A Phase 4 interventional study of OnabotulinumtoxinA (Upper Depressor Anguli Oris Injection) and OnabotulinumtoxinA (Lower Depressor Anguli Oris Injection) in Facial Aging, Melomental Folds and Oral Commissure Ptosis, sponsored by Peking University. Not yet recruiting. Open to participants aged 18 Years to 60 Years. Per ClinicalTrials.gov, last updated 2026-07-07.
Sponsored by Peking University · Phase 4, Interventional, and Treatment
This multicenter, prospective, randomized parallel-controlled, assessor-blinded clinical trial aims to address the core clinical pain point of lack of high-level evidence and non-standardized operation in injection site selection for BTX-A treatment of oral commissure ptosis. A total of 266 eligible subjects will be randomly assigned in a 1:1 ratio to receive either upper DAO or lower DAO BTX-A injection. The study will compare the clinical efficacy, time-effect characteristics and safety profiles of the two regimens, and conduct stratified analysis of treatment response in different patient subtypes. The results will determine the optimal injection site for Chinese population, establish standardized operation specifications, fill the international evidence gap, and provide level I evidence for clinical practice.
Oral commissure ptosis is a common aesthetic concern that presents as abnormal downward displacement of the mouth corners at rest, leading to a sad, angry or aged appearance. Botulinum toxin type A (BTX-A) injection is the first-line treatment, but there is no consensus on the optimal injection site in the depressor anguli oris (DAO) muscle.
This multicenter randomized controlled trial will enroll 266 subjects with oral commissure ptosis from 5 top Chinese stomatological hospitals. Subjects will be randomly assigned 1:1 to receive either upper DAO or lower DAO BTX-A injection. The primary endpoint is the improvement of oral commissure ptosis angle at 1 month post-treatment. Secondary endpoints include objective efficacy measures, subjective aesthetic evaluations, and safety profiles during a 6-month follow-up.
This study aims to determine the optimal injection site for Chinese population, establish standardized operation specifications, and provide level I evidence for clinical practice.
Peking University is the lead sponsor of 411 studies on the registry; 122 are open to participants now.
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Exclusion Criteria:
Single subcutaneous injection of OnabotulinumtoxinA (Botox®, Allergan, USA) into the upper half of the depressor anguli oris (DAO) muscle. * Drug preparation: 100U/vial reconstituted with 2mL sterile normal saline to a final concentration of 50U/mL * Injection sites: 3 points per side: ① Inferolateral to the oral commissure (skin depression site during DAO contraction); ② Midpoint of the line from the oral commissure to the mandibular line along the DAO course; ③ Midpoint of the line connecting the first two points * Dosage: 1U (0.02mL) per point, total 6U bilaterally * Technique: 45° semi-recumbent position, 1mL syringe with 34G 1.5mm needle, vertical subcutaneous injection with needle bevel facing outward; gentle pressure with sterile cotton swab for 15-30 seconds post-injection; no massage allowed * Follow-up: 6 months after single injection
Drug: OnabotulinumtoxinA (Upper Depressor Anguli Oris Injection)
Single subcutaneous injection of OnabotulinumtoxinA (Botox®, Allergan, USA) into the lower half of the depressor anguli oris (DAO) muscle. * Drug preparation: Identical to the experimental group (100U/vial reconstituted to 50U/mL) * Injection sites: 3 points per side forming a triangle: ① Midpoint between the oral commissure axis and the motor endplate; ② 0.5cm medial to the midpoint of the vertical line from the motor endplate to the mandibular margin; ③ 0.5cm lateral to the same midpoint * Dosage: 1U (0.02mL) per point, total 6U bilaterally * Technique: Identical to the experimental group (needle parameters, injection depth, post-injection instructions) * Follow-up: 6 months after single injection
Drug: OnabotulinumtoxinA (Lower Depressor Anguli Oris Injection)
Single subcutaneous injection of onabotulinumtoxinA into the upper half of the depressor anguli oris muscle, total dose 6U bilaterally.
Also known as: Botox®
Single subcutaneous injection of onabotulinumtoxinA into the lower half of the depressor anguli oris muscle, total dose 6U bilaterally.
Also known as: Botox®
Improvement of Bilateral Oral Commissure Ptosis Angle from Baseline at 1 Month Post-Treatment
The primary endpoint is the change in bilateral oral commissure ptosis angle (∠oba) from baseline. The angle is measured on standardized frontal facial photographs at rest by 3 independent assessors who are completely blinded to group assignment. The average value of 3 measurements is used as the final result.
Time frame: 30±3 days after treatment
Improvement of Oral Commissure Ptosis Angle at Maximum Smile and Maximum Depression Position
Change in oral commissure ptosis angle from baseline measured at maximum smile without teeth exposure and maximum oral commissure depression position on standardized facial photographs.
Time frame: 1, 3, 6 months after treatment
Vertical Elevation Amplitude of the Oral Commissure
Change in the vertical distance from the oral commissure point to the ipsilateral pupil from baseline, measured on standardized frontal facial photographs.
Time frame: 1, 3, 6 months after treatment
Merz Facial Aesthetic Scale Score
Physician-assessed aesthetic improvement using the full Merz Facial Aesthetic Scale. Scale range: 0 (No aging) to 4 (Severe aging). Lower scores indicate better aesthetic outcome.
Time frame: 1, 3, 6 months after treatment
Global Aesthetic Improvement Scale (GAIS)
Patient-reported global aesthetic improvement using the full Global Aesthetic Improvement Scale (GAIS). Scale range: 1 (Much worse) to 5 (Much improved). Higher scores indicate better aesthetic outcome.
Time frame: 1, 3, 6 months after treatment
Patient Satisfaction Score (FACE-Q)
Patient-reported facial appearance satisfaction using the full FACE-Q Facial Appearance Module. Scale range: 0 (Worst possible appearance) to 100 (Best possible appearance). Higher scores indicate better outcome.
Time frame: 1, 3, 6 months after treatment
Incidence of Adverse Events (AEs)
Incidence, time of onset, clinical manifestation, severity, treatment measures and outcome of all adverse events during the study period. Severity is graded according to CTCAE 5.0.
Time frame: From enrollment to 6 months after treatment
Incidence of Toxin Diffusion-Related Adverse Events
Incidence of adverse events related to unintended botulinum toxin diffusion, including oral commissure asymmetry, lower lip movement disorder, salivation, dysarthria and abnormal smile.
Time frame: From enrollment to 6 months after treatment
Incidence of Serious Adverse Events (SAEs)
Incidence of serious adverse events that result in death, life-threatening condition, hospitalization, persistent or significant disability, or congenital anomaly/birth defect.
Time frame: From enrollment to 6 months after treatment
Patient Satisfaction Score (Visual Analog Scale, VAS)
Patient satisfaction measured by the 10-point Visual Analog Scale (VAS). Scale range: 0 (Completely dissatisfied) to 10 (Completely satisfied). Higher scores indicate higher satisfaction.
Time frame: 1, 3, 6 months after treatment
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Plan to share: No
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This study is not yet recruiting, as verified in Jun 2026. You cannot join it, but the record below documents what was studied.
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