Clinical Pharmacology for Botox Cosmetic
Mechanism Of Action
BOTOX Cosmetic blocks neuromuscular transmission by binding to acceptor sites on motor nerve terminals, entering the nerve terminals, and inhibiting the release of acetylcholine. This inhibition occurs as the neurotoxin cleaves SNAP-25, a pre-synaptic protein integral to the successful docking and release of acetylcholine from vesicles situated within nerve endings. When injected intramuscularly at therapeutic doses, BOTOX Cosmetic produces partial chemical denervation of the muscle resulting in a localized reduction in muscle activity. In addition, the muscle may atrophy, axonal sprouting may occur, and extrajunctional acetylcholine receptors may develop. There is evidence that reinnervation of the muscle may occur, thus slowly reversing muscle denervation produced by BOTOX Cosmetic.
Pharmacodynamics
No formal pharmacodynamic studies have been conducted with BOTOX Cosmetic (onabotulinumtoxinA) for injection.
Pharmacokinetics
Using currently available analytical technology, it is not possible to detect BOTOX Cosmetic in the peripheral blood following intramuscular injection at the recommended doses.
Immunogenicity
Since BOTOX Cosmetic is a therapeutic protein, there is a potential for immunogenicity. The detection of antibody formation is highly dependent on the sensitivity and specificity of the assay. Additionally, the observed incidence of antibody (including neutralizing antibody) positivity in an assay may be influenced by several factors including assay methodology, sample handling, timing of sample collection, concomitant medications, and underlying disease. For these reasons, comparison of the incidence of antibodies to BOTOX Cosmetic in the studies described below with the incidence of antibodies in other studies or to other products may be misleading.
In three Lateral Canthal Line trials, 916 subjects (517 subjects at 24 Units and 399 subjects at 44 Units) treated with BOTOX Cosmetic had specimens analyzed for antibody formation. Among the 916 BOTOX Cosmetic treated subjects, 14 subjects (1.5%) developed binding antibodies and no subjects (0%) developed the presence of neutralizing antibodies.
The data reflect the subjects whose test results were considered positive or negative for neutralizing activity to BOTOX Cosmetic in a mouse protection assay.
The critical factors for neutralizing antibody formation have not been well characterized. The results from some studies suggest that botulinum toxin injections at more frequent intervals or at higher doses may lead to greater incidence of antibody formation. The potential for antibody formation may be minimized by injecting with the lowest effective dose given at the longest feasible intervals between injections.
Clinical Studies
Glabellar Lines
Two randomized, multi-center, double-blind, placebo-controlled studies of identical design were conducted to evaluate BOTOX Cosmetic for use in the temporary improvement of the appearance of moderate to severe glabellar facial lines. The studies enrolled healthy adults (ages 18 to 75) with glabellar lines of at least moderate severity at maximum frown. Subjects were excluded if they had ptosis, deep dermal scarring, or an inability to substantially lessen glabellar lines even by physically spreading them apart. Subjects received a single treatment with BOTOX Cosmetic (N=405, combined studies) or placebo (N=132, combined studies). Injection volume was 0.1 mL/injection site, for a dose/injection site in the active treatment groups of 4 Units. Subjects were injected intramuscularly in five sites, 1 in the procerus muscle and 2 in each corrugator supercilii muscle, for a total dose in the active treatment groups of 20 Units.
The co-primary efficacy endpoints were the investigator’s rating of glabellar line severity at maximum frown and the subject’s global assessment of change in appearance of glabellar lines, both at Day 30 post-injection. For the investigator rating, using a 4-point grading scale (0=none, 3=severe) a responder was defined as having a severity grade of 0 or 1. For the subject’s global assessment of change, the ratings were from +4 (complete improvement) to -4 (very marked worsening). A responder was defined as having a grade of at least +2 (moderate improvement). After completion of the randomized studies, subjects were offered participation in an open label, repeat treatment study to assess the safety of repeated treatment sessions.
The combined results of these two efficacy studies are presented here. The mean age was 46 years, with 32 subjects (6%) ≥65 years of age. Most of the subjects were women (82%), and White (84%). At baseline, 210 subjects (39%) had glabellar line severity scores at rest of moderate or severe.
In these studies, the severity of glabellar lines was reduced for up to 120 days in the BOTOX Cosmetic group compared to the placebo group as measured both by investigator rating of glabellar line severity at maximum frown (Table 8), and by subject’s global assessment of change in appearance of glabellar lines (Table 9).
Table 8: Investigator’s Assessment of Glabellar Line Severity at Maximum Frown – Responder Rates (% and Number of Subjects with Severity of None or Mild)
| Day |
BOTOX Cosmetic |
Placebo |
Differencea |
| 7 |
74% |
6% |
68% |
| 299/405 |
8/132 |
(62, 74) |
| 30b |
80% |
3% |
77% |
| 325/405 |
4/132 |
(72, 82) |
| 60 |
70% |
2% |
69% |
| 283/403 |
2/130 |
(64, 74) |
| 90 |
48% |
2% |
45% |
| 192/403 |
3/128 |
(40, 51) |
| 120 |
25% |
2% |
24% |
| 102/403 |
2/128 |
(19, 29) |
a 95% confidence intervals are shown in parenthesis
b Day 30: Co-Primary Efficacy Time point, p<0.001 |
Table 9: Subject’s Assessment of Change in Appearance of Glabellar Lines – Responder Rates (% and Number of Subjects with at Least Moderate Improvement)
| Day |
BOTOX Cosmetic |
Placebo |
Differencea |
| 7 |
82% |
9% |
73% |
| 334/405 |
12/132 |
(68, 80) |
| 30b |
89% |
7% |
83% |
| 362/405 |
9/132 |
(77, 88) |
| 60 |
82% |
4% |
78% |
| 330/403 |
5/130 |
(73, 83) |
| 90 |
63% |
3% |
60% |
| 254/403 |
4/128 |
(54, 66) |
| 120 |
39% |
1% |
38% |
| 157/403 |
1/128 |
(33, 43) |
a 95% confidence intervals are shown in parenthesis
b Day 30: Co-Primary Efficacy Time point, p<0.001 |
In the subset of subjects with resting severity scores of moderate or severe, the investigator assessment of a resting severity of mild or none at Day 30 was also achieved by more BOTOX Cosmetic treated subjects (74%, 119/161) than placebo treated subjects (20%, 10/49).
Analysis of the limited number of subjects 65 years or older suggested a lower treatment-associated response compared to subjects less than 65 years of age (Table 10).
Table 10: Investigator’s and Subject’s Assessment – Responder Rates for Subjects <65 and ≥65 Years of Age at Day 30
| Assessment |
Age Group |
BOTOX Cosmetic
(N=405) |
Placebo
(N=132) |
Differencea |
| Investigators (maximal frown) |
<65 |
83% |
2% |
81% |
| 316/382 |
2/123 |
(77, 86) |
| Subjects |
<65 |
91% |
7% |
84% |
| 346/382 |
8/123 |
(79, 90) |
| Investigators (maximal frown) |
≥65 |
39% |
22% |
17% |
| 9/23 |
2/9 |
(-17, 51) |
| Subjects |
≥65 |
70% |
1 1 % |
58% |
| 16/23 |
1/9 |
(31, 86) |
| a 95% confidence intervals are shown in parenthesis |
Exploratory analyses by gender suggested that responder rates in the BOTOX Cosmetic treated group were higher for women than for men for both the investigator assessment (Day 30; 85% of 334 women, 59% of 71 men) and the Subject Assessment (Day 30; 93% of women, 72% of men). In the limited number of subjects that identified as other races (n=64 in the BOTOX Cosmetic treated group) the responder rates were similar to those observed in White subjects.
Lateral Canthal Lines
Two multicenter, randomized, double-blind, placebo-controlled studies evaluated BOTOX Cosmetic (N=833, randomized to receive any BOTOX Cosmetic treatment or N=529 randomized to receive placebo) for the temporary improvement in the appearance of moderate to severe lateral canthal lines (LCL). Study 1 assessed BOTOX Cosmetic treatment of LCL alone; Study 2 also assessed simultaneous treatment of LCL and glabellar lines (GL). Both studies enrolled healthy adults with moderate to severe LCL at maximum smile at baseline; Study 2 also required subjects to have moderate to severe GL at maximum frown at baseline.
In the 5-month Study 1, subjects were randomized to receive a single blinded treatment of 24 Units/0.6 mL (12 Units per side) consisting of 4 Units/0.1 mL into 3 sites of each orbicularis oculi muscle with either BOTOX Cosmetic (N=222) or placebo (N=223).
In the 7-month Study 2, subjects were randomized to receive either BOTOX Cosmetic in the LCL region and placebo in the GL region (24 Units; N=306), or BOTOX Cosmetic in the LCL and GL regions (44 Units [24 Units for LCL and 20 Units for GL]; N=305), or placebo in the LCL and GL regions (0 Units; N=306). Subjects received the same 24 Units regimen for LCL as in Study 1, and the labeled 20 Units (5 injections, 4 Units per site) for GL. Subjects received the same treatment at days 1 and 120.
The primary efficacy measure was the assessment of LCL severity at maximum smile using the 4-point Facial Wrinkle Scale with Photonumeric Guide (FWS; 0=none, 1= mild, 2=moderate, 3=severe). The FWS assessment was performed independently by both investigators and subjects. The primary timepoint was day 30 following the first treatment, as compared to baseline.
The primary efficacy response definition was a composite ≥2-grade improvement from baseline in LCL severity at maximum smile, assessed by both investigator and subject on a per-subject basis. For Studies 1 and 2, the proportion of responders was statistically significant favoring BOTOX Cosmetic (24 Units [LCL alone] and 44 Units [LCL and GL]) compared to placebo at day 30 (Table 11).
Table 11: Studies 1 and 2: Composite Investigator and Subject Assessment of LCL at Maximum Smile at Day 30 – Responder Rates (% and Number of Subjects Achieving ≥2-Grade Improvement from Baseline)
| Study |
BOTOX Cosmetic 24 Units |
BOTOX Cosmetic 24 Units LCL and 20 Units GL |
Placebo |
| Study 1 |
26.1% |
- |
1.3% |
| 58/222 |
- |
3/223 |
| Study 2 |
20.3% |
21.3% |
0.0% |
| 62/306 |
65/305 |
0/306 |
The secondary endpoint of a responder defined as achieving a grade of none or mild for Study 1 as measured by the investigator is presented in Figure 7 below.
Figure 7: Percentage of Subjects with Treatment Success (% of Subjects achieving None or Mild from Baseline) by Visit (Study 1)
Forehead Lines
Two multicenter, randomized, double-blind, placebo-controlled studies evaluated BOTOX Cosmetic (N=921, randomized to receive any BOTOX Cosmetic treatment or N=257, randomized to receive placebo) for the temporary improvement in the appearance of moderate to severe forehead lines (FHL).
Study 1 assessed BOTOX Cosmetic treatment of FHL with glabellar lines (GL); Study 2 also assessed simultaneous treatment of FHL, GL, and lateral canthal lines [LCL]. Both studies enrolled healthy adults with moderate to severe FHL at maximum eyebrow elevation at baseline and moderate to severe GL at maximum frown at baseline; Study 2 also required subjects to have moderate to severe LCL at maximum smile at baseline.
In the 12-month Study 1, subjects were randomized to receive BOTOX Cosmetic 20 Units to the frontalis muscle with 20 Units to the glabellar region (for a total of 40 Units) or placebo in both areas.
In the 12-month Study 2, subjects were randomized to receive BOTOX Cosmetic 20 Units to the frontalis muscle, 20 Units to the glabellar region, and 0 Units to the LCL region (for a total of 40 units) or BOTOX Cosmetic 20 Units to the frontalis muscle, 20 Units to the glabellar region, and 24 Units to the LCL region (for a total of 64 Units) or placebo in all three areas.
The primary efficacy measure was the assessment of FHL severity at maximum eyebrow elevation using the 4-point Facial Wrinkle Scale with Photonumeric Guide (FWS; 0=none, 1= mild, 2=moderate, 3=severe). The FWS assessment was performed independently by both investigators and subjects. The primary timepoint was Day 30 following the first treatment.
The primary efficacy response definition was a composite ≥2-grade improvement from baseline in FHL severity at maximum eyebrow elevation, assessed by both investigator and subject on a per-subject basis. For Studies 1 and 2, the proportion of responders was greater in the BOTOX Cosmetic arms compared to placebo at Day 30 (p<0.0001 for Studies 1 and 2) (Table 12).
Table 12: Studies 1 and 2: Composite Investigator and Subject Assessment of FHL Severity at Maximum Eyebrow Elevation at Day 30 – Responder Rates (% and Number of Subjects Achieving ≥2-Grade Improvement from Baseline)
| Study |
BOTOX Cosmetic (20 Units FHL with 20 Units GL) |
BOTOX Cosmetic (20 Units FHL, 20 Units GL, and 24 Units LCL) |
Placebo |
| Study 1 |
N=290 |
- |
N=101 |
| 61% |
- |
0% |
| Study 2 |
N=318 |
N=313 |
N=156 |
| 46% |
53% |
1% |
A total of 165 and 197 subjects received 3 cycles over 1 year of BOTOX Cosmetic 40 Units (20 Units FHL with 20 Units GL) and 64 Units (20 Units FHL, 20 Units GL, and 24 Units LCL), respectively. The response rate for FHL was similar across all treatment cycles.
The results for a key secondary endpoint of responders achieving a grade of none or mild on investigator ratings at maximum eyebrow elevation of FHL severity are presented below for Studies 1 and 2.
Figure 8: Percentage of Subjects with Treatment Success (Achieving None or Mild FHL from Baseline at Maximum Eyebrow Elevation) by Visit (Study 1)
Figure 9: Percentage of Subjects with Treatment Success (Achieving None or Mild FHL from Baseline at Maximum Eyebrow Elevation) by Visit (Study 2)
The results of the Facial Line Satisfaction Questionnaire are presented in Table 13.
Table 13: Facial Lines Satisfaction Questionnaire Response Frequency at Day 60 (Percentage of Subjects)
|
Study 1 |
Study 2 |
BOTOX Cosmetic (20 Units FHL with 20 Units GL)
N=289 |
Placebo
N=99 |
BOTOX Cosmetic (20 Units FHL with 20 Units GL)
N=317 |
Placebo
N=155 |
| “Very satisfied” |
57% |
1% |
35% |
0% |
| “Mostly satisfied” |
33% |
0% |
47% |
3% |
| “Neither dissatisfied nor satisfied” |
4% |
22% |
9% |
23 % |
| “Mostly dissatisfied” |
4% |
21% |
7% |
20% |
| “Very dissatisfied” |
2% |
56% |
2% |
54% |
Platysma Bands
Two multicenter, randomized, double-blind, placebo-controlled trials (Study M21-309 [NCT04949399] and Study M21-310 [NCT04994535]) evaluated BOTOX Cosmetic (N=408 BOTOX Cosmetic and N=426 placebo) for the temporary improvement in the appearance of moderate to severe platysma bands. Based on baseline severity, subjects were randomized to receive a single treatment of BOTOX Cosmetic (26 Units, 31 Units, or 36 Units), or placebo.
The primary efficacy measure was the assessment of platysma band severity at maximum contraction using the 5-grade clinician platysma band scale by the investigators, and the 5-grade participant platysma band scale by the subjects. For both scales, the 5 grades are 1=Minimal, 2=Mild, 3=Moderate, 4=Severe, 5=Extreme (Table 14). The investigator and subject assessments were performed independently.
Table 14: Platysma Band Severity Grades and Descriptions
| Grade |
Severity Description |
| 1 |
Minimal; no visible neck bands and no impact to jawline definition |
| 2 |
Mild; visible neck bands and no impact to jawline definition |
| 3 |
Moderate; 1 visible continuous neck band impacting jawline definition |
| 4 |
Severe; 2 visible continuous neck bands impacting jawline definition |
| 5 |
Extreme; 3 or more visible neck bands impacting jawline definition |
The primary timepoint was Day 14 after the first treatment. The studies enrolled healthy adults with moderate to severe platysma bands. In these studies, 94% were female, 91% were White, 5% were Asian, 3% were Black or African American; for ethnicity, 86% identified as not Hispanic or Latino. Subjects were 19 to 82 years old, with a mean age of 49 years.
The primary efficacy endpoint was a multi-component endpoint defined as achievement of Grade 1 or 2 (Minimal or Mild) and at least a 2-grade improvement from baseline in platysma band severity at maximum contraction, assessed by both investigator and subject at Day 14 (Table 15).
Table 15: Studies M21-309 and M21-310: Percentage of Subjects Achieving a Grade 1 or 2 (Minimal or Mild) with ≥ 2-Grade Improvement from Baseline Based on Both Investigator and Subject Assessments of Platysma Band Severity at Maximum Contraction at Day 14
|
Study M21-309 |
Study M21-310 |
BOTOX Cosmetic 26, 31, or 36 Units
(N=199) |
Placebo
(N=209) |
Differenced |
BOTOX Cosmetic 26, 31, or 36 Units
(N=209) |
Placebo
(N=217) |
Differenced |
| Multi-component Assessmenta |
32% |
2% |
30% (24%, 37%) |
31% |
0% |
31% (24%, 37%) |
| Individual Components |
| Investigator Assessmentb |
45% |
4% |
- |
42% |
2% |
- |
| Subject Assessmentc |
44% |
4% |
- |
40% |
3% |
- |
aGrade 1 or 2 (Minimal or Mild) and ≥ 2-grade improvement from baseline at maximum contraction on both the investigator and subject assessments at Day 14.
bGrade 1 or 2 (Minimal or Mild) and ≥ 2-grade improvement from baseline at maximum contraction on the investigator assessment at Day 14.
cGrade 1 or 2 (Minimal or Mild) and ≥ 2-grade improvement from baseline at maximum contraction on the subject assessment at Day 14.
d95% confidence intervals are shown in parentheses. |
The percentages of subjects achieving these endpoints over time are shown in Figure 10 (Study M21-309) and Figure 11 (Study M21-310).
Figure 10: Percentages of Subjects Achieving Grade 1 or 2 (Minimal or Mild) and at Least 2-Grade Improvement from Baseline Based on Both the Investigator and Subject Assessments of Platysma Band Severity at Maximum Contraction Over Time (Study M21-309)
Figure 11: Percentages of Subjects Achieving a Grade 1 or 2 (Minimal or Mild) and at Least 2-Grade Improvement from Baseline Based on Both the Investigator and Subject Assessments of Platysma Band Severity at Maximum Contraction Over Time (Study M21-310)
The results for Appearance of Neck and Lower Face Questionnaire: Satisfaction (Follow-up) Item 5 at Day 14 secondary efficacy endpoints are presented for Studies M21-309 and M21-310 in Table 16.
Table 16: Studies M21-309 and M21-310: Results for Appearance of Neck and Lower Face Questionnaire: Satisfaction (Follow-up) Item 5 (Satisfaction with Effect of Treatment on Platysma Bands) at Day 14 (Percentage of Subjects)
| Responses |
Study M21-309 |
Study M21-310 |
BOTOX Cosmetic 26, 31, or 36 Units
(N = 199) |
Placebo
(N = 209) |
BOTOX Cosmetic 26, 31, or 36 Units
(N = 209) |
Placebo
(N = 217) |
| “Very satisfied” |
31% |
3% |
22% |
2% |
| “Satisfied” |
34% |
9% |
40% |
10% |
| “Neither satisfied nor dissatisfied” |
25% |
31% |
25% |
32% |
| “Dissatisfied” |
7% |
34% |
10% |
29% |
| “Very dissatisfied” |
2% |
24% |
3% |
27% |