{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,31]],"date-time":"2026-07-31T02:32:37Z","timestamp":1785465157309,"version":"3.56.0"},"reference-count":30,"publisher":"MDPI AG","issue":"10","license":[{"start":{"date-parts":[[2025,10,7]],"date-time":"2025-10-07T00:00:00Z","timestamp":1759795200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Toxins"],"abstract":"<jats:p>Anecdotal reports have recently circulated suggesting that intramuscular injection of bacteriostatic saline (BS)\u2014which contains benzyl alcohol (BnOH)\u2014can reverse botulinum toxin type A (BoNTA)-induced brow ptosis. Given the well-established intracellular persistence of BoNTA\u2019s light chain and its irreversible cleavage of SNAP-25, such rapid functional recovery challenges existing pharmacological understanding. This study employed high-resolution pharmacokinetic\/pharmacodynamic (PK\/PD) modelling using the AesthetiSim\u2122 platform to systematically evaluate this hypothesis. A total of 30,000 virtual patients were randomized to receive BoNTA alone, BoNTA followed by BS injection, or BoNTA followed by normal saline (NS) at Day 7. The model incorporated BoNTA diffusion, internalization, SNAP-25 cleavage, neuromuscular output, and transient BS effects on membrane permeability and endosomal trafficking. Simulated recovery trajectories were tracked over 90 days. The primary outcome, time to 80% restoration of baseline frontalis muscle force (T80), averaged 42.0 days in the BoNTA-only group and 35.5 days in the BS group (\u0394 = \u22126.5 days; p &lt; 0.001). Only 13.9% of BS-treated patients reached the T80 threshold by Day 30. Partial reactivation (T30) occurred earlier with BS (21.8 \u00b1 5.3 days vs. 27.3 \u00b1 4.9 days), and the area under the effect curve (AUEC) was increased by 9.7%, reflecting higher overall muscle function over time. In molecular simulations, BnOH produced a minor rightward shift in the BoNTA\u2013SNAP-25 dissociation curve, but receptor occupancy remained above 90% at therapeutic toxin concentrations, suggesting no meaningful impairment of binding affinity. A global Sobol sensitivity analysis demonstrated that the primary driver of recovery kinetics was intracellular LC degradation (49% of T80 variance), while BS-modulated extracellular parameters collectively contributed less than 20%. These findings indicate that BS does not reverse the molecular action of BoNTA but may transiently influence recovery kinetics via non-receptor-mediated pathways such as increased membrane permeability or altered vesicular trafficking. The magnitude and variability of this effect do not support the notion of a true pharmacologic reversal. Instead, these results emphasize the need for mechanistic scrutiny when evaluating rapid-reversal claims, particularly those propagated through anecdotal or social media channels without supporting biological plausibility.<\/jats:p>","DOI":"10.3390\/toxins17100498","type":"journal-article","created":{"date-parts":[[2025,10,7]],"date-time":"2025-10-07T15:48:30Z","timestamp":1759852110000},"page":"498","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["Computational Modelling Suggests Bacteriostatic Saline Does Not Reverse Botulinum Toxin-Induced Brow Ptosis"],"prefix":"10.3390","volume":"17","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-8443-8338","authenticated-orcid":false,"given":"Eqram","family":"Rahman","sequence":"first","affiliation":[{"name":"Research and Innovation Hub, Innovation Aesthetics, London WC2H 9JQ, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2907-4746","authenticated-orcid":false,"given":"Alain","family":"Michon","sequence":"additional","affiliation":[{"name":"The Ottawa Skin Clinic\/Project Skin MD Ottawa, Ottawa, ON K1K 2Z7, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Parinitha","family":"Rao","sequence":"additional","affiliation":[{"name":"The Skin Address, Aesthetic Dermatology Practice, Bangalore 560080, India"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"A. Q. M. Omar","family":"Sharif","sequence":"additional","affiliation":[{"name":"Shahid Suhrawardy Medical College & Hospital, Dhaka 1207, Bangladesh"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2701-626X","authenticated-orcid":false,"given":"William Richard","family":"Webb","sequence":"additional","affiliation":[{"name":"Research and Innovation Hub, Innovation Aesthetics, London WC2H 9JQ, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jean D. A.","family":"Carruthers","sequence":"additional","affiliation":[{"name":"Department of Ophthalmology, University of British Columbia, Vancouver, BC V5Z 4E1, Canada"},{"name":"Carruthers Cosmetics, Vancouver, BC V5Z 4E1, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,10,7]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"46","DOI":"10.1007\/s10354-017-0553-7","article-title":"The history of Botulinum toxin: From poison to beauty","volume":"167","author":"Kumar","year":"2017","journal-title":"Wien. Med. Wochenschr."},{"key":"ref_2","first-page":"761","article-title":"Botulinum toxin: From poison to remedy","volume":"18","author":"Kessler","year":"1997","journal-title":"Neurotoxicology"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"S119","DOI":"10.1097\/00002508-200211001-00002","article-title":"Therapeutic use of botulinum toxins: Background and history","volume":"18","author":"Setler","year":"2002","journal-title":"Clin. J. Pain"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"40","DOI":"10.1016\/j.toxicon.2013.02.014","article-title":"The life history of a botulinum toxin molecule","volume":"68","author":"Simpson","year":"2013","journal-title":"Toxicon"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"155","DOI":"10.1016\/j.neuroscience.2017.03.049","article-title":"Botulinum neurotoxin type A-cleaved SNAP25 is confined to primary motor neurons and localized on the plasma membrane following intramuscular toxin injection","volume":"352","author":"Cai","year":"2017","journal-title":"Neuroscience"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"197","DOI":"10.1016\/S0733-8635(03)00122-0","article-title":"Complications with the use of botulinum toxin","volume":"22","author":"Klein","year":"2004","journal-title":"Dermatol. Clin."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"570","DOI":"10.1111\/jocd.13266","article-title":"Complications of botulinum toxin and fillers: A narrative review","volume":"19","author":"Kassir","year":"2020","journal-title":"J. Cosmet. Dermatol."},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Rahman, E., Rao, P., Sayed, K., Garcia, P.E., Ioannidis, S., Yu, N., Sadeghi-Esfahlani, S., Nassif, A.D., Webb, W.R., and Rahman, Z. (2025). Decades of Scientific Data and Global Media Reporting on Complications in Non-surgical Aesthetic Treatments for a Transparent Safety Profile: Kissing Snow White Awake. Aesthetic Plast. Surg., Epub ahead of print.","DOI":"10.1007\/s00266-025-05007-3"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"1321","DOI":"10.1097\/00006534-199606000-00001","article-title":"An anatomically based study of the mechanism of eyebrow ptosis","volume":"97","author":"Knize","year":"1996","journal-title":"Plast. Reconstr. Surg."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"535","DOI":"10.1038\/nrmicro3295","article-title":"Botulinum neurotoxins: Genetic, structural and mechanistic insights","volume":"12","author":"Rossetto","year":"2014","journal-title":"Nat. Rev. Microbiol."},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Antonucci, F., Corradini, I., Fossati, G., Tomasoni, R., Menna, E., and Matteoli, M. (2016). SNAP-25, a Known presynaptic protein with emerging postsynaptic functions. Front. Synaptic Neurosci., 8.","DOI":"10.3389\/fnsyn.2016.00007"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"233","DOI":"10.1016\/j.jfo.2021.09.005","article-title":"Management of ptosis","volume":"45","author":"Martel","year":"2022","journal-title":"J. Fran\u00e7ais D\u2019ophtalmol."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"955","DOI":"10.1093\/asj\/sjad070","article-title":"Management of Severe Botulinum-Induced Eyelid Ptosis with Pretarsal Botulinum Toxin and Oxymetazoline Hydrochloride 0.1%","volume":"43","author":"Bernardini","year":"2023","journal-title":"Aesthetic Surg. J."},{"key":"ref_14","first-page":"688","article-title":"Botulinum Toxin Type A Induced Brow Ptosis Reversal Using Bacteriostatic Saline","volume":"50","author":"Rullan","year":"2024","journal-title":"Dermatol. Surg."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"67","DOI":"10.1016\/j.yexcr.2017.04.025","article-title":"Benzyl alcohol induces a reversible fragmentation of the Golgi apparatus and inhibits membrane trafficking between endosomes and the trans-Golgi network","volume":"357","author":"Simm","year":"2017","journal-title":"Exp. Cell Res."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"945","DOI":"10.1042\/bj2910945","article-title":"The role of Gi and the membrane-fluidizing agent benzyl alcohol in modulating the hysteretic activation of human platelet adenylate cyclase by guanylyl 5\u2032-imidodiphosphate","volume":"291","author":"Spence","year":"1993","journal-title":"Biochem. J."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"e00089-18","DOI":"10.1128\/mBio.00089-18","article-title":"The light chain defines the duration of action of botulinum toxin serotype a subtypes","volume":"9","author":"Pellett","year":"2018","journal-title":"mBio"},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Shoemaker, C.B., and Oyler, G.A. (2013). Persistence of Botulinum neurotoxin inactivation of nerve function. Botulinum Neurotoxins, Springer. Current Topics in Microbiology and Immunology.","DOI":"10.1007\/978-3-642-33570-9_9"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"89","DOI":"10.1016\/j.sbi.2015.03.013","article-title":"Architecture of the botulinum neurotoxin complex: Architecture_LAB molecular machine for protection and delivery","volume":"31","author":"Lam","year":"2015","journal-title":"Curr. Opin. Struct. Biol."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"3076","DOI":"10.1002\/jps.20219","article-title":"Mechanism for benzyl alcohol-induced aggregation of recombinant human interleukin-1 receptor antagonist in aqueous solution","volume":"93","author":"Zhang","year":"2004","journal-title":"J. Pharm. Sci."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"1605","DOI":"10.1002\/jps.10589","article-title":"Benzyl alcohol-induced destabilization of interferon-\u03b3: A study by hydrogen-deuterium isotope exchange","volume":"93","author":"Tobler","year":"2004","journal-title":"J. Pharm. Sci."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"52","DOI":"10.1007\/s00238-025-02311-8","article-title":"In silico multiscale comparison of LetibotulinumtoxinA and OnabotulinumtoxinA in glabellar line treatment: Diffusion dynamics, receptor affinity, and immunologic clearance","volume":"48","author":"Rahman","year":"2025","journal-title":"Eur. J. Plast. Surg."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"108560","DOI":"10.1016\/j.toxicon.2025.108560","article-title":"Targeting the glabellar frown lines with OnabotulinumtoxinA: In-silico evidence supporting concentrated, low-volume injection protocols","volume":"267","author":"Rahman","year":"2025","journal-title":"Toxicon"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"108548","DOI":"10.1016\/j.toxicon.2025.108548","article-title":"In Silico Multiscale Computational Modelling of Botulinum Toxin A Diffusion for Glabellar Wrinkle Treatment: Optimizing Injection Volumes across formulations","volume":"266","author":"Rahman","year":"2025","journal-title":"Toxicon"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"2147","DOI":"10.1007\/s13555-025-01458-3","article-title":"Diffusion Characteristics of LetibotulinumtoxinA, OnabotulinumtoxinA, and AbobotulinumtoxinA and its Impact on Muscle Relaxation: A Randomized Split-Face Clinical Trial","volume":"15","author":"Bennek","year":"2025","journal-title":"Dermatol. Ther."},{"key":"ref_26","doi-asserted-by":"crossref","unstructured":"Erg\u00fcden, B. (2022). Benzyl Alcohol Increases Diffusion Limit of Nuclear Membrane in Saccharomyces cerevisiae Cells. Eur. J. Biol., 81.","DOI":"10.26650\/EurJBiol.2022.1058174"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"259","DOI":"10.1016\/S0006-3495(79)85175-9","article-title":"Effect of the anesthetics benzyl alcohol and chloroform on bilayers made from monolayers","volume":"28","author":"Reyes","year":"1979","journal-title":"Biophys. J."},{"key":"ref_28","first-page":"429","article-title":"Optimizing the safety profile of botulinum neurotoxin","volume":"20","author":"Cohen","year":"2007","journal-title":"Cosmet. Dermatol."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"833","DOI":"10.1097\/DSS.0000000000000386","article-title":"Persistence of upper blepharoptosis after cosmetic botulinum toxin type A","volume":"41","author":"Steinsapir","year":"2015","journal-title":"Dermatol. Surg."},{"key":"ref_30","first-page":"e55970","article-title":"Treatment of Full Eyelid Ptosis Following Botox Injection: A Case Report","volume":"16","author":"Musharbash","year":"2024","journal-title":"Cureus"}],"container-title":["Toxins"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-6651\/17\/10\/498\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,9]],"date-time":"2025-10-09T18:50:13Z","timestamp":1760035813000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-6651\/17\/10\/498"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,10,7]]},"references-count":30,"journal-issue":{"issue":"10","published-online":{"date-parts":[[2025,10]]}},"alternative-id":["toxins17100498"],"URL":"https:\/\/doi.org\/10.3390\/toxins17100498","relation":{},"ISSN":["2072-6651"],"issn-type":[{"value":"2072-6651","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,10,7]]}}}