Generic-to-generic lamotrigine switches in people with epilepsy: the randomised controlled EQUIGEN trial

Impact and implications of national centralized drug procurement in China

The national centralized drug procurement (NCDP) policy, known as the "4 + 7" policy in China, has transformed pharmaceutical procurement and access by leveraging healthcare institutions' collective buying power to reduce drug prices substantially. This policy has profoundly impacted drug pricing mechanisms, healthcare expenditures, market dynamics, and the quality of available drugs. This commentary evaluates the efficacy, challenges, and broader implications of the NCDP, summarizes the current state of post-marketing monitoring of selected generic drugs for centralized procurement, and presents relevant considerations.

Lamotrigine add-on therapy for drug-resistant focal epilepsy

BACKGROUND

This is an updated version of a Cochrane Review last updated in 2020. Epilepsy is a common neurological disorder, affecting 0.5% to 1% of the population. In nearly 30% of cases, epilepsy is resistant to currently available drugs. Pharmacological treatment remains the first choice to control epilepsy. Lamotrigine is a second-generation antiseizure medication. When used as an add-on (in combination with other antiseizure medications), lamotrigine can reduce seizures, but with some adverse effects.

OBJECTIVES

To evaluate the benefits and harms of add-on lamotrigine, compared with add-on placebo or no add-on treatment in people with drug-resistant focal epilepsy.

SEARCH METHODS

For this update, we searched the Cochrane Register of Studies (CRS Web) and MEDLINE (Ovid) on 3 October 2022 with no language restrictions. CRS Web includes randomised and quasi-randomised controlled trials from PubMed, Embase, ClinicalTrials.gov, the World Health Organization International Clinical Trials Registry Platform (ICTRP), Cochrane Central Register of Controlled Trials (CENTRAL), and the Specialised Registers of Cochrane Review Groups, including Epilepsy.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that investigated add-on lamotrigine versus add-on placebo or no add-on treatment in people of any age with drug-resistant focal epilepsy. We used data from the first period of eligible cross-over trials.

DATA COLLECTION AND ANALYSIS

For this update, two review authors independently selected trials and extracted data. Our primary outcome was 50% or greater reduction in seizure frequency. Our secondary outcomes were treatment withdrawal, adverse effects, cognitive effects, and quality of life. Primary analyses were by intention-to-treat. We performed sensitivity best- and worse-case analyses to account for missing outcome data. We calculated pooled risk ratios (RRs) with 95% confidence intervals (95% Cls) for dichotomous outcomes.

MAIN RESULTS

We identified no new studies for this update, so the results and conclusions of the review are unchanged. We included five parallel-group studies in adults or children, eight cross-over studies in adults or children, and one parallel study with a responder-enriched design in infants. In total, these 14 studies enroled 1806 eligible participants (38 infants, 199 children, 1569 adults). Baseline phases ranged from four to 12 weeks and treatment phases ranged from eight to 36 weeks. We rated 11 studies (1243 participants) at low overall risk of bias and three (697 participants) at unclear overall risk of bias due to lack of information on study design. Four studies (563 participants) reported effective blinding. Lamotrigine compared with placebo probably increases the likelihood of achieving 50% or greater reduction in seizure frequency (RR 1.80, 95% CI 1.45 to 2.23; 12 trials, 1322 participants (adults and children); moderate-certainty evidence). There is probably little or no difference in risk of treatment withdrawal for any reason among people treated with lamotrigine versus people treated with placebo (RR 1.11, 95% CI 0.91 to 1.37; 14 trials; 1806 participants; moderate-certainty evidence). Lamotrigine compared with placebo is probably associated with a greater risk of ataxia (RR 3.34, 99% Cl 2.01 to 5.55; 12 trials; 1525 participants; moderate-certainty evidence), dizziness (RR 1.76, 99% Cl 1.28 to 2.43; 13 trials; 1768 participants; moderate-certainty evidence), nausea (RR 1.81, 99% CI 1.22 to 2.68; 12 studies, 1486 participants; moderate-certainty evidence), and diplopia (RR 3.79, 99% Cl 2.15 to 6.68; 3 trials, 944 participants; moderate-certainty evidence). There is probably little or no difference in the risk of fatigue between lamotrigine and placebo (RR 0.82, 99% CI 0.55 to 1.22; 12 studies, 1552 participants; moderate-certainty evidence).

AUTHORS' CONCLUSIONS

Lamotrigine as an add-on treatment for drug-resistant focal seizures is probably effective for reducing seizure frequency. Certain adverse effects (ataxia, dizziness, diplopia, and nausea) are probably more likely to occur with lamotrigine compared with placebo. There is probably little or no difference in the number of people who withdraw from treatment with lamotrigine versus placebo. The trials were of relatively short duration and provided no long-term evidence. In addition, some trials had few participants. Further trials are needed to assess the long-term effects of lamotrigine and to compare lamotrigine with other add-on drugs.

Safety of brand name to generic substitution of lacosamide in patients with epilepsy - A prospective single-center observational study

PURPOSE

Lacosamide is a widely used third-generation antiseizure medication. However, there is a lack of evidence regarding the safety of substituting brand-name lacosamide with its generic version. This study aimed to determine the clinical outcomes associated with switching from the brand-name to the generic form of lacosamide (LCM) in patients with epilepsy.

METHODS

This prospective observational study involved patients undergoing treatment with LCM at the university epilepsy clinic. In 2018, the price of the brand-name LCM in Poland increased up to 110-fold compared to generic products. Anticipating that most patients would opt to switch to the generic formulations due to financial constraints, we chose to follow up them prospectively to assess the safety of transitioning from the brand-name to the generic form of LCM.

RESULTS

A total of 81 patients, aged 18-62 years, diagnosed with focal epilepsy and undergoing LCM treatment at our institution, decided to switch from the brand-name (Vimpat) to generic variations (Lacosamide TEVA, Lacosamide Glenmark, and Lacosamide Accord). Following the switch, no significant difference was observed in terms of seizure frequency before and after (p = 0.55, Wilcoxon signed-rank test). Subsequently, adverse events were recorded in four patients (4.9%) during the initial follow-up visit post-switch, including somnolence (2 patients) and dizziness (2 patients). Notably, all adverse events resolved by the second follow-up visit without necessitating treatment modification. Importantly, no patient switched back to brand-name medication CONCLUSION: The generic substitution of lacosamide was found to be generally safe in our study. Nonetheless, to confirm our findings, larger prospective studies are required.

Brand Name Versus Generic?

Changes in the Use of Brand Name and Generic Medications and Total Prescription Cost Among Medicare Beneficiaries With Epilepsy Terman SW, Lin CC, Kerr WT, DeLott LB, Callaghan BC, Burke JF. Neurology . 2022;99(8):e751-e761. doi:10.1212/WNL.0000000000200779 Background and Objective: To characterize trends in antiseizure medication (ASM) fills and total prescription costs in people with epilepsy. Methods: This was a retrospective cohort study of beneficiaries with epilepsy (ASM, plus ICD codes) in a 20% random Medicare sample, with continuous Fee-For-Service coverage (Parts A, B, and D) in 2008–2018. We summed the number of pill days and costs (adjusted to 2018 dollars) per person-year for each ASM. ASMs were categorized into brand versus generic, first versus newer generation, and enzyme inducers versus noninducers. Results: There were 77,000–133,000 beneficiaries with epilepsy per year. The most common ASM was phenytoin in 2008, which shifted to levetiracetam in 2018 (2008: phenytoin 25%, levetiracetam 14%; 2018: phenytoin 9%, levetiracetam 27%). Brand name (2008: 56%; 2018: 14%), first-generation (2008: 55%; 2018: 32%), and enzyme-inducing ASMs (2008: 44%; 2018: 24%) each decreased over time as a proportion of pill days. The number of brand pill days per person-year initially decreased (e.g., 2008: 250; 2009: 121; 2010: 96) but then plateaued (2013–2018: between 66 and 69) given a notable increase in lacosamide pill days per person (2008: 0; 2018: 20). Total brand name costs per year initially decreased 2008–2010 (2008: $150 million; 2010: $72 million) but then increased after 2010 (2018: $256 million). In 2018, brand name ASMs represented 79% of costs despite representing only 14% of pill days, a 1-year pill supply became 277% more expensive for brand name medications but 42% less expensive for generic medications over time (2008: brand ∼$2,800 versus generic ∼$800; 2018: brand ∼$10,700 versus generic ∼$460), and many common brand name ASMs cost approximately 10-fold more per pill day than their generic equivalents. Discussion: First-generation and enzyme-inducing ASMs waned from 2008 to 2018. Although brand name ASMs initially waned translating into lower costs and potentially higher value care, after 2010, brand name costs markedly increased because of increasing use of lacosamide plus a 277% increase in per-pill cost of brand name ASMs. Brand name ASMs represented a minority of prescriptions, but the majority of costs.

Dissolution-Hollow Fiber Membrane (D-HFM) System to Anticipate Biopharmaceutics Risk of Tablets and Capsules

A dissolution-hollow fiber membrane (D-HFM) system with relatively high area/volume ratio was previously characterized and showed favorably high percent drug absorption. Also, it's in vitro permeation constant (K_p^.Ç.) was close to in vivo human permeation constant (k_p). The objective of the current study was to predict the in vivo human absorption profile and biopharmaceutic performance of five drug products using the D-HFM system. Four immediate-release (IR) and one extended-release (ER) solid oral dosage form were subjected to the D-HFM system. Tablets and capsule dissolution were also measured using USP apparatus II. Drug solutions were also subjected to D-HFM testing. Predicted and observed absorption profiles in D-HFM system showed close agreement for each solid oral dosage form. Levy-Polli plots from D-HFM system successfully predicted the four IR products to be low biopharmaceutic risk due to permeation rate limited or mixed dissolution/permeation rate limited absorption, and successfully predicted metoprolol ER product to be high biopharmaceutic risk due to dissolution rate limited absorption. These observations showed potential of the in vitro D-HFM system to be utilized in biopharmaceutics risk assessment of in vivo tablet and capsule performance.

Generic lamotrigine extended-release tablets are bioequivalent to innovator drug in fully replicated crossover bioequivalence study

OBJECTIVE

Lamotrigine is a commonly prescribed antiepileptic drug. U.S. Food and Drug Administration (FDA)-funded clinical studies have demonstrated bioequivalence (BE) for generic lamotrigine immediate-release (IR) products in epilepsy patients with generic substitution. To address the potential concerns about the risk of generic-brand substitution of lamotrigine extended-release (ER) products, considering the complexity of controlled release systems and pharmacokinetic variations associated with possible within-subject variability (WSV), this prospective study assessed (1) BE of generic and brand lamotrigine ER products in a fully replicated BE study design in healthy subjects and (2) whether such fully replicated study design and WSV data can better support the approval of generic lamotrigine ER products.

METHODS

This open-label, single-dose, two-treatment, four-period, two-sequence, fully replicated crossover BE study compared generic lamotrigine ER tablet to brand Lamictal XR (200 mg) in 30 healthy subjects under fed conditions. Pharmacokinetics (PK) profiles were generated based on intensive blood sampling up to 144 h.

RESULTS

The two products showed comparable peak plasma concentration (C_max ), area under the concentration-time curve (AUC) from time zero to the last measurable time point (AUC_0-t ) and AUC extrapolated to infinity (AUC_0-inf ), whereas median time to C_max (T_max ) values differed, that is, 10 h for generic and 22 h for brand products, respectively. WSVs for PK metrics were small (~8% of C_max and ~6% of AUC) and similar between these two products. PK simulation predicted equivalent PK measurements of both products at steady state and after brand-to-generic switch, except the first day upon switching. No serious adverse events were reported.

SIGNIFICANCE

The generic lamotrigine ER tablet product demonstrates BE to the brand product in a fully replicated BE study design with healthy subjects, supporting the adequacy of the two-way crossover study design to demonstrate BE and generic-brand substitution of lamotrigine ER products.

Generic switching: Do future physicians in Jordan have enough knowledge and a positive attitude?

Background: Generic switching is a policy that has shown success in minimising pharmaceutical costs. It has also been used to mitigate recurrent and sudden drug shortages. Not all countries have policies that allow pharmacists to switch to generic drugs independently. In Jordan, only pharmacists at Ministry of Health hospitals automatically switch to generics if doctors had not already done INN prescribing. Objectives: This study targeted medical students to assess their experience with generic switching as patients, their knowledge of the subject as students, and their attitude towards it as future prescribers and policymakers. Methods: This is a descriptive, cross-sectional study conducted online. Eligibility criteria were being a fourth, fifth, or sixth-year medical school student enrolled at any of the six Jordanian universities. The questionnaire was developed by the researchers after a careful review of the relevant literature. Results: Three hundred and ninety students responded to the online questionnaire. Most participants were females (244, 62.6%), senior students in their final (6th) year (162, 41.5%) and with very good academic achievement (166, 42.6%). The highest knowledge scores concerned patient rights (0.73/1.00), followed by knowledge about monitoring after generic switching (0.66/1.00), and patients with known drug allergies (0.66/1.00). Almost half of the participants believe that pharmacists should not be given the right to do generic switching and only 16% stated that they would choose generic drugs if they needed treatment in the future. Multivariate linear regression analysis showed that significant predictors of knowledge were gender, GPA, and family income. No correlations were found between participants' knowledge scores and their attitudes towards giving pharmacists the right to independently switch drugs, or whether they would accept a substitute from pharmacists rather than having to refer to the physician. Conclusion: Medical students in Jordan lack sufficient knowledge about generic switching. Students need to be more aware of the current policies and regulations of this practice, and the role of each healthcare worker involved in it. They also need to have a more positive attitude toward generic drugs and generic switching practice to facilitate its future implementation.

Therapeutic Basis of Generic Substitution of Antiseizure Medications

More than thirty antiseizure medications (ASMs) are available for treating epilepsy. ASMs differ in their potency and efficacy in controlling seizures by acting on diverse targets in the brain, often with variable pharmacokinetics. Moreover, nearly 30% of people with epilepsy have drug-resistant or intractable seizures. Generic substitution of ASMs is a complex issue. It is thought that frequent generic substitution in people with epilepsy may cause problems because the U.S. Food and Drug Administration (FDA) rules allow too much variability across products. The standard bioequivalence range (80% to 125%) appears too broad for many ASMs, especially those exhibiting little separation between therapeutic and toxic levels. Hence, sub-therapeutic concentration may lead to therapeutic failure with seizure recurrence, which could be life threatening. A supra-therapeutic level could result in adverse effects or compliance issues. There are reported issues with generic substitutions of phenytoin, topiramate, levetiracetam, carbamazepine, and lamotrigine. There is discussion in the epilepsy community about additional guidelines, including designation of generic ASMs as Narrow Therapeutic Index (NTI) drugs and how patient education plays a role in generic substitution. Overall, based on the published evidence on specific generic ASMs, FDA bioequivalence standards are not the cause of problems with generic ASM substitution. Rather, it is imperative that physicians and pharmacists provide adequate patient education on what to expect when switching to generic ASMs, including changes in medication shape and color. Another suggestion would be to consider that all ASMs be considered for inclusion in NTI class to prevent the clinical outcome issues associated with generic ASM switching. SIGNIFICANCE STATEMENT: There are critical aspects to consider when switching from a brand name antiseizure medication (ASM) when a generic becomes available or switching between generics. Generic ASMs are interchanged with little consideration of differences in therapeutic equivalence and other clinical factors. This article describes key issues on generic substitution of ASMs and highlights critical pharmacotherapeutic issues associated with generic ASMs.

Efficacy and safety of switching from brand-name to domestic generic levetiracetam in children with epilepsy

OBJECTIVES

To study the efficacy and safety of domestic generic levetiracetam in replacement of brand-name levetiracetam in the treatment of children with epilepsy.

METHODS

A retrospective analysis was performed on the medical data of 154 children with epilepsy who received domestic generic levetiracetam in the inpatient or outpatient service of Guangdong Provincial People's Hospital from May 2019 to December 2020. Domestic generic levetiracetam and brand-name levetiracetam were compared in terms of efficacy and safety.

RESULTS

For these 154 children, the epilepsy control rate was 77.3% (119/154) at baseline. At 6 months after switching to domestic generic levetiracetam, the epilepsy control rate reached 83.8% (129/154), which showed a significant increase (P<0.05). There was no significant change in the frequency of seizures from baseline to 6 months after switching (P>0.05). The incidence of refractory epilepsy in children with no response after switching treatment was significantly higher than that in children with response (P<0.05). Before switching, only 1 child (0.6%) experienced somnolence, while after switching, 3 children (1.9%) experienced mild adverse drug reactions, including dizziness, somnolence, irritability, and bad temper.

CONCLUSIONS

Switching from brand-name to generic levetiracetam is safe and effective and holds promise for clinical application, but more prospective randomized controlled trials are required in future.

Barriers to Generic Antiseizure Medication Use: Results of a Global Survey by the International League Against Epilepsy Generic Substitution Task Force

The objective of this study was to identify and quantify barriers to generic substitution of antiseizure medications (ASM). A questionnaire on generic ASM substitution was developed by the International League Against Epilepsy (ILAE) Task Force on Generic Substitution. Questions addressed understanding of bioequivalence, standards for generic products, experiences with substitution, and demographic data. The survey was web‐based and distributed to ILAE chapters, their membership, and professional colleagues of task force members. Comparisons in responses were between ILAE regions and country income classification. A total of 800 individuals responded, with 44.2% being from the Asia‐Oceania ILAE Region and 38.6% from European Region. The majority of respondents had little or no education in generic substitution or bioequivalence. Many respondents indicated lack of understanding aspects of generic substitution. Common barriers to generic substitution included limited access, poor or inconsistent quality, too expensive, or lack of regulatory control. Increase in seizures was the most common reported adverse outcome of substitution. Of medications on the World Health Organization Essential Medication list, problems with generic products were most frequent with carbamazepine, lamotrigine, and valproic acid. Several barriers with generic substitution of ASM revolved around mistrust of regulatory control and quality of generic ASM. Lack of education on generic substitution is also a concern. Generic ASM products may be the only option in some parts of the world and efforts should address these issues. Efforts to address these barriers should improve access to medications in all parts of the world.

Meeting report: an exploration into the scientific and regulatory aspects of pharmaceutical drug quality in the United States

INTRODUCTION

The University of Florida College of Pharmacy, Department of Pharmaceutical Outcomes and Policy hosted a seminar 6-7 March 2021, on the quality of pharmaceutical products in the United States. This meeting report summarizes the topics presented at the seminar and highlights the expert opinions offered by the presenters.Areas Covered: The seminar, held virtually due to the COVID-19 pandemic, included slide presentations and faculty-moderated panel discussions from experts in the field. These experts from regulatory, academic, and private sectors discussed bioequivalence standards, existing and emerging efforts to promote quality in brand and generic manufacturing, as well as market-based solutions throughout the drug supply chain.Expert Opinion: The time spent understanding bioequivalence standards during the seminar felt especially important and relevant in our current pandemic environment, given the present need to have confidence in the science of drug development and to advocate for the safety of pharmaceuticals. Also an important point to emphasize from the seminar, was that every stakeholder along the drug supply chain has a responsibility to do their part to maintain its quality. And those in attendance, many of whom were students of healthcare sciences, were encouraged to be leaders in their fields and develop strategies to advance innovative improvements.

Physicians' attitudes toward generic substitutions of antiseizure drugs in epilepsy

OBJECTIVES

The safety of generic substitution of antiseizure drugs (ASDs) has been questioned for many years. This study aimed to identify physicians' attitudes to the generic substitution of ASDs in epilepsy and which factors were of significance when deciding on compound substitutions.

MATERIAL AND METHODS

A cross-sectional web-based survey was sent to neurologists and neurology residents in public health care and at private practices in two Swedish regions between February and March 2020. The 30-item survey covered drug- and patient-related factors, as well as considerations relating to practical, cost-related, and pharmacokinetic issues.

RESULTS

The total response rate was 55.8%. Respondents were generally positive to cutting costs through generic ASD utilization (74%) and prescribing generic compounds when starting a new ASD treatment (84.9%). The most substantial concern was a deterioration in seizure control (17.1%). Physicians refrained from switching if the patient wished to remain on the original compound (76.1%), had a cognitive impairment (52.5%), was on a drug with a narrow therapeutic index (47%), or had shown prior susceptibility to adverse effects (45.6%). Opinions on substitution decisions differed significantly between the Stockholm and Skåne regions. Less than one-third of the respondents were aware of supporting guidelines.

CONCLUSIONS

Neurologists generally accept the use of generic antiseizure compounds. Patient preference to remain on brand-name drug treatment was the most important factor that led to avoiding a switch. Our results may constitute material for consensus discussions to decide on quality indicators of interest for future research on substitution outcomes.

Pharmacokinetics and Generic Drug Switching: A Regulator's View

There appears to be a mismatch between the assumed therapeutic equivalence of generic drugs, their interchangeability, and reported clinical discomfort following generic drug use and drug switches. In this article, we describe why we are of the opinion that the current regulatory approach to the evaluation of generic drugs based on average bioequivalence is sufficient to expect therapeutic equivalence in the clinical setting. This has often been debated, specifically as adverse drug reactions related to generic drug switches are regularly reported. We agree that clinical discomfort during a bioequivalent drug switch may indeed be caused by different exposures to the active substance. However, this difference in exposure is not a result of the characteristics or quality of generic drugs; it is caused by the pharmacokinetic within-subject variability of the active substance, i.e., the variability on the bioavailability of the active substance, when comparing two occasions of administration of the same drug product, to the same patient. Therefore, reported clinical discomfort following generic drug use and drug switches does not warrant a change in the regulatory approach to the evaluation of the bioequivalence of generic drugs. Switching from a brand-name drug to currently approved generic drugs, or between different generic drugs, will in principle result in comparable exposure, within boundaries determined by the within-subject variability of the pharmacokinetics of the active substance involved.

Use of antiseizure medications and safety of branded versus generic formulations: A comparative study on Tuscan administrative databases

PURPOSE

To assess patterns of use of antiseizure medications (ASMs) and to compare the safety of generic versus branded formulations in terms of admission to hospital or to emergency department (ED).

METHODS

We conducted a drug utilization study with a propensity score-matched design using the administrative databases of the Italian Tuscany region. New users of ASMs during 2015 with no history of neoplasia were considered and their first prescription was classified as: available only as branded (only-B-ASM); branded with generic available (B-ASM); and generic (G-ASM). Patients with G-ASM first prescription were matched with four patients with B-ASM prescription. Participants were followed up for one year or until the date of death or diagnosis of neoplasia. Cox regression models were fitted to estimate the risk of admission to hospital or ED.

RESULTS

We identified 36,601 ASM new-users, including 2094 (6.4%) with only-B-ASM as first prescription, 24,588 (74.9%) with B-ASM, and 5788 (17.6%) with G-ASM. We found no differences in the risk of admission to hospital or ED (Hazard Ratio (HR), 0.92; 95% Confidence Interval (CI), 0.85-1.02) among users of generic ASMs compared to those using branded ASMs.

CONCLUSIONS

In our study population, generic ASMs were used less than branded ones. The similarity in the safety of branded and generic formulations suggests that generic ASMs could be the preferred formulation in current clinical practice resulting in a substantial decrease in the cost of treatment.

Coffee and cigarette smoking interactions with lamotrigine

The objective of this analysis was to determine possible interactions between lamotrigine (LTG) and coffee or cigarette use. As part of the statistical analysis of factors influencing LTG pharmacokinetics (PK) in the Equigen chronic dose study, we collected prospective data from enrolled patients on their use of coffee and cigarettes. Subjects were part of a crossover replication study of generic LTG products with rigorous blood sampling and were instructed to not change their typical consumption of these products for the duration of the study. A total of 35 subjects were enrolled, with 33 subjects having sufficient data for analysis. Higher consumption of coffee was associated with a significantly lower area under the curve (AUC) and maximum concentration (Cmax) of lamotrigine (LTG). Higher cigarette use did not result in a significant change in AUC or Cmax. Coffee, but not cigarette use, either induces LTG metabolism or inhibits LTG absorption.

Bioequivalence and switchability of generic antiseizure medications (ASMs): A re-appraisal based on analysis of generic ASM products approved in Europe

The safety of switching between generic products of antiseizure medications (ASMs) continues to be a hot topic in epilepsy management. The main reason for concern relates to the uncertainty on whether, and when, two generics found to be bioequivalent to the same brand (reference) product are bioequivalent to each other, and the risk of a switch between generics resulting in clinically significant changes in plasma ASM concentrations. This article addresses these concerns by discussing the distinction between bioequivalence and statistical testing for significant difference, the importance of intra-subject variability in interpreting bioequivalence studies, the stricter regulatory bioequivalence requirements applicable to narrow-therapeutic-index (NTI) drugs, and the extent by which currently available generic products of ASMs comply with such criteria. Data for 117 oral generic products of second-generation ASMs approved in Europe by the centralized, mutual recognition or decentralized procedure were analyzed based on a review of publicly accessible regulatory assessment reports. The analysis showed that for 99% of generic products assessed (after exclusion of gabapentin products), the 90% confidence intervals (90% CIs) of geometric mean ratios (test/reference) for AUC (area under the drug concentration vs time curve) were narrow and wholly contained within the acceptance interval (90%-111%) applied to NTI drugs. Intra-subject variability for AUC was <10% for 53 (88%) of the 60 products for which this measure was reported. Many gabapentin generics showed broader, 90% CIs for bioequivalence estimates, and greater intra-subject variability, compared with generics of other ASMs. When interpreted within the context of other available data, these results suggest that any risk of non-bioequivalence between these individual generic products is small, and that switches across these products are not likely to result in clinically relevant changes in plasma drug exposure. The potential for variability in exposure when switching across generics is likely to be greatest for gabapentin.

Widespread skeptic attitudes among people with epilepsy toward generic antiseizure drugs - A Swedish survey study

PURPOSE

To explore associations between the characteristics of people with epilepsy (PWE) and their attitudes toward generic substitution of antiseizure drugs (ASDs) in epilepsy.

METHODS

This was a cross-sectional survey study directed at adults with epilepsy using selected brand drugs: Keppra®, Lamictal®, Lyrica® or Topimax®. Symptoms of anxiety and depression, sense of self-efficacy, and beliefs about medicines were assessed. Caregivers were asked to answer for persons with intellectual or communicative difficulties.

RESULTS

The total response rate was 41% (n = 178). Almost half (46%) of subjects stated that they would oppose generic substitution (Gen-NEG) if suggested by their neurologist, while 71% would worry about adverse effects and/or increased seizure frequency after a putative switch. Age ≥50 increased the odds of being Gen-NEG (adjusted OR: 2.20, 95% CI: 1.18-4.11). Negative associations with both Gen-NEG and worriers were found for education level of high-school diploma or above, employment/studies, and prior experience of generic ASD switch. The proportion of worriers was much higher among caregivers (21/22) compared to subjects with epilepsy (106/156).

CONCLUSION

High proportions of PWE express concerns regarding generic substitution of ASDs. The elderly and caregivers seem to express particular concerns. Identifying ways to diminish negative outcomes and worries in connection with a switch is an important future field of research in order to ensure high quality, cost-effective health care for the most vulnerable people in our societies.

Effects of generic exchange of solid oral dosage forms in neurological disorders: a systematic review

Background Generic drug exchange is common practice in most healthcare systems. While generics certainly contribute to economic savings, the altered drug formulation might be associated with potential therapeutic problems. Given the narrow therapeutic windows in neurologic indications, any detrimental effect on the therapy can lead to significant consequences. Aim of the review This review aims to investigate potential problems related to a switch from brand-name to generic or from generic to generic drug products in patients with neurologic diseases. Method The review was conducted following the PICO framework and the PRISMA guidelines. MEDLINE and Scopus databases were searched for articles published in English and German language between January 1, 1995 and October 17, 2018. Studies included in this review were randomized controlled studies, reviews, systematic reviews, overviews, cohort studies and case-control studies. Studies excluded were letters, comments, authors view, congress or seminar papers and studies with a focus on economic impact or costs. Results were synthesized qualitatively. The primary outcomes were pharmacokinetic parameters such as the area under the curve (AUC), the peak serum concentration (c_max) or the time at which c_max is observed (t_max). Results The search identified 67 studies with a great variety of endpoints and study designs. The leading indication was epilepsy. Two small RCTs were found on lamotrigine switch. Analysis of the other studies found no significant differences in pharmacokinetic parameters when switching to generic drugs. A more heterogeneous picture was revealed regarding hospitalizations, breakthrough seizures, failure of therapy, adherence and patient concerns. Conclusion While most reports were of poor quality, lamotrigine was the drug with the best available data. Summarizing the results of the available studies, pharmacokinetic parameters of antiepileptic drugs show low deviation. In contrast, data on clinical parameters are less consistent. Some studies found increased seizure frequencies and adverse-drug events, while others showed no complications. Adherence and patient satisfaction seemed to be impaired. In daily practice, generic exchange in epilepsy should be a carefully balanced decision, conducted with great caution. Further research is needed, especially regarding neurologic indications other than epilepsy.

Relationship of antiepileptic drugs to generic brittleness in patients with epilepsy

PURPOSE

The purpose of the study was to assess if any antiepileptic drug (AED) was associated with patients being generic brittle (GB) and if any specific AED caused - and was not merely associated with - more frequent switch problems.

METHODS

Chi square and binary logistical regression analysis were performed, using a previously described study in patients with epilepsy who were routinely followed at the University of Maryland epilepsy outpatient clinic in Baltimore, Maryland. Determination of generic brittleness mirrored clinical practice and included patient opinion about generic formulations, usually based on a history of worsened seizures or side effects with prior AED formulation switching. The dataset included a total of 148 patients, who took 30 different AED formulations. Patients collectively took 530 AED formulation products.

RESULTS

Taking lamotrigine immediate release (IR) tablets was associated with a greater probability of being GB and tended to cause more frequent switch problems. Interestingly, six AEDs - Vimpat tablet, carbamazepine IR tablet, phenobarbital (any formulation), gabapentin capsule, Lyrica capsules, and phenytoin (any formulation) - were associated with a reduced probability of being GB, although perhaps not through greater efficacy and tolerability, or better formulation quality. Since tablet and capsule appearance may influence patient perceptions and clinical outcomes, it was observed that the six AEDs less associated with being GB also tended to have fewer generics, and hence possibly lessen treatment uncertainties from the patient perspective. A patient taking more AEDs had significantly increased odds of having a switch problem. An additional observation was that, when a generic was available for their most problematic AED, GB patients took a generic AED only 50% of the time, while not GB patients took a generic AED all the time.

CONCLUSIONS

Taking lamotrigine IR tablets was associated with a greater probability of being GB and tended to cause more frequent switch problems than other AEDs in this cohort of patients. Six AEDs were associated with a reduced probability of being GB. The lower number of different generics for these six drugs may result in greater patient certainty in medication identity, due to greater consistency in medication color, shape, and size, and hence less generic skepticism or generic brittleness. Also, patients taking more AEDs showed increased odds of a switch problem.

Lamotrigine add-on therapy for drug-resistant focal epilepsy

BACKGROUND

This is an updated version of the Cochrane Review previously published in 2016. Epilepsy is a common neurological disorder, affecting 0.5% to 1% of the population. For nearly 30% of these people, their epilepsy is resistant to currently available drugs. Pharmacological treatment remains the first choice to control epilepsy. Lamotrigine is one of the newer antiepileptic drugs. Lamotrigine, in combination with other antiepileptic drugs (add-on), can reduce seizures, but with some adverse effects.

OBJECTIVES

To determine the effects of lamotrigine on (1) seizures, (2) adverse-effect profile, and (3) cognition and quality of life, compared to placebo, when used as an add-on treatment for people with drug-resistant focal epilepsy.

SEARCH METHODS

For the latest update of the review, we searched the following databases on 9 March 2020: Cochrane Register of Studies (CRS Web), MEDLINE (Ovid, 1946 to March 06, 2020). CRS Web includes randomized or quasi-randomized, controlled trials from PubMed, EMBASE, ClinicalTrials.gov, the World Health Organization International Clinical Trials Registry Platform (ICTRP), the Cochrane Central Register of Controlled Trials (CENTRAL), and the Specialized Registers of Cochrane Review Groups including Epilepsy. No language restrictions were imposed.

SELECTION CRITERIA

Randomised placebo-controlled trials of people with drug-resistant focal epilepsy of any age, in which an adequate method of concealment of randomisation was used. The studies were double-, single- or unblinded, placebo-controlled. For cross-over studies, the first treatment period was treated as a parallel trial. Eligible participants were adults or children with drug-resistant focal epilepsy.

DATA COLLECTION AND ANALYSIS

For this update, two review authors independently assessed the trials for inclusion, and extracted data. Outcomes included 50% or greater reduction in seizure frequency, treatment withdrawal (any reason), adverse effects, effects on cognition and quality of life. Primary analyses were by intention-to-treat. Sensitivity best- and worse-case analyses were undertaken to account for missing outcome data. Pooled risk ratios (RRs) with 95% confidence intervals (95% Cls) were estimated for the primary outcomes of seizure frequency and treatment withdrawal. For adverse effects, we calculated pooled RRs and 99% Cls.

MAIN RESULTS

We did not identify any new studies for this update, therefore, the results and conclusions are unchanged. In previous updates of this review, the authors found five parallel add-on studies, eight cross-over studies in adults or children with drug-resistant focal epilepsy, and one parallel add-on study with a responder-enriched design in infants. In total, these 14 studies included 1806 eligible participants (38 infants, 199 children, 1569 adults). Baseline phases ranged from four to 12 weeks; treatment phases from eight to 36 weeks. Overall, 11 studies (1243 participants) were rated as having low risk of bias, and three (697 participants) had unclear risk of bias due to lack of reported information around study design. Effective blinding of studies was reported in four studies (563 participants). The overall risk ratio (RR) for 50% or greater reduction in seizure frequency was 1.80 (95% CI 1.45 to 2.23; 12 trials, 1322 participants (adults and children); moderate-certainty evidence) indicating that lamotrigine was significantly more effective than placebo in reducing seizure frequency. The overall RR for treatment withdrawal (for any reason) was 1.11 (95% CI 0.91 to 1.37; 14 trials; 1806 participants; moderate-certainty evidence). The adverse events significantly associated with lamotrigine were: ataxia, dizziness, diplopia (double vision), and nausea. The RR of these adverse effects were as follows: ataxia 3.34 (99% Cl 2.01 to 5.55; 12 trials; 1525 participants; high-certainty evidence); dizziness 2.00 (99% Cl 1.52 to 2.64;13 trials; 1768 participants; moderate-certainty evidence); diplopia 3.79 (99% Cl 2.15 to 6.68; 3 trials, 944 participants; high-certainty evidence); nausea 1.81 (99% Cl 1.22 to 2.68; 12 studies,1486 participants; moderate-certainty evidence). The limited data available precluded any conclusions about effects on cognition and quality of life. No important heterogeneity between studies was found for any of the outcomes. Overall, we assessed the evidence as high to moderate certainty, due to incomplete data for some outcomes.

AUTHORS' CONCLUSIONS

Lamotrigine as an add-on treatment for drug-resistant focal seizures appears to be effective in reducing seizure frequency, and seems to be fairly well-tolerated. However, the trials were of relatively short duration and provided no evidence for the long term. Further trials are needed to assess the long-term effects of lamotrigine, and to compare lamotrigine with other add-on drugs.

Lack of Association of Generic Brittle Status with Genetics and Physiologic Measures in Patients with Epilepsy

PURPOSE

A patient was denoted to be generic brittle (GB) if they had a negative opinion about generics (e.g. prior history of a switch problem) or took the innovator brand of their most problematic anti-epileptic drug (AED) when generic was available. The aim of this hypothesis-generating study was to assess possible genetic and physiologic differences between GB and not GB patients with epilepsy.

METHODS

Patients (n = 148) with epilepsy were previously characterized as being either GB or not GB. Blood was collected from each subject for genotyping and physiologic testing. Genotyping for 24 single nucleotide polymorphisms (SNPs) and two copy number variants (CNVs) was performed across 12 genes in each patient. Forty-four physiologic tests were conducted in each patient. Chi square analysis was performed to assess for associations between genotyping results and GB status, as well as between physiologic test results and GB status.

RESULTS

No SNP or CNV discriminated GB status in genetic analysis (genotype or allele frequency). Physiologic test results in this study were not associated with GB status.

CONCLUSIONS

Questions from neurologists and patients about generics is frequently based on applicability of generic drug standards to individual subjects. However, findings here in patients with epilepsy did not uncover genetic or physiologic reasons that explained which patients were GB and which were not GB.

Genetic and Non-genetic Factors Contributing to the Significant Variation in the Plasma Trough Concentration-to-Dose Ratio of Valproic Acid in Children With Epilepsy

Objective: This study was conducted to evaluate the potential genetic and non-genetic factors contributing to plasma trough concentration-to-dose (C ₀/D) ratio of valproic acid (VPA) in pediatric patients with epilepsy. Study Design: A single-center, retrospective cohort study was performed by collecting data from 194 children aged 1-14 years between May 2018 and November 2018. The oral solution (n = 135) group and the sustained-release (SR) tablet group (n = 59) were defined, and the plasma VPA C ₀ was measured. Twenty-six single-nucleotide polymorphisms (SNPs) were chosen for genotyping with the MassARRAY system. A multiple logistic regression model was used for data analysis. Results: Body weight (BW) and age were positively correlated with the C ₀/D ratio in 194 patients, but the positive correlation disappeared after the patients were divided into oral solution and SR tablet subgroups. The average C ₀/D ratio was significantly increased by 2.11-fold (P = 0.000) in children who took VPA SR tablets compared with children who were administered VPA oral solutions. No significant association between genetic variants and the C ₀/D ratio was found, even for the five well-studied SNPs, namely UGT2B7 G211T, C802T, C161T, T125C, and CYP2C9 ^* 3 A1075C. However, a significant association between the C ₀/D ratio and UGT1A6/9 Del>A (rs144486213) was observed in the VPA oral solution group, but not in the VPA SR tablet group. Conclusions: The dosage forms of sodium valproate, rather than BW, age, or genetic polymorphisms, significantly affected the VPA C ₀/D ratios in pediatric patients with epilepsy. Based on our findings, switching the dosage form between solution and SR tablet should be performed cautiously. Total daily dose adjustment should be considered, and the plasma concentration, seizure-control effect, and adverse drug reaction should also be monitored very closely.

Nocebo in Biosimilars and Generics in Neurology: A Systematic Review

Background: Nocebo refers to adverse events related to patients’ negative expectations and previous experiences, mediated by several neurobiological pathways within the brain. It is common among neurological patients and affects adherence and treatment outcomes, representing a real clinical challenge.

Methods: We conducted a systematic search based on the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines in MEDLINE database, using several keywords for studies that can be processed to investigate the magnitude of nocebo in generics and biosimilars used in the most common neurological diseases. The aim was to estimate its size and suggest strategies to minimize its prevalence in clinical trials and practice.

Results: Of a total of 2,606 identified articles, after criteria-based selection, 35 studies were included for analysis. Overall, there was vast heterogeneity across the studies concerning population, study design, and outcomes. Nocebo response could be estimated only in one double-blind randomized trial of generic glatiramer acetate in relapsing remitting multiple sclerosis that included a placebo arm. In this trial, no significant differences observed between the three arms (innovator, bioequivalent, and placebo) in favorable and unfavorable outcomes. In the open-label phase of the trial, an increased withdrawal rate was recorded in patients switched from placebo to bioequivalent (8.4%) that may be related to nocebo. In other open-label and real-world studies evaluating biosimilars or generics for brain disorders, a similar indirect nocebo effect is assuming by several investigators. Also, knowledge gaps between health-care providers and patients exist towards generics and biosimilars.

Conclusions: Despite its presence, the true burden of the nocebo response and effect cannot be accurately estimated in existing studies with generics and biosimilars in neurological diseases. Targeted strategies for clinical trials’ design are needed in order to measure the exact nocebo’s size.

Quality of life after switching to generic levetiracetam - A prospective comparative study

BACKGROUND

Improved quality of life (QoL) is one of the most important objectives in the treatment of epilepsy. Recent prospective, clinical studies proved no significant differences between brand antiepileptic drugs (AEDs) and their generic equivalents in terms of seizure control, pharmacokinetics, or safety. In this study, we focused on possible changes in QoL and adverse events in connection with generic substitution of levetiracetam (LEV).

METHODS

This was a prospective, naturalistic, two-cohort, twin-center study. After a baseline period of 10 weeks, outpatients with epilepsy on stable treatment with Keppra® either continued on this brand (reference group, n = 16) or switched to generic LEV (1A Pharma®) (study group, n = 16) for an eight-week study period. The Quality of Life in Epilepsy Inventory-31 (QOLIE-31) and an adverse events' questionnaire were administered at inclusion, after baseline, and at the end of the study period. The study protocol included a close clinical follow-up with repeated LEV serum concentration measurements and nurse-led outpatient visits.

RESULTS

Clinically relevant improvements in overall QOLIE-31 scores according to minimally important change (MIC) estimates were seen in both groups. QOLIE-31 subscales in both groups showed significantly less worry about seizures at the end of the study compared to scores at inclusion (study group: p = 0.01; reference group: p = 0.02). No significant deterioration in QoL or adverse events were observed following generic substitution. No switchbacks occurred.

CONCLUSIONS

We found reduced seizure worries over time among people with epilepsy allocated to either generic switch or continued treatment with brand LEV. We hypothesize that the nurse-led structured follow-up had an impact on seizure worries and switchback rates because of reduced nocebo effects. Further studies on generic AED substitution, focusing on psychological outcome measures, are warranted to test this supposition.

Therapeutic Drug Monitoring of Antiepileptic Drugs in Epilepsy: A 2018 Update

BACKGROUND

Antiepileptic drugs (AEDs) are the mainstay of epilepsy treatment. Since 1989, 18 new AEDs have been licensed for clinical use and there are now 27 licensed AEDs in total for the treatment of patients with epilepsy. Furthermore, several AEDs are also used for the management of other medical conditions, for example, pain and bipolar disorder. This has led to an increasingly widespread application of therapeutic drug monitoring (TDM) of AEDs, making AEDs among the most common medications for which TDM is performed. The aim of this review is to provide an overview of the indications for AED TDM, to provide key information for each individual AED in terms of the drug's prescribing indications, key pharmacokinetic characteristics, associated drug-drug pharmacokinetic interactions, and the value and the intricacies of TDM for each AED. The concept of the reference range is discussed as well as practical issues such as choice of sample types (total versus free concentrations in blood versus saliva) and sample collection and processing.

METHODS

The present review is based on published articles and searches in PubMed and Google Scholar, last searched in March 2018, in addition to references from relevant articles.

RESULTS

In total, 171 relevant references were identified and used to prepare this review.

CONCLUSIONS

TDM provides a pragmatic approach to epilepsy care, in that bespoke dose adjustments are undertaken based on drug concentrations so as to optimize clinical outcome. For the older first-generation AEDs (carbamazepine, ethosuximide, phenobarbital, phenytoin, primidone, and valproic acid), much data have accumulated in this regard. However, this is occurring increasingly for the new AEDs (brivaracetam, eslicarbazepine acetate, felbamate, gabapentin, lacosamide, lamotrigine, levetiracetam, oxcarbazepine, perampanel, piracetam, pregabalin, rufinamide, stiripentol, sulthiame, tiagabine, topiramate, vigabatrin, and zonisamide).

Evaluation of Switching Patterns in FDA's Sentinel System: A New Tool to Assess Generic Drugs

INTRODUCTION

Nearly 90% of drugs dispensed in the US are generic products.

OBJECTIVE

The aim of this study was to develop and implement a tool for analyzing manufacturer-level drug utilization and switching patterns within the US Food and Drug Administration's Sentinel system.

METHODS

A descriptive tool was designed to analyze data in the Sentinel common data model and was tested with two case studies-metoprolol extended release (ER) and lamotrigine ER-using claims data from four Sentinel data partners. We plotted initiators of each brand and generic product over time. For metoprolol ER, we evaluated rates of switching from generics around the time of manufacturing issues. For lamotrigine ER, we examined rates of switching back to the brand among those who switched from brand to generic.

RESULTS

We identified 1,651,285 initiators of metoprolol ER products between July 2008 and September 2015. We observed a large decrease in monthly metoprolol ER initiators (from 25,465 in December 2008 to 13,128 in February 2009), corresponding to recalls by generic manufacturers. We observed simultaneous increases in utilization of the authorized generic and brand products. We identified 4266 initiators of lamotrigine ER with an epilepsy diagnosis between January 2012 and September 2015. Among those who switched from brand to generic, the cumulative incidence of switching back was close to 20% at 2 years. Switchback rates were higher for the first available generic products.

CONCLUSIONS

This developed tool was able to elucidate novel utilization and switching patterns in two case studies. Such information can be used to support surveillance of generic drugs and biosimilars.

Innovation for Generic Drugs: Science and Research Under the Generic Drug User Fee Amendments of 2012

Regulatory science is science and research intended to improve decision making in a regulatory framework. Improvements in decision making can be in both accuracy (making better decisions) and in efficiency (making faster decisions). Science and research supported by the Generic Drug User Fee Amendments of 2012 (GDUFA) have focused on two innovative methodologies that work together to enable new approaches to development and review of generic drugs: quantitative models and advanced in vitro product characterization. Quantitative models faithfully represent current scientific understanding. They are tools pharmaceutical scientists and clinical pharmacologists use for making better and faster product development decisions. Advances in the in vitro product comparisons provide the measurements of product differences that are the critical input into the models. This paper outlines four areas where science and research funded by GDUFA support synergistic use of models and characterization at critical decision points during generic drug product development and review.

A Survey of Patients' Perceptions of Pill Appearance and Responses to Changes in Appearance for Four Chronic Disease Medications

BACKGROUND

Generic versions of a drug can vary in appearance, which can impact adherence.

OBJECTIVE

To assess the preferences, perceptions, and responses of patients who experienced a change in the appearance of a generic medication.

DESIGN

Cross-sectional survey of patients from a large commercial health plan.

PARTICIPANTS

Adults receiving generic versions of lisinopril, fluoxetine, lamotrigine, or simvastatin who experienced a change in the color or shape of their pills between March 2014 and November 2015.

MAIN MEASURES

Likert-scale responses to questions concerning perceptions of generic drug safety and effectiveness, reliance on and preferences for pill appearance, and responses to pill appearance changes. Multivariable logistic regression-modeled predictors of seeking advice and adjusting use following a pill appearance change.

KEY RESULTS

Of 814 respondents (response rate = 41%), 72% relied on pill appearance to ensure they took the correct medication. A similar percentage wanted their pills to remain the same color (72%), shape (71%), and size (75%) upon refill, but 58% would not have paid a $1 premium on a $5 co-pay to ensure such consistency. Most respondents (86%) wanted their pharmacists to notify them about pill appearance changes, but only 37% recalled such notification; 21% thought they received the wrong medication, and 8% adjusted medication use. Younger respondents (18-33 vs. 50-57 years) were more likely to seek advice (odds ratio [OR] = 1.91; 95% confidence interval [CI],1.02-3.59), and respondents with lower household income (< $30,000 vs. > $100,000) were more likely to adjust medication use (OR = 3.40; 95% CI,1.09-10.67).

CONCLUSIONS

Requiring uniform pill appearance may help increase adherence but presents challenges. Standardized pharmacy notification and education policies may be a more feasible short-term solution.

Is Bioequivalence Established Based on the Reference-Scaled Average Bioequivalence Approach Relevant to Chronic Administration of Phenytoin? Perspectives Based on Population Pharmacokinetic Modeling and Simulations

Phenytoin demonstrates time-dependent and nonlinear pharmacokinetics (PK) within the therapeutic range of 10 to 20 μg/mL. There are discussions on the relevance of bioequivalence (BE) demonstrated in a single-dose BE study in healthy subjects to exposure under chronic use conditions in patients, particularly given that phenytoin has a narrow therapeutic index. The objective of this study was to quantitatively evaluate the appropriateness of single-dose PK BE through simulations for the phenytoin extended-capsule products. A previously published population PK model was updated to account for the interoccasion variability using the dense PK data of the reference listed drug (Dilantin) from 5 single-dose, fully replicated BE studies (n = 124). BE studies with alternative designs were simulated using the developed PK model and subsequently analyzed accordingly: Scenario 1, multiple-dose, 2-period, crossover BE studies with an average BE approach; Scenario 2, single-dose, 4-period, fully replicated BE studies with a reference-scaled average BE approach as recommended in the product-specific guidance. In both scenarios, hypothetical phenytoin capsules with different formulation-related PK parameters, such as relative bioavailability and absorption rates, were included in the simulations. The results showed that the both scenarios provided the same results with respect to BE conclusions.

Exploring generic brittleness and the demographic factors for its susceptibility in patients with epilepsy

PURPOSE

The purpose of this study was to provide an algorithm for generic brittleness and to elucidate the demographic factors that anticipate generic brittleness for patients with epilepsy.

METHODS

This exploratory, observational, and nontherapeutic study was conducted in patients with epilepsy who were routinely followed at the University of Maryland epilepsy outpatient clinic in Baltimore, Maryland. Patients were taking at least one antiepileptic drug (AED) for treatment of epilepsy. Based on patient interview and medical history, 12 demographic factors were collected. Each patient was assessed to be either generic brittle (GB) or not GB. Demographic factors were subjected to binary logistical regression and other statistical tests, to elucidate determinants of GB status.

RESULTS

N = 148 patients completed the study. An algorithm to define whether a patient was GB or not GB was devised. The two elements that defined GB status are as follows: patient opinion about generics and (if needed) whether patients were currently taking brand or generic of their most problematic AED. About 40% of patients were GB. From binary logistical regression, two demographic factors that contributed to patients being GB were whether a patient was currently taking a problem AED and total number of current medications for a patient, with odds ratios of 4.06 (95% confidence interval [CI] from 1.53 to 10.81) and 1.10 (95% CI from 1.003 to 1.21), respectively. Of the patients on a problem AED, 46.9% were GB, while only 18.2% of patients not currently on a problem AED were GB. The total number of current medications ranged from 1 to 22, with mode of four medications. From regression, for each additional medication that a patient took, the odds of being GB increased 1.10-fold. Although patient seizure and adverse event history was not employed to define GB status, being GB was associated with less seizure control and greater adverse events.

CONCLUSIONS

An algorithm for generic brittleness was derived, and about 40% of patients were GB, usually due to prior history of a switch problem. Two demographic factors favored patients being GB: whether the patient was currently taking a problem AED and the total number of current medications.

Factors influencing the use of the "not for generic substitution" mention for prescriptions in primary care: a survey with general practitioners

BACKGROUND

Generic drug substitution is a public health policy challenge with high economic potential. Generic drugs are generally cheaper than brand-name drugs. Drugs are a significant part of the total health expenditure, especially in ambulatory care. We conducted a cross-sectional study with general practitioners in the Champagne-Ardenne region to determine physician-related factors and beliefs causing doctors to use the Not for Generic Substitution (NGS) mention.

METHODS

Questionnaires were sent to General Practitioners (GPs) practicing in Champagne-Ardenne via 3 shipments, from January 2015 to May 2015. Prescriber characteristics and beliefs influencing the use of the NGS mention were assessed for frequent (≥ 5%) and less frequent (< 5%) users of the NGS mention.

RESULTS

Factors associated with above average NGS mention use in bivariate analysis included patient comorbidity, polypharmacy, a concern that generic and brand-name drugs are not bioequivalent and belief in higher efficacy of the brand name drug. The use of an e-prescribing system (EPS) and medical practice in rural areas appeared to be associated with lower use of NGS mention in bivariate analysis but not in multivariable analysis. In multivariable analysis, patient request was associated with a higher use of the NGS mention (NGS ≥ 5%, adjusted Odds Ratio (aOR) = 2.52; 95% CI = [1.46-4.35]; p = 0.001), which was also linked to patient age over 65 (NGS ≥ 5%, aOR = 2.33; 95% CI = [1.03-5.30]; p = 0.04). The NGS mention was often used for drugs where substitution is debated in the literature (thyroid hormones, antiepileptic drugs).

CONCLUSION

This work highlights the involvement of the doctor-patient pair for the use of the NGS mention. Patient request was the major reason for using the NGS mention, even though it was not always endorsed by prescribers. Further studies are needed to assess patient views on generic drugs and drug substitution, accounting for their health status and socio-economic condition, to help improve the relevance of the information available to them.

Construction of the Design Matrix for Generalized Linear Mixed-Effects Models in the Context of Clinical Trials of Treatment Sequences

The estimation of carry-over effects is a difficult problem in the design and analysis of clinical trials of treatment sequences including cross-over trials. Except for simple designs, carry-over effects are usually unidentifiable and therefore nonestimable. Solutions such as imposing parameter constraints are often unjustified and produce differing carry-over estimates depending on the constraint imposed. Generalized inverses or treatment-balancing often allow estimating main treatment effects, but the problem of estimating the carry-over contribution of a treatment sequence remains open in these approaches. Moreover, washout periods are not always feasible or ethical. A common feature of designs with unidentifiable parameters is that they do not have design matrices of full rank. Thus, we propose approaches to the construction of design matrices of full rank, without imposing artificial constraints on the carry-over effects. Our approaches are applicable within the framework of generalized linear mixed-effects models. We present a new model for the design and analysis of clinical trials of treatment sequences, called Antichronic System, and introduce some special sequences called Skip Sequences. We show that carry-over effects are identifiable only if appropriate Skip Sequences are used in the design and/or data analysis of the clinical trial. We explain how Skip Sequences can be implemented in practice, and present a method of computing the appropriate Skip Sequences. We show applications to the design of a cross-over study with 3 treatments and 3 periods, and to the data analysis of the STAR*D study of sequences of treatments for depression.

A Clinician's Guide to Oral Extended-Release Drug Delivery Systems in Epilepsy

Epilepsy is one of the most common chronic neurologic disorders that affects individuals of all ages. It is primarily managed with antiepileptic drugs (AEDs), with the goal of maintaining complete seizure control combined with minimal or no adverse effects. Oral administration is the mainstay of AED delivery for patients with chronic epilepsy and consists essentially of immediate-release (IR) and modified-release (delayed-release and extended-release [ER]) dosage formulations. Extended-release formulations (hydrophilic or hydrophobic matrix systems, reservoir systems, and osmotic-release systems) release a drug in a controlled manner during an extended period of time following administration. Extended-release formulations have many advantages compared with IR formulations, including simplification of dosing regimens, reduction in pill burden, and reduction in the peak-to-trough fluctuations in serum drug concentration that may be associated with a decreased risk of adverse effects and of seizures. These advantages have the potential to increase adherence to antiepileptic therapy, improve the quality of life of patients, and reduce health care costs. This article, which is intended as a practical guide for clinicians, reviews the properties of the different ER AED formulations currently available and discusses the advantages of ER over IR formulations. Subsequently, an explanation of the technologic basis of the different oral ER formulations, the critical attributes that differentiate ER products, and their individual strengths and weaknesses is provided. Specific recommendations to practitioners on treating patients with ER formulations are included.

Generic antiepileptic drugs-Safe or harmful in patients with epilepsy?

Generic antiepileptic drugs (AED) are significantly cheaper than brand name drugs, and may reduce overall health care expenditures. Regulatory bodies in Europe and North America require bioequivalence between generic and innovator drugs with regard to area under the plasma concentration-time curve (AUC) and peak plasma concentration (C_max ); strict cutoff values have been defined. The main issue is if bioequivalence ensures therapeutic equivalence. Are switches from brand to generic, or between generic AEDs entirely safe or potentially harmful in patients with epilepsy? We summarized and evaluated the available evidence from bioequivalence, health care utilization, and clinical studies on safety of generic AEDs. In most cases, variations in AUC and C_max were negligible when comparing innovator and generic AEDs. Due to interindividual pharmacokinetic and pharmacodynamic variability, measured differences between innovator and generic drugs may be the same as differences between different lots of the same brand. Studies from several countries based on insurance data have reported an increase in health care usage after switch from brand to generic AEDs; switchback rates are significantly higher for AEDs compared to other compounds. Patients may be confused, and nonadherence may increase, when AEDs are switched between manufacturers, perhaps due to changes in medication shape and color. But clinical studies do not report changes in seizure frequency and tolerability attributable to generics. Sufficient evidence indicates that most generics are bioequivalent to innovator AEDs; they do not pose a relevant risk for patients with epilepsy. However, some patients are reluctant towards variations in color and shape of their AEDs which may result in nonadherence. We recommend administering generics when a new AED is initiated. Switches from brand to generic AEDs for cost reduction and between generics, which is rarely required, generally seem to be safe, but should be accompanied by thorough counseling of patients on low risks.

Advocacy for children with epilepsy: Leveraging the WHA resolution. Advocacy Task Force, Commission of Pediatrics, International League Against Epilepsy

In May 2015 the World Health Assembly (WHA) approved the Resolution on the Global Burden of Epilepsy. This report addresses how the Resolution can be leveraged to improve the care of children with epilepsy worldwide. Children with epilepsy have unique needs and face unique challenges from stigma at all levels of society. Children lack a voice to lobby for their own needs, including their right to have access to education. Effective leadership and governance should be enhanced through the support of stakeholders empowered to counsel, advise, and lobby for appropriate care. National health care plans should integrate primary and specialist care, and they need to be adapted to local specificities. Antiepileptic medicines should be widely accessible in appropriate, sustained, and affordable ways. Public awareness initiatives are needed to improve the inclusion of affected children in society and to reduce stigma. Cost-effective interventions are also needed to address preventable causes of epilepsy. Without greater investment in research, evidence-based interventions cannot be implemented. Through all of this, civil society must be engaged to ensure that the multivariate dimensions from the clinic to the community are addressed to fulfil the needs of children with epilepsy.

Knowledge, attitude, and beliefs on epilepsy among adults in Erute South, Lira District, Uganda

Objective

To assess the knowledge, attitudes, and beliefs of adults on epilepsy in Erute South County, Lira District, Uganda.

Methods

A cross-sectional study was conducted in rural Erute South County. Two hundred seventeen of 220 randomly selected adults 18 years or older participated in the study. A standardized self-administered questionnaire (Attitudes towards persons with Epilepsy "ATPE") was used for data collection. Protocol approval was sought from International Health Sciences University, and informed consent was obtained from participants at all times.

Results

Two hundred seventeen of 220 invited community members completed the study. Females comprised the majority 51.6%.. Most of the respondents had a low level of knowledge on epilepsy. The mean ATPE scale knowledge score was 4.57 (standard deviation [SD] = 3.24) of a maximum score of 11. The male respondents almost had mean knowledge scores almost equal to their female counterparts (4.23, SD = 2.48; 4.51, SD = 2.54, respectively). Most respondents had negative attitudes toward epilepsy, with a mean ATPE attitude score of 73.2 (SD = 2.11) of a possible maximum score of 126. The mean attitude scores for the male and female respondents were 58.18 (SD = 4.23) and 86.62 (SD = 5.23), respectively. Most respondents had negative beliefs such as attributing epilepsy to supernatural spirits, heredity, and preference of traditional medicine and healers to conventional medicine as a treatment for epilepsy. A significant number of respondents expressed sympathetic feelings toward people living with epilepsy, specifically tolerance and kindness to those living with epilepsy.

Significance

Findings could benefit policymakers, the district health team, researchers, community members, affected families, and people with epilepsy in designing awareness strategies. Knowledge on epilepsy could improve the quality of life and care for people living with epilepsy, through reducing misconceptions and stigmatization in the communities where they live.

Differences in rates of switchbacks after switching from branded to authorized generic and branded to generic drug products: cohort study

OBJECTIVES

To compare rates of switchbacks to branded drug products for patients switched from branded to authorized generic drug products, which have the same active ingredients, appearance, and excipients as the branded product, with patients switched from branded to generic drug products, which have the same active ingredients as the branded product but may differ in appearance and excipients.

DESIGN

Observational cohort study.

SETTING

Private (a large commercial health plan) and public (Medicaid) insurance programs in the US.

PARTICIPANTS

Beneficiaries of a large US commercial health insurer between 2004 and 2013 (primary cohort) and Medicaid beneficiaries between 2000 and 2010 (replication cohort).

MAIN OUTCOME MEASURES

Patients taking branded products for one of the study drugs (alendronate tablets, amlodipine tablets, amlodipine-benazepril capsules, calcitonin salmon nasal spray, escitalopram tablets, glipizide extended release tablets, quinapril tablets, and sertraline tablets) were identified when they switched to an authorized generic or a generic drug product after the date of market entry of generic drug products. These patients were followed for switchbacks to the branded drug product in the year after their switch to an authorized generic or a generic drug product. Cox proportional hazard models were used to estimate hazard ratios and 95% confidence intervals after adjusting for demographics, including age, sex, and calendar year. Inverse variance meta-analysis was used to pool adjusted hazard ratios across all drug products.

RESULTS

A total of 94 909 patients switched from branded to authorized generic drug products and 116 017 patients switched from branded to generic drug products and contributed to the switchback analysis. Unadjusted incidence rates of switchback varied across drug products, ranging from a low of 3.8 per 100 person years (for alendronate tablets) to a high of 17.8 per 100 person years (for amlodipine-benazepril capsules), with an overall rate of 8.2 per 100 person years across all drug products. Adjusted switchback rates were consistently lower for patients who switched from branded to authorized generic drug products compared with branded to generic drug products in the primary cohort (pooled hazard ratio 0.72, 95% confidence interval 0.64 to 0.81). Similar results (0.75, 0.62 to 0.91) were observed in the replication cohort.

CONCLUSION

Switching from branded to authorized generic drug products was associated with lower switchback rates compared with switching from branded to generic drug products.

Community pharmacists' understanding and perceptions of FDA therapeutic equivalence standards

BACKGROUND

Pharmacists need to demonstrate knowledge of and have confidence in Food and Drug Administration (FDA) therapeutic equivalence (TE) standards to improve acceptance of generic medicines amongst patients and other healthcare professionals.

OBJECTIVE

To evaluate community pharmacists' understanding, interpretation and perceptions of the FDA TE standards to identify if further education is needed on this topic.

METHODS

An anonymous, 13-item survey was piloted and then distributed by e-mail to a random sample of 287 Indiana community pharmacists. The 5-min survey included demographic, knowledge-based, and perception-based questions on FDA TE criteria that participants were given one week to complete. Participants completed the survey using a Web-based survey tool (Qualtrics).

RESULTS

192 pharmacists completed the survey achieving a response rate of 66.9%. Only 7.3% of respondents correctly identified FDA bioequivalence criteria for approval of generic drug products. Two questions presented TE codes from the Orange Book and asked respondents to identify if a pair of drug products were therapeutically equivalent: 62.6% and 61.0% of respondents answered correctly. However, 89.4% of respondents correctly indicated that the Orange Book is the location of FDA TE evaluations. 74.9% of responding pharmacists indicated a positive perception of the rigor of FDA approval standards associated with generic medications and 66.0% believed that generic drug products made by different manufacturers are of similar quality.

CONCLUSIONS

The results suggest that community pharmacists need additional education on the interpretation of TE codes and FDA bioequivalence criteria for approval of generic drug products. The safety and efficacy of generics are often questioned by patients and physicians. It is important for pharmacists to be knowledgeable of FDA TE standards as they are experts in medicines and need to be confident with the criteria to effectively convey them to patients and healthcare professionals.

Generic-reference and generic-generic bioequivalence of forty-two, randomly-selected, on-market generic products of fourteen immediate-release oral drugs

Background

The extents of generic-reference and generic-generic average bioequivalence and intra-subject variation of on-market drug products have not been prospectively studied on a large scale.

Methods

We assessed bioequivalence of 42 generic products of 14 immediate-release oral drugs with the highest number of generic products on the Saudi market. We conducted 14 four-sequence, randomized, crossover studies on the reference and three randomly-selected generic products of amlodipine, amoxicillin, atenolol, cephalexin, ciprofloxacin, clarithromycin, diclofenac, ibuprofen, fluconazole, metformin, metronidazole, paracetamol, omeprazole, and ranitidine. Geometric mean ratios of maximum concentration (C_max) and area-under-the-concentration-time-curve, to last measured concentration (AUC_T), extrapolated to infinity (AUC_I), or truncated to C_max time of reference product (AUC_Reftmax) were calculated using non-compartmental method and their 90% confidence intervals (CI) were compared to the 80.00%–125.00% bioequivalence range. Percentages of individual ratios falling outside the ±25% range were also determined.

Results

Mean (SD) age and body-mass-index of 700 healthy volunteers (28–80/study) were 32.2 (6.2) years and 24.4 (3.2) kg/m², respectively. In 42 generic-reference comparisons, 100% of AUC_T and AUC_I CIs showed bioequivalence, 9.5% of C_max CIs barely failed to show bioequivalence, and 66.7% of AUC_Reftmax CIs failed to show bioequivalence/showed bioinequivalence. Adjusting for 6 comparisons, 2.4% of AUC_T and AUC_I CIs and 21.4% of C_max CIs failed to show bioequivalence. In 42 generic-generic comparisons, 2.4% of AUC_T, AUC_I, and C_max CIs failed to show bioequivalence, and 66.7% of AUC_Reftmax CIs failed to show bioequivalence/showed bioinequivalence. Adjusting for 6 comparisons, 2.4% of AUC_T and AUC_I CIs and 14.3% of C_max CIs failed to show bioequivalence. Average geometric mean ratio deviation from 100% was ≤3.2 and ≤5.4 percentage points for AUC_I and C_max, respectively, in both generic-reference and generic-generic comparisons. Individual generic/reference and generic/generic ratios, respectively, were within the ±25% range in >75% of individuals in 79% and 71% of the 14 drugs for AUC_T and 36% and 29% for C_max.

Conclusions

On-market generic drug products continue to be reference-bioequivalent and are bioequivalent to each other based on AUC_T, AUC_I, and C_max but not AUC_Reftmax. Average deviation of geometric mean ratios and intra-subject variations are similar between reference-generic and generic-generic comparisons.

Trial registration

ClinicalTrials.gov identifier: NCT01344070 (registered April 3, 2011).

Electronic supplementary material

The online version of this article (doi:10.1186/s40360-017-0182-1) contains supplementary material, which is available to authorized users.

Generic Versions of Narrow Therapeutic Index Drugs: A National Survey of Pharmacists' Substitution Beliefs and Practices

Small changes in bioavailability of narrow therapeutic index (NTI) drugs can alter clinical outcomes, raising concern over generic NTI substitution. We surveyed pharmacists to identify their perceptions of generic NTI drugs, their frequency of performing generic NTI substitution, and predictors of this behavior. Of 710 respondents (33% response rate), 87% perceived generic NTI drugs as effective as their brand-name versions and 94% as safe. Whereas 82% almost always performed generic NTI substitution for initial prescriptions, only 60% did for refills. Pharmacists in non-chain settings (odds ratio (OR) = 2.37; 95% confidence interval (CI) = 1.40-4.02), in practice longer (per year OR = 1.04; 95% CI = 1.02-1.06), in states with affirmative patient consent laws (OR = 1.88; 95% CI = 1.06-3.32), and in states with NTI-specific substitution requirements (OR = 1.95; 95% CI = 1.16-3.26) were more likely not to substitute initial prescriptions. Education of non-chain and veteran pharmacists and elimination of affirmative patient consent and NTI-specific substitution requirements could increase generic NTI substitution.