Therapeutic equivalence of antipsychotics and antidepressants – A systematic review

Pharmacoeconomic implications of preference toward reference- versus generic-brand antidepressants in primary care

BACKGROUND

The prevalence of depression is gradually increasing worldwide with an increasing utilization of antidepressants. Nevertheless, despite their lower costs, generic-brand antidepressants were reported to be less prescribed. We aimed to examine the costs of reference- versus generic-brand antidepressant prescriptions in primary care practice.

METHODS

This cross-sectional study included electronic prescriptions for adult patients that contained antidepressants (World Health Organization's Anatomical Therapeutic Chemical (ATC) code: N06A), which were generated by a systematically selected sample of primary care doctors (n = 1431) in Istanbul in 2016. We examined the drug groups preferred, the reference- versus generic-brand status, and pharmacotherapy costs.

FINDINGS

The majority of the prescriptions were prescribed for women (71.8%), and the average age of the patients was 53.6 ± 16.2 years. In prescriptions with a depression-related indication (n = 40 497), the mean number and cost of drugs were 1.5 ± 1.0 and 22.7 ± 26.4 United States Dollar ($) per prescription, respectively. In these prescriptions, the mean number and cost of antidepressants per encounter were 1.1 ± 0.2 and $17.0 ± 13.2, respectively. Reference-brand antidepressants were preferred in 58.2% of depression-related prescriptions, where the mean cost per prescription was $18.3 ± 12.4. The mean cost per prescription of the generics, which constituted 41.8% of the antidepressants in prescriptions, was $15.1 ± 11.4. We found that if the generic version with the lowest cost was prescribed instead of the reference-brand, the mean cost per prescription would be $12.9 ± 11.2.

CONCLUSIONS

Our study highlighted the substantial pharmacoeconomic impact of generic-brand antidepressant prescribing, whose preference over reference-brands could reduce the cost of antidepressant medication treatment by 17.5% in primary care, which could be approximately doubled if the cheapest generic antidepressant had been prescribed.

Harmonization of summaries of product characteristics (SmPCs) of drugs with the same active ingredients: an evaluation of SmPCs of the most frequently prescribed active substances

Purpose

In aut-idem or generic substitution, discrepancies between summaries of product characteristics (SmPCs) referring to the same active substance (AS) may cause difficulties regarding informed consent and medical liability. The qualitative and quantitative characteristics of such discrepancies are insufficiently studied, impeding harmonization of same-substance SmPCs and compromising safe drug treatment.

Methods

SmPCs of the one hundred most frequently prescribed ASs in Germany were analyzed for discrepancies in the presentation of indications (Inds) and contraindications (CInds). Inclusion and exclusion criteria of drugs/SmPCs were chosen according to the standards of the aut-idem substitution in Germany.

Results

According to the study protocol, we identified 1486 drugs, of which 1426 SmPCs could be obtained. 41% respectively 65% of the ASs had same-substance SmPCs that differed from the respective reference SmPC in the number of listed Inds respectively CInds. The number of listed Inds/CInds varied considerably between same-substance SmPCs with maximum ranges in Inds of 7 in amoxicillin, and in CInds of 11 in lisinopril. Many ASs had large proportions (> 50%) of associated same-substance SmPCs that differed from the respective reference SmPC. A considerable proportion of ASs had same-substance SmPCs with formal and content-related differences other than the discrepancy in the number of Inds/CInds.

Conclusion

This evaluation of same-substance SmPCs shows a clear lack of harmonization of same-substance SmPCs. Considering that generic substitution has become the rule and that physicians usually do not know which drug the patient receives in the pharmacy, these discrepancies raise several questions, that require a separate legal evaluation.

[Treatment persistence with brand-name vs. generic metformin in monotherapy for type 2 diabetes: real-life retrospective study using the propensity matching score]

OBJECTIVE

To evaluate treatment persistence in patients with polymedicated type 2 diabetes (DM2) receiving new treatment with brand-name vs. generic metformin 850mg in usual clinical practice.

PATIENTS AND METHODS

Observational, retrospective study based on the medical records of patients aged ≥50 years who initiated metformin treatment (brand-name vs. generic) between 01/01/2016 and 31/12/2017. The follow up was two years.

MAIN MEASURES

treatment persistence and clinical consequences (metabolic control [HbA1c] and hospital admissions). Each patient in the brand-name group (reference) was paired with a patient from the generic group using propensity score matching. A Cox proportional risk model was constructed (p<0.05).

RESULTS

863 patients receiving brand-name metformin were matched (ratio 1:1) with patients receiving generic metformin. The median age was 60.8 years (SD: 8.8) years and 52.6% were female. Persistence at 24 months was 8.6% higher for brand-name vs. generic metformin (63.2% vs. 58.2%; p=0.034). The hazard ratio for brand-name metformin was 0.83 (95% CI: 0.71-0.96, p=0.013). During the follow-up there was a greater percentage reduction of HbA1c in the brand-name vs. generic group (-6.8% vs. -4.1%; p=0.013). There was a non-significant 19.1% reduction in hospital admissions in the brand-name vs. generic group (8.9% vs. 11.0%; p=0.148).

CONCLUSIONS

Polymedicated patients who initiated new brand-name metformin treatment for DM2 had greater treatment persistence than those who initiated it with generic metformin and had better metabolic control (percentage reduction in HbA1c).

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.

Brand-Name Antidepressants Outperform Their Generic Counterparts in Preventing Hospitalization for Depression: The Real-World Evidence from Taiwan

BACKGROUND

Generic antidepressants are approved on the market based on evidence of bioequivalence to their brand-name versions. We aimed to assess whether generic antidepressants exert equal effectiveness as their brand-name counterparts for treating patients with depressive disorders.

METHODS

In a nationwide, population-based cohort in Taiwan from 1997 through 2013, patients with a diagnosis of a depressive disorder aged between 18 and 65 years who were new users of antidepressant drugs were classified into either the brand-name group or the generic group. All patients were followed up until medication discontinuation or the end of the study period. We assessed the risk for hospitalization as a primary outcome and augmentation therapy, daily dose, medication discontinuation, or switching to another antidepressant as secondary outcomes.

RESULTS

A total of 277 651 brand-name users (35.8% male; mean age: 41.2 years) and 270 583 generic users (35.8% male; mean age: 41.0 years) were divided into 10 different antidepressant groups (fluoxetine, sertraline, paroxetine, escitalopram, citalopram, venlafaxine, mirtazapine, moclobemide, imipramine, and bupropion). We found that patients treated with the generic form of sertraline, paroxetine, escitalopram, venlafaxine, mirtazapine, and bupropion demonstrated significantly higher risks of psychiatric hospitalization (adjusted hazard ratios ranged from 1.20-2.34), compared to their brand-name counterparts. The differences between brand-name antidepressants and their generic counterparts in secondary outcomes varied across different drugs.

CONCLUSIONS

Compared to most generic antidepressants, brand-name drugs exhibited more protective effects on psychiatric hospitalization for depressive patients. These findings could serve as an important reference for clinicians when encountering patients with depressive disorder.

[Clinical and economic consequences in patients initiating therapy with clopidogrel brand-name vs. generic: A real-life retrospective study]

OBJECTIVE

To evaluate the adherence to treatment, resource use, and costs in subjects initiating treatment with brand-name versus generic clopidogrel for acute coronary syndrome (ACS) and peripheral arterial disease (PAD).

PATIENTS AND METHODS

Observational, retrospective study based on the medical records of patients aged ≥18 years who initiated treatment with clopidogrel (brand-name vs. generic) between 4 April 2015 and 31 March 2017. Four study groups were compared, and the follow-up was one year. The main measurements were: comorbidity, treatment adherence, medication possession ratio (MPR), resource use, and costs. The results were analysed using multivariate analysis. The level of statistical significance was P<.05.

RESULTS

Four groups were compared: a) ACS: brand-name clopidogrel (N=1,067) vs. generic (N=3,504), and b) PAD: brand-name clopidogrel (N=425) vs. generic (N=994). In the ACS comparison (mean age: 69.7 years, 61.4% male), adherence (65.3% vs. 61.0%, P<.001), adjusted hazard ratio 0.85 and MPR (89.8% vs. 86.7%, P=.045) were more superior with brand-name clopidogrel than with the generic and with a lower mean cost per unit (€2,890 vs. €3,865, P=.001). In the PAD comparison, similar results were observed: persistence (64.7% vs. 58.9%, P=.039); adjusted hazard-ratio 0.86 and MPR (88.6% vs. 81.7%; P=.013) were more superior with brand-name clopidogrel than for the generic, with a lower mean cost per unit (€2,880 vs. €3,532, P=.044).

CONCLUSIONS

There was better treatment adherence in patients initiating treatment with brand-name compared with generic clopidogrel for ACS and PAD, resulting in lower health costs for the Spanish National Health System.

Treatment persistence and adherence and their consequences on patient outcomes of generic versus brand-name statins routinely used to treat high cholesterol levels in Spain: a retrospective cost-consequences analysis

Background

High blood lipoprotein concentrations are one of the major risk factors for cardiovascular diseases. Drug therapy is the base of treatment; statins in particular. Both brand-name and generic presentations are available for statin therapy of high cholesterol levels. Factors that may influence their use in routine medical practice include, among others, patient persistence and adherence to treatment as prescribed by physicians. The aim of this retrospective analysis was to provide real-world evidence of treatment persistence and adherence and their consequences on economic and patient outcomes of generic versus brand-name statins routinely used to treat high cholesterol levels in Spain.

Methods

Existing real-world electronic medical records abstracted from a database of two regions in Spain were analyzed. The analysis compared generic versus brand-name statins data from subjects’ who started treatment between July 1, 2010 and June 30, 2012. Treatment persistence, adherence expressed as medication possession ratio (MPR), healthcare resource utilization and their costs were analyzed together with patient’s at-goal rates of low-density-lipoprotein-cholesterol (LDL-c), incidence of any major cardiovascular event (CVE) and all-cause mortality during a 5-year follow-up period. Multivariate analyses were applied.

Results

A total of 13,244 records were included. Persistence was lower with generics; adjusted hazard ratio -HR- [95% confidence interval]: 0.86 [0.82–0.91], p < 0.001) and MPR was also lower: 61.5% vs. 65.1% (p < 0.001). Less patients with generics reached their LDL-c goal: 39.2% [38.3–40.2%] vs. 42.0% [40.2–43.7%]; adjusted odds ratio; 0.87 [0.80–0.95], p = 0.003. Compared to brand-name statins, the observed probability of occurrence of a CVE; HR: 1.31 [1.15–1.50], p < 0.001, and also all-cause deaths; HR: 1.36 [1.15–1.62], was significantly higher with generics; p < 0.001 in both cases. Adjusted mean total healthcare cost per patient was also higher with generic than with brand-name statins: €9118 (9059–9176) vs. €7980 (7853–8808) [adjusted difference: €1137 (997–1277), p < 0.001].

Conclusion

This retrospective cost-consequences analysis found poorer treatment persistence and adherence in patients who first started therapy with generic instead of brand-name statins in routine medical practice in Spain. Also, patients receiving generics were more unlikely to reach LDL-c goals, showed increased probability of having CVE and all-cause mortality at a higher cost to payers.

Electronic supplementary material

The online version of this article (10.1186/s12944-018-0918-y) contains supplementary material, which is available to authorized users.

Bioequivalence and Therapeutic Equivalence of Generic and Brand Bupropion in Adults With Major Depression: A Randomized Clinical Trial

Controversy persists about bupropion XL 300 mg generic equivalence to brand product. A prospective, randomized, double-blinded crossover in 70 adults with major depression in stable remission taking any bupropion XL 300 mg tested bioequivalence and therapeutic equivalence of available XL 300 mg products. After a 4-week lead-in on patients' existing bupropion, four 6-week phases evaluated brand and three generics. Patients were uninformed of switching. Drug overencapsulation ensured blinding. There were no differences between any generic and brand, or between generics, in peak plasma concentration (C_max ) and area under the plasma concentration-time curve over the 24-hour dosing interval (AUC_0-24 ) for racemic bupropion or major metabolites. All generics met formal bioequivalence criteria for bupropion and metabolites. There were no differences between generics and brand, or between generics, in depression symptoms or side effects, assessed by every 3-week in-person interview and daily smartphone-based self-report. There were no differences in patients' perceptions of bupropion products. Results show three bupropion XL 300 mg generic products are both bioequivalent and not therapeutically different from brand drug and each other.

Comparison of the effectiveness of brand-name and generic antipsychotic drugs for treating patients with schizophrenia in Taiwan

The purpose of this nationwide population-based study is to compare the long-term effectiveness of brand-name antipsychotics with generic antipsychotics for treating schizophrenia. We identified patients with schizophrenia who were prescribed antipsychotics from a random sample of one million records from Taiwan's National Health Insurance database, observed between January 1, 2000 and December 31, 2012. Only those with no prior use of antipsychotics for at least 180days were included. We selected patients who were prescribed brand-name risperidone (N=404), generic risperidone (N=145), brand-name sulpiride (N=334), or generic sulpiride (N=991). The effectiveness of the treatments researched in this study consisted of average daily doses, rates of treatment discontinuation, augmentation therapy, and psychiatric hospitalization. We found that compared to patients treated with generic risperidone, those treated with brand-name risperidone required lower daily doses (2.14mg vs. 2.61mg). However, the two groups demonstrated similar rates of treatment discontinuation, augmentation, and psychiatric hospitalization. On the other hand, in comparison with patients prescribed generic sulpiride, those treated with brand-name sulpiride not only required lower daily doses (302.72mg vs. 340.71mg) but also had lower psychiatric admission rates (adjusted hazard ratio: 0.24, 95% confidence interval: 0.10-0.56). In conclusion, for both risperidone and sulpiride, higher daily doses of the respective generic drugs were prescribed than with brand-name drugs in clinical settings. Furthermore, the brand-name sulpiride is more effective at preventing patients from hospitalization than generic sulpiride. These findings can serve as an important reference for clinical practices and healthcare economics for treating schizophrenic patients.

Drug Brand Response and Its Impact on Compliance and Efficacy in Depression Patients

Introduction: Patient's response to drug brand is a comprehensive physiological and psychological effect which might impact the compliance and efficacy of drugs. Whether the therapeutic outcome altered on patients with brand response after they experience drug switch is not clear.

Methods: 459 outpatients with mild-to-moderate depression were divided into the imported (joint venture) drug group and the domestic drug group according to their current drug application. Two groups of patients were assessed by drug brand preference questionnaire and medication compliance questionnaire. Patients with brand preference in imported (joint venture) drugs group received rational use of limited medical resource and pharmacoeconomics education, and then switched with domestic drug for 8 weeks. Safety and efficacy were evaluated both before and after the drug switch.

Results: Overall, there were 27% of patients in imported drug group and 35% of patients in domestic drug group have brand response, respectively. About 2/3 patients in both groups showed low or no brand response. The compliance was similar in both groups with no significant difference (6.04 ± 2.08 vs. 4.74 ± 2.13, respectively, P > 0.05). The efficacy of imported drug group was significantly better than of the domestic drug group. Correlation analysis showed that in imported (joint venture) drugs group, medication compliance was closely related with brand response, but negatively correlated with age and duration. In domestic drugs group, medication compliance was independent of brand response, but closely related with education, age, and duration. After drug switch with domestic drug on patients with brand response, patients continued to maintain good antidepressant effect, and no severe adverse reaction occurred.

Conclusion: The results suggested that domestic drugs switch might be feasible for patients using imported drugs with brand response, while providing patients with rational use of drug education and psychological support. The medical staff should focus on medication education to help patients make better use of limited medical resources.