A Study to Evaluate AI-09 In Participants With Glabellar Lines

Inclusion Criteria: * 20 to 70 years of age * moderate to severe glabellar lines (IGA 2 to 3) at maximum frown * moderate to severe glabellar lines (SSA 2 to 3) at maximum frown * willingness to refrain from the use of facial fillers, retinoids, Botox®, laser * female participants of child-bearing potential must have a negative urine pregnancy test and be non-lactating at the Baseline (Day 0) visit and must utilize birth control throughout the study * participants should be in good general health as determined by the investigator and free of any disease that may interfere with study evaluations or the Investigational Product Exclusion Criteria: * the inability to substantially lessen glabellar lines by physically spreading them apart * eyelid ptosis, and/ or excessive weakness or atrophy in the target muscle(s) * presence or history of "dry eye" * history of periocular surgery, brow lift or related procedures, or deep dermal scarring * concurrent or recent (within the last 6 months) use of any other botulinum toxin drug product anywhere in the body * history of immunization or hypersensitivity to any botulinum toxin serotype * history of non-response to any prior botulinum toxin treatments anticipated need for treatment with botulinum toxin of any serotype for any reason during the trial (other than the investigational treatment) * any medical condition that may put the subject at increased risk with exposure to botulinum toxin including diagnosed myasthenia gravis, Eaton-Lambert syndrome, amyotrophic lateral sclerosis, or any other condition that might interfere with neuromuscular function * pregnancy or lactation * application of any topical prescription medication to the treatment area within 14 days prior to treatment * participation in another investigational drug trial or receiving any investigational treatment(s) within 30 days of Baseline (Day 0) * alcohol or drug abuse within the past 3 years * refusal or inability with the subject's ability to give informed consent or comply with the requirements of the protocol for any reason