Medicine
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Studies in the 1920s found that botulinum neurotoxin type A (BoNT/A) inhibited the activity of motor and parasympathetic nerve endings, confirmed several decades later to be due to decreased acetylcholine release. The 1970s were marked by studies of cellular mechanisms aided by use of neutralizing antibodies as pharmacologic tools: BoNT/A disappeared from accessibility to neutralizing antibodies within minutes, although it took several hours for onset of muscle weakness. The multi-step mechanism was experimentally confirmed and is now recognized to consist broadly of binding to nerve terminals, internalization, and lysis or cleavage of a protein (SNAP-25: synaptosomal associated protein-25 kDa) that is part of the SNARE (Soluble NSF Attachment protein REceptor) complex needed for synaptic vesicle docking and fusion. ⋯ Exploration into migraine mechanisms led to anatomical studies documenting pain fibers that send axons through sutures of the skull to outside the head-a potential route by which extracranial injections could affect intracranial processes. Several clinical studies have also identified benefits of onabotulinumtoxinA in major depression, which have been attributed to central responses induced by feedback from facial muscle and skin movement. Overall, the history of BoNT/A is distinguished by basic science studies that stimulated clinical use and, conversely, clinical observations that spurred basic research into novel mechanisms of action.
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Strabismus, deviation of the ocular alignment, can adversely affect quality of life and activities of daily living. Surgery was the prior standard of care for strabismus, but up to 40% of patients required additional surgeries. This need for more effective and less invasive treatment, along with the convergence of other events such as the development of electromyography, purification of botulinum toxin A, and the finding that injection of botulinum toxin type A could paralyze the hind limbs of chicks, led Dr. ⋯ Scott's formulation, then known as Oculinum, received its first Food and Drug Administration approvals in 1989 for strabismus and blepharospasm. Allergan acquired Oculinum in 1991, renaming it Botox. These initial uses led to its application in a myriad of other indications as outlined in other articles of this supplement.
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Randomized Controlled Trial
Treatment of neurogenic detrusor overactivity and overactive bladder with Botox (onabotulinumtoxinA): Development, insights, and impact.
Neurogenic detrusor overactivity (NDO) is a complication of multiple sclerosis, spinal cord injury (SCI), stroke, head injury, and other conditions characterized by damage to the upper motor neuronal system. NDO often leads to high bladder pressure that may cause upper urinary tract damage and urinary incontinence (UI). Prior to the use of onabotulinumtoxinA, oral anticholinergics and surgical augmentation cystoplasty were the treatment options. ⋯ These randomized, double-blind, placebo-controlled trials for NDO showed significant improvements in UI episodes, urodynamic parameters, and QOL; the most frequent adverse events were urinary tract infection (UTI) and urinary retention. Similarly, randomized, double-blind, placebo-controlled trials of onabotulinumtoxinA 100U for OAB found significant improvements in UI episodes, treatment benefit, and QOL; UTI and dysuria were the most common adverse events. Long-term studies in NDO and OAB showed sustained effectiveness and safety with repeat injections of onabotulinumtoxinA, the use of which has profoundly improved the QOL of patients failing anticholinergic therapy and has expanded the utilization of onabotulinumtoxinA into smooth muscle.
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Randomized Controlled Trial
Treatment of adult spasticity with Botox (onabotulinumtoxinA): Development, insights, and impact.
Upper and lower limb spasticity (ULS, LLS) often occur following a stroke or in patients with other neurological disorders, leading to difficulties in mobility and daily living and decreased quality of life. Prior to the use of onabotulinumtoxinA, antispastic medications had limited efficacy and often caused sedation. Phenol injections were difficult for physicians to perform, painful, and led to tissue destruction. ⋯ Lessons learned from the successful ULS trials were applied to design an LLS trial that led to approval for the latter indication. Additional observational trials mimicking real-world treatment have shown continued effectiveness and patient satisfaction. The use of onabotulinumtoxinA for spasticity has ushered in a more patient-centered treatment approach that has vastly improved patients' quality of life.
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Randomized Controlled Trial
Treatment of hyperhidrosis with Botox (onabotulinumtoxinA): Development, insights, and impact.
Hyperhidrosis (chronic excessive sweating) may substantially affect an individual's emotional and social well-being. Therapies available before onabotulinumtoxinA were generally topical, with limited effectiveness, application-site skin reactions, and frequent, time-consuming treatments. Intradermal injection of onabotulinumtoxinA to treat sweat glands arose as a novel therapeutic approach. ⋯ Treatment with onabotulinumtoxinA was associated with significant quality of life improvements based on Short Form-12 physical and mental component scores. The Hyperhidrosis Impact Questionnaire also indicated greater treatment satisfaction, reduced negative impact on aspects of daily life, and improved emotional well-being with onabotulinumtoxinA versus placebo. The clinical development program and subsequent clinical experience showed that onabotulinumtoxinA treatment for hyperhidrosis was well tolerated with no new safety signals, and led to greater disease awareness.