Brand and generic medications: are they interchangeable?

BACKGROUND AND OBJECTIVES

Generic substitution has become a common practice since the late 1970s in the United States. At that time, many of these generics caused bioavailability problems, which fueled suspicions about their efficacy and safety, and the Food and Drug Administration (FDA) standards for bioequivalence. In Saudi Arabia, the increasing number of local products raised several concerns with regard to switching from brands to generics. Our objective was to review and examine the basis of the controversy surrounding brand and generic interchangeability and to explore a practical approach in pursuing a switch.

DATA SOURCES

Articles indexed initially under terms such as generic medications, generic substitution, bioequivalence and bioinequivalence were identified. These terms were used to search the indexing service, MEDLINE (1966-2006). References from the extracted articles, and additional data sources, including the Code of Federal Regulations and Regulatory Guidance from the FDA Center for Drug Evaluation and Research were also reviewed.

DATA SYNTHESIS

For most drugs, bioequivalence testing generally should enable clinicians to routinely substitute generic for innovator products. However, for narrow therapeutic, critical dose drugs, or for highly variable drugs, safe switching between products cannot be assured. These drugs need special precautions and blood level monitoring upon switching. FDA firmly believes that approved generic and brand drugs can be dispensed with the full expectation that the consumer will receive the same clinical benefit.

CONCLUSION

Performing the switch process is an advisable practice to reduce health care costs in countries with strong post-marketing surveillance program, but caution is to be exercised when narrow therapeutic index drugs or highly variable drugs are prescribed.

The challenge of biosimilars

BACKGROUND

The purpose of this report was to review issues associated with the introduction of alternative versions of biosimilars used in the oncology setting.

DESIGN

Data were obtained by searches of MEDLINE, PubMed, references from relevant English-language articles, and guidelines from the European Medicines Agency.

RESULTS

When biosimilars are approved in EU, they will be considered 'comparable' to the reference product, but this does not ensure therapeutic equivalence. Inherent differences between biosimilars may produce dissimilarities in clinical efficacy, safety, and immunogenicity. Switching biosimilars should be considered a change in clinical management. Regulatory guidelines have been established for some biosimilar categories but, because of the limited clinical experience with biosimilars at approval, pharmacovigilance programs will be important to establish clinical databases. Guidelines also provide a mechanism for the extrapolation of clinical indications (approved indications for which the biosimilar has not been studied). This may be of concern where differences in biological activity can result in adverse outcomes or when safety is paramount (e.g. stem cell mobilization in healthy donors). These issues should be addressed in biosimilar labeling.

CONCLUSIONS

Biosimilars should provide cost savings and greater accessibility to biopharmaceuticals. A thorough knowledge surrounding biosimilars will ensure the appropriate use of biopharmaceuticals.

Generic products of antiepileptic drugs (AEDs): is it an issue?

The availability of generic products of antiepileptic drugs (AEDs) has raised the following concerns: (1) Do generic AEDs work as well as brand AEDs in terms of their efficacy, safety and quality? (2) Can generic AEDs be used as substitutions for brand AEDs? and (3) Can generic products of AEDs be used interchangeably? The traditional average bioequivalence analysis addresses concern 1 but does not provide a complete adequate response to concerns 2 and 3. Drug interchangeability can be classified as drug prescribability or drug switchability. Drug prescribability refers to the situation where a patient is treated for the first time so that either a brand or a bioequivalent generic AED can be chosen. Drug switchability refers to the situation in which a brand AED is switched to a bioequivalent generic product of the same AED. The traditional average bioequivalence approach is sufficient to evaluate the prescribability of generic products, but does not ensure the switchability between prescribable formulations. The necessity of assuring switchability of two formulations can be addressed by individual bioequivalence. While the switch to generic AEDs is well tolerated by many patients and in general cost-effective, seizure control should not be sacrificed on the basis of cost alone, as the major end point in treating epilepsy with AEDs is seizure control without side effects. Until we have individual (within patient) bioequivalence data on generic AEDs and/or the tools to a priori identify the subset of patients susceptible to the generic switch, a switch of AED products in seizure-free patients is not recommended.

Current approaches to the use of generic antiepileptic drugs

Generic substitution is encouraged as a cost containment strategy for the management of health care resources. However, in epilepsy, the consequences of loss of symptom control are important, and antiepileptic drugs have narrow therapeutic indices. For this reason, generic substitution may be problematic, and certain health authorities have excluded antiepileptic drugs from overall policy recommendations on generic prescribing. The absence of bioequivalence data among generic forms and the relatively broad criteria for bioequivalence with the branded drug allow differences in drug exposure to arise that may be clinically relevant and necessitate monitoring of plasma levels when switching formulations to avoid loss of seizure control or emergence of side effects. Management of these issues carries a significant cost, which should be weighed carefully against the cost savings acquired when purchasing the drug. Both physicians and patients have a right to be informed and approve before pharmacists make a generic substitution or switch between generics.

Basic Facts about Biosimilars

Biotechnological drugs have become an essential part of modern pharmacotherapy and are expected to reach a 50% share in the pharmaceutical market in the next few years. The expiry of patent protection for many original biotechnological medicines has led to the development of what are called biosimilars or follow-on biologics. Biosimilars attempt to copy the original technology leading to the production of innovative biotechnological medicines to obtain a product which is similar to the original one. The first two biosimilars have recently been approved in the European Union and one application was rejected. Many more biosimilars will likely see approval in the near future. Our experience with biosimilars has been very limited to date and long-term safety data including immunogenicity are not available. Although biosimilars will likely lower the cost of modern therapies there are issues which have to be discussed at this stage among physicians regarding in particular the differences between biosimilars and generics of the classical chemical drugs, need for appropriate regulations as well as identification of potential problems with biosimilars. Other specific problems which will also be addressed in this review are safety of biosimilars, pharmacovigilance, automatic substitution, naming and labeling/prescription rules.

A comparison between senior medical students' and pharmacy pre-registrants' knowledge and perceptions of generic medicines

OBJECTIVE

To ascertain any differences in knowledge and perceptions of generic medicines between senior (final year) medical students and pharmacy pre-registrants in Australia.

METHODS

National web-based surveys containing 16 common questions were administered to each group. Responses were compared using Mann-Whitney U-test.

RESULTS

Responses were received from 400 medical students (response rate 26.7%) and 289 pharmacy pre-registrants (response rate 30.5%). Both groups scored poorly on the allowable bioequivalence limits when comparing a brand-name medicine with a generic medicine, with pharmacy pre-registrants scoring better (P < 0.001). Pharmacy pre-registrants were more likely (P < 0.001) to report having been introduced to bioequivalence during their courses, and less likely (P < 0.001) to desire more information on bioequivalence testing. Both groups correctly agreed that generic medicines are bioequivalent to corresponding brand-name medicines but not necessarily to each other, and that generic medicines are cheaper. Pharmacy pre-registrants were more aware that generic medicines must be in the same dosage form (P < 0.001) and contain the same dose (P < 0.001) as the comparator brand-name medicine. Both groups incorrectly believed that generic medicines are required to meet higher safety standards, are inferior in quality, are less effective and produce more side-effects. Both groups agreed that it is easier to recognise a drug's therapeutic class from its generic name and that they needed more information about the safety and efficacy of generic medicines, with medical students feeling more strongly about this (P < 0.001).

CONCLUSIONS

Although there were some differences in responses, both groups had knowledge deficits about the quality, safety and effectiveness of generic medicines, which need to be addressed by educators in order to increase the future use of generic medicines in Australia.

Quality and behavior of glimepiride generics versus amaryl under stressed conditions

BACKGROUND

The use of generic versions of drugs, such as those for glimepiride [Amaryl, Amarel, Solosa (sanofi-aventis, Paris, France)], a third-generation sulfonylurea, can reduce healthcare costs. However, the quality and performance of these generics should be carefully evaluated.

METHODS

We compared the quality and behavior of 23 marketed generic forms with Amaryl (all 2 mg) under stressed conditions. Deblistered samples were stored at 60 degrees C for 21 days in order to mimic temperature-stressed conditions. Samples were analyzed at Days 0, 7, and 21 for content of active compound, levels of impurities, levels of residual solvent (Day 0 only), and dissolution profile, and results were compared against Amaryl specifications.

RESULTS

Levels of the degradation product GS [corrected] were < or = 1% in all products at Day 0; however, GS levels [corrected] increased to above Amaryl specifications [corrected] in two generics at Day 7 (Dolcyl and GLA-DM) [corrected] and in four generics at Day 21 [Dolcyl, GLA-DM, glimepiride (Hanni), and glimepirida (Esterlina)] (Fig. 2) [corrected] Total levels of other impurities and levels of residual solvents were above Amaryl specifications (<or=1.0% and >1,400 ppm, respectively) in two generics at Day 0. At Day 0, the dissolution of 12 generics (52%) failed to meet Amaryl specifications (>or=85% dissolved in 15 min); this trend was confirmed at Day 21. Overall, 74% (17 of 23) of the generics were not of equivalent quality or performance compared with Amaryl.

CONCLUSIONS

This study indicates that a relevant percentage of glimepiride generics may offer reduced quality and performance when compared with the original drug.

[Defining generic drugs: an end or a means? Analysis of regulations in 14 countries in the Region of the Americas]

OBJECTIVES

To characterize current regulatory practices and trends relating to competing medications in 14 Latin American and Caribbean countries.

METHODS

Between July 2004 and April 2005 we collected information on national regulations and policies that established or contained a definition of "generic drug" and related terms in 14 Latin American and Caribbean countries: Argentina, Barbados, Bolivia, Brazil, Colombia, Costa Rica, Ecuador, Guatemala, Mexico, Nicaragua, Panama, Paraguay, Peru, and Venezuela. We also compiled information on the incentives to register and produce competing medications, promotion of the use of International Nonproprietary Names (INNs) for pharmaceutical substances, the regulation of bioequivalence studies, and the replacement of prescription medications with less expensive alternatives.

RESULTS

We noted three patterns in the regulations: (1) countries that encourage financial support for competing medications, extensively promote the use of INNs, and place no restrictions on the replacement of innovative (proprietary) medications with competing products (Argentina, Colombia, Costa Rica, Ecuador, and Paraguay); (2) countries with policies aimed at showing therapeutic equivalence, which limits substitutions to approved products from a list of authorized competing medications that must be prescribed by their INN and must use distinctive labeling (Brazil, Mexico, Panama, and Venezuela); and (3) countries at a beginning stage in the process of regulation (Barbados, Bolivia, Guatemala, Nicaragua, and Peru). This variety leads to difficulties in characterizing pharmaceutical markets, and can lead to misleading categorizations.

CONCLUSIONS

Efforts to harmonize policies should consider the possible relationship among definitions adopted in different countries, the development of national pharmaceutical markets, and national policies to stimulate competition.

HIV/AIDS drugs for Sub-Saharan Africa: how do brand and generic supply compare?

Background

Significant quantities of antiretroviral drugs (ARVs) to treat HIV/AIDS have been procured for Sub-Saharan Africa for the first time in their 20-year history. This presents a novel opportunity to empirically study the roles of brand and generic suppliers in providing access to ARVs.

Methodology/Principal Findings

An observational study of brand and generic supply based on a dataset of 2,162 orders of AIDS drugs for Sub-Saharan Africa reported to the Global Price Reporting Mechanism at the World Health Organization from January 2004-March 2006 was performed. Generic companies supplied 63% of the drugs studied, at prices that were on average about a third of the prices charged by brand companies. 96% of the procurement was of first line drugs, which were provided mostly by generic firms, while the remaining 4%, of second line drugs, was sourced primarily from brand companies. 85% of the generic drugs in the sample were manufactured in India, where the majority of the drugs procured were ineligible for patent protection. The remaining 15% was manufactured in South Africa, mostly under voluntary licenses provided by brand companies to a single generic company. In Sub-Saharan African countries, four first line drugs in the dataset were widely patented, however no general deterrent to generic purchasing based on a patent was detected.

Conclusions/Significance

Generic and brand companies have played distinct roles in increasing the availability of ARVs in Sub-Saharan Africa. Generic companies provided most of the drugs studied, at prices below those charged by brand companies, and until now, almost exclusively supplied several fixed-dose combination drugs. Brand companies have supplied almost all second line drugs, signed voluntary licenses with generic companies, and are not strictly enforcing patents in certain countries. Further investigation into how price reductions in second line drugs can be achieved and the cheapest drugs can actually be procured is warranted.

Group Sequential Design and Analysis of Clinical Equivalence Assessment for Generic Nonsystematic Drug Products

Clinical trials with therapeutical endpoints are designed with three arms to demonstrate both the efficacy and the equivalence of the test generic treatment and the reference treatment. A generic drug product is determined to be equivalent to the reference drug product if the ratio or difference between the mean responses is bounded within the pre-specified equivalence limits. Often the trials are oversized for the placebo arm. For improvement, we propose a group sequential design with hierarchical testing for the purpose of terminating the placebo arm before testing equivalence between the test and the reference treatments. The hierarchical feature of the proposal will reduce the sample size of the placebo arm and provide treatments to patients in a more efficient manner in a clinical trial setting. After dropping the placebo arm, the option of allocating the planned but unused sample size from the placebo group to the test and reference groups will increase the sample size and power of the equivalence test without inflating the type I error rate by delaying spending it.

Impurities in generic pharmaceutical development

The current practice of characterization and control of impurities in pharmaceuticals is reviewed with emphasis on issues specific to the generic industry. Case studies are discussed to demonstrate that generic pharmaceuticals are therapeutically equivalent to the branded product, even though the color, size, shape, and excipients utilized may not be identical.

Comparative study of the quality and efficacy of originator and generic albendazole for mass treatment of soil-transmitted nematode infections in Nepal

The quality and efficacy of two locally manufactured generic albendazole (ABZ) products (Curex and Royal Drug) used for deworming children in Nepal since 1999 were tested against the originator product (GlaxoSmithKline (GSK)). The study included disintegration and dissolution testing according to the Indian Pharmacopoeia (IP) and the United States Pharmacopeia (USP), respectively, as well as a randomised controlled clinical trial comparing cure rates (CR) and egg reduction rates (ERR) for Ascaris lumbricoides, Trichuris trichiura and hookworm infections. Stool samples from 1277 children were examined before and 21 days after treatment. For A. lumbricoides, GSK (97.0%) and Royal Drug (95.0%) ABZ achieved significantly higher CRs than Curex ABZ (82.6%); however, all products achieved ERRs >90%. For T. trichiura, Curex ABZ showed significantly lower ERRs (63.2%). For hookworms, GSK ABZ performed significantly better (CR 74.3%, ERR 87.1%) than Royal Drug ABZ (CR 53.3%, ERR 80.8%) and Curex ABZ (CR 50.7%, ERR 73.1%). Only the GSK product passed both disintegration and dissolution tests according to the IP and USP. Both generic products failed the dissolution tests. Curex ABZ showed poor disintegration. Despite its lower efficacy, the cheaper Curex product achieved good results in controlling morbidity due to soil-transmitted helminth infections. This study shows that the cost effectiveness of drugs used in mass deworming campaigns should not be inferred on the basis of a single quality testing parameter.