or from a healthcare policy viewpoint. The EMA's criteria were acknowledged by other agencies, but a significant regulatory gap with a vast majority of regulatory bodies still remains. This leaves room for the so-called non-original biologics (NOB), i.e. non-biosimilar biologics, to be launched in many regions. Raising awareness of what a biosimilar is and what it is not, will generate trust in biosimilars among healthcare professionals and will ultimately benefit patients.

Comparison of Serious Adverse Events Between the Original and a Generic Docetaxel in Breast Cancer Patients

Background: Generic formulations are not necessarily identical to the original in terms of efficacy and adverse events. Generic docetaxel has been available in Canada since 2011. Objective: To compare the occurrence of grade III to IV adverse events between original docetaxel and a generic formulation in breast cancer patients. Methods: A consecutive series of 400 patients were assessed retrospectively: 200 who received the original docetaxel and 200 who received a generic formulation. Patients who received both formulations or received their chemotherapy outside our center were excluded. The primary outcome was the occurrence of grade III to IV adverse events related to docetaxel (febrile neutropenia, hand and foot syndrome, intestinal perforation, thrombotic event, and death). Results: Three hundred-sixty-four patients were available for analysis (182/group). The use of a granulocyte colony-stimulating factor (G-CSF) was more frequent in the generic group (44.5% vs 28.8%), as well as treatment discontinuation (26.4% vs 14.8%). The occurrence of grade III to IV febrile neutropenia, hand and foot syndrome, intestinal perforation, thrombotic event, and docetaxel-related deaths were similar between the 2 formulations. However, grade IV febrile neutropenia was more frequent with the generic formulation (78.8% vs 56.3%). Limitations were the retrospective nature of the study and the variety of chemotherapy regimens. Conclusion: Adverse events occurrence was similar between the 2 formulations. However, febrile neutropenia was more serious with generic docetaxel, despite increased G-CSF use. Results suggest that the studied generic formulation may be safe, but more caution during treatments might be warranted, especially concerning febrile neutropenia events.

Study on requirements of bioequivalence for registration of pharmaceutical products in USA, Europe and Canada

The present study was aimed to study the requirements of bioequivalence for the registration of pharmaceutical products in the USA, Europe and Canada. Before going into bioequivalence studies it is essential for the pharmaceutical industry to study the guidelines of bioequivalence for the respective country where the industry wants to market its products and thus enter into generic market. This study reviews the requirements of bioequivalence with study parameters such as study design, fasting or fed state studies, volunteers recruitment, study dose, sampling points, analytical method validation parameters, moieties to be measured in plasma, pharmacokinetic parameters, criteria for bioequivalence, GCP requirements etc, which are needed for the pharmaceutical industry to carry out bioequivalence studies and to file ANDA. Test products and reference products are needed for this study. Test products are usually manufactured by a sponsor and reference products are provided by the government laboratories of the respective countries. Sampling points also vary with respect to the regulatory guidelines of these countries. All these countries follow ICH GCP guidelines. The criterion of bioequivalence for these countries is 90% CI 80-125% for C max, AUC t , AUC0-∞.

Comparative potencies of contemporary generic vancomycin lot: in vitro assay results from nine products and a reference reagent-grade sample

Numerous studies of generic vancomycin (GV) lots have emerged since the 1980s, casting some doubt on product quality. Publications question the in vivo activity, even when concurrent in vitro and chemical assays meet regulatory guidelines. This study assessed contemporary GV lots by an in vitro assay capable of measuring small variations from target-benchmark (BM) activity. Nine GV lots (Hospira [6 lots; 0.5- or 1.0-g vials], Akorn [1 lot; 1.0-g vial], APP [2 lots; 1.0-g vials]) were obtained from local United States distributors. A reagent-grade lot (Sigma lot 080M1341V) was tested as BM component due to the inability to purchase branded product vials in the USA. All lots of GV did not vary significantly from the analytical control when testing the 3 Staphylococcus aureus (wild-type 4B25, ATCC 25923, and 29213) and Enterococcus faecalis (ATCC 29212) strains. These MIC end points were read at 18 h of incubation, and Hospira lots averaged +3.5% potency (range, -3% to +8%), and Akorn and APP at 0% variance, e.g., acceptable performance. In conclusion, with a validated, precise multi-organism assay, current GV lots marketed in the USA showed minimal activity variations from a selected BM control lot. Generic antimicrobial products, in general, should be regularly monitored for potency, chemical purity, and in vivo activity before routine use in medical centers.

Bioequivalence Study of Donepezil Hydrochloride Tablets in Healthy Male Volunteers

The objective of this study was to investigate the bioequivalence of two formulations of 5 mg donepezil HCL tablets: Tonizep as the test and Aricept as the reference. The two products were administered as a single oral dose according to a randomized two-phase crossover with a 3-week washout period in 20 healthy Thai Male volunteers. After drug administration, serial blood samples were collected over a period of 216 hours. Plasma donepezil concentrations were measured by high performance liquid chromatography with UV detection. Pharmacokinetic parameters were analyzed based on noncompartmental analysis. The logarithmically transformed data of AUC0–∞ and were analyzed for 90% confidence intervals (CI) using ANOVA. The mean (90% CI) values for the ratio of AUC0–∞ and values of the test product over those of the reference product were 1.08 (1.02–1.14) and 1.08 (0.99–1.17), respectively (within the bioequivalence range of 0.8–1.25). The median for the test product was similar to that of the reference product (2.0 hr), and the 90% CI for the difference between the two preparations was –0.19 to 0.29 hr and within the bioequivalence range of ± 20% of the of the reference formulation. Our study demonstrated the bioequivalence of the two preparations.

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.

Generic antibiotic industries: Challenges and implied strategies with regulatory perspectives

Ever since the discovery of antibiotics, the quality of human life greatly improved in the 20(th) century. The discovery of penicillin transformed the medicine industry and initiated a search for a better antibiotic every time resulting in several synthetic and semi-synthetic antibiotics. Beginning with the 1937 sulfa drug tragedy, the drug regulations had a parallel growth along with the antibiotics and the antibiotic-based generic Pharma industries. This review article is focused on the scenario depicting current global Pharma industries based on generic antibiotics. Several regulatory aspects involved with these industries have been discussed along with the complexity of the market, issues that could affect their growth, their struggle for quality, and their compliance with the tightened regulations. With the skyrocketing commercialization of antibiotics through generics and the leveraging technologic renaissance, generic industries are involved in providing maximum safer benefits for the welfare of the people, highlighting its need today..

The pharmacokinetics of fluconazole in healthy Chinese adult volunteers: influence of ethnicity and gender

OBJECTIVE

The purpose of the present study was to investigate and compare the influence of ethnicity (including Han, Mongolian, Korean, Hui and Uygur) and gender on the pharmacokinetics of fluconazole in healthy adult volunteers after administration of 200-mg fluconazole tablet.

METHODS

Ten healthy subjects (five males and five females) of each ethnicity were recruited and given a single 200-mg dose of fluconazole in tablet form. Blood samples were obtained before dosing and at various predetermined time points after administration up to 96 h. Drug levels were measured by high-performance liquid chromatography. The blood concentration-time profiles were analyzed using a non-compartmental approach to estimate the absorption parameters (AUC((0-96)), C(max) and t(max)), the distribution parameter (V(d)) and the disposition parameters (t(1/2) and CL).

RESULTS

Ethnicity did not affect the parameter estimates, but gender did. However, the gender differences in pharmacokinetic parameter could be accounted for by differences in weight. There was a high linear correlation between weight and ln C(max), ln AUC (ln means natural logarithmic transformation), V(d) and CL.

CONCLUSIONS

Ethnicity (Chinese Han, Mongolian, Korean, Hui and Uygur) influences the pharmacokinetics of fluconazole tablet. However, there were statistically significant gender differences in AUC, C(max), V(d) and CL. But these could be accounted for by weight differences. If fluconazole dose-adjustment is deemed necessary, this can be done on a weight basis rather than gender basis.

Generic vancomycin products fail in vivo despite being pharmaceutical equivalents of the innovator

Generic versions of intravenous antibiotics are not required to demonstrate therapeutic equivalence with the innovator because therapeutic equivalence is assumed from pharmaceutical equivalence. To test such assumptions, we studied three generic versions of vancomycin in simultaneous experiments with the innovator and determined the concentration and potency of the active pharmaceutical ingredient by microbiological assay, single-dose pharmacokinetics in infected mice, antibacterial effect by broth microdilution and time-kill curves (TKC), and pharmacodynamics against two wild-type strains of Staphylococcus aureus by using the neutropenic mouse thigh infection model. The main outcome measure was the comparison of magnitudes and patterns of in vivo efficacy between generic products and the innovator. Except for one product exhibiting slightly greater concentration, vancomycin generics were undistinguishable from the innovator based on concentration and potency, protein binding, in vitro antibacterial effect determined by minimal inhibitory or bactericidal concentrations and TKC, and serum pharmacokinetics. Despite such similarities, all generic products failed in vivo to kill S. aureus, while the innovator displayed the expected bactericidal efficacy: maximum antibacterial effect (Emax) (95% confidence interval [CI]) was 2.04 (1.89 to 2.19), 2.59 (2.21 to 2.98), and 3.48 (2.92 to 4.04) versus 5.65 (5.52 to 5.78) log10 CFU/g for three generics and the innovator product, respectively (P<0.0001, any comparison). Nonlinear regression analysis suggests that generic versions of vancomycin contain inhibitory and stimulatory principles within their formulations that cause agonistic-antagonistic actions responsible for in vivo failure. In conclusion, pharmaceutical equivalence does not imply therapeutic equivalence for vancomycin.

Bioequivalence between novel ready-to-use liquid formulations of the recombinant human GH Omnitrope and the original lyophilized formulations for reconstitution of Omnitrope and Genotropin

OBJECTIVE

Two strengths of a novel ready-to-use liquid preparation of the recombinant human GH (rhGH) Omnitrope were developed to increase the convenience for the patients.

DESIGN

Omnitrope 3.3 mg/ml solution or Omnitrope 6.7 mg/ml solution was compared to Omnitrope 5 mg/ml powder and Genotropin 5 mg/ml powder in terms of pharmacokinetics, pharmacodynamics, safety, and local tolerance after a single s.c. dose of 5 mg.

METHODS

Two randomized, double-blind, single-dose, three-way crossover studies were carried out in 36 young healthy volunteers each. Endogenous GH secretion was suppressed with a 25-h continuous i.v. infusion of octreotide (40 microg/h) starting 1 h before rhGH administration.

RESULTS

Pharmacokinetic parameters were similar for the three treatments in both studies respectively. Bioequivalence criteria were met for area under the concentration-time curve (AUC) and C(max). Likewise, the pharmacodynamic parameters for IGF1, IGF-binding protein 3, and non-esterified fatty acid were similar for all preparations. No differences in adverse events were observed between groups.

CONCLUSIONS

Omnitrope 3.3 mg/ml solution, 6.7 mg/ml solution, and 5 mg/ml powder, and Genotropin 5 mg/ml powder are bioequivalent, have similar pharmacokinetic and pharmacodynamic profiles, and are equally safe. Overall, the products can be considered to be therapeutically interchangeable.

Determination of therapeutic equivalence of generic products of gentamicin in the neutropenic mouse thigh infection model

Background

Drug regulatory agencies (DRA) support prescription of generic products of intravenous antibiotics assuming therapeutic equivalence from pharmaceutical equivalence. Recent reports of deaths associated with generic heparin and metoprolol have raised concerns about the efficacy and safety of DRA-approved drugs.

Methodology/Principal Findings

To challenge the assumption that pharmaceutical equivalence predicts therapeutic equivalence, we determined in vitro and in vivo the efficacy of the innovator product and 20 pharmaceutically equivalent generics of gentamicin. The data showed that, while only 1 generic product failed in vitro (MIC = 45.3 vs. 0.7 mg/L, P<0.05), 10 products (including gentamicin reference powder) failed in vivo against E. coli due to significantly inferior efficacy (E_max = 4.81 to 5.32 vs. 5.99 log₁₀ CFU/g, P≤0.043). Although the design lacked power to detect differences in survival after thigh infection with P. aeruginosa, dissemination to vital organs was significantly higher in animals treated with generic gentamicin despite 4 days of maximally effective treatment.

Conclusion

Pharmaceutical equivalence does not predict therapeutic equivalence of generic gentamicin. Stricter criteria based on solid experimental evidence should be required before approval for human use.

Generics and cost-effective prescribing in Belgium: does bioequivalence always translate in therapeutic equivalence?

As many other countries, Belgium has a policy to promote the use of generic pharmaceutical products. In order to protect consumers, these generic products must be demonstrated to be essentially similar to the previously approved product, typically an innovator product. The therapeutic equivalence of a generic and an innovator product is most commonly based on the demonstration of bioequivalence, i.e. clinically insignificant differences in the rate and extent of drug absorption usually assessed from pharmacokinetic measurements, in a normal and healthy population. This article reviews the bioequivalence requirements for generic products and examines whether bioequivalence always adequately substantiates therapeutic equivalence and interchangeability. Clinical practice has identified a number of drug classes for which generic substitution should be approached with caution. Current bioequivalence requirements are based on a measure of average bioequivalence. There are fears that use of this measure may be inappropriate in the case of a drug with a narrow therapeutic range or high intrasubject or intersubject variability. Under these circumstances, measures of individual and population bioequivalence are proposed to be more accurate than measures of average bioequivalence. Bioequivalence issues are discussed together more general concerns about generic drug substitution, such as differences in product and packaging appearance and differences in excipients.

Evaluation of Bioequivalence of Two Formulations Containing 100 Milligrams of Aceclofenac

The bioequivalence of two oral formulations containing aceclofenac 100 mg was determined in 24 healthy Indian male volunteers. The study was designed as a single dose, fasting, two-period two-sequence crossover study with a washout period of 1 week. The content of aceclofenac in plasma was determined by a validated HPLC method with UV detection. The preparations were compared using the parameters area under the plasma concentration-time curve (AUC0-t), area under the plasma concentration-time curve from zero to infinity (AUC0-infinity), peak plasma concentration (Cmax), and time to reach peak plasma concentration (tmax). No statistically significant difference was observed between the logarithmic transformed AUC0-infinity and Cmax values of the two preparations. The 90% confidence interval for the ratio of the logarithmic transformed AUC0-t, AUC0-infinity, and Cmax were within the bioequivalence limit of 0.80-1.25.

Bioavailability of diclofenac potassium at low doses

AIM

Diclofenac-K has been recently launched at low oral doses in different countries for over-the-counter use. However, given the considerable first-pass metabolism of diclofenac, the degree of absorption of diclofenac-K at low doses remained to be determined. The aim of this study was to determine the bioavailability of low-dose diclofenac-K.

METHODS

A randomized, three-way, cross-over study was performed in 10 subjects. Each received diclofenac-K, 22.5 mg via short-term i.v. infusion and orally at single doses of 12.5 mg and 25 mg.

RESULTS

Mean (+/- SD) times to maximal plasma concentration (t(max)) of diclofenac were 0.48 +/- 0.28 h (12.5 mg) and 0.93 +/- 0.96 h (25 mg). The absolute bioavailability of diclofenac-K after oral administration did not differ significantly in the 12.5-mg and 25-mg dose group (63.1 +/- 12.6%vs. 65.1 +/- 19.4%, respectively). The 90% confidence intervals for the AUC(infinity) and AUC(t) ratios for the two oral regimes were 82.6, 103.4% (point estimate 92.4%) and 86.2, 112.9% (point estimate 98.6%), respectively. These values were within the acceptance criteria for bioequivalence (80-125%).

CONCLUSIONS

Our data indicate that diclofenac-K is rapidly and well absorbed at low dose, and are consistent with a rapid onset of action of the drug. Abbreviations AUC, area under plasma concentration-time curve; C(max), peak plasma concentration; CI, confidence interval; COX, cyclooxygenase; D, dose; F, absolute bioavailability; t(max), time to reach C(max).

Evaluation of the bioequivalence of capsules containing 150 mg of fluconazole

Fluconazole is an antifungal agent. The purpose of this study was to evaluate bioequivalence of two commercial 150 mg capsule formulations of fluconazole available in the Brazilian market. The study was an open, randomized, two-period, two-group crossover trial with a 2-week washout interval. Blood samples were collected throughout a 96-h period after administration of reference product (R) and test product (T) to 28 fasting volunteers. A simple, accurate, precise and sensitive high-performance liquid chromatographic (HPLC) method with ultraviolet detection was developed and validated for quantification of fluconazole in plasma samples after liquid-liquid extraction. Bioequivalence between the products was determined by calculating 90% confidence intervals (90% C.I.) for the ratio of C(max), AUC(0-t) and AUC(0-infinity) values for the test and reference products, using logarithmic transformed data. The 90% confidence intervals for the ratio of C(max) (101.06-105.45%), AUC(0-t) (97.11-104.69%) and AUC(0-infinity) (97.96-103.36%) values for the test and reference products are within the 80-125% interval, proposed by FDA and EMEA. It was concluded that the two fluconazole formulations are bioequivalent in their rate and extent of absorption.

Individualizing therapy - in search of approaches to maximize the benefit of drug treatment (II)

Adjusting drug therapy to the individual, a common approach in clinical practice, has evolved from 1) dose adjustments based on clinical effects to 2) dose adjustments made in response to drug levels and, more recently, to 3) dose adjustments based on deoxyribonucleic acid (DNA) sequencing of drug-metabolizing enzyme genes, suggesting a slow drug metabolism phenotype. This development dates back to the middle of the 20^th century, when several different drugs were administered on the basis of individual plasma concentration measurements. Genetic control of drug metabolism was well established by the 1960s, and pharmakokinetic-based individualized therapy was in use by 1973.

Bioequivalence and other unresolved issues in generic drug substitution

BACKGROUND

Substitution of generic drugs for brand-name products is highly controversial and often is met with suspicion by health care providers and patients. Historically, the debate has focused on the issue of bioequivalence, and clinical practice has identified a number of drug classes for which generic substitution should be approached with caution. Current bioequivalence requirements are based on a measure of average bioequivalence; however, there are fears that use of this measure may be inappropriate in the case of a drug with a narrow or wide therapeutic range or high intrasubject or intersubject variability. Under these circumstances, measures of individual and population bioequivalence are proposed to be more accurate than measures of average bioequivalence.

OBJECTIVE

This paper addresses issues of bioequivalence and other concerns with generic drug substitution.

METHODS

I conducted a MEDLINE search of the English-language literature containing the key terms generic, multisource, quality, and brand and published between 1973 and 2003. The names of branded pharmaceuticals whose patents had recently expired (eg, Ventolin HFA, Adalat, Capoten, Tagamet HB 200, and Valium) also were used to search for articles on generic substitution. Reference lists of relevant articles also were searched. Bioequivalence issues are presented together with more general concerns over generic drug substitution, such as consumer perception of risk, differences in product and packaging appearance, and differences in excipients.

RESULTS

The literature reviewed act to highlight a number of different drug categories and patient subpopulations for which generic substitution can still prove to be problematic.

CONCLUSION

I recommend that health care providers continue to exercise caution in the consideration of generic drug substitution under certain circumstances.

Report of the American Society of Transplantation conference on immunosuppressive drugs and the use of generic immunosuppressants

Considerable economic and health-related costs are associated with the life-long maintenance immunosuppressive therapy required to prevent transplant rejection. Generic medications have the potential of providing equivalent therapeutic efficacy at a lower economic cost. In 2001, the American Society of Transplantation invited experts to review the data and issues associated with the approval and use of generic immunosuppressants. A summary of that meeting is reported here. The generic medication approval process has been in effect for more than 30 years. All marketed generic cyclosporin formulations have met FDA criteria demonstrating bioequivalence in healthy subjects, and some were also tested in transplant recipients. Most participants agreed that generic narrow therapeutic index immunosuppressive agents provide adequate de novo immunosuppression in low-risk transplant recipients. However, some participants expressed concern regarding the currently unquantified risk that may be associated with switching immunosuppressive agents under uncontrolled circumstances. There was broad agreement among the participants that generic medications should be clearly labeled and distinguishable from innovator drugs, and that patients should be educated to inform their physicians of any switch to or among generic alternatives. There was also strong support in favor of requiring studies to demonstrate bioequivalence in potentially at-risk patient populations, specifically African-Americans and pediatric patients.

Understanding the scientific issues embedded in the generic drug approval process

OBJECTIVE

To review the major scientific issues embedded in the generic drug approval process.

DATA SOURCES

Articles indexed initially under terms such as generic medications, generic drugs, bioequivalence, and bioinequivalence. These terms were used to search indexing services such as MEDLINE, International Pharmaceutical Abstracts, CINAHL (a database of nursing and allied health literature), and Science Citation Index. Additional data sources included the Code of Federal Regulations and regulatory guidances from the Food and Drug Administration (FDA) Center for Drug Evaluation and Research.

STUDY SELECTION

Performed by the authors.

DATA EXTRACTION

Not applicable.

DATA SYNTHESIS

Despite the fact that regulations regarding bioequivalence have been in place for more than 20 years, controversies over bioequivalence continue to arise. Consensus on many of these issues is driving the development of new FDA guidances regarding bioequivalence. Still, despite the issuance of new guidance and consensus building among scientists, many clinicians and consumers remain uninformed regarding the scientific basis for establishing bioequivalence and the generic drug approval process in general. Although some have suggested that the generic drug approval process is flawed, overall, it appears that the process works.

CONCLUSION

Understanding the generic drug approval process and the issues surrounding bioequivalence is of paramount importance to both clinicians and scientists.

A comparative analysis of generics markets in five European countries

A generic medicine is a faithful copy of a mature drug--no longer under patent marketed with the chemical name of the active ingredient. This article analyses generics markets in five European countries: France, Germany Italy, The Netherlands and the U.K. The study investigate all the main issues--patent, approval to market, pricing and reimbursement, prescription and distribution--which affect the life cycle of a pharmaceutical product. The situation in the five countries varied widely. Because of European harmonization, patent legislation and approval procedures no longer affect much the development of generics. Only national legislation on patent protection approved before the EU directive came into force still plays a role. Approval differences seem to be due mainly to common practice, rather than to the regulations themselves. None of the countries have an efficient public information system on patent expiry. Generics have had more success in countries with more flexible pricing policies. Reimbursement has not yet been used widely to discriminate between generics and proprietary drugs. Financial incentives are based more on physicians' prescribing behaviour than on pharmacists. The freedom of pharmacy ownership and the consequent possibility of dispensing pharmaceuticals through different channels affects dramatically the structure of generics markets. A free market of wholesalers and retailers can enhance a comparative market, through horizontal and vertical integration all along the distribution chain. Such an environment has stimulate the success of unbranded generics by delegating strong purchasing power to distributors.

Management of narrow therapeutic index drugs

Summary. Narrow therapeutic index (NTI) drugs are agents for which small changes in systemic concentration can lead to significant changes in pharmacodynamic response. This may result in potentially subtherapeutic or toxic effects, particularly in patients with advanced age, comorbid illness, or those receiving multiple medications. Bioequivalence among generic and innovator drug products does not always ensure therapeutic equivalence, especially with regard to NTI drugs. Warfarin is a NTI drug for which substitution is now available and may occur routinely without the knowledge of the patient or practitioner. To avoid overanticoagulation or underanticoagulation, the additional cost of patient education and monitoring may actually exceed cost savings by using the less expensive generic drug product. When brand name drug is preferred by the practitioner, "no substition" must be specified on the prescription to avoid mandated generic interchange of warfarin and other NTI drugs.

Use of jackknife influence profiles in bioequivalence evaluations

Generic drug product-development involves many bioavailability trials in an attempt to establish bioequivalence of the test drug product with an innovator's drug product. A major challenge for decision makers in the generic drug product-development process is to identify a successful test product based on the outcome of individual bioavailability trials, which may be misleading as a result of influential observations. The author identifies the need for a graphical diagnostic technique and then introduces such a technique, the jackknife influence profile, for the systematic scanning of influential observations. This review also describes the possible application of the technique in deriving the required reliable statistic values for bioequivalence assessment.

The effect of steady-state ropinirole on plasma concentrations of digoxin in patients with Parkinson's disease

AIMS

The aim of this single-blind study was to assess the effect of ropinirole, a novel treatment for Parkinson's disease, on the steady-state pharmacokinetics and safety of digoxin in 10 patients with Parkinson's disease.

METHODS

There were three parts to the study: digoxin once daily plus placebo three times daily for 1 week; digoxin once daily plus ropinirole three times daily for 6 weeks; and digoxin once daily plus placebo three times daily for 1 week. Serial blood samples were collected over 24 h at the end of each part of the study for pharmacokinetic assessment. Pre-dose blood samples were collected on specific days throughout the study to assess the attainment of steady-state plasma levels of digoxin. The primary endpoints were AUC(0, tau) and Cmax for digoxin.

RESULTS

There was a mean decrease of 10% in digoxin AUC (0, tau) (90% CI: 0.79, 1.01) and a 25% decrease in digoxin Cmax (90% CI: 0.58, 0.97) when ropinirole was co-administered, compared with digoxin alone Cmin plasma values for digoxin, however, were fairly constant throughout the study (point estimates 0.99, 95% CI: 0.85, 1.15). Changes in trough levels of digoxin are believed to be the most reliable way of assessing steady-state concentrations of digoxin, and therefore the clinical significance of an interaction. Changes in Cmax are too readily influenced by other factors.

CONCLUSIONS

These results therefore indicate that on pharmacokinetic grounds no dose adjustment is necessary for digoxin co-administered with ropinirole.

Simple bioequivalence criteria: are they relevant to critical dose drugs? Experience gained from cyclosporine

A critique of the current bioequivalence regulations is presented with reference to critical dose drugs. Using the development of a new cyclosporine formulation as an example, the deficiencies in current bioequivalence testing guidelines are examined and discussed. Based on the experience gained with cyclosporine, recommendations are made on how therapeutic equivalence, rather than just bioequivalence, should be established.

Enantioselective assays in comparative bioavailability studies of racemic drug formulations: nice to know or need to know?

The importance of enantiospecific assays in studying pharmacokinetic/pharmacodynamic (PK/PD) and drug-drug interactions of racemic drugs is widely recognized. Use of such assays in comparative bioavailability studies, however, remains controversial. This commentary proposes a PK/PD-based rationale for deciding whether an enantioselective assay is important in such studies. Racemic drugs are divided into three major categories: those with negligible or nonenantioselective first-pass metabolism (category I), those where the first-pass metabolism of the less-active enantiomer is predominant (category II), and those where the first-pass metabolism of the more active and/or toxic enantiomer is predominant (category III). In addressing the need for assay selectivity, a simple analogy is made between these drug categories and the protein-binding phenomenon. Enantioselective assays are not essential for category I drugs, or for category II drugs in the majority of cases. A special consideration, however, is needed for those category II drugs that undergo racemic inversion that may be influenced by the dose level and/or the residence time of the drug formulation in the gastrointestinal tract. It is with category III drugs that enantioselective assays become important, especially when metabolism, distribution, and/or elimination processes of the active or toxic enantiomer are saturable, leading to variable enantiomeric ratios in the plasma. Factors contributing to these ratio changes include routes of administration, dose level, and input rate differences. In put rate differences are particularly relevant to bioavailability evaluation of category III drugs.