Antimicrobial activity and pathogen mutation prevention of originator and generics of cefepime, linezolid and piperacillin/tazobactam against clinical isolates of Staphylococcus aureus

OBJECTIVES

Although generic medicinal products are required to have the same qualitative and quantitative composition of the active substance as their reference originator product, patients and health care professionals express concerns about their interchangeability and safety. Therefore, the present study investigated the antimicrobial activity and pathogen mutation prevention of original and generic cefepime, linezolid and piperacillin/tazobactam against Staphylococcus aureus.

METHODS

Two generic formulations of cefepime, linezolid and piperacillin/tazobactam were tested against their respective originator products. Susceptibility testing was performed with twenty-one clinical isolates of S. aureus and ATCC-29213 using broth microdilution. Time kill curves (TKC) were performed with ATCC-29213 at drug concentrations above and below the respective minimum inhibitory concentrations (MIC). Mutation prevention concentration was determined for each drug formulation against ATCC-29213. All experiments were performed in triplicate. Mutant colonies from mutation prevention concentration (MPC) experiments were genotypically tested by sequence analysis.

RESULTS

MIC ratios between contiguous originator and generic drugs were similar for each isolate. No visual differences were observed in TKCs between originator and generic substances. The MPC did not differ between different formulations of the same substance. Although sequence analysis of mutant colonies revealed genomic differences compared with the original ATCC-29213, no differences in mutation frequencies were observed between clinical isolates and ATCC-29213 treated with originator or generic substances.

CONCLUSIONS

Similar antimicrobial activity and pathogen mutation prevention was observed between contiguous substances. These results support the interchangeability of generic and originator drug formulations with the same active ingredient.

Comparative Effectiveness of Generic vs Brand-Name Levothyroxine in Achieving Normal Thyrotropin Levels

IMPORTANCE

Whether the use of generic vs brand levothyroxine affects thyrotropin levels remains unclear.

OBJECTIVE

To compare the effectiveness of generic vs brand levothyroxine in achieving and maintaining normal thyrotropin levels among new users.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective, 1:1 propensity score-matched longitudinal cohort study used the OptumLabs Data Warehouse administrative claims database linked to laboratory results from commercially insured and Medicare Advantage enrollees throughout the United States. Eligible patients were adults (aged ≥18 years) with thyrotropin levels ranging from 4.5 to 19.9 mIU/L who initiated use of generic or brand-name levothyroxine from January 1, 2008, to October 1, 2017. Data were analyzed from August 13, 2018, to October 25, 2019.

EXPOSURE

Patients received generic or brand-name levothyroxine.

MAIN OUTCOMES AND MEASURES

Proportion of patients with normal vs markedly abnormal thyrotropin levels (<0.1 or >10 mIU/L) within 3 months and with stable thyrotropin levels within 3 months after the thyrotropin value fell into the normal range.

RESULTS

A total of 17 598 patients were included (69.0% female; 74.0% White; mean [SD] age, 55.1 [16.0] years), of whom 15 299 filled generic and 2299 filled brand-name levothyroxine prescriptions during the study period. Among 4570 propensity score-matched patients (mean [SD] age, 50.3 [13.8] years; 3457 [75.6%] female; 3510 [76.8%] White), the proportion with normal thyrotropin levels within 3 months of filling levothyroxine prescriptions was similar for patients who received generic vs brand-name levothyroxine (1722 [75.4%; 95% CI, 71.9%-79.0%] vs 1757 [76.9%; 95% CI, 73.4%-80.6%]; P = .23), as was the proportion with markedly abnormal levels (94 [4.1%; 95% CI, 3.4%-5.0%] vs 88 [3.9%; 95% CI, 3.1%-4.7%]; P = .65). Among 1034 propensity score-matched patients who achieved a normal thyrotropin value within 3 months of initiation of levothyroxine, the proportion maintaining subsequent normal thyrotropin levels during the next 3 months was similar for patients receiving generic vs brand-name levothyroxine (427 [82.6%] vs 433 [83.8%]; P = .62).

CONCLUSIONS AND RELEVANCE

Initiation of generic vs brand-name levothyroxine formulations was associated with similar rates of normal and stable thyrotropin levels. These results suggest that generic levothyroxine as initial therapy for mild thyroid dysfunction is as effective as brand-name levothyroxine.

Evaluation of Generic versus Original Prostaglandin Analogues in the Treatment of Glaucoma: A Systematic Review and Meta-Analysis

TOPIC

An evaluation of the efficacy and tolerability of generic prostaglandin analogues (PGAs) compared with their original counterpart.

CLINICAL RELEVANCE

This systematic review was initiated to enlighten ophthalmologists and patients in the use of original and generic ophthalmic solutions.

METHODS

A literature search was conducted on PubMed, EMBASE, MEDLINE, Clinicaltrials.gov, and the World Health Organization International Clinical Trials Registry Platform, along with a manual search, from the marketing of the first PGA, latanoprost, in 1995 to the present. Randomized controlled trials comparing an original PGA with its generic counterpart were included. The last literature search was conducted in June 2019. Risk of bias was assessed by 2 independent reviewers using the Cochrane Handbook for Systematic Reviews Tool. The primary outcome was reduction of intraocular pressure (IOP) from baseline. Secondary outcomes included tolerability, ocular surface health, quality of life, disease progression, and cost-effectiveness. Meta-analysis of the primary outcome was planned.

RESULTS

Of 385 screened articles, 6 were included in a broad characterization and in the meta-analysis. A total of 619 patients were enrolled. The duration of the studies ranged from 3 to 16 weeks. Meta-analysis of all 6 studies denied any clinically significant difference in efficacy, and the 95% confidence interval included nil (-0.50 to 0.04 mmHg). The evidence was of moderate certainty because of unclear or high risk of bias in all studies. There were no reported differences in tolerability.

CONCLUSIONS

Trials comparing original and generic PGAs did not show a clinically significant difference in IOP-lowering effect or tolerability. However, the quality of the trials is suboptimal. Overall, there is uncertainty, and further research is needed to confirm equivalence.

Knowledge, attitude, and practice of pharmacy professionals on generic medicines in Eastern Ethiopia: A cross-sectional study

Background

Generic medicines are similar to innovator medicine in terms of safety, quality, efficacy, dosage form, strength, and route of administration. They have the same therapeutic use to innovator medicines and available at a far lower price. However, health professionals' poor knowledge and attitude may limit its utilization. The present study aimed at assessing the knowledge, attitude, and practice of pharmacy professionals towards generic medicines in Harar city, Eastern Ethiopia.

Methods

A cross-sectional survey was conducted among community pharmacists in Harar city. A self-administered thirty-three item questionnaire on Knowledge, attitude, and practice of community pharmacists was utilized. Logistic regression analysis was performed to predict the determinants of knowledge and attitude of pharmacists. An odds ratio at 95% confidence interval along with a p-value < 0.05 was considered significant.

Results

Among 80 community pharmacists’ approached, 74 completed the survey, providing a response rate of 92.5%. Sixty-seven percent of the respondents knew that generic drugs are bioequivalent to brand drugs and claimed generic medicines are cheaper (86.5%). Nearly half (48.6%) of participants believe that generic medicines are less effective and slower in the onset of action (58.1%). More than half (54.1%) of study participants revealed their lack of belief in generic medicine as a factor hindering the selection and dispensing of generic medicines. In multivariate logistic regression, experience in community pharmacy practice (Adjusted odds ratio (AOR = 2.18, 95%CI: 1.21–63.1) and Sex (AOR = 3.88, 95%CI: 2.12–39.62) were significantly associated with knowledge and attitude toward generic medicines, respectively.

Conclusion

The current study revealed that there is a gap in the knowledge and attitude of community pharmacists towards generic and brand drugs. More than averages of the respondents have known the concept of generic medicine including their right to perform generic substitution and had a positive attitude toward generics. Female pharmacists were more likely to have a positive attitude and the overall knowledge was higher in those who have more than 5 years of work experience.

Bioequivalence and pharmacodynamics of a generic dabigatran etexilate capsule in healthy Chinese subjects under fasting and fed conditions

To assess bioequivalence of a generic dabigatran etexilate capsule in healthy Chinese subjects under fasting and fed conditions. This was an open-label, single-center, randomized four-period crossover study with a 7-day washout period. A single oral dose of 150 mg generic dabigatran etexilate capsule (test drug) or a commercial dabigatran etexilate capsule (Pradaxa® , reference drug) was given to healthy volunteers under the fasting and fed conditions. Plasma concentrations of total and free dabigatran were detected using a validated HPLC-MS/MS method. A noncompartmental method was used for pharmacokinetic analysis and established coagulation assays were applied for pharmacodynamic analysis. The 90% CIs of the test/reference ratios of Cmax , AUC0-t , and AUC0-∞ for the total dabigatran concentration were 92.57%-106.58%, 91.63%-106.32%, and 92.54%-106.17%, respectively, under fasting condition, and 99.30%-110.74%, 98.58%-105.37%, and 97.75%-103.99%, respectively, under fed conditions. The 90% CIs of the ratios of the parameters for the free dabigatran were 93.18%-106.98%, 92.13%-107.10%, 92.89%-106.48%, respectively, under fasting condition, and 100.05%-110.89%, 99.37%-106.23%, 97.59%-103.98%, respectively, under the fed condition. Additionally, the upper limit of the 90% CIs for σWT/σWR was below 2.5. There were no significant differences in the coagulation parameters including thrombin clotting time, activated partial thromboplastin time, and anti-IIa activity between the two preparations. The generic dabigatran etexilate capsule is bioequivalent to the brand-named product in healthy Chinese volunteers under fasting and fed conditions. The two products have comparable pharmacodynamic parameters, with a good safety profile. In addition, food intake influences absorption of both products in a similar way.

Comparison of In Vivo Pharmacokinetics and Pharmacodynamics of Vancomycin Products Available in Korea

PURPOSE

Few studies have been investigated the in vivo efficacy of generic vancomycin products available outside of the United States. In this study, we aimed to compare the in vivo pharmacokinetics (PK) and pharmacodynamics (PD) of five generic vancomycin products available in Korea with those of the innovator.

MATERIALS AND METHODS

The in vitro vancomycin purity of each product was examined using high-pressure liquid chromatography. Single-dose PK analyses were performed using neutropenic mice. The in vivo efficacy of vancomycin products was compared with that of the innovator in dose-effect experiments (25 to 400 mg/kg per day) using a thigh-infection model with neutropenic mice.

RESULTS

Generic products had a lower proportion of vancomycin B (range: 90.3-93.8%) and a higher proportion of impurities (range: 6.2-9.7%) than the innovator (94.5% and 5.5%, respectively). In an in vivo single-dose PK study, the maximum concentration (C_max) values of each generic were lower than that of the innovator, and the geographic mean area under the curve ratios of four generics were significantly lower than that of the innovator (all p<0.1). In the thigh-infection model, the maximum efficacies of generic products reflected in maximal effect (E_max) values were not significantly different from the innovator. However, the PD profile curves of some generic products differed significantly from that of the innovator in mice injected with a high level of Mu3 (all p≤0.05).

CONCLUSION

Some generic vancomycin products available in Korea showed inferior PK and PD profiles, especially in mice infected with hetero-vancomycin-resistant Staphylococcus aureus.

Generic Substitution of Orphan Drugs for the Treatment of Rare Diseases: Exploring the Potential Challenges

Generic drugs are important components of measures introduced by healthcare regulatory authorities to reduce treatment costs. In most patients and conditions the switch from a branded drug to its generic counterpart is performed with no major complications. However, evidence from complex diseases suggests that generic substitution requires careful evaluation in some settings and that current bioequivalence criteria may not always be adequate for establishing the interchangeability of branded and generic products. Rare diseases, also called orphan diseases, are a group of heterogeneous diseases that share important characteristics: in addition to their scarcity, most are severe, chronic, highly debilitating, and often present in early childhood. Finding a treatment for a rare disease is challenging. Thanks to incentives that encourage research and development programs in rare diseases, several orphan drugs are currently available. The elevated cost of orphan drugs is a highly debated issue and a cause of limited access to treatment for many patients. As patent protection and the exclusivity period of several orphan drugs will expire soon, generic versions of orphan drugs should reach the market shortly, with great expectations about their impact on the economic burden of rare diseases. However, consistent with other complex diseases, generic substitution may require thoughtful considerations and may be even contraindicated in some rare conditions. This article provides an overview of rare disease characteristics, reviews reports of problematic generic substitution, and discusses why generic substitution of orphan drugs may be challenging and should be undertaken carefully in rare disease patients.

Nontherapeutic equivalence of a generic product of imipenem-cilastatin is caused more by chemical instability of the active pharmaceutical ingredient (imipenem) than by its substandard amount of cilastatin

Background

We demonstrated therapeutic nonequivalence of “bioequivalent” generics for meropenem, but there is no data with generics of other carbapenems.

Methods

One generic product of imipenem-cilastatin was compared with the innovator in terms of in vitro susceptibility testing, pharmaceutical equivalence, pharmacokinetic (PK) and pharmacodynamic (PD) equivalence in the neutropenic mouse thigh, lung and brain infection models. Both pharmaceutical forms were then subjected to analytical chemistry assays (LC/MS).

Results and conclusion

The generic product had 30% lower concentration of cilastatin compared with the innovator of imipenem-cilastatin. Regarding the active pharmaceutical ingredient (imipenem), we found no differences in MIC, MBC, concentration or potency or AUC, confirming equivalence in terms of in vitro activity. However, the generic failed therapeutic equivalence in all three animal models. Its E_max against S. aureus in the thigh model was consistently lower, killing from 0.1 to 7.3 million less microorganisms per gram in 24 hours than the innovator (P = 0.003). Against K. pneumoniae in the lung model, the generic exhibited a conspicuous Eagle effect fitting a Gaussian equation instead of the expected sigmoid curve of the Hill model. In the brain infection model with P. aeruginosa, the generic failed when bacterial growth was >4 log₁₀ CFU/g in 24 hours, but not if it was less than 2.5 log₁₀ CFU/g. These large differences in the PD profile cannot be explained by the lower concentration of cilastatin, and rather suggested a failure attributable to the imipenem constituent of the generic product. Analytical chemistry assays confirmed that, besides having 30% less cilastatin, the generic imipenem was more acidic, less stable, and exhibited four different degradation masses that were absent in the innovator.

Ophthalmologist and Optometrist Glaucoma Prescribing Patterns Based on 2015 Medicare Part D Data

PURPOSE

To determine differences in prescribing patterns of glaucoma drugs between ophthalmologists and optometrists in terms of (1) the proportions of generics prescribed when brand-name drugs were also available, (2) the relative proportions of drugs prescribed within a drug class, and (3) the relative frequency of all glaucoma drugs prescribed.

DESIGN

Cross-sectional study.

PARTICIPANTS

All ophthalmologists and optometrists in the United States who prescribed any of the 36 drugs studied through Medicare Part D in 2015.

METHODS

Outcome measures were calculated using Excel 2016 (Microsoft, Redmond, WA) based on the 2015 Medicare Part D Prescriber data. The total number of drug claims for 36 glaucoma drugs by all ophthalmologists and optometrists through Medicare Part D in 2015 was determined. These data were then used to calculate, for each drug class, the relative proportions of each drug prescribed by ophthalmologists and optometrists in addition to the proportion of claims that were for the generic drug when at least 1 brand-name alternative was available for both professions.

RESULTS

The difference between ophthalmologists' and optometrists' proportions of claims that were for generics when at least 1 brand-name drug was available was generally less than 1%, with both professions' patients receiving primarily generic drugs. However, patients of both ophthalmologists and optometrists use relatively low proportions of generic betaxolol, brimonidine, travoprost, and bimatoprost (approximately 46%, 58%, 1%, and 0% of claims were for these generics, respectively, when compared with brand-name drugs for both ophthalmologists and optometrists). Within each drug class, ophthalmologists and optometrists generally chose the same drug. Overall, ophthalmologists prescribed a wider range of drugs, but both ophthalmologists and optometrists prescribed latanoprost most often.

CONCLUSIONS

Ophthalmologists and optometrists exhibit similar clinical judgement when choosing a particular drug within a drug class. However, ophthalmologists tend to prescribe more drugs from a wider range of drug classes. Both ophthalmologists and optometrists could prescribe more generic betaxolol, brimonidine, travoprost, and bimatoprost, though generic bimatoprost only became available in 2015.

In vitro antibacterial susceptibility of different brands of oral levofloxacin 250 mg tablet against Staphylococcus aureus and Escherichia coli

Antibiotics are not only used in morbidity but also help in prevention of infection. The irrational use of broad spectrum antibiotics is now increasing the resistance against pathogens. This present study has been carried out to evaluate the in-vitro antibacterial effect of levofloxacin against clinical isolates. According to Clinical and Laboratory Standards Institute (CLSI) guidelines, minimum inhibitory concentrations 90% (MIC₉₀) of the levofloxacin tested were evaluated by an agar dilution method. Total 63 clinical isolates Staphylococcus aureus (n=34) and Escherichia coli (n=29) were collected from different hospitals at Karachi and were evaluated MIC90 of eleven different brands of levofloxacin tablet (250 mg). Levofloxacin (Reference) was tested against E.coli standard (American Type Culture Collection) (ATCC=25922) with (MIC₉₀; 0.03μg/ml) and compared with different eleven brands of levofloxacin tablets 250mg (MIC90; 0.5μg/ml -16.0μg/ml). Levofloxacin (Reference) sensitivity against S. aureus standard (ATCC=25923) is (MIC90; 0.12μg/ml) and similarly when it was compared with same levofloxacin tablets (MIC₉₀; 0.5-16.0μg/ml). It has been concluded by the present study, a large number of strains of bacteria have shown better bactericidal action of different brands of levofloxacin and nearly all commercialized drugs were appropriate for therapeutic use.

Generics for the Treatment of Hepatitis C in Monoinfected and HIV-coinfected Patients: Pros and Cons

The treatment of hepatitis C virus in monoinfected and HIV-coinfected patients has greatly changed over recent years as a result of the introduction of direct-acting antiviral agents (DAAs), which have revolutionized clinical outcomes and led to sustained virological response rates above 90-95%. The discovery of new molecules and the subsequent competition between pharmaceutical companies, together with the negotiated price policies pursued by many national health systems, have led to a gradual reduction in the cost of DAAs, and expand their use to an increasing number of patients, including those with mild liver damage. However, the cost of branded DAAs is still too high for many developing countries, and many patients are still left without therapy. In this context, the availability of generic DAAs certainly provides a major opportunity for further cost savings in industrialized countries and will ensure broader access to treatment elsewhere. However, their more widespread use must not lead to a reduction in pharmaceutical quality because this could result in serious clinical consequences, including high rat failures, and selection of drug resistance. It is therefore essential that all generic formulations of DAAs are pre-qualified by the World Health Organization, and that real-life studies are carried out to verify their pharmacokinetic bioequivalence (ideally in patients, and not just in healthy volunteers) and clinical effectiveness. In this regard, lessons from expanding access programs in the HIV field would be very helpful.

Differences in Peripheral Blood Lymphocytes between Brand-Name and Generic Tacrolimus Used in Stable Liver Transplant Recipients

OBJECTIVES

In this study, peripheral blood lymphocytes were compared between a brand-name and a generic tacrolimus group in stable liver transplant recipients.

SUBJECTS AND METHODS

Sixteen patients who underwent ABO-compatible living donor liver transplants between 2012 and 2013 and had stable graft function were included in this study. Ten patients received brand-name tacrolimus and 6 patients received generic tacrolimus. CD3, CD4, CD8, γδ, CD4+FoxP3+, and CD3-CD56+ T cells were analyzed in peripheral blood obtained preoperatively and 4, 8, 12, and 24 weeks after liver transplantation. Categorical variables were compared using a χ2 test or Fisher exact test, and continuous variables were compared using the Mann-Whitney U test.

RESULTS

Regarding the baseline and perioperative characteristics, there were no statistically significant differences between the 2 groups. Immunosuppression also was not different. Subtype analysis of T-cell populations carried out in parallel showed similar levels of CD3, CD4, CD8, and γδT cells with brand-name tacrolimus and generic tacrolimus in stable liver transplant recipients. However, the levels of CD4+Foxp3+ and CD3-CD56+ T cells were higher in the brand-name tacrolimus group than in the generic tacrolimus group 8 weeks after transplantation (p < 0.05).

CONCLUSIONS

The level of CD4+Foxp3+ T cells was higher in the brand-name tacrolimus group than in the generic tacrolimus group after transplantation. This finding showed that brand-name tacrolimus could have more potential immunosuppressive activity than generic tacrolimus regarding the contribution of CD4+Foxp3+ T cells to graft tolerance in liver transplant recipients.

A Bioequivalence Test by the Direct Comparison of Concentration-versus-Time Curves Using Local Polynomial Smoothers

In order to test if two chemically or pharmaceutically equivalent products have the same efficacy and/or toxicity, a bioequivalence (BE) study is conducted. The 80%/125% rule is the most commonly used criteria for BE and states that BE cannot be claimed unless the 90% CIs for the ratio of selected pharmacokinetics (PK) parameters of the tested to the reference drug are within 0.8 to 1.25. Considering that estimates of these PK parameters are derived from the concentration-versus-time curves, a direct comparison between these curves motivates an alternative and more flexible approach to test BE. Here, we propose to frame the BE test in terms of an equivalence of concentration-versus-time curves which are constructed using local polynomial smoother (LPS). A metric is presented to quantify the distance between the curves and its 90% CIs are calculated via bootstrapping. Then, we applied the proposed procedures to data from an animal study and found that BE between a generic drug and its brand name cannot be concluded, which was consistent with the results by applying the 80%/125% rule. However, the proposed procedure has the advantage of testing only on a single metric, instead of all PK parameters.

Clinical implications for substandard, nonproprietary medicines in multiple sclerosis: focus on fingolimod

Both proprietary and nonproprietary medicines are expected to undergo rigorous preapproval testing and both should meet stringent health authority regulatory requirements related to quality to obtain approval. Nonproprietary (also known as copy, or generic) medicines, which base their authorization and use on the proprietary documentation and label, are often viewed as a means to help lower the cost and, thus, increase patient access. If these medicines fail to meet quality standards, such as good manufacturing practice and bioequivalence (in humans), they are then defined as substandard copies and can pose serious risks to patients in terms of safety and efficacy. Potentially noncontrolled or different manufacturing process and excipients in nonproprietary medicines may result in poor batch-to-batch reproducibility (accurate and consistent quantity of each ingredient in each capsule/tablet) and lower quality. Substandard, nonproprietary copies of medicines that are immunomodulatory or immunosuppressive are of concern to patients due to their possible untoward safety and lack of efficacy events. This article reviews the potential risks associated with nonproprietary medicines that do not meet the regulatory requirements of the United States Food and Drug Administration, the European Medicines Agency, or the World Health Organization. The clinical implications for patients are described. This article focuses on nonproprietary medicines for multiple sclerosis, particularly fingolimod, that are not identical to proprietary versions and could thus fail to meet efficacy expectations or have different impact on the safety of patients with multiple sclerosis.

[Efficiency and safety of generic Atorvastatine in patients at high cardiovascular risk]

Statines are first choice medications for hypercholesterolemia and combined hyperlipidemia of varying severity in wide population of patients. Atorvastatine is one of the most effective statines. In Russia, Atorvastatine is represented by nearly twenty drugs most of which are generics. The article covers data on efficiency, safety and good tolerance of Liptonorm--a generic Atorvastatine.

Clinical pharmacology of tyrosine kinase inhibitors becoming generic drugs: the regulatory perspective

Over the last decades, billions have been spent and huge efforts have been taken in basic and clinical cancer research [CA Cancer J Clin63:11-30]. About a decade ago, the arms race between drugs and cancer cells reached a new level by introduction of tyrosine kinase inhibitors (TKI) into pharmacological anti-cancer therapy. According to their molecular mechanism of action, TKI in contrast to so-called "classic" or "conventional" cytostatics belong to the group of targeted cancer medicines, characterized by accurately fitting with biological structures (i.e. active centers of kinases). Numerous (partly orphan) indications are covered by this new class of substances. Approximately ten years after the first substances of this class of medicines were authorized, patent protection will end within the next years. The following article covers clinical meaning and regulatory status of anti-cancer TKI and gives an outlook to what is expected from the introduction of generic anti-cancer TKI.

Comparing the biological impact of glatiramer acetate with the biological impact of a generic

For decades, policies regarding generic medicines have sought to provide patients with economical access to safe and effective drugs, while encouraging the development of new therapies. This balance is becoming more challenging for physicians and regulators as biologics and non-biological complex drugs (NBCDs) such as glatiramer acetate demonstrate remarkable efficacy, because generics for these medicines are more difficult to assess. We sought to develop computational methods that use transcriptional profiles to compare branded medicines to generics, robustly characterizing differences in biological impact. We combined multiple computational methods to determine whether differentially expressed genes result from random variation, or point to consistent differences in biological impact of the generic compared to the branded medicine. We applied these methods to analyze gene expression data from mouse splenocytes exposed to either branded glatiramer acetate or a generic. The computational methods identified extensive evidence that branded glatiramer acetate has a more consistent biological impact across batches than the generic, and has a distinct impact on regulatory T cells and myeloid lineage cells. In summary, we developed a computational pipeline that integrates multiple methods to compare two medicines in an innovative way. This pipeline, and the specific findings distinguishing branded glatiramer acetate from a generic, can help physicians and regulators take appropriate steps to ensure safety and efficacy.

Appraisal of multifarious brands of Cephradine for their in vitro antibacterial activity against varied microorganisms

The astounding and exceptional growth of generic pharmaceutical Industry in Pakistan has raised certain questions for drug regulatory authorities contemplating their efficacy and quality. The current study focuses on assessing the in-vitro antimicrobial activity of 24 brands of Cephradine 500mg capsules against 4 different strains by employing standardized methods. Disk diffusion method was performed on all brands to look into the susceptibility and resistance patterns. Standard disk of 5µg Cephradine powder were used during evaluation. The zones of inhibitions were ranged from 24-40mm against S. aureus, 24-40mm against E. coli, 20-25mm against K. pneumonia and 19-23mm P. mirabilis. On the basis of mean value, the multinational brands were found to have better zone of inhibitions and were better than local Pharmaceutical companies but ANOVA cooperative study showed that all brands of Cephradine showed similar comparable results. Further investigations by employing MIC method, quality of raw material with special emphasis on the shelf-life, excepients and method of manufacturing will be needed to obtain more authenticated results. The price of National and Multinational brands ranges from Rs.156.00-212.00 for 10 capsules. It is concluded that Public health is at risk because of noticeable growing widespread curse of the manufacture and trade of sub-standard or below par pharmaceuticals. The pecuniary accountability of management of pharmaceutical agents is additionally apparent. The results of the study need to be made public to boost the confidence of medical profession about the quality of locally manufactured pharmaceuticals. It will succour the foreign exchange being incurred on the trade in of medicines.

Thromboelastographic evaluation of blood coagulation in the presence of branded and generic enoxaparins

AIM

Enoxaparin is the most widely used low-molecular-weight heparin (LMWH) in the USA and has been approved for clinical use in multiple indications. Enoxaparin is a complex biological product with multiple known activities relevant to its antithrombotic effects, and variations in different forms of enoxaparin may have important clinical implications. This study aimed to compare the physiological anticoagulant activity of branded and a generic enoxaparin, using thromboelastography (TEG) to evaluate their effect on the dynamic formation of the blood clot as quantitated by interactions between coagulation factors and inhibitors, fibrinogen, platelets and the fibrinolytic system.

METHODS

Whole native (no preservative) blood was obtained from 7 healthy volunteers. Samples were immediately mixed with various concentrations of branded or generic enoxaparin and TEG was performed to assess anticoagulant activity. Five different batches of each enoxaparin (branded and generic) were tested.

RESULTS

Generic enoxaparin showed more variation in anticoagulation response with a less predictable concentration-dependent and linear response compared with branded enoxaparin. There was also an apparent batch-to-batch variation for generic enoxaparin. The results demonstrated a lower overall anticoagulant effect (P=0.05; no overlap of 95% confidence intervals) with a wider inter-individual variation for generic enoxaparin in comparison with branded enoxaparin. Some individuals responded with a higher than expected anticoagulant response to the given concentration of the generic enoxaparin.

CONCLUSION

The findings of this study suggest that other pre-clinical and clinical studies should be done to validate the clinical interchangeability between branded and generic enoxaparin.

Biosimilar growth hormone

As the first wave of biopharmaceuticals is expiring, biosimilars or follow-on -protein products (FOPP's) have emerged. Biosimilar drugs are cheaper than the originator/comparator drug. The regulatory foundation for these products is more advanced and better codified in Europe than in the US. Biosimilar soamtropin has been approved in both the US and Europe. The scientific viability of biosimilar drugs and especially growth hormone has been proven by several rigorously conducted clinical trials. Efficacy and safety data (growth rates, IGF-1 generation) for up to 7 y for pediatric indications measure up favorably to previously approved growth hormones which served as reference comparators. The Obama Administration appears to be committed to establish innovative pathways for the approval of biologics and biosimilars in the US. The cost savings in health care expenditures will be substantial as the global sales of biologics have reached $ 93 billion in 2009.

Efficacy and safety of high dose generic sildenafil in Thai patients with pulmonary arterial hypertension

OBJECTIVE

Sildenafil, an orally administered phosphodiesterase type 5 (PDE-5) inhibitor, was known for enhancing the downstream effects of NO. It was approved for treatment in patients with pulmonary arterial hypertension (PAH). Recently, a generic sildenafil (Unison Laboratories, Thailand) was proved to have the same bioequivalent as in the original formula. The authors conducted a 12-week case series to study the efficacy and safety of Elonza (generic sildenafil) in PAH patients.

MATERIAL AND METHOD

Comparison of both hemodynamic data from cardiac catheterization and clinical outcome such as six minute walk test (6MWT) were performed to assess the efficacy of generic sildenafil at the dosage of 50 mg given orally three times daily in patients with PAH over a 12 weeks period.

RESULTS

There were 20 patients whose average age was 31.4 +/- 14.3 years old (13-58) and their average weight was 48.1 +/- 11.9 kg (31-79). There were three idiopathic pulmonary artery hypertensions (IPAH) and 17 congenital left to right shunts. There was a 15.1% decrease in pulmonary vascular resistance index (PVRi) from 20.5 +/- 13.9 to 17.4 +/- 2.9 Wood unit m2 at the end of 12 weeks (p = 0.044). The ratio of pulmonary to systemic vascular resistance (PVR/SVR) was also decreased from 0.71 +/- 0.57 to 0.52 +/- 0.41 (p = 0.014). 6MWT increased significantly from 271 +/- 59 meters (m) at baseline to 297 +/- 48 m, 307 +/- 43 m and 321 +/- 52 m at week 2, 6 and 12, respectively (p = 0.01). There was no significant change in other hemodynamic parameter, Borg dyspnea score, and functional class.

CONCLUSION

At the end of the 12-week treatment, a 50 mg three times daily of generic sildenafil given to patients with PAH was shown to have benefit on decreasing PVRi, PVR/SVR ratio. There was also an increase in mean average of 6MWT at the end of 12 weeks.

Monitoring of effectiveness and safety of generic formulation of meropenem for treatment of infections at Siriraj Hospital

OBJECTIVE

In Siriraj Hospital, generic meropenem (Monem) has been available and was substituted for original meropenem, but the effectiveness and safety of using generic meropenem in a clinical setting are the main concern.

MATERIAL AND METHOD

From July 2007 to June 2009, hospitalized patients aged 18 or older who received meropenem for 48 hours were identified from the pharmacy database of Siriraj hospital. A retrospective study was conducted. Three hundred patients in each of original and generic meropenem groups were required to demonstrate non-inferiority of generic to original meropenem.

RESULTS

The mean age of all patients was 63 years. Most of the patients had co-morbidities. Approximately 90% of the infections were health-care associated. Drug-resistant gram-negative bacteria including ESBL producing E. coli and K. pneumoniae, P. aeruginosa and A. baumannii account for nearly 50% of all organisms. No significant difference was found regarding characteristics, type or site of infection and pathogen between generic and original groups but for more patients in the original group having cardiovascular disease and more patients in the generic group receiving immunosuppressive agents. Eighty-two to 85% received meropenem with one of appropriate indications. No statistically significant difference occurred either in an overall favorable outcome (63% vs.70.4%, p = 0.07) or in overall mortality (38% vs. 32%, p = 0.17), as well as adverse effects between the original and the generic groups.

CONCLUSION

Generic meropenem (Monem) was not inferior to original meropenem for therapy of infections in the hospitalized patients at Siriraj Hospital.

Microbiological equivalence of bacteriostatic and bactericidal activities of the sera from healthy volunteers receiving generic piperacillin/tazobactam (Pipertaz) and original piperacillin/tazobactam (Tazocin)

BACKGROUND

Several generic piperacillin/ tazobactam formulations have been approved by Thai Food andDrugAdministration, Ministry of Public Health. Piperacillin/ tazobactam is a parenteral drug. Therefore, a study demonstrating a biological equivalence of generic piperacillin/ tazobactam is not required for drug registration in Thailand.

OBJECTIVE

The study was to determine microbiological equivalence of serum bacteriostatic and bactericidal activities of the sera from healthy volunteers receiving generic piperacillin/ tazobactam (PipertazA) and original piperacillin/tazobactam (Tazocin).

MATERIAL AND METHOD

This was a randomized crossover study in 16 adult healthy volunteers. Each subject received 4.5 grams of Pipertaz and Tazocin in 50 ml of normal saline via intravenous infusion for 30 minutes. The blood samples were drawn at baseline prior to receiving the study drug, at 30 minutes after initiating infusion, and at 8 hours after initiating infusion. The serum bacteriostatic activity against E. coli ATCC 25922, K. pneumoniae, P aeruginosa ATCC 27853 and A. baumannii was performed by disk diffusion The serum bactericidal activity against E. coli ATCC 25922 was performed by Serum Bactericidal Titre.

RESULTS

The average inhibition zone diameter of the serum samples from the subjects while receiving Pipertaz against each tested organisms was <1 mm smaller than that while receiving Tazocin and such difference was not significantly different. All serum samples collected at 30 minutes after initiating Tazocin and Pipertaz had bactericidal titres 1:64 to 1:256 against E. coli ATCC 25922. All serum samples collected at 8 hours after initiating Tazocin and Pipertaz had bactericidal titres < 1:2 against E. coli ATCC 25922. The differences of serum bactericidal titres of the serum samples collected at 30 minutes (p = 0.7) and 8 hours (p = 1.0) after initiating Tazocin and Pipertaz were not statistically significant.

CONCLUSION

The sera from healthy volunteers receiving Pipertaz contain bacteriostatic and bactericidal activities not significantly different from those receiving Tazocin.

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

Background

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

Methodology/Principal Findings

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

Conclusion

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

Therapeutic equivalence of generic imipenem/cilastatin for therapy of infections at Siriraj Hospital

BACKGROUND

Several generic imipenem/cilastatin formulations have been approved by Thai FDA and a generic imipenem/cilastatin (Yungjin) has been available in SirirajHospital since 2007. Since imipenem/cilastatin is usually given to the patients with serious hospital-acquired infections, the generic imipenem/cilastatin must be therapeutically equivalent to the original imipenem/cilastatin. The objective of the study was to compare effectiveness and safety of generic imipenem/cilastatin with original imipenem/cilastatin for therapy of infections in hospitalized patients at Siriraj Hospital.

MATERIAL AND METHOD

Medical records of adult hospitalized patients at Siriraj Hospital who received imipenem/cilastatin at least 48 hours during June 2007 to September 2008 were reviewed. The effectiveness data of 300 patients who received original imipenem/cilastatin were compared with those of 300 patients who received generic imipenem/cilastatin in order to determine if a difference in composite favorable outcome of both formulations was within 10%.

RESULTS

The demographics, clinical features of infections, site of infections, type of causative organisms and concomitant antibiotics of the patients in both groups were not significantly different. The overall favorable outcomes in the original imipenem/cilastatin and the generic imipenem/cilastatin groups were 65% and 58.7% respectively (absolute difference 6.3%, 95% CI -1.4% to 14%). Cure rates of infections in the original imipenem/cilastatin and the generic imipenem/cilastatin groups were 35% and 28.7% respectively (absolute difference 6.3%, 95% CI -1.1% to 13.7%). Super-infection rates in the original imipenem/cilastatin and the generic imipenem/cilastatin groups were 4.7% and 9% respectively (absolute difference -4.3%, 95% CI -8.5% to 0.3%). Mortality due to infections in the original imipenem/cilastatin and the generic imipenem/cilastatin groups were 18.3% and 21.3% respectively (absolute difference -3%, 95% CI -9.4% to 3.4%). Overall mortality in the original imipenem/cilastatin and the generic imipenem/cilastatin groups were 35.3% and 43% respectively (absolute difference -7.7%, 95% CI -15.3% to 0.1%). The occurrence of adverse events in the patients in both groups was not significantly different.

CONCLUSION

Although the point estimate of composite favorable outcome of the patients who received generic imipenem/cilastatin (Yungjin) was < 10% of those who received original imipenem/cilastatin (Tienam), generic imipenem/cilastatin showed a trend for therapeutic non-equivalence to original imipenem/cilastatin because the upper limits of 95% confidence interval of differences of several important clinical outcomes were more than 10%.

Microbiological equivalence of serum bacteriostatic and bactericidal activities of the sera from healthy volunteers receiving original meropenem (Meronem) and generic meropenem (Mero)

BACKGROUND

Several generic meropenem formulations have been approved by Thai Food and Drug Administration, Ministry of Public Health since 2008. Meropenem is a parenteral drug. Therefore, a study demonstrating a biological equivalence of generic meropenem is not required for drug registration in Thailand. The objective of the study was to determine microbiological equivalence of serum bacteriostatic and bactericidal activities of the sera from healthy volunteers receiving original meropenem (Meronem) and generic meropenem (Mero).

MATERIAL AND METHOD

This was a randomized crossover study in 16 adult healthy volunteers. Each subject received one gram of Meronem and Mero in 50 ml of normal saline via intravenous infusion for 30 minutes. The blood samples were drawn at baseline prior to receiving the study drug, at 30 minutes after initiating infusion, and at 8 hours after initiating infusion. The serum bacteriostatic activity against E. coli ATCC 25922, K. pneumoniae, P. aeruginosa ATCC 27853 and A. baumannii was performed by disk diffusion. The serum bactericidal activity against E. coli ATCC 25922 was performed by Serum Bactericidal Titre.

RESULTS

The average inhibition zone diameter of the serum samples from the subjects while receiving Mero against each tested organisms was < 1 mm smaller than that while receiving Meronem and such difference was not significantly different. All serum samples taken at 30 minutes after initiating Meronem and Mero had bactericidal titres against E. coli ATCC 25922 > or = 1:256. Only 3 serum samples taken from the subjects while receiving Mero at 8 hours had less bactericidal titre for 1-fold dilution when compared with that of Meronem.

CONCLUSION

The sera from healthy volunteers receiving Meronem and Mero had microbiological equivalence in terms of serum bacteriostatic and bactericidal activities.

[Interaction of omnic (tamsulozine) and its generic analogues with alpha-adrenoreceptors]

In current practice of pharmacotherapy of prostatic adenoma alpha1-adrenoblockers are first-line drugs the efficacy and safety of which have been proved in many randomized studies. Because of the appearance of a large amount of generic analogues of tamsulozine on the market we studied the ability of tamsulozine analogues to bind with alpha-adrenoreceptors on rat and human prostate affected by adenoma. Significant differences on the receptor level of interaction were found. Omnik, compared to other generic analogues of tamsulozine, has the highest affinity to alpha1-adrenoreceptors.

The scope and requirements related to preclinical and clinical studies of a new medicinal product, including biotechnological and biosimilar products

The article presents an outline of the requirements concerning the planning of preclinical and clinical studies, necessary for the legal approval of a medicinal product. It describes the clinical research plan of innovative and generic pharmaceutical products, taking into account the specific situations in which the assessment of biological equivalence of a generic product is not possible based on pharmacokinetic parameters. The article also discusses the guidelines which determine the scope of studies which are necessary in the process of registration of biotechnological and biosimilar products.

Pharmaceutical brand substitution in Australia - are there multiple switches per prescription?

BACKGROUND

In Australia, brand substitution by pharmacists has been possible since 1994. There is no limit to the number of substitutions per prescription. Doctors have expressed concern that patients may receive a different product each time their prescription repeats are dispensed, which has the potential to confuse patients. It is unknown how often multiple substitutions per prescription occur.

OBJECTIVES

We aimed to identify the number of switches per prescription for a range of medicines and to determine the number of different brand and generic products supplied on each prescription.

METHODS

Repatriation Pharmaceutical Benefits Scheme prescription claims between 1 January 2001 and 28 February 2006 were identified for atenolol, citalopram, enalapril, metformin, omeprazole, ramipril, and simvastatin. Original prescriptions with five repeats and all supplies dispensed were included. Switches were identified if a different product was supplied on consecutive repeat dispensings.

RESULTS

533,279 original prescriptions were included. 488,735 (92%) had no switches on repeats and 37,513 (7%) had only one switch. Only 1% of all prescriptions had more than one switch identified on repeats, and in most cases only two different products were supplied. None of the prescriptions had a different product supplied on each dispensing.

CONCLUSION AND IMPLICATIONS

Multiple switches per prescription are uncommon and multiple different products are rarely supplied on repeats of the same prescription. The rules of the brand substitution policy appear to be adequate in allowing brand choice for patients, without leading to multiple switches per prescription.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Comparative testing and pharmacovigilance of biosimilars

Unlike traditional generic pharmaceuticals, biosimilars (also called 'follow-on biopharmaceuticals' in the USA) aim to copy a complex recombinant, three-dimensional protein structure with high molecular weight. Small changes in the manufacturing process can alter the product's effect and safety. According to the guidelines of the European Agency for the Evaluation of Medicinal products (EMEA), extensive comparability testing will be required to demonstrate that the biosimilar has a comparable profile in terms of quality, safety and efficacy as the reference product. Various analytical assays are available to compare physicochemical and biological properties between production batches of a potentially similar biopharmaceutical (comparability) and in comparison with a reference product (similarity). It is important to recognize the limits of existing assays so that the results can be accurately interpreted for market authorization. This article examines the quality and limits of such analytical methods. The analytical tests to demonstrate comparability and similarity of a biosimilar product to a reference drug with respect to protein content, activity, physiochemical integrity, stability, impurities and additives, as well as immunogenicity are discussed. Although several assays are available, reliable tests for safety and efficacy still require development. Furthermore, international standards are missing and materials and methods differ from laboratories making the comparison of results very difficult. Clinical trials and post-authorization pharmacovigilance are essential to guarantee the product's safety and efficacy over time. Pharmacovigilance, as part of a comprehensive risk management programme, will need to include regular testing for consistent manufacturing of the drug.

A randomized, prospective double-blind comparison of the efficacy of generic propofol (sulphite additive) with Diprivan®

BACKGROUND AND OBJECTIVE

We compared the dose requirement and side effect profile of total intravenous anaesthesia using Diprivan to generic propofol at a specific anaesthetic target level utilizing the bispectral index monitor to determine efficacy differences between the two products.

METHODS

Sixty women undergoing abdominal hysterectomy were induced with propofol 2 mg kg-1 and maintained with infusion (20-200 microg kg-1 min-1) adjusted to maintain a bispectral index of 50-65. Plasma propofol concentration was measured at 1 and 2 h post induction in 25 patients.

RESULTS

Mean (SD) drug doses adjusted for weight and time were similar in the Diprivan and generic propofol groups: 90 (30) microg kg-1 min-1 vs. 90 (20) microg kg-1 min-1 respectively. Mean (SD) plasma propofol levels at 1 and 2 h were also similar (3.0 (1.0) microg mL-1 vs. 3.6 (1.4) microg mL-1, P = 0.2 and 3.0 (1.9) microg mL-1 vs. 3.4 (1.6) microg mL-1, P = 0.58).

CONCLUSIONS

Diprivan and generic propofol have similar efficacy at a specified, bispectral index-defined, depth of anaesthesia.

Clinical significance of brand versus generic formulations: focus on oral minocycline

Minocycline is an oral antibiotic widely prescribed throughout the world, primarily for the treatment of acne vulgaris; other uses include the treatment of rosacea and perioral dermatitis. In the United States, Propionibacterium acnes resistance is lowest with minocycline compared with other tetracyclines and with erythromycin. The availability of generic formulations of minocycline has created confusion regarding the clinical significance of brand versus generic minocycline products. This article reviews available data on minocycline use for acne vulgaris and discusses a patented brand of minocycline versus generic formulations, including evaluations of pharmacologic activity and safety.

A method for the determination of minoxidil in hair-regrowth formulations by micellar electrokinetic capillary chromatography

A method based on micellar electrokinetic capillary chromatography (MEKC) was developed for determination of minoxidil in Rogaine and competing products. The original intent of the work was to offer an orthogonal means to HPLC for testing illicit imitations of Rogaine. However, because the patent has since expired, we offer the procedure as a confirmatory measure to HPLC for assay of generic minoxidil products. The MEKC procedure complements an earlier method based on free solution capillary electrophoresis (FSCE), designed to the same end. Validation was carried out on both a Dionex CES-1, which utilizes gravity injection, and a PE-ABI 270HT, which employs vacuum injection. The procedure was validated for both active pharmaceutical ingredient and for minoxidil solutions. The run buffer is pH 7.0, 20 mM sodium phosphate, 20 mM sodium dodecyl sulfate, with 10% isopropanol; the internal standard is dl-tryptophan. The method bears the attributes of simplicity, ease of use, and short analysis time (12 min). It is selective with respect to known process and degradation impurities. High efficiency was achieved on the CES-1, with a plate count exceeding 200,000 for minoxidil at an elution time of 9 min. Although slight differences in performance were noted across the two instruments, results on both were in conformance with modern day validation expectations. Comparison of MEKC with HPLC resulted in slightly higher values for the former, but all results met registration specifications and internal targets.

The bioequivalence and therapeutic efficacy of generic versus brand-name psychoactive drugs

BACKGROUND

For the purposes of drug approval, the interchangeability of a generic drug and the corresponding brand-name drug is based on the criterion of "essential similarity," which requires that the generic drug have the same amount and type of active principle, the same route of administration, and the same therapeutic effectiveness as the original drug, as demonstrated by a bioequivalence study. However, bioequivalence and therapeutic effectiveness are not necessarily the same.

OBJECTIVE

This review summarizes available data comparing the bioequivalence and therapeutic efficacy of brand-name psychoactive drugs with those of the corresponding generic products.

METHODS

Relevant information was identified through searches of MEDLINE, Current Contents/Clinical Medicine, and EMBASE for English-language articles and English abstracts of articles in other languages published between 1975 and the present. The search terms used were generic drug, branded drug, safety, toxicity, adverse events, clinical efficacy, bioequivalence, bioavailability, psychoactive drugs, and excipients.

RESULTS

Few publications compared the bioequivalence and efficacy of brand-name and generic psychoactive drugs. Those that were identified revealed differences in the efficacy and tolerability of brand-name and generic psychoactive drugs that had not been noted in the original bioequivalence studies. Specifically, l study found that plasma levels of phenytoin were 31% lower after a switch from a brand-name to a generic product. Several controlled studies of carbamazepine showed a recurrence of convulsions after the shift to a generic formulation. After a sudden recurrence of seizures when generic valproic acid was substituted for the brand-name product, an investigation by the US Food and Drug Administration found a difference in bioavailability between the 2 formulations. Statistically significant differences in pharmacokinetic variables have been reported in favor of brand-name versus generic diazepam (P < 0.001). Finally, a case report involving paroxetine mesylate cast doubt on the tolerability and efficacy of the generic formulation.

CONCLUSION

The essential-similarity requirement should be extended to include more rigorous analyses of tolerability and efficacy in actual patients as well as in healthy subjects.