Comparing Generic and Innovator Drugs: A Review of 12 Years of Bioequivalence Data from the United States Food and Drug Administration

Generic products of antiepileptic drugs: a perspective on bioequivalence, bioavailability, and formulation switches using Monte Carlo simulations

INTRODUCTION

Generic products of antiepileptic drugs (AEDs) are currently a controversial topic as neurologists and patients are reluctant to switch from brand products to generics and to switch between generics.

OBJECTIVE

The aim of this study was to provide enlightenment on issues of bioequivalence (BE) and interchangeability of AED products.

METHODS

Monte Carlo simulations of the classic 2 × 2 BE studies were performed to study the effect of sample size, within-subject variability, and the true difference in pharmacokinetic values of the products under comparison on BE acceptance of generic AED products. Simulations were extended to study the comparative performance of two generic AED products against the same innovative product. The simulated results are compared with literature data on AEDs.

RESULTS

The question with regard to bioavailability (BA) is whether two formulations are different, while for BE the question is whether two formulations are sufficiently similar in terms of extent and rate of absorption. Therefore, the criteria for BA and BE and the statistical analysis involved in their analysis are different. Two generic formulations that meet regulatory approval requirements for generics by being bioequivalent to the same innovative AED may not be bioequivalent to one another and therefore should not be regarded as equal or as therapeutically equivalent products. A switch from a standard or an immediate-release formulation to a modified-release product, which comprises extended-release or delayed-release formulations, should not be regarded as a switch between generics, but rather as a switch between different formulation types.

DISCUSSION

Switches between bioequivalent generic AED products could potentially lead to larger changes in plasma levels and exposure than the brand-to-generic switch. The simulation work verified the clinical findings that not all generic AED products bioequivalent to the same innovative product are bioequivalent to one another.

CONCLUSIONS

Two generic formulations that meet regulatory approval requirements for generics, by being bioequivalent to the innovative AED, may not be bioequivalent to one another. Additional BE criteria are needed for a formulation switch, particularly in epilepsy, where a breakthrough seizure may change a patient's status from seizure-free to refractory.

Off-patent generic medicines vs. off-patent brand medicines for six reference drugs: a retrospective claims data study from five local healthcare units in the Lombardy Region of Italy

The scientific documentation supporting the potential clinical and economic benefits of a growing use of off-patent generic drugs in clinical practice seems to be limited in Italy as yet.

METHODS

We compared differences in outcomes between off-patent generic drugs and off-patent brand drugs in real clinical practice. The outcomes were: persistence and compliance with therapy, mortality, and other health resources consumption (hospitalizations, specialist examinations, other drugs) and total costs. Retrospective analysis was carried out by using the administrative databases of five Local Healthcare Units (ASLs - Aziende Sanitarie Locali) in the Lombardy Region of Italy. Data from the five ASLs were aggregated through a meta-analysis, which produced an estimate indicator of the mean or percentage difference between the two groups (branded vs. generic) and their respective significance tests. The therapeutic areas and studied drugs were: diabetes: metformin - A10BA02; hypertension: amlodipine - C08CA01; dyslipidemia: simvastatin - C10AA01; psychiatry: sertraline - N06AB06; cardiology: propafenone - C01BC03; osteoporosis: alendronate - M05BA04.

RESULTS

The 5 Local Healthcare Units (ASL) represent a population of 3,847,004 inhabitants. The selected sample included 347,073 patients, or 9.02% of the total ASL population; 67% of the patients were treated with off-patent brand drugs. The average age was 68 years, with no difference between the two groups. After 34 months of observation, compliance and persistence were in favor to generic drugs in all therapeutic areas and statistically significant in the metformin, amlodipine, simvastatin, and sertraline groups. The clinical outcomes (hospitalizations, mortality, and other health costs) show no statistically significant differences between off-patent generic vs. off-patent brand medicines.

CONCLUSIONS

Off-patent generic drugs appear to be a therapy option of choice in Italy as well, based on clinical outcomes and economic consequences, both for the National Health Service and patients, considering that the price difference between brand and generic drugs is completely charged on patients.

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

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

Safety and efficacy of generic drugs with respect to brand formulation

Generic drugs are equivalent to the brand formulation if they have the same active substance, the same pharmaceutical form and the same therapeutic indications and a similar bioequivalence respect to the reference medicinal product. The use of generic drugs is indicated from many countries in order to reduce medication price. However some points, such as bioequivalence and the role of excipients, may be clarified regarding the clinical efficacy and safety during the switch from brand to generic formulations. In conclusion, the use of generic drugs could be related with an increased days of disease (time to relapse) or might lead to a therapeutic failure; on the other hand, a higher drug concentration might expose patients to an increased risk of dose-dependent side-effects.

Confidence in generic drug substitution

Patients should have confidence that the generic drugs they are prescribed in the United States can be effectively substituted for the brand product or another generic product. Through new bioequivalence study designs for narrow therapeutic index (NTI) drugs and postapproval studies of generic substitution, the US Food and Drug Administration's (FDA's) ongoing generic drug regulatory science activities are designed to ensure successful generic substitution for all drug products.

[Generic substitution in primary care in 2011: differences according to pharmacological classes?]

BACKGROUND

Generic substitution has been permitted for several years in France and is promoted in order to reduce health expenditures. However, reluctance concerning use of generic drugs exists for different reasons: suspicions about their efficacy and/or safety, differences in content (excipients) and discussions about bioequivalency. The aim of our study was to determine whether or not the substitution ratio differs according to pharmacological classes used in primary care.

METHODS

We conducted a descriptive study in the French Health Insurance Database using reimbursement data on drugs prescribed and delivered in the Midi-Pyrénées administrative district between March 2010 and March 2011. We selected different pharmacological classes largely used in primary care. For each class, a substitution ratio was calculated (DDD of generics delivered/DDD of brand name plus generics). A Chi(2) test was used in order to detect a difference between these substitution ratios.

RESULTS

The global substitution ratio was 72.32%. Values varied from 28.36% for thyroid hormones to 90.39% for antibiotics, with significant statistical difference (P<0.001). The substitution ratio was less than 50% for thyroid hormones (28.36%) and antiepileptics (45.28%). Higher substitution ratios were observed for protein pump inhibitors (88.81%), statins (87.81%), antidepressors (87.37%) and diuretics (86.1%).

CONCLUSION

This study highlights major differences in terms of the generic substitution ratio between different pharmacological classes. This difference can be explained in part by published guidelines. Further studies are needed to ascertain the precise point of view of patients, general practitioners and pharmacists concerning this issue.

Brand name versus generic drugs: the ethical quandary in caring for our sophisticated patients while trying to reduce health-care costs: facts and controversies

Medical ethics are the values and guidelines that govern decisions made in medical practice. Four prima facie moral principles can serve as a framework to help physicians analyze problems and make ethical decisions: (1) respect for autonomy, (2) beneficence, (3) non-maleficence, and (4) justice. With the cost of health care rising, all parties involved in the delivery of health care need to work to reduce costs, while continuing to provide quality care to our patients. One mechanism to reduce costs is to increase utilization of generic medications in daily practice, but there are many ethical issues inherent in utilizing brand name versus generic medications in dermatology.

Generics, chemisimilars and biosimilars: is clinical testing fit for purpose?

The effectiveness and safety of generic drugs are backed by sound physicochemical control and regulatory bioequivalence acceptance criteria. Statistical testing of bioequivalence, comparing the pharmacokinetic profiles of the test and reference products, was made possible by modern drug assays. When the pharmacokinetic profile correlates with the dose, such comparisons show assay sensitivity and readily detect differences in dose. For large biological molecules, different manufactured batches cannot be validated using pharmacokinetic data alone. For these biosimilars, there is a three-stage assessment of pharmaceutical quality, laboratory testing and clinical data. This approach has also been applied to certain chemical products, termed 'chemisimilars', which have variable or complex synthesis of the active substance, or complex formulation, or a complex delivery device. Although there may be no detectable difference between the test and reference on clinical testing, many of the outcome measures are insensitive to even large differences in dose. For testing to be fit for purpose it should distinguish important dose differences, but many clinical tests of chemisimilars and biosimilars do not. As pharmacokinetic and pharmacodynamic technology advances, the trend of replacing dose-insensitive clinical trial data with equivalence tests that show assay sensitivity can be expected to continue.

International guidelines for bioequivalence of systemically available orally administered generic drug products: a survey of similarities and differences

The objective of this article is to discuss the similarities and differences among bioequivalence approaches used by international regulatory authorities when reviewing applications for marketing new generic drug products which are systemically active and intended for oral administration. We focused on the 13 jurisdictions and organizations participating in the International Generic Drug Regulators Pilot. These are Australia, Brazil, Canada, China, Chinese Taipei, the European Medicines Association, Japan, Mexico, Singapore, South Korea, Switzerland, the USA, and the World Health Organization. We began with a comparison of how the various jurisdictions and organizations define a generic product and its corresponding reference product. We then compared the following bioequivalence approaches: recommended bioequivalence study designs, method of pharmacokinetic calculations and bioequivalence acceptance limits, recommendations for modifying bioequivalence study designs and limits for highly variable drugs and narrow therapeutic index drugs, provisions for waiving bioequivalence study requirements (granting biowaivers), and implementation of the Biopharmaceutics Classification System. We observed that, overall, there are more similarities than differences in bioequivalence approaches among the regulatory authorities surveyed.

Management of advanced lung cancer in resource-constrained settings: a perspective from India

Advanced lung cancer (LC) is an important cause of cancer-related morbidity and mortality in resource-constrained settings (RCSs). Cytological/pathological confirmation of diagnosis of LC is essential prior to treatment initiation for ruling out mimickers such as pulmonary tuberculosis. Accurate staging is necessary for optimal management, and investigations should be prioritized based on availability and cost-effectiveness. Platinum-based doublet chemotherapy remains the standard of care for advanced LC. Cost of therapy, lack of medical insurance and frequency of visits are important determinants of treatment regimen. EGF receptor mutation testing may not be readily available in RCSs and chemotherapy should be preferred for unselected patients with advanced non-small-cell lung cancer. Generic drugs may be more affordable than innovator brands. Treatment efficacy should be assessed with traditional end points (survival and objective response rates) as well as those relevant to RCSs (quality of life, toxicity profile and healthcare facility utilization). Issues related to LC treatment in first- and subsequent-line settings in RCSs are discussed in detail in this evidence-based review.

Generic substitution of antiepileptic drugs: What's a clinician to do?

Generic substitution of antiepileptic drugs remains a controversial area without a clear consensus to guide clinicians. The US Food and Drug Administration (FDA) requires rigorous testing of generic products and states that all approved products are interchangeable. FDA studies involve single doses in normal subjects so may not represent the performance of generic products in people with epilepsy. Physician surveys, case reports, and retrospective pharmacy database analyses suggest that antiepileptic drug generic substitution is associated with more health problems and high switchback rates, but these studies have insufficient detail on seizure control and blood levels. Several ongoing prospective randomized trials with rigorous pharmacokinetic methods aim to provide more data for decision-making.

A review of the differences and similarities between generic drugs and their originator counterparts, including economic benefits associated with usage of generic medicines, using Ireland as a case study

Generic medicines are those where patent protection has expired, and which may be produced by manufacturers other than the innovator company. Use of generic medicines has been increasing in recent years, primarily as a cost saving measure in healthcare provision. Generic medicines are typically 20 to 90% cheaper than originator equivalents. Our objective is to provide a high-level description of what generic medicines are and how they differ, at a regulatory and legislative level, from originator medicines. We describe the current and historical regulation of medicines in the world's two main pharmaceutical markets, in addition to the similarities, as well as the differences, between generics and their originator equivalents including the reasons for the cost differences seen between originator and generic medicines. Ireland is currently poised to introduce generic substitution and reference pricing. This article refers to this situation as an exemplar of a national system on the cusp of significant health policy change, and specifically details Ireland's history with usage of generic medicines and how the proposed changes could affect healthcare provision.

Implementation of a reference-scaled average bioequivalence approach for highly variable generic drug products by the US Food and Drug Administration

Highly variable (HV) drugs are defined as those for which within-subject variability (%CV) in bioequivalence (BE) measures is 30% or greater. Because of this high variability, studies designed to show whether generic HV drugs are bioequivalent to their corresponding HV reference drugs may need to enroll large numbers of subjects even when the products have no significant mean differences. To avoid unnecessary human testing, the US Food and Drug Administration's Office of Generic Drugs developed a reference-scaled average bioequivalence (RSABE) approach, whereby the BE acceptance limits are scaled to the variability of the reference product. For an acceptable RSABE study, an HV generic drug product must meet the scaled BE limit and a point estimate constraint. The approach has been implemented successfully. To date, the RSABE approach has supported four full approvals and one tentative approval of HV generic drug products.

Ezogabine: An Evaluation of Its Efficacy and Safety as Adjunctive Therapy for Partial-Onset Seizures in Adults

Objective:

To evaluate the safety, efficacy, pharmacokinetics, pharmacodynamic properties, and clinical application of ezogabine (retigabine. INN), an antiepileptic drug approved in 2011.

Data Sources:

Published data from in vitro, animal, and clinical studies were obtained from PubMed and CINAHL searches, from January 1980 to March 31, 2012. Other relevant data regarding the safety and efficacy of ezogabine were obtained from the Food and Drug Administration and the European Medication Agency Web sites.

Study Selection and Data Extraction:

Selected articles were prospective in vitro, animal, and controlled clinical studies of ezogabine. Non-English-language articles were excluded.

Data Synthesis:

In vitro and animal studies show that ezogabine activates voltage-gated potassium channels, leading to reduction of seizure frequency by inhibiting hyperexcitability activity in the central nervous system. Additionally, ezogabine enhances γ-aminobutyric acid (GABA) activity and de novo GABA synthesis. Eight clinical studies of ezogabine have been published, 5 being Phase 1 clinical trials in healthy subjects and 3 being Phase 3 clinical trials in patients with pharmacoresistant partial-onset seizures. Phase 3 clinical trials demonstrated the safety and efficacy of ezogabine in patients with partial-onset seizures.

Conclusions:

Clinical trials have shown that ezogabine is efficacious as an adjunctive agent in patients with pharmacoresistant partial seizures. Careful monitoring of drug interactions and adverse reactions is necessary. While ezogabine is efficacious (or partial seizures, its precise role in the management of patients with epilepsy is yet to be determined.

Generic substitution of lamotrigine among medicaid patients with diverse indications: a cohort-crossover study

BACKGROUND

Controversy exists about the safety of substituting generic antiepileptic drugs (AEDs). Lamotrigine, the prototypical newer AED, is often used for psychiatric and neurological conditions other than epilepsy. The safety of generic substitution of lamotrigine in diverse populations of AED users is unclear.

OBJECTIVE

The objective of this study was to evaluate potential associations between generic substitution of lamotrigine and adverse consequences in a population of diverse users of this drug.

STUDY DESIGN

This study was a retrospective cohort-crossover design using state Medicaid claims data from July 2006 through June 2009.

METHODS

Subjects were included in the cohort if they converted from brand to generic lamotrigine and had 2 years of lamotrigine use prior to conversion. The frequency of emergency department (ED) visits, hospitalizations and condition-specific ED visits or hospitalizations were recorded in the 60 days immediately following the conversion to generic lamotrigine, then compared with the incidence of the same events during a randomly selected time period indexed to one of the patient's past refills of branded lamotrigine. Multivariate conditional logistic regression was used to quantify the association between generic conversion and health services utilization while controlling for changes in lamotrigine dose and concurrent drug use.

RESULTS

Of the 616 unique subjects included in this analysis, epilepsy was the most common diagnosis (41%), followed by bipolar disorder (32%), pain (30%) and migraine (18%). Conversion to generic lamotrigine was not associated with a statistically significant increase in the odds of an ED visit (adjusted odds ratio [AOR] = 1.35; 95% confidence interval [CI] 0.92, 1.97), hospitalization (AOR = 1.21; 95% CI 0.60, 2.50) or condition-specific encounter (AOR 1.75; 95 CI 0.87, 3.51).

CONCLUSIONS

A statistically significant increase in ED visits, hospitalizations or condition-specific encounters was not observed following the switch from brand to generic lamotrigine, although a type II error cannot be ruled out.

Generic drugs in dermatology: part I

The cost of health care in the United States is increasing. In order to help control these rising costs, all parties involved in the delivery of health care, including dermatologists, need to be part of the solution of ethically reducing the cost of delivery of care. One potential means of meeting this goal is to increase the use of generic medications in daily practice. Generic medications can offer equally efficacious therapy at significantly lower prices, which can translate into large scale savings for the individual patient, the payer, and the overall health care system. Herein we provide an overview of new drug development, review the history of the generic drug industry, describe how generic drugs are approved by the US Food and Drug Administration, and define the concepts of bioequivalence and therapeutic equivalence. In part II, we explore various factors impacting generic drug use, provide cost analyses of dermatologic brand name and generic drugs, and review data addressing potential differences in the effectiveness of brand name versus generic drugs in dermatology. The cost of brand name and generic medications is highly variable by pharmacy, state, and payer. We used one source (www.drugstore.com) as an example and for consistency across all medications discussed herein. Prices included here may not reflect actual retail prices across the United States.

Use of partial AUC to demonstrate bioequivalence of Zolpidem Tartrate Extended Release formulations

PURPOSE

FDA's bioequivalence recommendation for Zolpidem Tartrate Extended Release Tablets is the first to use partial AUC (pAUC) metrics for determining bioequivalence of modified-release dosage forms. Modeling and simulation studies were performed to aid in understanding the need for pAUC measures and also the proper pAUC truncation times.

METHODS

Deconvolution techniques, In Vitro/In Vivo Correlations, and the CAT (Compartmental Absorption and Transit) model were used to predict the PK profiles for zolpidem. Models were validated using in-house data submitted to the FDA. Using dissolution profiles expressed by the Weibull model as input for the CAT model, dissolution spaces were derived for simulated test formulations.

RESULTS

The AUC(0-1.5) parameter was indicative of IR characteristics of early exposure and effectively distinguished among formulations that produced different pharmacodynamic effects. The AUC(1.5-t) parameter ensured equivalence with respect to the sustained release phase of Ambien CR. The variability of AUC(0-1.5) is higher than other PK parameters, but is reasonable for use in an equivalence test.

CONCLUSIONS

In addition to the traditional PK parameters of AUCinf and Cmax, AUC(0-1.5) and AUC(1.5-t) are recommended to provide bioequivalence measures with respect to label indications for Ambien CR: onset of sleep and sleep maintenance.

Deficiencies of the FDA in evaluating generic formulations: addressing narrow therapeutic index drugs

Generic drugs represent a significant portion of the medical arsenal in treating disease. As copies of originator drugs, these drugs have been permitted abbreviated approval under the Hatch-Waxman Act. Yet with the current cost focus upon generic formulations, potential safety issues with generics have arisen. Although there is an established criterion of "bioequivalence" that generic formulations must demonstrate, narrow-therapeutic index drugs for sensitive clinical circumstances such as epilepsy, antiplatelet therapies, and mental health treatments may require different regulatory treatment than other generic drugs. Further, in these circumstances, differences in generic formulations may lead to adverse clinical outcomes due to less stringent bioequivalence tolerances. Yet there is no mandate for comparison between different generic formulations. Countries outside the United States advocate for narrowing tolerance ranges for these high risk health situations and the drugs for their treatment. We argue in this paper that additional patient safety matters must be taken into account for narrow therapeutic disease drugs, and regulatory bodies should emphasize greater tightness in bioequivalence before these narrow-therapeutic drug generic formulations are approved.

Generic Substitution of Antiepileptic Drugs: A Systematic Review of Prospective and Retrospective Studies

Objective:

To systematically review the literature on generic antiepileptic drugs (AEDs), evaluate the efficacy and safety of generic AED substitution, and perform pharmacokinetic (PK) analysis using the American Academy of Neurology (AAN) scheme to classify evidence.

Data Sources:

PubMed and Cumulative Index to Nursing and Allied Health Literature searches from January 1, 1980, to October 15, 2010, were performed using the search terms anticonvulsant, antiepileptic drug, carbamazepine, divalproex, ethosuximide, gabapentin, lamotrigine, levetiracetam, oxcarbazepine, phénobarbital, Phenytoin, primidone, topiramate, valproate, valproic acid, and zonisamide; bioavailability, bioequivalence, bioequivalency, bioequivalent, and substitution; and generic.

Study Selection and Data Extraction:

Retrospective and prospective controlled studies of generic substitution of AEDs were included in the review. Non-English-language articles and uncontrolled clinical studies were excluded, Published articles were categorized using the AAN criteria for systematic reviews.

Data Synthesis:

We identified 156 articles. Of these, 20 met our inclusion criteria; 7 were retrospective studies, 6 were prospective studies in patients with epilepsy, and 7 were prospective studies in healthy subjects. All articles were rated Class I to Class III, using AAN criteria. The retrospective studies were categorized as Class III and showed a significant relationship between generic substitution and increased use of health care resources because of seizures or AED toxicity. Prospective studies were categorized as Class I, II, and III. Prospective studies in patients showed no differences between brand and generic drugs in PK parameters of bioequivalence. Three prospective studies in healthy subjects reported significant differences in maximum drug concentrations. Comparison of brand and generic drugs revealed no significant difference in seizure frequency; however, some prospective studies showed significant differences in PK parameters, primarily those not used for bioequivalence determinations.

Conclusions:

There is inconsistency between retrospective and prospective studies of generic AED substitution. The highest levels of evidence indicate that there should not be a problem with generic substitution, although some patients are more prone to problems with the generic products. Some evidence suggests that switches between multiple generic AED products in certain individuals may be problematic.

An empirical review of major legislation affecting drug development: past experiences, effects, and unintended consequences

CONTEXT

With the development of transformative drugs at a low point, numerous commentators have recommended new legislation that uses supplementary market exclusivity as an incentive to promote innovation in the pharmaceutical market.

METHODS

This report provides an historical perspective on proposals for encouraging drug research. Four legislative programs have been primarily designed to offer market exclusivity to promote public health goals in the pharmaceutical or biomedical sciences: the Bayh-Dole Act of 1980, the Orphan Drug Act of 1983, the Hatch-Waxman Act of 1984, and the pediatric exclusivity provisions of the FDA Modernization Act of 1997. I reviewed quantitative and qualitative studies that reported on the outcomes from these programs and evaluated the quality of evidence generated.

FINDINGS

All four legislative programs generally have been regarded as successful, although such conclusions are largely based on straightforward descriptive reports rather than on more rigorous comparative data or analyses that sufficiently account for confounding. Overall, solid data demonstrate that market exclusivity incentives can attract interest from parties involved in drug development. However, using market exclusivity to promote innovation in the pharmaceutical market can be prone to misuse, leading to improper gains. In addition, important collateral effects have emerged with substantial negative public health implications.

CONCLUSIONS

Using market exclusivity to promote pharmaceutical innovation can lead to positive outcomes, but the practice is also characterized by waste and collateral effects. Certain practices, such as mechanisms for reevaluation and closer ties of incentives programs to public health outcomes, can help address these problems.

A comparative evaluation of price and quality of some branded versus branded-generic medicines of the same manufacturer in India

Objective:

To compare and evaluate the price and quality of “branded” and branded-generic equivalents of some commonly used medicines manufactured by the same pharmaceutical company in India.

Materials and Methods:

Five commonly used medicines: alprazolam, cetirizine, ciprofloxacin, fluoxetine, and lansoprazole manufactured in branded and branded-generic versions by the same company were selected. Price-to-patient and price-to-retailers were found for five “pair” of medicines. Both quantitative and qualitative analysis were performed following the methods prescribed in the Indian Pharmacopoeia 2007 on five pair of medicines. The tests performed were identification test, chemical composition estimation test, uniformity of contents test, uniformity of weight, and dissolution studies.

Main Outcome Measures:

Price-to-patient, retailer mark-up and qualitative analysis of branded and branded-generic medicines.

Results:

Retailer margin for five branded medicines were in the range of 25-30% but for their branded-generics version manufactured by the same company it was in the range of 201-1016%. Price-to-patient for the branded version of cetirizine, fluoxetine, ciprofloxacin, lansoprazole, and alprozolam was higher by 41%, 33%, 0%, 14%, and 31% than branded-generic. Both versions of five medicines were within their permissible range for all the quantitative and qualitative parameters as prescribed in Indian Pharmacopoeia.

Conclusion:

Difference in price-to-patient was not as huge as it is expected for generics but margins for retailer were very high for branded-generics. Quality of branded-generics is same as for their branded version. The study highlights the need to modify the drug price policy, regulate the mark-ups in generic supply chain, conduct and widely publicize the quality testing of generics for awareness of all stakeholders.

Physician perceptions about generic drugs

BACKGROUND

With constrained health-care resources, there is a need to understand barriers to cost-effective medication use.

OBJECTIVE

To study physician perceptions about generic medications.

METHODS

Physicians used 5-point Likert scales to report perceptions about cost-related medication nonadherence, the efficacy and quality of generic medications, preferences for generic use, and the implications of dispensing medication samples. Descriptive statistics were used to assess physician perceptions and logistic regression models were used to evaluate predictors of physician perceptions.

RESULTS

Among the invited sample, 839 (30.4%) responded and 506 (18.3%) were eligible and included in the final study population. Over 23% of physicians surveyed expressed negative perceptions about efficacy of generic drugs, almost 50% reported negative perceptions about quality of generic medications, and more than one quarter do not prefer to use generics as first-line medications for themselves or for their family. Physicians over the age of 55 years were 3.3 times more likely to report negative perceptions about generic quality, 5.8 times more likely to report that they would not use generics themselves, and 7.5 times more likely to state that they would not recommend generics for family members (p < 0.05 for all). Physicians reported that pharmaceutical company representatives are the most common (75%) source of information about market entry of a generic medication. Almost half of the respondents expressed concern that free samples may adversely affect subsequent affordability, yet two thirds of respondents provide free samples.

CONCLUSIONS

A meaningful proportion of physicians expressed negative perceptions about generic medications, representing a potential barrier to generic use. Payors and policymakers trying to encourage generic use may consider educational campaigns targeting older physicians.

Cost effectiveness of letrozole versus anastrozole in postmenopausal women with HR+ early-stage breast cancer

BACKGROUND

The Breast International Group (BIG) 1-98 and Arimidex, Tamoxifen Alone or in Combination (ATAC) trials demonstrated that, in postmenopausal women with hormone receptor positive (HR+) early-stage breast cancer, 5 years of initial adjuvant endocrine therapy with letrozole or anastrozole is superior to tamoxifen. With expected generic availability of anastrozole in July 2010 and letrozole in June 2011, there may be financial pressures prior to letrozole's generic availability to start treatment-naïve patients on anastrozole vs. letrozole or to switch patients already receiving letrozole to anastrozole.

METHODS

A Markov model was used to estimate cost per quality-adjusted life-year (QALY) gained with letrozole vs. anastrozole from the US healthcare system perspective. Cost effectiveness was examined separately in treatment-naïve patients and in patients already receiving letrozole. For the latter, cost effectiveness of continued letrozole vs. therapeutic substitution (TS) to generic anastrozole was evaluated separately in cohorts defined on years of endocrine therapy remaining. TS to generic anastrozole was assumed to result in an additional 5% of patients discontinuing endocrine therapy. Probabilities of distant recurrence and death were taken from reports of BIG 1-98, ATAC, the Early Breast Cancer Trialists' Collaborative Group meta-analysis of tamoxifen, and other published sources. Carry-over effects of aromatase inhibitors were assumed to be proportional to treatment duration. Costs of aromatase inhibitors were assumed to decline by 75% with generic availability.

RESULTS

In treatment-naïve patients, total expected lifetime costs are $3916 greater with letrozole vs. anastrozole. However, initiation of treatment with letrozole results in a gain of 0.15 QALYs. Cost per QALY gained with letrozole vs. anastrozole is $25,846. In patients already receiving letrozole, the increase in total expected lifetime costs with continued letrozole vs. TS to anastrozole is between $4200 and $4500 in all cohorts. QALYs gained with letrozole range from 0.21 in those with 4 years of endocrine therapy remaining to 0.13 in those with 1 year of therapy remaining. Cost per QALY gained ranges from $20,276 to $34,356.

CONCLUSION

For postmenopausal women with HR+ early-stage breast cancer, letrozole is more likely to be cost effective vs. anastrozole in treatment-naïve patients and in patients already receiving letrozole. Limitations of the study include a lack of direct evidence comparing letrozole and anastrozole and lack of data on rates of discontinuation due to therapeutic substitution with aromatase inhibitors.

Refilling and switching of antiepileptic drugs and seizure-related events

We sought to estimate the risk of seizure-related events associated with refilling prescriptions for antiepileptic drugs (AEDs) and to estimate the effect of switching between brand-name and generic drugs or between two generic versions of the same drug. We conducted a case-crossover study using health-care databases from British Columbia, Canada, among AED users who had an emergency room visit or hospitalization for seizure (index seizure-related event), defined using International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9) codes 345.xx (epilepsy and recurrent seizures) and 780.3x (convulsions), between 1997 and 2005. AED prescription refilling itself was associated with 2.3-fold elevated odds of seizure-related events when the refill occurred within 21 days before the index event (odds ratio (OR) 2.31; 95% confidence interval (CI) 1.56-3.44). The OR was 2.75 (95% CI 0.88-8.64) for refills that involved switching, yielding a refill-adjusted OR for switching of 1.19 (95% CI 0.35-3.99). Refilling the same AED prescription was associated with an elevated risk of seizure-related events whether or not the refill involved switching from a brand-name to a generic product.

Topics in transplantation medicine for general nephrologists

Before transplantation, the general nephrologist is the primary resource for potential kidney transplantation recipients. After transplantation, the general nephrologist is increasingly managing transplant medications and complications. We provide evidence-based management strategies for common clinical issues. Linking our approach with the data allows the clinician to explore each subject in greater depth to tailor care to individual patients.