CLINICAL PHARMACOLOGY
Mechanism Of Action
KYBELLA® (deoxycholic acid) injection is a cytolytic
drug, which when injected into tissue physically destroys the cell membrane
causing lysis.
Pharmacodynamics
Cardiac Electrophysiology
At therapeutic doses, KYBELLA® does not prolong the QTc
interval.
Pharmacokinetics
Endogenous deoxycholic acid plasma levels are highly
variable within and between individuals; most of this natural bile component is
sequestered in the enterohepatic circulation loop.
Absorption And Distribution
Deoxycholic acid from KYBELLA® is rapidly absorbed
following subcutaneous injection. After dosing with the maximum recommended
single treatment dose with KYBELLA® (100 mg), maximum plasma concentrations
(mean Cmax) were observed with a median Tmax of 18 minutes after injection. The
mean (±SD) Cmax value was 1024 ± 304 ng/mL and was 3.2-fold higher than average
Cmax values observed during a 24-hour baseline endogenous period in the absence
of KYBELLA®. After maximum recommended single treatment dose (100 mg), mean
(±SD) deoxycholic acid exposure (AUC0-24) was 7896 ± 2269 ng.hr/mL and was
1.6-fold higher over endogenous exposure. Post-treatment deoxycholic acid
plasma levels returned to the endogenous range within 24 hours. No accumulation
is expected with the proposed treatment frequency.
Deoxycholic acid is extensively bound to proteins in
plasma (98%).
Metabolism And Excretion
Endogenous deoxycholic acid is a product of cholesterol
metabolism and is excreted intact in feces. Deoxycholic acid is not metabolized
to any significant extent under normal conditions. Deoxycholic acid from
KYBELLA® joins the endogenous bile acid pool in the enterohepatic circulation
and is excreted along with the endogenous deoxycholic acid.
In Vitro Assessment Of Drug Interactions
Results from in vitro studies indicate that deoxycholic
acid does not inhibit or induce human cytochrome P450 (CYP) enzymes at
clinically relevant concentrations. Deoxycholic acid does not inhibit the
following transporters: P-gp, BCRP, MRP4, MRP2, OATP1B1, OATP2B1, OATP1B3,
OCT1, OCT2, OAT1, OAT3, NTCP, and ASBT.
Specific Populations
Hepatic Impairment
KYBELLA® has not been studied in subjects with hepatic
impairment. Considering the intermittent dose frequency, the small dose
administered that represents approximately 3% of the total bile acid pool, and
the highly variable endogenous deoxycholic acid levels, the pharmacokinetics of
deoxycholic acid following KYBELLA® injection is unlikely to be influenced by
hepatic impairment.
Pharmacokinetic Effects Of Gender
Deoxycholic acid pharmacokinetics were not influenced by
gender.
Clinical Studies
Two randomized, multi-center, double-blind,
placebo-controlled trials of identical design were conducted to evaluate
KYBELLA® (deoxycholic acid) injection for use in improvement in the appearance
of convexity or fullness associated with submental fat. The trials enrolled
healthy adults (ages 19 to 65, BMI ≤ 40 kg/m²) with moderate or severe
convexity or fullness associated with submental fat (i.e., grade 2 or 3 on
5-point grading scales, where 0 = none and 4 = extreme), as judged by both
clinician and subject ratings. Subjects received up to 6 treatments with
KYBELLA® (N=514, combined trials) or placebo (N=508, combined trials) at no
less than 1 month intervals. Use of ice/cold packs, topical and/or injectable
local anesthesia was allowed during the clinical trials. Injection volume was
0.2 mL per injection site, spaced 1 cm apart into the submental fat tissue,
which is also expressed in dose per area as 2 mg/cm². For each treatment
session a maximum of 100 mg (10 mL) was permitted over the entire treatment
area.
Subjects were administered an average of 6.4 mL at the
first treatment session, and subjects who received all six treatments were
administered an average of 4.4 mL at the sixth treatment session. Fifty-nine
percent of subjects received all six treatments.
In these trials, the mean age was 49 years and the mean
BMI was 29 kg/m². Most of the subjects were women (85%) and Caucasian (87%). At
baseline, 51% of the subjects had a clinician-rated submental fat severity
rating of moderate and 49% had a severe submental fat rating.
The co-primary efficacy assessments were based on at
least 2-grade and at least 1-grade improvements in submental convexity or
fullness on the composite of clinician-reported and patient-reported ratings of
submental fat 12 weeks after final treatment. Additionally, changes in
submental fat volume were evaluated in a subset of subjects (N=449, combined trials)
using magnetic resonance imaging (MRI). Visual and emotional impacts of
submental fat (happy, bothered, self-conscious, embarrassed, looking older or
overweight) were also evaluated using a 6-question survey, with each question
rated from 0 (not at all) to 10 (extremely/very much).
Reductions in submental fat volume were observed more
frequently in the KYBELLA® group compared to the placebo group as measured by
the composite clinician and patient ratings (Table 2). The composite response
rates by visit are presented in Figure 5.
Table 2: ≥ 2-Grade and ≥ 1-Grade Composite
Clinician and Patient Response 12 Weeks After Final Treatment
Endpoint |
Trial 1 |
Trial 2 |
KYBELLA®
(N=256) |
Placebo
(N=250) |
KYBELLA®
(N=258) |
Placebo
(N=258) |
2-Grade Composite Response a |
13.4% |
<0.1% |
18.6% |
3.0% |
1-Grade Composite Response b |
70.0% |
18.6% |
66.5% |
22.2% |
a At least 2 grade reduction on both the
clinician-reported and patient-reported ratings of submental fat
b At least 1 grade reduction on both the clinician-reported and
patient-reported ratings of submental fat |
Figure 5: ≥ 2-Grade and ≥ 1-Grade
Composite Clinician and Patient Response
Note: Subjects were followed up 4, 12 and 24 weeks after
the last treatment. Forty-one percent of subjects received fewer than 6 treatments
and entered the post-treatment period earlier than Week 24.
A greater proportion of KYBELLA®-treated subjects had at
least a 10% reduction in submental fat volume as compared to placebo-treated
subjects when evaluated by MRI (43% vs 5%, respectively).
The overall patient-reported satisfaction and
self-perceived visual attributes showed greater improvement in the KYBELLA® group
than in the placebo group.