Evaluation of an interchangeability switch in patients treated with clozapine: A retrospective review

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.

Clozapine and Norclozapine Plasma Levels in Patients Switched Between Different Liquid Formulations

BACKGROUND AND OBJECTIVE

Clozapine is the drug of choice for treatment-resistant schizophrenia. The primary objective of this study was to compare plasma clozapine and N-desmethylclozapine levels in patients switched between 2 liquid formulations [Denzapine suspension and clozapine oral solution (St George's ZTAS)]. Secondary objectives included comparison of safety, tolerability, and patient acceptability.

METHODS

This was a noninterventional, observational, prospective follow-up of patients consecutively switched between formulations of clozapine liquid in a large inner-city NHS mental health trust. The authors also performed retrospective analysis of outcomes from patient case notes.

RESULTS

The authors identified 43 patients receiving Denzapine suspension in the trust. Data were available for 43 patients switched from Denzapine to clozapine oral solution (St George's ZTAS), among whom, 15 (32%) were excluded from the analysis. Of the 28 patients for whom data were available, the 90% confidence interval for the ratio of mean values for corrected Cmin 91.5 (85.2%-98.4%) and uncorrected Cmin 91.2 (84.4%-98.6%) were within the guideline range of bioequivalence (80%-125%). Safety and tolerability profiles were comparable between the 2 formulations (P = 0.10). Patient acceptability was also similar between the brands in most domains. However, there was a taste preference for Denzapine suspension.

CONCLUSIONS

No significant difference in clozapine plasma levels was observed after switching from Denzapine suspension to a recently introduced clozapine solution. This study also highlights the significance of medicinal characteristics such as taste for patient acceptability and compliance.

The Impact of Generic Substitution on Health and Economic Outcomes: A Systematic Review

BACKGROUND

Generic drugs are considered therapeutically equivalent to their original counterparts and lower in acquisition costs. However, the overall impact of generic substitution (GS) on global clinical and economic outcomes has not been conclusively evaluated.

OBJECTIVE

To test whether (1) generics and original products yield the same health outcomes, and (2) generic therapies save economic resources versus original therapies.

METHODS

We performed a systematic literature review in Medline, Embase, and the Cochrane Database of Systematic Reviews to identify original studies that examine clinical or economic outcomes of GS. After standardized data extraction, reported outcomes were categorized as supporting or rejecting the hypotheses. Each reported outcome was assessed and accounted for supporting and opposing GS. One publication could provide multiple outcome comparisons.

RESULTS

We included 40 studies across ten therapeutic areas. Fourteen studies examined patients on de novo therapy; 24 studies investigated maintenance drug therapy, and two studies considered both settings. Overall, 119 outcome comparisons were examined. Of 97 clinical outcome comparisons, 67% reported no significant difference between generic drugs and their off-patent counterparts. Of 22 economic comparisons, 64% suggested that GS increased costs. Consequently, hypothesis (1) was supported but hypothesis (2) was not. We found no major differences among studies that investigated clinical outcomes with de novo or maintenance therapy.

CONCLUSION

The review suggests that clinical effects are similar after GS. However, economic savings are not guaranteed. More systematic research comparing clinical and economic outcomes with or without GS is needed to inform policy on the use of generic substitution.

Regulatory and clinical aspects of psychotropic medicinal products bioequivalence

Introduction of generic medicinal products to the market has increased access to modern therapies but also enabled significant reduction in their cost, leading to containment of public expenditures on medicinal products reimbursement. The critical assessment of bioequivalence of any reference medicinal product and its counterpart is based on comparison of their rate and extent of absorption. It is assumed that two medicinal products are bioequivalent when their rate and extent of absorption do not show significant differences when administered at the same dose under similar experimental conditions. Bioequivalent medicinal products are declared to be also therapeutically equivalent and can be used interchangeably. However, despite regulatory declaration, switching from reference to generic drugs is often associated with concerns of healthcare providers about decreased treatment effectiveness or occurrence of adverse drug reactions. The aim of this article is to provide a description of rules that guide registration of generic medicinal products in the European Union and to analyze specific examples from the scientific literature concerning therapeutic equivalence of reference and generic antidepressant and antipsychotic medicinal products.

Systematic review of long-acting injectables versus oral atypical antipsychotics on hospitalization in schizophrenia

OBJECTIVE

To assess the impact of long-acting injectables (LAIs) versus oral antipsychotics (OAs) on hospitalizations among patients with schizophrenia by conducting a systematic literature review of studies with different study designs and performing a meta-analysis.

METHODS

Using the PubMed database and major psychiatric conference proceedings, a systematic literature review for January 2000 to July 2013 was performed to identify English-language studies evaluating schizophrenia patients treated with atypical antipsychotics. Studies reporting hospitalization rates as a percentage of patients hospitalized or as the number of hospitalizations per person per year were selected. The primary meta-analysis assessed the percentage decrease in hospitalization rates before and after treatment initiation for matched time periods. The secondary meta-analysis assessed the absolute rate of hospitalization during follow-up. Pooled treatment-effect estimates were calculated using random-effects models. To account for differences in patient and study-level characteristics between studies, meta-regression analyses were used. Subset analyses further explored the heterogeneity across study designs.

RESULTS

Fifty-eight studies evaluating 25 arms (LAIs: 13 arms, 4516 patients; OAs: 12 arms, 23,516 patients) in the primary meta-analysis and 78 arms (LAIs: 12 arms, 4481 patients; OAs: 66 arms, 96,230 patients) in the secondary meta-analysis were identified. Reduction in hospitalization rates for LAIs was 20.7 percentage points higher than that of OAs (random-effects estimates: LAIs = 56.2% vs. OAs = 35.5%, P = 0.023). Controlling for patient and study characteristics, the adjusted percentage reduction in hospitalization rates for LAIs was 26.4 percentage points higher than for OAs (95% CI: 3.3-49.5, P = 0.027). As for the secondary meta-analysis, no significant difference between LAIs and OAs was observed (random-effects estimate: -8.6, 95% CI: -18.1-1.0, P = 0.077). Subset analyses across type of study yielded consistent results. Limitations of this analysis include the long observation period, which may not reflect current treatment patterns, the use of all-cause hospitalization, which may not be solely related to schizophrenia, and the fact that most studies in the LAI cohort evaluated risperidone.

CONCLUSION

The primary results of this meta-analysis, including studies with both interventional and non-interventional designs and using meta-regressions, suggest that LAIs are associated with higher reductions in hospitalization rates for schizophrenia patients compared to OAs.

Rational use of generic psychotropic drugs

For economic reasons, the generic substitution of branded medications is common and welcome. These replacements are based on the concept of bioequivalence, which is considered equal to therapeutic equivalence. Regulatory standards for bioequivalence require the 90 % confidence intervals of group averages of pharmacokinetic measures of a generic and the original drug to overlap within ±20 %. However, therapeutic equivalence has been challenged for several psychotropic agents by retrospective studies and case reports. To evaluate the degree of bioequivalence and therapeutic equivalence of branded and generic psychotropic drugs, we performed an electronic search (from database inception until 24 May 2012 and without language restrictions) in PubMed/MEDLINE, Cochrane Library, and Web of Science. Search terms were "(generic) AND (psychotropic OR psychoactive OR antipsychotic OR antiepileptic OR antidepressant OR stimulant OR benzodiazepine)" or the respective individual substances. We included clinical studies, regardless of design, comparing branded with generic psychotropic drug formulations, identifying 35 such studies. We also included case reports/series reporting on outcomes after a switch between brand and generic psychotropics, identifying 145 clinical cases. Bioequivalence studies in healthy controls or animals, in-vitro studies, and health economics studies without medical information were excluded. An overview of the few randomized controlled studies supports that US FDA regulations assure clinically adequate drug delivery in the majority of patients switched from brand to generic. However, with a growing number of competing generic products for one substance, and growing economic pressure to substitute with the currently cheapest generic, frequent generic-generic switches, often unbeknownst to prescribing clinicians, raise concerns, particularly for antiepileptics/mood stabilizers. Generic-generic switches may vary by more than ±20 % from each other in individual patients since the pharmacokinetic properties of each generic may differ from the innovator drug in opposing directions. Ideally, therapeutic equivalence studies in addition to pharmacokinetic equivalence studies would be performed for each generic, reflecting the full variability of clinical responses due to changes of pharmacokinetic properties related to age, sex, ethnicity, genetic factors, and body mass index. This is particularly relevant, as bioequivalence studies are based on single-dose studies in healthy controls who are likely not representative of the patients who are prescribed the psychotropic medications. Additionally, individual case reports suggest potential clinical effects during brand-generic switches. Knowledge and consideration of intra-individual variations can help guide the clinical management during brand-generic or generic-generic switch periods. To optimize outcomes, clinicians need to consider that when using generic psychotropic medications, a change in the patient's clinical status can be related to psychological, interactional, physiological, and pharmacological factors that may or may not be related to the change to a generic drug. In addition, throughout all treatment periods, clinicians need to be aware of the currently dispensed product (i.e., branded or exact generic formulation), particularly when evaluating clinical changes in efficacy, tolerability, and adherence. If clinical problems occur, the first response should be an assessment of adherence and a careful dose adjustments of the generic drug rather than an immediate switch back to the originator.

Are specific initiatives required to enhance prescribing of generic atypical antipsychotics in Scotland?: International implications

BACKGROUND

National and regional authorities in Scotland have introduced multiple measures to appreciably enhance prescribing efficiency for the proton pump inhibitors (PPIs), statins and renin-angiotensin inhibitor drugs. Generic oral risperidone recently became available in Scotland; however, schizophrenia is a complex disease with advice from respected authorities suggesting that treatment should be individualised.

AIMS

To assess (i) changes in atypical antipsychotic drug (AAP) utilisation and expenditure following the availability of oral generic risperidone in Scotland; (ii) to determine (a) current INN prescribing rates for risperidone following generic availability and (b) decrease in expenditure/DDD for generic risperidone; (iii) to suggest additional measures that could possibly be introduced in Scotland to further enhance prescribing of generic AAPs; and (iv) to provide guidance to NHS Scotland as well as other European authorities on the implications.

METHODS

Retrospective observational study and an interrupted time series design.

RESULTS

No appreciable change in the utilisation patterns of risperidone pre- and postgeneric availability. Appreciable INN prescribing averaged 93-98% of total oral risperidone. Generic risperidone was 84% below prepatent loss prices by study end, reducing annual expenditure for oral risperidone in 2010 by GB£3.19mn compared with prepatent loss situation. However, overall expenditure on AAPs increased by 42% from 2005 to 2010.

DISCUSSION

As expected, there was no change in utilisation patterns for risperidone, although potential to influence prescribing patterns. Continued high INN prescribing suggests no problems with generic risperidone in practice. Costs will start to decrease as more AAPs lose their patents (olanzapine and quetiapine). There is the possibility to accelerate this reduction through educational activities.

CONCLUSION

There is potential to realise some savings with generic AAPs. However, this is limited by the complexity of the disease area. Any measures introduced must aim at increasing the prescribing of generic AAPs first line in suitable patients.

Potential to enhance the prescribing of generic drugs in patients with mental health problems in austria; implications for the future

BACKGROUND

Scrutiny over pharmaceutical expenditure is increasing leading to multiple reforms. This includes Austria with measures to lower generic prices and enhance their utilization. However the situation for newer antidepressants and atypical antipsychotic medicines (AAPs) is different to PPIs, statins, and renin-angiotensin inhibitor drugs with greater tailoring of therapy and no wish to switch products in stable patients. Authorities welcome generics though given the high costs particularly of single-sourced AAPs.

OBJECTIVE

Assess (a) changes in utilization of venlafaxine versus other newer antidepressants before and after availability of generics, (b) utilization of generic versus originator venlafaxine, (c) price reductions of venlafaxine over time and their influence on total expenditure, (d) utilization of risperidone versus other AAPs, (e) suggest potential additional reforms that could be introduced if pertinent to further enhance the use of generics.

METHODOLOGY

A quasi-experimental study design with a segmented time series and an observational study. Utilization measured in defined daily doses (DDDs) and total expenditure per DDD and over time.

RESULTS

No appreciable changes in the utilization of venlafaxine and risperidone after generics. The reduction in expenditure/DDD for venlafaxine decreased overall expenditure on newer antidepressants by 5% by the end of the study versus just before generics despite a 37% increase in utilization. Expenditure will further decrease if reduced prescribing of duloxetine.

CONCLUSION

Depression, schizophrenia, and bipolar diseases are complex diseases. As a result, specific measures are needed to encourage the prescribing of generic risperidone and venlafaxine when multiple choices are appropriate. Authorities cannot rely on a "Hawthorne" effect between classes to enhance the use of generics. Measures may include prescribing restrictions for duloxetine. No specific measures planned for AAPs with more multiple-sourced AAPs becoming available.

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.

Generic olanzapine: health authority opportunity or nightmare?

Pressures to contain pharmaceutical expenditure have led to increased prescribing and dispensing of generic drugs in addition to low prices for generics. Atypical antipsychotics are prescribed for schizophrenia leading to resource pressures with their higher acquisition costs than typical antipsychotics. Drug costs can be reduced once multiple sources are available. However, this must be balanced against possible efficacy, safety and compliance concerns given the high cost of relapses for patients with schizophrenia. Generic clozapine has been launched. There was an increase in relapse rates with early formulations in the USA. However, this has not been the case with more recent formulations. Despite this, there could be patient and physician concerns when additional generic atypicals, such as olanzapine are available, reducing potential savings. A retrospective survey of patients prescribed Zyprexa((R)), generic olanzapine or both, over an extensive period was undertaken in Poland to help address these concerns given the difficulties with conducting randomized clinical trials with generics in complex situations. The survey showed similar effective doses of olanzapine in all groups. Relapse rates were similar in patients before and after switching to generic olanzapine, and no untoward side effects were seen in any patient prescribed generic olanzapine. Consequently, generic olanzapine should be welcomed with savings redirected to improving compliance or funding new premium priced drugs that can reduce relapses in refractory patients. This should give reassurance to health authorities to continue their reforms where pertinent to optimize resources by increasing availability of generics.

Optimizing clozapine treatment

OBJECTIVE

Clozapine treatment remains the gold standard for treatment-resistant schizophrenia, but treatment with clozapine is associated with several side-effects that complicate the use of the drug. This clinical overview aims to provide psychiatrists with knowledge about how to optimize clozapine treatment. Relevant strategies for reducing side-effects and increasing the likelihood of response are discussed.

METHOD

Studies of clozapine available in MEDLINE were reviewed.

RESULTS

A slow up-titration of clozapine is recommended in order to reach the optimal dosage of clozapine and diminish the risk of dose-dependent side-effects. Particularly, in case of partial response or non-response, the use of therapeutic drug monitoring of clozapine is recommended. Plasma levels above the therapeutic threshold of 350-420 ng/ml are necessary to determine non-response to clozapine. To ease the burden of dose-dependent side-effects, dose reduction of clozapine should be tried and combination with another antipsychotic drug may facilitate further dose reduction. For most side-effects, counteracting medication exists. Augmentation with lamotrigine, antipsychotics, or electroconvulsive therapy may be beneficial in case of partial response to clozapine.

CONCLUSION

Treatment with clozapine should be optimized in order to increase the rate of response and to minimize side-effects, thus diminishing the risk of discontinuation and psychotic relapse.

Switching from brand-name to generic psychotropic medications: a literature review

Generic medications do not undergo the rigorous approval process required of original medications. Their effectiveness and safety is expected to be equal to that of their more expensive counterparts. However, several case reports and studies describe clinical deterioration and decreased tolerability with generic substitution. Pubmed was searched from January 1, 1974 to March 1, 2010. The MeSH term "generic, drugs" was combined with "anticonvulsants," "mood stabilizers," "lithium," "antidepressants," "antipsychotics," "anxiolytics," and "benzodiazepines." Additional articles were obtained by searching the bibliographies of relevant references. Articles in English, French, or Spanish were considered if they discussed clinical equivalence of generic and brand-name medications, generic substitution, or issues about effectiveness, tolerability, compliance, or economics encountered with generics. Clinical deterioration, adverse effects, and changes in pharmacokinetics are described with generic substitution of several anticonvulsants/mood stabilizers (carbamazepine, valproate, lamotrigine, gabapentin, topiramate, lithium), antidepressants (amitriptyline, nortriptyline, desipramine, fluoxetine, paroxetine, citalopram, sertraline, venlafaxine, mirtazapine, bupropion), antipsychotics (risperidone, clozapine), and anxiolytics (clonazepam, alprazolam). Generics do not always lead to the anticipated monetary savings and also raise compliance issues. Although the review is limited by publication bias and heterogeneity of the studies in the literature, we believe there is enough concern to advise generic switching on an individual basis with close monitoring throughout the transition. Health professionals should be aware of the stakes around generic substitution especially when health economics promote universal use of generics.

Use of Generics-A Critical Cost Containment Measure for All Healthcare Professionals in Europe?

Pharmaceutical expenditures in ambulatory care rose rapidly in Europe in the 1990s and early 2000s. This was typically faster than other components of healthcare spending, leading to reforms to moderate future growth. A number of these centered on generic medicines with measures to lower reimbursed prices as well as enhance their prescribing and dispensing. The principal objective of this paper is to review additional measures that some European countries can adopt to further reduce reimbursed prices for generics. Secondly, potential approaches to address concerns with generics when they arise to maximize savings. Measures to enhance the prescribing of generics will also briefly be discussed. A narrative review of the extensive number of publications and associated references from the co-authors was conducted supplemented with known internal or web-based articles. In addition, health authority and health insurance databases, principally from 2001 to 2007, were analyzed to assess the impact of the various measures on price reductions for generic omeprazole and generic simvastatin vs. pre-patent loss prices, as well as overall efficiency in Proton Pump Inhibitor (PPI) and statin prescribing. The various initiatives generally resulted in considerable lowering of the prices of generics as well as specifically for generic omeprazole and generic simvastatin vs. pre-patent loss prices. At one stage in the UK, generic simvastatin was just 2% of the originator price. These measures also led to increased efficiency for PPI and statin prescribing with reimbursed expenditure for the PPIs and statins either falling or increasing at appreciably lower rates than increases in utilization. A number of strategies have also been introduced to address patient and physician concerns with generics to maximize savings. In conclusion, whilst recent reforms have been successful, European countries must continue learning from each other to fund increased volumes and new innovative drugs as resource pressures grow. Policies regarding generics and their subsequent impact on reimbursement and utilization of single sourced products will continue to play a key role to release valuable resources. However, there must continue to be strategies to address concerns with generics when they exist.