Mechanism of action
Trospium chloride is an antispasmodic, antimuscarinic agent.
Trospium chloride antagonizes the effect of acetylcholine on muscarinic receptors in cholinergically innervated organs including the bladder. Its parasympatholytic action reduces the tonus of smooth muscle in the bladder.
In vitro receptor binding studies have demonstrated the selectivity
of trospium chloride for muscarinic over nicotinic receptors, and similar affinity
for the M2 and M3 muscarinic receptor subtypes. M2 and M3 receptors are found
in the bladder and may play a role in the pathogenesis of overactive bladder.
Pharmacodynamics
Placebo-controlled studies assessing the impact on urodynamic variables of an immediate-release formulation of trospium chloride were conducted in patients with conditions characterized by involuntary detrusor contractions. The results demonstrated that trospium chloride increases maximum cystometric bladder capacity and volume at first detrusor contraction.
Pharmacokinetics
Absorption: Mean absolute bioavailability of a 20 mg immediate-release dose is 9.6% (range 4.0-16.1%). Following a single 60 mg dose of SANCTURA XR™ , peak plasma concentration (Cmax) of 2.0 ng/mL occurred 5.0 hours post dose. By contrast, following a single 20 mg dose of an immediate-release formulation of trospium chloride, Cmax was 2.7 ng/mL.
A summary of mean (± standard deviation) pharmacokinetic parameters for a single dose of 60 mg SANCTURA XR™ is provided in Table 3.
Table 3: Mean (±SD) Pharmacokinetic Parameter Estimates
for a Single 60 mg Oral Dose of SANCTURA XR™ in Healthy Volunteers
| Treatment |
AUC(0-24)
(ng•h/mL) |
Cmax
(ng/mL) |
Tmaxa
(h) |
t ˝b
(h) |
| SANCTURA XR™ 60 mg |
18.0 ± 13.4 |
2.0 ± 1.5 |
5.0 (3.0-7.5) |
36 ± 22 |
a Tmax expressed as median (range).
b t ˝ was determined following multiple (10) doses. |
The mean sample concentration-time (+ standard deviation) profile for SANCTURA XR™ is shown in Figure 1.
Figure 1: Mean (+SD) Concentration-Time Profile for a Single
60 mg Oral Dose of SANCTURA XR™ in Healthy Volunteers
Administration of SANCTURA XR™ capsules immediately after a high
(50%) fat-content meal reduced the oral bioavailability of trospium chloride
by 35% for AUC(0-Tlast) and by 60% for Cmax. Other pharmacokinetic
parameters such as Tmax and t ˝ were unchanged in the presence of food. Coadministration
with antacid had inconsistent effects on the oral bioavailability of SANCTURA XR™ .
Distribution: Protein binding ranged from 48 to 78%, depending
upon the assessment method used, when a range of concentration levels of trospium
chloride (0.5-100 µg/L) were incubated in vitro with human serum.
The ratio of 3H-trospium chloride in plasma to whole blood was 1.6:1.
This ratio indicates that the majority of 3H- trospium chloride is
distributed in plasma.
Trospium chloride is widely distributed, with an apparent volume of distribution > 600 L.
Metabolism: The metabolic pathway of trospium in humans has not
been fully defined. Of the dose absorbed following oral administration, metabolites
account for approximately 40% of the excreted dose. The major metabolic pathway
of trospium is hypothesized as ester hydrolysis with subsequent conjugation
of benzylic acid to form azoniaspironortropanol with glucuronic acid. Cytochrome
P450 does not contribute significantly to the elimination of trospium. Data
taken from in vitro studies of human liver microsomes, investigating
the inhibitory effect of trospium on seven cytochrome P450 isoenzyme substrates
(CYP1A2, 2A6, 2C9, 2C19, 2D6, 2E1, and 3A4), suggest a lack of inhibition at
clinically relevant concentrations.
Excretion: The plasma half-life for trospium following oral administration
of SANCTURA XR™ is approximately 35 hours. After oral administration of
an immediate-release formulation of 14C-labeled trospium chloride,
a majority of the dose (85.2%) was recovered in feces and a smaller amount (5.8%
of the dose) was recovered in urine. Of the radioactivity excreted into the
urine, 60% was unchanged trospium.
The mean renal clearance for trospium (29.07 L/hour) is 4-fold higher than
average glomerular filtration rate, indicating that active tubular secretion
is a major route of elimination. There may be competition for elimination with
other compounds that are also renally eliminated (see DRUG INTERACTIONS).
Pharmacokinetics in Specific Populations
Age: In a phase 3 clinical trial of SANCTURA XR™ , the
observed plasma trospium concentrations were similar in older ( ≥ 65 years)
and younger ( < 65 years) OAB patients.
Pediatric: The pharmacokinetics of SANCTURA XR™ were not
evaluated in pediatric patients.
Race: Pharmacokinetic differences due to race have not been studied.
Gender: Gender differences in pharmacokinetics of SANCTURA XR™
have not been formally assessed. Data from healthy subjects suggests lower exposure
in males compared to females.
Hepatic: There is no information regarding the effect of moderate
to severe hepatic impairment on exposure to SANCTURA XR™ .
Renal Impairment: The pharmacokinetics of SANCTURA XR™
in patients with severe renal impairment has not been evaluated.
In a study of an immediate-release formulation of trospium chloride, 4.5-fold
and 2-fold increases in mean AUC(0–∞) and Cmax, respectively,
were detected in patients with severe renal impairment (creatinine clearance
< 30 mL/minute), compared with healthy subjects, along with the appearance
of an additional elimination phase with a long half-life (~33 hours vs. 18 hours).
Use of SANCTURA XR™ is not recommended in patients with severe
renal impairment (see DOSAGE AND ADMINISTRATION). The pharmacokinetics
of trospium chloride have not been studied in people with mild or moderate renal
impairment (CLcr ranging from 30-80 mL/min).
Clinical Studies
SANCTURA XR™ was evaluated for the treatment of patients with overactive
bladder who had symptoms of urinary frequency, urgency and urge urinary incontinence
in two 12-week, randomized, double-blind, placebo-controlled studies. For both
studies, entry criteria required the presence of urge incontinence (predominance
of urge), at least one incontinence episode per day, and 10 or more micturitions
(voids) per day (assessed by 3-day urinary diary). Medical history and data
from the baseline urinary diary confirmed the diagnosis. Approximately 88% of
the patients enrolled completed the 12-week studies. The mean age was 60 years,
and the majority of patients were female (84%) and Caucasian (86%).
The co-primary endpoints in the trials were the mean change from baseline to Week 12 in number of voids/24 hours (reductions in urinary frequency) and the mean change from baseline to Week 12 in number of incontinence episodes/24 hours. Secondary endpoints included mean change from baseline to Week 12 in volume per void.
Study 1 included 592 patients in both SANCTURA XR™ 60 mg and placebo groups. As illustrated in Table 4 and Figures 2 and 3, SANCTURA XR™ demonstrated statistically significantly (p < 0.01) greater reductions in the urinary frequency and incontinence episodes, and increases in void volume when compared to placebo starting at Week 1 and maintained through Weeks 4 and 12.
Table 4: Mean (SE) Change from Baseline in Urinary Frequency,
Urge Incontinence Episodes and Void Volume in Study 1
| Efficacy Endpointa |
Week |
Placebo |
SANCTURA XR™ |
P-Value |
| Urinary frequency/24 hours |
|
(N = 300) |
(N = 292) |
|
| Mean Baseline |
0 |
12.7 (0.2) |
12.8 (0.2) |
|
| Mean Change from Baseline |
1 |
-1.2 (0.1) |
-1.7 (0.1) |
0.0092 |
| |
4 |
-1.6 (0.2) |
-2.4 (0.2) |
< 0.0001 |
| |
12 |
-2.0 (0.2) |
-2.8 (0.2) |
< 0.0001 |
| Urge incontinence episodes/week |
|
(N = 300) |
(N = 292) |
|
| Mean Baseline |
0 |
29.0 (1.3) |
28.8 (1.3) |
|
| Mean Change from Baseline |
1 |
-8.7 (1.0) |
-13.0 (0.9) |
0.0003 |
| |
4 |
-12.2 (1.1) |
-16.5 (1.2) |
0.0054 |
| |
12 |
-13.5 (1.1) |
-17.3 (1.2) |
0.0024 |
| Urinary volume/void (mL) |
|
(N = 300) |
(N = 290) |
|
| Mean Baseline |
0 |
155.9 (3.0) |
151.0 (2.9) |
|
| Mean Change from Baseline |
1 |
12.1 (2.1) |
21.6 (2.8) |
0.0036 |
| |
4 |
17.2 (2.5) |
30.0 (3.1) |
0.0007 |
| |
12 |
18.9 (2.8) |
29.8 (3.2) |
0.0039 |
| a treatment differences assessed by rank ANOVA
for intent-to-treat population, last observation carried forward (ITT:LOCF)
data set |
Figure 2: Mean Change from Baseline in Urinary Frequency/24
hours by Visit: Study 1
Figure 3: Mean Change from Baseline in Incontinence Episodes/Week
by Visit: Study 1
Study 2 included 543 patients in both SANCTURA XR™ 60 mg and placebo groups and was identical in design to Study 1. As illustrated in Table 5 and Figures 4 and 5, SANCTURA XR™ capsules demonstrated statistically significantly (p < 0.01) greater reductions in urinary frequency and incontinence episodes, and increases in void volume when compared to placebo at Weeks 4 and 12. However, at Week 1, statistically significant reductions were seen in urinary incontinence episodes and volume void only.
Table 5: Mean (SE) Change from Baseline in Urinary Frequency,
Urge Incontinence Episodes and Void Volume in Study 2
| Efficacy Endpointa |
Week |
Placebo |
SANCTURA XR™ |
P-Value |
| Urinary frequency/24 hours |
|
(N = 276) |
(N = 267) |
|
| Mean Baseline |
0 |
12.9 (0.2) |
12.8 (0.2) |
|
| Mean Change from Baseline |
1 |
-1.2 (0.1) |
-1.4 (0.2) |
0.0759 |
| |
4 |
-1.7 (0.2) |
-2.3 (0.2) |
0.0047 |
| |
12 |
-1.8 (0.2) |
-2.5 (0.2) |
0.0009 |
| Urge incontinence episodes/week |
|
(N = 276) |
(N = 267) |
|
| Mean Baseline |
0 |
28.3 (1.4) |
28.2 (1.2) |
|
| Mean Change from Baseline |
1 |
-7.3 (1.0) |
-11.9 (1.0) |
< 0.0001 |
| |
4 |
-10.6 (1.1) |
-15.8 (1.1) |
< 0.0001 |
| |
12 |
-11.3 (1.2) |
-16.4 (1.3) |
< 0.0001 |
| Urinary volume/void (mL) |
|
(N = 276) |
(N = 266) |
|
| Mean Baseline |
0 |
151.8 (2.8) |
149.6 (2.9) |
|
| Mean Change from Baseline |
1 |
11.9 (2.5) |
24.1 (2.4) |
< 0.0001 |
| |
4 |
19.6 (3.1) |
29.3 (3.0) |
0.0020 |
| |
12 |
17.8 (3.3) |
31.5 (3.4) |
0.0014 |
| a treatment differences assessed by rank ANOVA
for intent-to-treat population, last observation carried forward (ITT:LOCF)
data set |
Figure 4: Mean Change from Baseline in Urinary Frequency/24
hours by Visit: Study 2
Figure 5: Mean Change from Baseline in Incontinence Episodes/Week
by Visit: Study 2
Last updated on RxList: 6/28/2009