A new modelling study explores how GLP-1 receptor agonists may shorten botulinum toxin duration, highlighting an emerging consideration for aesthetic practice.
The rapid uptake of GLP-1 receptor agonists (GLP-1 RAs) for weight management and metabolic disease has introduced new physiological variables into aesthetic medicine. Many patients presenting for cosmetic treatments are also using these medications, prompting clinicians to question whether changes in metabolism, lean mass and overall physiology might influence aesthetic outcomes.
Among the treatments potentially affected is botulinum toxin A (BoNT-A), where duration of effect depends on neuromuscular dynamics and may be indirectly influenced by broader metabolic changes. A new computational modelling study, published online ahead of print in Toxicon (Rahman et al, 2025), explores this potential relationship – examining whether concurrent GLP-1 RA therapy could alter the duration of botulinum toxin effect across neurological and aesthetic applications.
The simulation indicated a measurable reduction in BoNT-A treatment duration across all GLP-1 groups when compared with controls.
Revisiting BoNT-A & SNAP-25
Before considering potential interactions with GLP-1 RAs, it is worth briefly revisiting the pharmacological action of BoNT-A.
BoNT-A is a purified neurotoxin produced by Clostridium botulinum. It acts at the neuromuscular junction to inhibit the release of acetylcholine, the neurotransmitter responsible for initiating muscle contraction. By temporarily blocking this signal, BoNT-A produces a controlled reduction in muscle activity, softening the appearance of dynamic facial lines. Once injected, BoNT-A is taken up into the nerve terminal within minutes to hours, with complete synaptic blockade developing over several days. Visible effects typically begin within three to seven days for most BoNT-A products, reaching maximum effect around two weeks.
Results generally persist for three to four months, though this can vary depending on individual factors such as muscle strength, metabolism and the specific product used.
BoNT-A exerts its effect by cleaving synaptosomal-associated protein 25 kDa (SNAP-25), a component of the SNARE complex responsible for releasing acetylcholine at the neuromuscular junction. By disrupting SNAP- 25, the toxin blocks the fusion of synaptic vesicles with the nerve membrane, temporarily preventing neurotransmission.
SNAP-25 function is naturally regulated by phosphorylation, a reversible process that alters how it interacts with other SNARE proteins. Intracellular pathways such as cyclic AMP (cAMP) and protein kinase A (PKA) can modify this phosphorylation state, influencing normal vesicle release.
Activation of GLP-1 receptors is known to increase intracellular cAMP and stimulate PKA activity in several tissue types, including neurons. In the Toxicon modelling study, Rahman et al incorporated this pathway to explore whether such signalling could, in theory, modify SNAP-25 phosphorylation and thereby influence how quickly the protein is restored after BoNT-A cleavage. The model treated this as one potential mechanism contributing to reduced toxin duration in virtual patients using GLP-1 RAs.
As the study authors note, ‘GLP-1 receptor agonists are widely used in metabolic and weight-management medicine, but their potential influence on botulinum toxin type A (BoNT-A) pharmacodynamics has not previously been examined.’
Study design
Rahman and colleagues used a computer-based microsimulation platform, AesthetiSIM™, to examine potential interactions between GLP-1 RAs and BoNT-A. Their simulation generated 25,000 virtual patients: 20,000 representing individuals treated for chronic migraine and 5,000 receiving aesthetic masseter treatment.
Each virtual patient was randomised to either a control group or one of four GLP-1 exposure groups – semaglutide, tirzepatide, liraglutide or dulaglutide – and given a standardised 100-unit BoNT-A dose. The model ran over a 52-week period, estimating how long treatment effects lasted under each condition.
Three principal mechanisms were included in the model:
- Synaptic modulation. GLP-1 signalling was modelled to influence SNAP-25 phosphorylation via cyclic-AMP and PKA pathways, potentially affecting the same synaptic machinery targeted by BoNT-A.
- Lean-mass reduction. Body- composition changes, a known outcome of GLP-1 therapy, were included to simulate alterations in BoNT-A diffusion and volume of distribution.
- Systemic metabolic variability. Parameters reflecting diabetic and rapid weight-loss states were introduced to capture differences in metabolic clearance and neuromuscular responsiveness.
Study findings
The simulation indicated a measurable reduction in BoNT-A treatment duration across all GLP-1 groups when compared with controls.
In the chronic-migraine model, mean duration decreased from 14.0 ± 2.3 weeks in controls to between 11.8 and 12.6 weeks among GLP-1 groups (p < 0.001; hazard-ratio 1.54–1.95).
In the aesthetic masseter model, mean duration fell from 20.1 ± 2.9 weeks in controls to between 16.2 and 17.3 weeks (p < 0.001; hazard- ratio 1.72–2.08).
Among the GLP-1 agents modelled, tirzepatide showed the greatest impact, followed by liraglutide, dulaglutide and semaglutide.
Further analyses indicated that approximately 55 percent of the reduction in duration was attributable to synaptic modulation, 30 percent to lean-mass decline and 15 percent to metabolic variability. ‘These findings suggest a biologically plausible interaction between GLP-1 signalling and BoNT-A recovery dynamics,’ the authors note.
Importantly, no evidence of increased adverse-event risk or abnormal toxin diffusion was observed in the simulation. The effect was specific to duration rather than safety.
Rahman et al’s computational study provides an early theoretical framework for examining how GLP-1 RAs might influence the duration of BoNT-A activity. The model predicts a reduction of approximately 10 to 20 percent in treatment longevity, attributed to synaptic modulation, lean-mass loss and metabolic change.
APPROXIMATELY 55 PERCENT OF THE REDUCTION IN DURATION WAS ATTRIBUTABLE TO SYNAPTIC MODULATION, 30 PERCENT TO LEAN-MASS DECLINE AND 15 PERCENT TO METABOLIC VARIABILITY.
Study limitations & future directions
Rahman et al describe their work as exploratory and note that all outcomes were derived entirely from computational modelling rather than clinical observation. ‘Experimental validation – such as neuronal culture assays or prospective patient cohorts – is required before any modification of treatment intervals or dosing practices can be considered,’ the authors write.
The model’s absence of real-world variables, such as injection technique, dose variations, product differences or prior BoNT exposure, mean the findings offer useful insights but should not be interpreted as conclusive. Still, the analysis offers a structured starting point for understanding how systemic therapies like GLP-1 agonists might intersect with neurotoxin pharmacodynamics.
‘Although based on virtual cohorts, the results highlight a potentially important drug- procedure interaction at the intersection of metabolic and aesthetic medicine. If validated in translational or clinical studies, such an interaction would carry practical implications for treatment durability, reinjection intervals, dosing strategies and patient satisfaction,’ the authors conclude.
As the GLP-1 era continues to reshape the patient profile in aesthetics, being ahead of potential interactions will help practitioners optimise outcomes, manage expectations and plan for potential treatment protocol changes.
Implications for clinical practice
For aesthetic practitioners, the study provides an early framework for considering pharmacological interactions between GLP-1 therapy and BoNT-A treatment response. While not yet practice-changing, it raises sufficiently plausible scenarios to prompt clinicians to ask different questions and monitor for different outcomes and treatment timelines.
While the findings require clinical validation, they highlight the importance of detailed patient histories, careful follow-up and data collection as GLP-1 therapies become increasingly common among aesthetics patients.
