CLINICAL PHARMACOLOGY
Mechanism Of Action
Eluxadoline is a mu-opioid receptor agonist; eluxadoline is also a delta opioid receptor
antagonist and a kappa opioid receptor agonist. The binding affinities (Ki) of eluxadoline for the
human mu and delta opioid receptors are 1.8 nM and 430 nM, respectively. The binding affinity
(Ki) of eluxadoline for the human kappa opioid receptor has not been determined; however, the
Ki for guinea pig cerebellum kappa opioid receptor is 55 nM. In animals, eluxadoline interacts
with opioid receptors in the gut.
Pharmacodynamics
Cardiac Electrophysiology
At a dose 10 times the maximum recommended dose (100 mg), VIBERZI does not prolong the
QT interval to any clinically relevant extent.
Pharmacokinetics
Following oral administration of 100 mg VIBERZI in healthy subjects, the Cmax of eluxadoline
was approximately 2 to 4 ng/mL and AUC was 12 to 22 ng.h/mL. Eluxadoline has
approximately linear pharmacokinetics with no accumulation upon repeated twice daily dosing.
The variability of eluxadoline pharmacokinetic parameters ranges from 51% to 98%.
Absorption
Absolute bioavailability of eluxadoline has not been determined.
Effect of Food
The median Tmax value was 1.5 hours (range: 1 to 8 hours) under fed conditions and 2 hours
(range: 0.5 to 6 hours) under fasting conditions [see DOSAGE AND ADMINISTRATION].
The administration of VIBERZI with a high fat meal that contained approximately 800 to 1000
total calories, with 50% of calories being derived from fat content decreased the Cmax of
eluxadoline by 50% and AUC by 60%.
Distribution
Plasma protein binding of eluxadoline was 81%.
Elimination
The mean plasma elimination half-life of eluxadoline ranged from 3.7 hours to 6 hours.
Metabolism
Cytochrome P450 (CYP) and UGT pathways have minimal involvement in the metabolism of
eluxadoline. It is unlikely that metabolism of eluxadoline by these enzymes has a clinically
meaningful impact on systemic exposure.
Excretion
Following a single oral dose of 300 mg [14C] eluxadoline in healthy male subjects, 82.2% of the
total radioactivity was recovered in feces within 336 hours and less than 1% was recovered in
urine within 192 hours.
Specific Populations
Patients With Hepatic Impairment
Following a single oral 100–mg dose in subjects with varying degrees of liver impairment and
healthy subjects, mean eluxadoline plasma exposure was 6-fold, 4-fold, and 16-fold higher in
mild, moderate, and severe hepatically impaired subjects (Child Pugh Class A, B, C),
respectively, compared to the subjects with normal liver function [see DOSAGE AND ADMINISTRATION, CONTRAINDICATIONS, Use In Specific Populations].
Drug Interaction Studies
In Vitro Assessment Of Drug Interactions
In vitro studies indicate that eluxadoline is neither an inducer of CYP1A2, CYP2C9, CYP2C19,
and CYP3A4, nor an inhibitor of CYP1A2, CYP2A6, CYP2B6, CYP2C9, CYP2C19, and
CYP2D6 at clinically relevant systemic concentrations. Although CYP2E1 was slightly inhibited
by eluxadoline (IC50 of approximately 20 micromolar [11 mcg/mL]), clinically meaningful
interactions are unlikely. Despite mechanism-based inhibition of CYP3A4 in vitro, eluxadoline
did not have a clinically meaningful drug-drug interaction with the CYP3A4 substrate
midazolam.
In vitro studies suggest that eluxadoline is a substrate for OAT3, OATP1B1, BSEP and MRP2,
but not for OCT1, OCT2, OAT1, OATP1B3, P-gp and BCRP. Based on the in vitro studies,
clinically meaningful interaction via inhibition of OCT1, OCT2, OAT1, OAT3, OATP1B3,
BSEP and MRP2 by eluxadoline is unlikely.
In Vivo Assessment Of Drug Interactions
The following drug interactions were studied in healthy subjects:
Oral Contraceptives
Coadministration of multiple doses of 100 mg VIBERZI with multiple dose administration of an
oral contraceptive (norethindrone 0.5 mg/ethinyl estradiol 0.035 mg) does not change the
exposure of either drug.
Cyclosporine
Coadministration of a single dose of 100 mg VIBERZI with a single dose of 600 mg
cyclosporine resulted in 4.4-fold and 6.2-fold increase in AUC and Cmax of eluxadoline,
respectively, compared to administration of VIBERZI alone [see DRUG INTERACTIONS].
Probenecid
Coadministration of a single dose of 100 mg VIBERZI with a single dose of 500 mg probenecid
resulted in a 35% and 31% increase in eluxadoline AUC and Cmax, respectively, compared to
administration of VIBERZI alone. This change in eluxadoline exposures is not expected to be
clinically meaningful.
Rosuvastatin
Coadministration of multiple doses of 100 mg VIBERZI twice daily with a single dose 20 mg
rosuvastatin resulted in an increase in the AUC (40%) and Cmax (18%) of rosuvastatin compared
to administration of rosuvastatin alone. Similar results were observed with the active, major
metabolite, n-desmethyl rosuvastatin [see DRUG INTERACTIONS].
Midazolam
Coadministration of multiple doses of 100 mg VIBERZI twice daily with single dose
administration of 4 mg midazolam did not affect midazolam pharmacokinetics in humans,
suggesting that eluxadoline will not affect the exposure of concomitantly administered CYP3A4
substrates.
Clinical Studies
The efficacy and safety of VIBERZI in IBS-D patients was established in two randomized,
multi-center, multi-national, double-blind, placebo-controlled trials (Studies 1 and 2). A total of
1281 patients in Study 1 and 1145 patients in Study 2 received treatment with VIBERZI 75 mg,
VIBERZI 100 mg or placebo twice daily [overall, patients had a mean age of 45 years (range 18
to 80 years with 10% at least 65 years of age or older), 66% female, 86% white, 11% black, and
27% Hispanic].
All patients met Rome III criteria for IBS-D (loose [mushy] or watery stools ≥25% and hard or
lumpy stools <25% of bowel movements) and were required to meet both of the following
criteria:
- an average of worst abdominal pain scores in the past 24 hours of >3.0 on a 0 to 10 scale
over the week prior to randomization.
- an average daily stool consistency score (Bristol Stool Scale or BSS) of ≥5.5 and at least
5 days with a BSS score ≥5 on a 1 to 7 scale over the week prior to randomization.
Pertinent exclusion criteria included: prior pancreatitis, alcohol abuse, cholecystitis prior
6 months, sphincter of Oddi dysfunction, inflammatory bowel disease, intestinal obstruction,
gastrointestinal infection or diverticulitis within prior 3 months, lipase greater than 2 xULN,
ALT or AST greater than 3 xULN.
Study 1 and Study 2 included identical 26-week double-blind, placebo-controlled treatment
periods. Study 1 continued double-blinded for an additional 26 weeks for long-term safety (total
of 52 weeks of treatment), followed by a 2-week follow-up. Study 2 included a 4-week singleblinded,
placebo-withdrawal period upon completion of the 26-week treatment period. During
the double-blind treatment phase and the single-blinded placebo withdrawal phase, patients were
allowed to take loperamide rescue medication for the acute treatment of uncontrolled diarrhea,
but were not allowed to take any other antidiarrheal, antispasmodic agent or rifaximin for their
diarrhea. Additionally, patients were allowed to take aspirin-containing medications or
nonsteroidal anti-inflammatory drugs, but no narcotic or opioid containing agents.
Efficacy of VIBERZI was assessed in both trials using an overall composite responder primary
endpoint. The primary endpoint was defined by the simultaneous improvement in the daily worst
abdominal pain score by ≥30% as compared to the baseline weekly average AND a reduction in
the BSS to <5 on at least 50% of the days within a 12-week time interval. Improvement in daily
worst abdominal pain in the absence of a concurrent bowel movement was also considered a
response day. Results for endpoints were based on electronic daily diary entries by patients.
The proportion of composite responders over 12 weeks is shown in Table 4. In both trials, the
proportion of patients who were composite responders to VIBERZI was statistically significantly
higher than placebo for both doses. The proportion of patients who were composite responders
to VIBERZI was similar for male and female patients in both trials.
Table 4: Efficacy Results in Randomized Clinical Trials
|
Study 1 |
Study 2 |
VIBERZI
100mg
twice daily
n=426 |
VIBERZI
75mg
twice daily
n=427 |
PBO
n=427 |
VIBERZI
100mg
twice daily
n=382 |
VIBERZI
75mg
twice daily
n=381 |
PBO
n=382 |
Composite1 Response
over 12 weeks |
Responder rates |
25% |
24% |
17% |
30% |
29% |
16% |
Treatment difference |
8%2 |
7%4 |
|
13%3 |
13%3 |
|
95% CI (%) |
(2.6, 13.5) |
(1.4, 12.2) |
|
(7.5, 19.2) |
(6.8, 18.5) |
|
Composite Response
over 26 weeks |
Responder rates |
29% |
23% |
19% |
33% |
30% |
20% |
Treatment difference |
10% |
4% |
|
13% |
10% |
|
95% CI (%) |
(4.7, 16.1) |
(-1.0, 9.9) |
|
(6.4, 18.8) |
(4.2, 16.4) |
|
Abdominal Pain
Response Improved
≥30%
over 12 weeks |
Responder rates |
43% |
42% |
40% |
51% |
48% |
45% |
Treatment difference |
4% |
3% |
|
6% |
3% |
|
95% CI (%) |
(-3.0, 10.2) |
(-3.8, 9.4) |
|
(-1.3, 12.8) |
(-4.3, 9.8) |
|
BSS <5 Response
over 12 weeks |
Responder rates |
34% |
30% |
22% |
36% |
37% |
21% |
Treatment difference |
12% |
8% |
|
15% |
16% |
|
95% CI (%) |
(6.3, 18.2) |
(2.1, 13.8) |
|
(8.4, 21.0) |
(9.7, 22.4) |
|
1 Composite= Simultaneous improvement of Worst Abdominal Pain (WAP) by ≥30% and Bristol Stool Score (BSS)
< 5 on the same d ay for ≥ 50% of days over the interval
2 P<0.01
3 P<0.001
4 P<0.05 |
Additionally, the proportion of patients who were composite responders to VIBERZI at each 4-
week interval was numerically higher than placebo for both doses as early as month 1 through
month 6 demonstrating that efficacy is maintained throughout the course of treatment.
During the 4 week single-blind withdrawal period in Study 2, no evidence of worsening of
diarrhea or abdominal pain compared to baseline was demonstrated at either dose.