Key words pharmacokinetics - drug delivery - drug research - clinical trials - cardiovascular
pharmacology
Introduction
Trimetazidine (TMZ), an anti-ischemic and anti-anginal metabolic agent, is indicated
in adults as an add-on therapy for the symptomatic treatment of patients with stable
angina pectoris who are inadequately controlled by or intolerant to first-line
anti-anginal therapies. Its modified release (MR) tablet is recommended as TMZ
35 mg tablet to administer twice daily. The pharmacokinetics (PK) of TMZ is
described in the product labeling [1 ].
Elimination of TMZ has been found to be predominantly renal with
79 –84% of administered radioactivity appearing in the urine
within 24 h, of which at least 60% was due to unchanged TMZ [2 ]. Yet, there is limited knowledge on the PK
of TMZ in both the elderly and in subjects with renal function impairment. The
effect of age and renal function on the PK profile of the modified release (MR)
tablet of TMZ 35 mg administered twice daily has been studied previously
[3 ]. TMZ renal clearance was approximately
25.2 L/h (420 mL min−1 ) in subjects with normal
renal function, 3.5-fold higher than the glomerular filtration rate (GFR). The high
renal clearance as a result of the relatively low plasma protein binding of TMZ
(15%) suggests a significant renal tubular secretion. Moreover, it has been
observed that stable angina pectoris, for which TMZ is indicated, is more frequent
in the elderly and impaired kidney function patients. Given the role of the kidneys
in the pharmacokinetics (PK) and specifically the clearance of TMZ, further
evaluation of the target population for TMZ, i.e., elderly and patients with
impaired kidney function, is needed for any potential dosing adjustment [3 ]
[4 ].
In 2011, TMZ was subjected to an Article 31 Referral procedure in Europe, initiated
by the French Health products Agency (AFSSAPS, now ANSM) at the European Medicines
agency (EMA) due to both efficacy and safety concerns (including Parkinson’s
syndrome and lack of data in frail target populations) [5 ]. After the review, the Committee for
Medicinal Products for Human Use (CHMP) requested that “The MAH should
perform a PK study assessing the effect of renal impairment and age on TMZ PK
according to the CHMP agreed protocol” as data were lacking in these subject
groups because the elderly (above 65 and even 75 years of age) were an important
target population for treatment with TMZ. However, the linearity of PK of
trimetazidine had not been established. Thus, as a first step we conducted the
current single ascending dose study to assess linearity of PK of trimetazidine. We
conducted this study in healthy subjects with various dosage regimen to assess
linearity of PK of TMZ-modified release. Based on the results of current study, we
also conducted a multiple-dose to evaluate the effect of age and renal impairment
on
the pharmacokinetics of trimetazidine (TMZ) in healthy elderly and renally-impaired
subjects and to assess its safety and tolerability profile. Results of the
multiple-dose study have been published elsewhere[6 ].
Therefore, the current study was conducted in accordance with the CHMP requirements
to evaluate PK and safety of TMZ. Specifically, the objectives of this study were
to
assess: (1) linearity of PK of TMZ-modified release, and (2) the safety and
tolerability of TMZ in healthy subjects.
Methods
Study Design
This was a randomized, open-label, single ascending-dose study. Eighteen healthy
subjects of any gender of 18–55 years of age with normal renal function
were enrolled. Subjects were screened within 2 months of admission. Sample size
was determined based on ‘the evaluation of the ‘Pharmacokinetics
of medicinal products in patients with decreased renal function
EMA/83874/2014.’ Subjects were included in this study if
they had no clinically relevant abnormalities identified by a detailed medical
history, full physical examination, blood pressure (BP), pulse measurements,
temperature, respiratory rate (RR), height, weight, 12-lead electrocardiogram
(ECG), and clinical laboratory tests. Subjects were excluded from the study if
they had a condition that could be affected by participation in the study or by
administration of TMZ-modified release or might interfere with the
interpretation of the study. Subjects with hypersensitivity to TMZ, excipients,
any structurally related drugs and/or any excipient were also excluded.
No concomitant medications were allowed during the study, except for hormone
replacement therapy and/or paracetamol (up to 1 g/day
for analgesia). The eligibility status of the participants was reconfirmed on
the day before the study. This joint study was sponsored by a consortium of TMZ
Marketing Authorization Holders in the European Union. All study procedures were
conducted in accordance with the ethical principles of Good Clinical Practice
(GCP) and the Declaration of Helsinki. An Independent Ethics Committee reviewed
and approved the study protocol and informed consent form before participants
were screened. All participants provided written informed consent before
admission to the study.
Intervention and posology
The 18 study subjects were randomly assigned to 3 parallel cohorts of 6 subjects
each to receive a single ascending dose of 35, 70 mg or 105 of oral
TMZ-modified release tablet. According to SmPC (summary of product
characteristics) for trimetazidine, the normal dose for trimetazidine for adult
is 35 mg twice a day. Based on this standard dosing, we selected these
single doses. The study medication was provided as the branded
Moduxin® MR 35 mg, retard tablet (manufactured by
Gedeon Richter, Romania). The tablets were administered orally at scheduled
dosing time in sitting position with 240 mL of drinking water and
standard breakfast (single dosing).
Pharmacokinetic evaluation
Blood samples (4 mL) were collected before dosing and at 1, 2, 2.5, 3,
3.5, 4, 4.5, 5, 5.5, 6, 7, 8, 10, 12, 24, 36, and 48 h after dosing.
Drug administration and blood sampling processes were under continuous medical
supervision. Collected blood samples were centrifuged at 3000 g for
10 min. The plasma was separated and stored at approximately
−20°C for further analysis. Quantification of trimetazidine in
plasma samples was carried out using analytical assay method of High-Performance
Liquid Chromatography (HPLC) with Tandem Mass Spectrometer (MS/MS)
detection which was developed and validated before the start of the clinical
study. This method was developed for a concentration range spanning the TMZ
levels from 4.8 – 28.0 μg/mL which was expected
to be present in the plasma samples collected during the clinical study. Blood
and urine samples were also analysed in central laboratory to measure clinical
laboratory parameters.
The pharmacokinetic parameters of TMZ were calculated by non-compartmental
analysis methods using Phoenix® WinNonlin®
software, version 6.3. Actual sampling times relative to dosing rather than
nominal times were used in the calculation of all derived PK parameters. There
was no imputation of missing data. Pharmacokinetic parameters evaluated were:
area under the plasma concentration-time curve from time 0 to the last
quantifiable concentration (AUC(0-t) ), area under the plasma
concentration-time curve from time 0 to ∞ was calculated as
AUC(0-inf) =AUC(0-t) +
Clast/ λz , where Clast was
the last quantifiable plasma concentration and λz was the
apparent terminal elimination rate constant (AUC(0-inf) ), apparent
total body clearance (CL/F) and maximum observed plasma concentration
(Cmax ) were used for the assessment of linearity. Secondary
endpoints included the renal elimination of TMZ (renal clearance
[CLR ]) and safety parameters. Pharmacokinetic concentration data were
listed by subject including actual sampling times relative to dosing. Plasma and
urine concentrations were analyzed by analyte (TMZ), intervention
group/cohort, and nominal time point. Descriptive statistics of PK
parameters for plasma concentrations obtained at each nominal time point were
summarized by intervention group/cohort. Coefficient of variation
(CV%), and geometric CV% (calculated as:
gCV%=SQRT[exp(SD2 )-1] * 100; where
SD=standard deviation of the natural-logarithmically-transformed data)
values were calculated. Mean plasma concentrations versus nominal times were
also presented in a linear and semi-logarithmic scale. To confirm renal function
in these healthy subjects, renal function was assessed by estimating creatinine
clearance (from serum creatinine [Scr]) using the Modification of Diet in Renal
Disease (MDRD) approach, prior to enrollment or screening period [7 ].
The MDRD formula was:
eGFR (mL/min/1.73 m
2
)=175×(Scr, std)
−1.154
(Age)
-0.203
×(0.742 if female)×(1.212 if African American)
Assessment of Dose-Proportionality
Dose-proportionality was assessed for Cmax , AUC(0-t) and
AUC(0-inf) using the following power model:
ln <Parameter>=α+β ln
<Dose>
When both sides are exponentiated:
<Parameter>=
exp(α)∙<Dose>β
Thus, when β=1, the drug is proportional.
Actual and planned dose values were used in the analyses. The parameter estimates
for β and 95% confidence interval were presented to assess
dose-proportionality. No inferential analysis was performed other than the
dose-proportionality analysis.
Safety evaluation
Numbers of Treatment-emergent adverse events (TEAEs) were summarized by System
Organ Class (SOC) and preferred term and severity/causality to the study
drug. The following safety variables were assessed: physical examination, vital
signs (BP, pulse, oral temperature, respiratory rate (RR) measured in breaths
per minute, 12-lead ECG in triplicate, haematology (red blood cell count, mean
corpuscular volume [MCV]), mean corpuscular haemoglobin, haemoglobin,
haematocrit, platelet count, white blood cell count and differentials
(neutrophils, eosinophils, basophils, lymphocytes, monocytes), biochemistry
(magnesium, sodium, potassium, chloride, creatinine, creatine phosphokinase,
glucose, urea, uric acid, calcium, inorganic phosphorus, alkaline phosphatase
[AP], Aspartate aminotransferase [AST], Alanine aminotransferase [ALT],
gamma-glutamyl transferase, total bilirubin, total protein, albumin, total
cholesterol and triglycerides), and urine analysis. A midstream, clean-catch
urine specimen was collected for dipstick analysis of bilirubin, protein, blood,
glucose, nitrite, ketone, and pH. Urine samples positive for blood or protein,
were sent for microscopy if deemed appropriate by the investigator. Pregnancy,
adverse events (AEs), and QTc interval were also recorded. The grading and
reporting of AE were performed according to Common Terminology Criteria for
Adverse Events (CTCAE).
Results
Demographics
Of the 51 subjects who were screened in the study, 18 subjects met all the study
eligibility criteria and completed treatment and follow-up ([Table 1 ]). Most of the subjects in the
study were female (72.2%), Caucasian (94.4%) and aged between 19
and 51 years. In the 35-mg dose group, all the subjects were females.
Table 1 Subject demographics.
Intervention group
Total
Parameter
35 mg (n=6)
70 mg (n=6)
105 mg (n=6)
N=18
Age (years)
Mean (±SD)
38.5 (±12.39)
29.2 (±8.91)
34.8 (±11.05)
34.2 (±10.96)
Gender
Male
0
2 (33.3%)
3 (50.0%)
5 (27.8%)
Female
6 (100%)
4 (66.7%)
3 (50.0%)
13 (72.2%)
Race
Caucasian
6 (100%)
5 (83.3%)
6 (100%)
17 (94.4%)
American Indian or Alaska Native
0
1 (16.7%)
0
1 (5.6%)
Height (cm)
Mean (±SD)
163.2 (±4.26)
167.5 (±13.37)
177.5 (±10.48)
169.4 (±11.33)
Weight (kg)
Mean (±SD)
60.18 (±6.1)
61.35 (±12.68)
73.50 (±14.27)
65.01 (±12.51)
BMI (kg∙m
−2
)
Mean (±SD)
22.57 (±1.64)
21.68 (±1.98)
23.13 (±2.69)
22.46 (±2.11)
Serum Creatinine (mg∙L
−1
)
Mean (±SD)
57.00 (±7.3)
62.62 (±9.93)
64.70 (±8.81)
61.44 (±8.87)
Abbreviation: N=total number of enrolled subjects;
n=number of subjects in each group; SD=Standard
Deviation.
TMZ pharmacokinetic analysis
The arithmetic mean maximum plasma concentration (Cmax ) of
TMZ-modified release following a single-dose of 35, 70, and 105 mg was 79.32
(±23.08), 153.172 (±23.08), and 199.677 (±23.08)
ng/mL, respectively ([Fig. 1 ]).
The corresponding median time to Cmax (Tmax ) was
comparable across the dose range investigated [5.42 (±0.49), 4.51
(±1.27), and 4.57 (±0.96), respectively] ([Table 2 ]). Following attainment of
Cmax , the plasma concentration-time profile declined in a broadly
mono-exponential fashion with a mean t1/2 which was similar
in each of the dose groups ranging from 6.40 to 7.75 h. An increase in
total exposure (AUC(0-inf) ) [1116.897 (±378.35), 1838.39
(±284.50), and 2504.845 (±348.35) ng.h mL−1 ,
respectively] was observed with increasing dose. CLR was increased in
an apparently dose-dependent manner [3.70 (±2.24), 14.80
(±5.91), and 19.58 (±6.24) L·h−1 ,
respectively] ([Table 2 ]). A concomitant
increase in the apparent CL following oral administration (CL/F) was
also observed [33.69 (±8.51), 38.85 (±6.15), and 42.74
(±7.10) L·h−1 , respectively].
Fig. 1 Trimetazidine plasma concentration (mean±SD) vs.
time profile following administration of 35, 70, or 105 mg
trimetazidine to healthy subjects (linear scale). Assessment of
linearity.
Table 2 Summary of pharmacokinetic parameters following
administration of 35, 70 or 105 mg trimetazidine to healthy
subjects (N=18) mean (±SD).
PK Parameter
35 mg (n=6)
70 mg (n=6)
105 mg (n=6)
C
max
(ng mL
−1
)
79.32 (±23.08)
153.17 (±32.53)
199.67 (±42.5)
T
max
(h)
5.42 (±0.49)
4.51 (±1.27)
4.57 (±0.96)
t
1/2
(h)
7.75 (±1.62)
6.40 (±1.23)
6.50 (±1.18)
AUC
(0-t)
(ng.h mL
−1
)
1090.09 (±353.01)
1822.18 (±278.57)
2480.80 (±345.88)
AUC
(0-inf)
(ng.h mL
−1
)
1116.89 (±378.35)
1838.59 (±284.50)
2504.84 (±348.35)
CL/F (L·h
−1
)
33.69 (±8.51)
38.85 (±6.15)
42.74 (±7.10)
CL
R
(L·h
−1
)
13.70 (±2.24)
14.80 (±5.91)
19.58 (±6.24)
Abbreviation: AUC=Area under the curve; N=total number of
subjects; SD=standard deviation, n=number of subjects in
the group.
Effect of a single dose (35, 70, and 105 mg) of TMZ-modified release on
the PK parameters AUC(0-inf) , AUC(0-t) , and
Cmax was analyzed. The slope estimates for all three parameters
were less than 1, indicating that a less than dose-proportional increase in
systemic exposure was observed with increasing dose ([Table 3 ]). The corresponding 95%
CI of the slope for the AUC parameters excluded 1, indicating that the deviation
from dose-proportionality is statistically significant. Conversely, the
corresponding 95% CI of the slope for Cmax included 1,
indicating that the less than dose-proportional increase in Cmax was
not statistically significant. Taken together, these results showed a non-linear
PK for a single ascending dose of TMZ in healthy subjects.
Table 3 Statistical analysis of trimetazidine pharmacokinetic
parameters for the assessment of linearity (slope estimate and
95% CI) (N=18).
PK parameter
Slope estimate (β) (95% CI)
AUC
(0-inf)
(ng.h mL−1 )
0.76 (0.54, 0.99)
AUC
(0-t)
(ng.h mL−1 )
0.77 (0.56, 0.99)
C
max
(ng mL−1 )
0.87 (0.60, 1.13)
Dose Range=35 mg (n=6), 70 mg
(n=6), and 105 mg (n=6)
Abbreviation: AUC=Area Under the Curve; CI=Confidence
Interval
Safety results
There was no notable change in biochemistry and hematology parameters of the
subjects in the study (data not shown). Changes in vital signs from screening
were small and there were no differences among the groups in the study (data not
shown). There were no clinically significant changes from screening for any
subject in the study with respect to ECG findings (data not shown). Overall, the
incidence of treatment-emergent adverse events (TEAE) was low. Among the 18
subjects in the study, 7 subjects (38.9%) experienced a total of 10 AEs
during the study. Of these 10 AEs, 9 were TEAEs. All TEAEs reported were mild.
Three of the nine TEAEs were considered related to the study drug by the
investigator and all TEAEs were resolved ([Table 4 ]). The most common TEAE reported in the study was oral herpes
(infections and infestations SOC, two subjects). Three TEAEs (upper abdominal
pain, headache, and agitation) in three subjects were considered related to
study drug by the investigator in the study. During the study, no fatal outcomes
were observed. There were no severe and no serious adverse event (SAEs) reported
in the study. No subject discontinued due to AE from the study. Thus,
single-dosing of 35, 70, and 105 mg strengths of TMZ-modified release
was well-tolerated by the healthy subjects in the study.
Table 4 Treatment-emergent adverse events by system organ
class, preferred term, and causality by groups (N=18).
System Organ Class Preferred Term
Causality
35 mg (n=6) n (%), #E
70 mg (n=6) n (%), #E
105 mg (n=6) n (%), #E
Gastrointestinal disorders
Abdominal pain (upper)
Related
1 (16.7%), 1
0
0
General disorders and administration site conditions
Injection site pain
Not related
0
0
1 (16.7%), 1
Infections and infestations
Oral herpes
Not related
1 (16.7%), 1
0
1 (16.7%), 1
Nervous system disorders
Headache
Related
0
0
1 (16.7%), 1
Sciatica
Not related
0
1 (16.7%) 1
0
Psychiatric disorders
Agitation
Related
1 (16.7%), 1
0
0
Respiratory, thoracic, and mediastinal disorders
Cough
Not related
0
0
1 (16.7%), 1
Oropharyngeal pain
Not related
0
1 (16.7%), 1
0
Abbreviations: N=total number of subjects in safety analysis Set;
n=number of subjects; #E=number of events.
Discussion
In this single ascending dose study, pharmacokinetic parameters after administration
of 35 mg, 70 mg, and 105 mg TMZ-modified release were
evaluated in healthy subjects. A less than dose-proportional increase in
AUC(0-inf) , AUC(0-t) , and Cmax was noted. A
dose-dependent increase in CLR and CL/F after single dose
administration was observed. Statistical analysis of linearity confirmed that the
less than dose-proportional increase in AUC(0-inf) and
AUC(0-t) was significant, indicating that the pharmacokinetics of
TMZ-modified release is dose dependent over the range of 35 to 105 mg. It
may be due to an increase in CLR with increasing dose. Taken together,
our results suggest that TMZ-modified release follow a non-linear pharmacokinetics
in human subjects. In addition, the TMZ-modified release was well tolerated in all
dose groups. No new or unexpected safety concerns were identified during the
study.
To our knowledge, this is the first single ascending dose to evaluate the PK of
TMZ-modified release in healthy subjects. No phase I study has been performed for
TMZ-modified release which determined the linearity of TMZ-modified release after
the single ascending dose. However, a few investigators have reported different PK
characteristics of TMZ-modified release. In this study, mean Cmax of
79.32 (±23.08) ng mL−1 was observed with a single
dose of 35 mg TMZ-modified release. This result is in line with a previous
study by Ozbay et al that reported a median Cmax of 63.1
(±17.1) ng mL−1 with TMZ [8 ]. In addition, the median Tmax of 5 h reported
previously in healthy subjects taking TMZ-modified release (35 mg) is
similar to results obtained in our study (5.42 h) [8 ]. Moreover, the mean AUC(0-inf)
reported in this study was 1116.89 (±378.35) ng.h mL−1 as
compared to 793.4 (±249.0) ng.h mL−1 reported by others
[8 ]. In addition, total body clearance of
TMZ in this study [33.69 (±8.51) L·h−1 ] was found
comparable to other studies [25.2 (±4.5) L h−1 ] [3 ]. Of note, the comparison of the study
results to other studies should be done with caution due to the differences in study
designs and/or subject demographics.
A few clinical trials have evaluated the safety profile of TMZ in humans. However,
for the first time, we conducted a single ascending dose study that included a dose
of 105 mg, three times more than the recommended dose. No SAE, death or
discontinuation due to AEs was observed at any dose in this study, suggesting that
a
single dose of TMZ-modified release is well tolerated in healthy subjects, even at
a
dose three times higher than the recommended dose. Only a few TEAE were observed in
this study which were mild to moderate in nature and in line with other published
studies [9 ]. Only one case of each of upper
abdominal pain, headache, and agitation in three subjects was observed. These AE
were considered related to study drug by the investigator. However, in other studies
gastric or esophageal burning, muscular cramps, dizziness, effort induced
discomfort, depression, sedation, and/or drowsiness, palpitations, visual
disturbances, anorexia and hyperorexia have been reported more frequently. TMZ has
also been shown to induce parkinsonism, gait disorders and tremor as well. However,
the benefits of TMZ therapy continue to outweigh the risks in patients with angina
pectoris [5 ]. Few study limitations should be
mentioned. The study was designed as an open-label study rather than a blind
placebo-controlled trial. Moreover, the study was conducted with a single-dose and
was also limited by the small sample size. Therefore, interpretations of
treatment-related AEs should keep this study design in mind.
Only 6 subjects were recruited for each dose regimen. Thus, individual differences
in
PK parameters may have led to non-linear PK. However, we have taken the blood
samples for measurement of PK parameters at short time intervals and included only
healthy subjects. We believe these two factors mitigated the effect of small sample
size. Moreover, it was a single ascending dose study to assess the linearity of PK
of trimetazidine in accordance with the standard guidelines which suggest a small
sample size for single ascending dose study. A detailed population pharmacokinetic
analysis can be performed using the data obtained from this study to assess effect
of individual differences and small sample size. However, it is beyond the scope of
this study. Furthermore, number of females was not similar among all three groups
(50−100%). AUC could be different for male and female and could be a
reason for the less than dose-proportional increase in AUC(0-inf) ,
AUC(0-t) , and Cmax . Of note, all subjects in the
35 mg treatment group were female which might be a reason for higher
AUC(0-inf) , AUC(0-t) , and Cmax in this group.
However, it has been reported that gender does not affect clinical efficacy of
trimetazidine [10 ]. In addition, it has also
been reported in the literature that except for a few drugs, gender-related
difference in the pharmacokinetics does not lead to significant effect on clinical
efficacy of the drugs [11 ]. Furthermore, this
study was designed according to standard guidelines for PK studies. Therefore, we
did not perform any sub-group analysis in this study including effect of gender
difference among various dose groups on the linearity of PK of trimetazidine.
Conclusions
Results of this study fills the gap in the data regarding PK parameters of
TMZ-modified release. Our results showed a non-linear PK of TMZ-modified release in
human subjects. In addition, it was well-tolerated, and no major safety issue was
reported. Hence, our study provides adequate preliminary data on dose, safety, and
tolerability of TMZ-modified release. The CHMP has requested to conduct
pharmacokinetic study in special population including elderly and renal-impaired
patients. However, clinical trial data on the linearity of PK of trimetazidine was
not available. Thus, as a first step, we conducted the current study to assess
linearity of PK of trimetazidine in healthy subjects. Since results from this study
showed a non-linear PK of trimetazidine, we designed another multiple-dose study
evaluating ‘effect of age and glomerular filtration rate on the
pharmacokinetics and safety of trimetazidine. Results from the multiple-dose dose
study have been published elsewhere.
Disclosures
Thomas Koernicke is an employee of the PAREXEL International GmbH, Germany. Abdus
Samad, Deepa Arora, and Shashank Jain are employees of Lupin Limited, India. Sigal
Kaplan is an employee of Teva Pharmaceutical Industries Ltd, Israel. Mónika
Domahidy is an employee of Gedeon Richter Plc., Hungary. Hanka de Voogd is an
employee of Mylan EPD, The Netherlands. Stella Böhmert is an employee of
Sandoz International GmbH, Germany. Rita Silveira Ramos is an employee of
Generis® Farmacêutica, Portugal.
