A Single-blind, Split-face, Randomized, Pilot Study Comparing the Effects of Intradermal and Intramuscular Injection of Two Commercially Available Botulinum Toxin A Formulas to Reduce Signs of Facial Aging

Abstract

Objective: To examine the effectiveness of intradermal botulinum toxin type A injection in improving skin texture and midface lift while reducing pore size and sebum production, as well as investigate the differences in effectiveness between onabotulinumtoxinA and abobotulinumtoxinA using intradermal and intramuscular injection methods. Design: A 16-week, single-blind, split-face, randomized study. Each patient served as their own control, receiving onabotulinumtoxinA and abobotulinumtoxinA randomized to either the left or right side of the face. Patients received intradermal botulinum toxin type A injections at Week 0 and intramuscular botulinum toxin type A injections at Week 2. Participants: Ten women aged 35 to 65 years who exhibited static rhytids in the glabellar and periorbital area. Measurements: The primary endpoint was efficacy of split-face treatment of intradermal and intramuscular onabotulinumtoxinA and abobotulinumtoxinA as assessed by a blinded evaluator using baseline and post-treatment photographs. The secondary endpoints included safety as assessed by adverse events and patient satisfaction measured by questionnaires completed at baseline and post-treatment. Results: Intradermal injection of botulinum toxin type A led to a statistically significant improvement in skin texture (p=0.004) while also resulting in mild midface lift (p=0.024), but did not provide a significant reduction of pore size and sebum production. There was no statistically significant difference between onabotulinumtoxinA and abobotulinumtoxinA when injected intradermally or intramuscularly. Conclusion: Intradermal injection of botulinum toxin type A appears to be a safe and effective therapy that provides an improvement in facial skin texture and midface lift. Registry: clinicaltrials.gov (ID#: NCT02907268).

Figure 1.

Typical markings at 1cm2 for intradermal administration

Figure 2.

Facial regions for the assessment of wrinkles

Figure 3.

Grey-scale 3D Vectra Photographic Evidence from Patient 04. A) Vectra 3D photo of patient 04 at baseline; B) Vectra 3D Photos of patient 04 at Week 2 (post-intradermal). Improved skin texture. Slight decrease in nasolabial folds, marionette lines, and jowls. Increased distance between lateral canthus and inferior border of lateral brow; C) Vectra 3D Photos of patient 04 at Week 4 (post-intramuscular). Added improvement in glabellar and periorbital lines.

Figure 4.

Grey-scale 3D Vectra Photographic Evidence from Patient 05. A) Vectra 3D photo of patient 05 at baseline; Vectra 3D Photos of patient 05 at Week 2 (post-intradermal). Improved skin texture. Slight decrease in nasolabial folds, marionette lines. Increased distance between lateral canthus and inferior border of lateral brow; C) Vectra 3D Photos of patient 05 at Week 4 (post-intramuscular). Added improvement of glabellar and periorbital lines.

Figure 5.

Grey-scale 3D Vectra Photographic Evidence from Patient 06. A) Vectra 3D photo of patient 06 at baseline; B) Vectra 3D Photos of patient 06 at Week 2 (post-intradermal). Improved skin texture. Slight decrease in nasolabial folds, marionette lines. C) Vectra 3D Photos of patient 06 at Week 4 (post-intramuscular). Added improvement in glabellar and periorbital lines.

Figure 6.

Grey-scale 3D Vectra Photographic Evidence from Patient 08. A) Vectra 3D photo of patient 08 at baseline; B) Vectra 3D Photos of patient 08 at Week 2 (post-intradermal). Improved skin texture. Slight decrease in nasolabial folds, marionette lines, and jowls. Increased distance between lateral canthus and inferior border of lateral brow; C) Vectra 3D Photos of patient 08 at Week 4 (post-intramuscular). Added improvement in glabellar and periorbital lines.