Results of a phase III, 8-week, multicenter, prospective, randomized, double-blind, parallel-group clinical trial to assess the effects of amlodipine camsylate versus amlodipine besylate in Korean adults with mild to moderate hypertension

Are Generic Drugs Used in Cardiology as Effective and Safe as their Brand-name Counterparts? A Systematic Review and Meta-analysis

BACKGROUND

Previous systematic reviews (2008; 2016) concluded similarity in outcomes between brand-name and generic drugs in cardiology, but they included ≥ 50% comparative bioavailability studies, not designed or powered to detect a difference in efficacy or safety between drug types. We aimed to summarise best-evidence regarding the effectiveness and safety of generic versus brand-name drugs used in cardiology.

METHODS

For this systematic review of the literature, scientific databases (MEDLINE and EMBASE) were searched from January 1984 to October 2018. Original research reports comparing the clinical impact of brand-name versus generic cardiovascular drugs on humans treated in a real-life setting, were selected. Meta-analyses and subgroup analyses were performed. Heterogeneity (I²) and risk of bias were tested.

RESULTS

Among the 3148 screened abstracts, 72 met the inclusion criteria (n ≥ 1,000,000 patients, mean age 65 ± 10 years; 42% women). A total of 60% of studies showed no difference between drug types, while 26% concluded that the brand-name drug was more effective or safe, 13% were inconclusive and only 1% concluded that generics did better. The overall crude risk ratio of all-cause hospital visits for generic versus brand-name drug was 1.14 (95% confidence interval: 1.06-1.23; I²: 98%), while it was 1.05 (0.98-1.14; I²: 68%) for cardiovascular hospital visits. The crude risk ratio was not statistically significant for randomised controlled trials only (n = 4; 0.92 [0.63-1.34], I²: 35%).

CONCLUSION

The crude risk of hospital visits was higher for patients exposed to generic compared to brand-name cardiovascular drugs. However, the evidence is insufficient and too heterogeneous to draw any firm conclusion regarding the effectiveness and safety of generic drugs in cardiology.

Clinical effectiveness and safety of low cost versus innovator brand amlodipine in hypertension: A single-blinded, randomized, crossover, noninferiority trial

Objectives:

A single-blinded, randomized, crossover, noninferiority trial was conducted to evaluate clinical effectiveness and safety of low-cost brand (LCB) versus innovator brand (IB) amlodipine in essential hypertension.

Materials and Methods:

The primary end-point was change of systolic blood pressure (BP) from baseline to study end. Adult patients with Stage 1 hypertension or isolated systolic hypertension were randomized to receive 5 mg amlodipine LCB or IB once daily for 6 weeks in each period in a 2 × 2 crossover manner with three follow-up visits in each sequence. In 28 evaluable patients, the reduction of systolic BP (SBP), diastolic BP, and safety profile between two brands was comparable.

Results:

The lower bound of the 95% confidence interval of the difference in reduction of SBP (−5.04 mmHg) was within the noninferiority margin of 10 mmHg.

Conclusion:

LCB amlodipine is noninferior to IB in terms of BP reduction and is a cost-effective alternative as it is less expensive than IB.

Comparisons of the pharmacokinetics and tolerability of fixed-dose combinations of amlodipine besylate/losartan and amlodipine camsylate/losartan in healthy subjects: a randomized, open-label, single-dose, two-period, two-sequence crossover study

Background

A fixed-dose combination (FDC) of amlodipine and losartan has been used to reduce blood pressure in patients whose hypertension is not sufficiently controlled with either drug alone. The aim of this study was to evaluate the pharmacokinetic (PK) characteristics and tolerability of an FDC of 6.94 mg amlodipine besylate (5 mg as amlodipine)/50 mg losartan potassium compared to an FDC of 5 mg amlodipine camsylate/50 mg losartan potassium in healthy subjects.

Subjects and methods

A randomized, open-label, single-dose, two-period, two-sequence crossover study was conducted on 46 healthy male subjects. Blood concentrations were measured by liquid chromatography–tandem mass spectrometry. Blood samples were collected up to 144 hours post dose for each period. PK parameters were calculated in each treatment group using a noncompartmental method. The 90% confidence intervals (CIs) of the geometric mean ratios of the two treatments for the maximum plasma concentration (C_max) and the area under the concentration curve from time zero to the last quantifiable time point (AUC_0–t) were estimated. Tolerability assessments were performed for all subjects who received the drug at least once.

Results

The PK profiles of the two treatments were similar. For amlodipine, the geometric mean ratios (90% CIs) of amlodipine besylate to amlodipine camsylate for the C_max and AUC_0–t were 0.98 (0.94−1.01) and 0.97 (0.93−1.01), respectively. The corresponding values for losartan were 0.91 (0.81−1.02) and 1.05 (0.98−1.12), respectively. The incidence of adverse events was not significantly different between the two treatments, and both were well tolerated.

Conclusion

An FDC of 6.94 mg amlodipine besylate (5 mg as amlodipine)/50 mg losartan potassium produced similar results to an FDC of 5 mg amlodipine camsylate/50 mg losartan potassium treatment with respect to the PK parameters of amlodipine and losartan based on C_max and AUC_0–t values. The amlodipine besylate/losartan potassium combination was well tolerated by healthy male subjects.

Generic versus brand-name drugs used in cardiovascular diseases

This meta-analysis aimed to compare the efficacy and adverse events, either serious or mild/moderate, of all generic versus brand-name cardiovascular medicines. We searched randomized trials in MEDLINE, Scopus, EMBASE, Cochrane Controlled Clinical Trial Register, and ClinicalTrials.gov (last update December 1, 2014). Attempts were made to contact the investigators of all potentially eligible trials. Two investigators independently extracted and analyzed soft (including systolic blood pressure, LDL cholesterol, and others) and hard efficacy outcomes (including major cardiovascular adverse events and death), minor/moderate and serious adverse events. We included 74 randomized trials; 53 reported ≥1 efficacy outcome (overall sample 3051), 32 measured mild/moderate adverse events (n = 2407), and 51 evaluated serious adverse events (n = 2892). We included trials assessing ACE inhibitors (n = 12), anticoagulants (n = 5), antiplatelet agents (n = 17), beta-blockers (n = 11), calcium channel blockers (n = 7); diuretics (n = 13); statins (n = 6); and others (n = 3). For both soft and hard efficacy outcomes, 100 % of the trials showed non-significant differences between generic and brand-name drugs. The aggregate effect size was 0.01 (95 % CI -0.05; 0.08) for soft outcomes; -0.06 (-0.71; 0.59) for hard outcomes. All but two trials showed non-significant differences in mild/moderate adverse events, and aggregate effect size was 0.07 (-0.06; 0.20). Comparable results were observed for each drug class and in each stratified meta-analysis. Overall, 8 serious possibly drug-related adverse events were reported: 5/2074 subjects on generics; 3/2076 subjects on brand-name drugs (OR 1.69; 95 % CI 0.40-7.20). This meta-analysis strengthens the evidence for clinical equivalence between brand-name and generic cardiovascular drugs. Physicians could be reassured about prescribing generic cardiovascular drugs, and health care organization about endorsing their wider use.

Bioequivalence evaluation of two amlodipine salts, besylate and orotate, each in a fixed-dose combination with olmesartan in healthy subjects

A fixed-dose combination of amlodipine and olmesartan is used to treat high blood pressure in patients whose hypertension is not sufficiently controlled with either drug alone. The objective of this study was to evaluate the bioequivalence of two fixed-dose combinations, ie, amlodipine orotate/olmesartan medoxomil 10/40 mg and amlodipine besylate/olmesartan medoxomil 10/40 mg, in healthy subjects. A randomized, open-label, single-dose, two-sequence, two-period, crossover study was conducted in 30 healthy adult volunteers. Blood samples were collected for up to 72 hours post-dose in each period. Safety data included the results of physical examinations, clinical laboratory tests, vital signs, an electrocardiogram, and adverse events. For both amlodipine and olmesartan, the 90% confidence intervals for the geometric mean ratios of AUC_last and time to peak plasma concentration fell within the bioequivalence acceptance criteria. The two fixed-dose combinations showed similar safety profiles. Amlodipine orotate/olmesartan medoxomil 10/40 mg was bioequivalent to amlodipine besylate/olmesartan medoxomil 10/40 mg.

Clinical equivalence of generic and brand-name drugs used in cardiovascular disease: a systematic review and meta-analysis

CONTEXT

Use of generic drugs, which are bioequivalent to brand-name drugs, can help contain prescription drug spending. However, there is concern among patients and physicians that brand-name drugs may be clinically superior to generic drugs.

OBJECTIVES

To summarize clinical evidence comparing generic and brand-name drugs used in cardiovascular disease and to assess the perspectives of editorialists on this issue.

DATA SOURCES

Systematic searches of peer-reviewed publications in MEDLINE, EMBASE, and International Pharmaceutical Abstracts from January 1984 to August 2008.

STUDY SELECTION

Studies compared generic and brand-name cardiovascular drugs using clinical efficacy and safety end points. We separately identified editorials addressing generic substitution.

DATA EXTRACTION

We extracted variables related to the study design, setting, participants, clinical end points, and funding. Methodological quality of the trials was assessed by Jadad and Newcastle-Ottawa scores, and a meta-analysis was performed to determine an aggregate effect size. For editorials, we categorized authors' positions on generic substitution as negative, positive, or neutral.

RESULTS

We identified 47 articles covering 9 subclasses of cardiovascular medications, of which 38 (81%) were randomized controlled trials (RCTs). Clinical equivalence was noted in 7 of 7 RCTs (100%) of beta-blockers, 10 of 11 RCTs (91%) of diuretics, 5 of 7 RCTs (71%) of calcium channel blockers, 3 of 3 RCTs (100%) of antiplatelet agents, 2 of 2 RCTs (100%) of statins, 1 of 1 RCT (100%) of angiotensin-converting enzyme inhibitors, and 1 of 1 RCT (100%) of alpha-blockers. Among narrow therapeutic index drugs, clinical equivalence was reported in 1 of 1 RCT (100%) of class 1 antiarrhythmic agents and 5 of 5 RCTs (100%) of warfarin. Aggregate effect size (n = 837) was -0.03 (95% confidence interval, -0.15 to 0.08), indicating no evidence of superiority of brand-name to generic drugs. Among 43 editorials, 23 (53%) expressed a negative view of generic drug substitution.

CONCLUSIONS

Whereas evidence does not support the notion that brand-name drugs used in cardiovascular disease are superior to generic drugs, a substantial number of editorials counsel against the interchangeability of generic drugs.

Efficacy and safety profiles of a new S(-)-amlodipine nicotinate formulation versus racemic amlodipine besylate in adult Korean patients with mild to moderate hypertension: an 8-week, multicenter, randomized, double-blind, double-dummy, parallel-group, phase III, noninferiority clinical trial

BACKGROUND

"Chiral switching" from an existing racemate to a pure enantiomeric compound is a popular theme in drug development, especially when the enantiomer is found to have better efficacy and safety profiles. Amlodipine is a racemic mixture, composed of the S(-)-enantiomer, which is the pharmacologically active isomer, and the R(+)-enantiomer, which is 1000-fold less active. S(-)-amlodipine nicotinate, a chirally switched form of amlodipine nicotinate, has been developed and found to be bioequivalent to amlodipine besylate in Phase I clinical trials in Korea.

OBJECTIVE

The aim of this study was to compare the efficacy and safety profiles of S(-)-amlodipine nicotinate with those of amlodipine besylate in adult Korean patients with mild to moderate hypertension (diastolic blood pressure [DBP] >or=90 mm Hg and <or=109 mm Hg).

METHODS

This was an 8-week, multicenter, randomized, double-blind, double-dummy, parallel-group, Phase III, noninferiority clinical trial. After an initial 2-week placebo run-in period, patients aged 18 to 75 years with sitting DBP (SiDBP) >or=90 and <or=109 mm Hg at day 0 (baseline) were randomly allocated to receive S(-)-amlodipine nicotinate 2.5 mg QD or amlodipine besylate 5 mg QD for 8 weeks. The dose of study medication was doubled after 4 weeks in patients who had not responded to treatment (SiDBP >or=90 mm Hg). The primary end point was noninferiority of the difference in mean SiDBP from baseline to week 8 for S(-)-amlodipine nicotinate compared with amlodipine besylate. Secondary end points were as follows: (1) noninferiority of the difference in mean sitting systolic blood pressure (SiSBP) from baseline to week 8 between the study groups; and (2) SiDBP response rate (defined as the proportion of patients whose SiDBP was <90 mm Hg or whose SiDBP reduction was >or=10 mm Hg from baseline) after the 8-week treatment. Also, the incidence and severity of adverse events (AEs) and adverse drug reactions (ADRs) were reported. Severe AEs/ADRs were defined as those associated with any of the following: death; an event associated with a high risk of mortality; an event requiring hospitalization; or development of a permanent disability or congenital malformation.

RESULTS

One hundred fifty-seven patients were assessed for inclusion in the study. Of these, 124 patients were randomly allocated to receive S(-)-amlodipine nicotinate (42 men, 21 women; mean [SD] age, 52.4 [10.3] years [range, 23-70 years]; weight, 67.7 [10.8] kg [range, 44-92 kg]) or amlodipine besylate (45 men, 16 women; mean [SD] age, 54.5 [10.0] years [range, 30-73]; weight, 68.9 [9.8] kg [range, 49-95 kg]). One hundred sixteen patients completed the study, but 11 patients (8.9%) were dropped from the per-protocol analysis due to violations; therefore, 105 patients were included in the modified intent-to-treat population analysis (S[-]-amlodipine nicotinate, 55 patients; amlodipine besylate, 50 patients). There were no significant between-group differences in the baseline characteristics. Baseline mean (SD) SiSBP and SiDBP were 142.6 (11.3) and 94.9 (4.8) mm Hg in the S(-)-amlodipine nicotinate group, and 141.8 (8.3) and 96.1 (4.9) mm Hg in the amlodipine besylate group. Mean (SD) changes in SiSBP were 17.6 (11.2) mm Hg in the S(-)-amlodipine nicotinate group and 18.6 (12.3) mm Hg in the amlodipine besylate group. The SiDBP response rates were 92.7% in the S(-)-amlodipine nicotinate group and 88.0% in the amlodipine besylate group. There were no significant between-group differences in the prevalence of AEs and ADRs. In the S(-)-amlodipine nicotinate group, 15 patients (23.8%) reported a total of 28 AEs, and 19 patients (31.1%) reported a total of 27 AEs in the amlodipine besylate group. Six patients (9.5%) in the S(-)-amlodipine nicotinate group and 7 patients (11.4%) in the amlodipine besylate group experienced a total of 19 ADRs (11 and 8, respectively). The most common ADRs were liver enzyme elevation (3/63 [4.8%]) in the S(-)-amlodipine nicotinate group and facial flushing (3/61 [4.9%]) in the amlodipine besylate group. No cases of severe AEs or ADRs were reported in either group.

CONCLUSIONS

The reduction of SiDBP after 8 weeks of treatment with S(-)-amlodipine nicotinate was noninferior compared with that of racemic amlodipine besylate in these adult Korean patients with mild to moderate hypertension. The SiDBP response rate and the reduction of SiSBP after 8 weeks of treatment with S(-)-amlodipine nicotinate were not significantly different from those with racemic amlodipine besylate. Both treatments were generally well tolerated.