Botox (onabotulinumtoxinA) mechanism of action

Clinical Conditions Targeted by OnabotulinumtoxinA in Different Ways in Medicine

OnabotulinumtoxinA (BT-A) is used in different medical fields for its beneficial effects. BT-A, a toxin originally produced by the bacterium Clostridium botulinum, is widely known for its ability to temporarily paralyze muscles by blocking the release of acetylcholine, a neurotransmitter involved in muscle contraction. The literature continually reports new hypotheses regarding potential applications that do not consider blockade of acetylcholine release at the neuromuscular junction as a common pathway. In this opinion article, it is our aim to investigate the different pathway targets of BT-A in different medical applications. First of all, the acetylcholine effect of BT-A is used to reduce wrinkles for cosmetic purposes, in the treatment of urological problems, excessive sweating, temporomandibular joint disorders, obesity, migraine, spasticity in neurological diseases, and in various cases of muscle overactivity such as cervical dystonia, blepharospasm, and essential head tremor. In another potential pathway, glutamate A, CGRP, and substance P are targeted for pain inhibition with BT-A application in conditions such as migraine, trigeminal neuralgia, neuropathic pain, and myofascial pain syndrome. On the other hand, as a mechanism different from acetylcholine and pain mediators, BT-A is used in the treatment of hair loss by increasing oxygenation and targeting transforming growth factor-beta 1 cells. In addition, the effect of BT-A on the apoptosis of cancer cells is also known and is being developed. The benefits of BT-A applied in different doses to different regions for different medical purposes are shown in literature studies, and it is also emphasized in those studies that repeating the applications increases the benefits in the long term. The use of BT-A continues to expand as researchers discover new potential therapeutic uses for this versatile toxin.

Myofascial pain - A major player in musculoskeletal pain

Myofascial pain is a soft tissue pain syndrome with local and referred musculoskeletal pain arising from trigger points. Myofascial pain and myofascial pain syndromes are among some of the most common acute and chronic pain conditions. Myofascial pain can exist independently of other pain generators or can coexist with or is secondary to other acute and chronic painful musculoskeletal conditions. Myofascial pain is most effectively treated with a multimodal treatment plan including injection therapy (known as trigger point injections, physical therapy, postural or ergonomic correction, and treatment of underlying musculoskeletal pain generators. The objectives of this review are to outline the prevalence of myofascial pain, describe the known pathophysiology of myofascial pain and trigger points, discuss the clinical presentation of myofascial pain, and present evidence-based best practices for pharmacologic, non-pharmacologic, and interventional treatments for myofascial pain.

Real-world effectiveness of Anti-CGRP monoclonal antibodies compared to OnabotulinumtoxinA (RAMO) in chronic migraine: a retrospective, observational, multicenter, cohort study

BACKGROUND

Chronic migraine (CM) is a disabling condition with high prevalence in the general population. Until the recent approval of monoclonal antibodies targeting the calcitonin gene-related peptide (Anti-CGRP mAbs), OnabotulinumtoxinA (BoNT-A) was the only treatment specifically approved for CM prophylaxis. Direct comparisons between the two treatments are not available so far.

METHODS

We performed an observational, retrospective, multicenter study in Italy to compare the real-world effectiveness of Anti-CGRP mAbs and BoNT-A. Patients with CM who had received either treatment according to Italian prescribing regulations were extracted from available clinical databases. Efficacy outcomes included the change from baseline in monthly headache days (MHD), MIgraine Disability ASsessment test (MIDAS), and monthly acute medications (MAM) evaluated at 6 and 12 months of follow-up. The primary outcome was MHD change from baseline at 12 months. Safety outcomes included serious adverse events (SAE) and treatment discontinuation. Unadjusted and adjusted models were used for the analyses.

RESULTS

Two hundred sixteen potentially eligible patients were screened; 183 (86 Anti-CGRP mAbs; 97 BoNT-A) were included. One hundred seventy-one (80 Anti-CGRP mAbs; 91 BoNT-A) and 154 (69 Anti-CGRP mAbs; 85 BoNT-A) patients were included in the efficacy analysis at 6 and 12 months of follow-up, respectively. Anti-CGRP mAbs and BoNT-A both resulted in a mean MHD reduction at 6 (-11.5 and -7.2 days, respectively; unadjusted mean difference -4.3; 95%CI -6.6 to -2.0; p = 0.0003) and 12 months (-11.9 and -7.6, respectively; unadjusted mean difference -4.4; 95%CI -6.8 to -2.0; p = 0.0002) of follow-up. Similar results were observed after adjusting for baseline confounders. Anti-CGRP mAbs showed a significant MIDAS (-31.7 and -19.2 points, p = 0.0001 and p = 0.0296, respectively) and MAM reduction (-5.1 and -3.1 administrations, p = 0.0023 and p = 0.0574, respectively) compared to BoNT-A at 6 and 12 months. No SAEs were reported. One patient receiving fremanezumab discontinued treatment due to arthralgia. Treatment discontinuations, mainly for inefficacy, were comparable.

CONCLUSION

Both Anti-CGRP mAbs and BoNT-A were effective in CM patients with Anti-CGRP mAbs presenting higher effect magnitude, with comparable safety. Still, BoNT-A remains a valuable option for CM patients with contraindications to Anti-CGRP mAbs or for frail categories who are candidates to local therapy with limited risk of systemic administration.

Assessment of Quality of Life in Patients with Chronic Anal Fissures: A 1-Year Follow-Up Study before and after Botulinum Toxin (Botox) Injection

This longitudinal study aimed to assess the quality of life in patients with anal fissures treated with botulinum toxin (Botox) injections over a one-year period. The study hypothesized that Botox injections would significantly improve quality of life and that these improvements would be sustained over a year. Conducted as a cross-sectional study, it assessed adults diagnosed with chronic anal fissures unresponsive to conventional treatments. Participants received 25 U of Botox in two sessions and their quality of life was assessed using the WHOQOL-BREF, COPE-60, Hospital Anxiety and Depression Scale (HADS), and SF-36 surveys. Data were collected at baseline six months and one year post-treatment. The study involved 113 patients, with a mean age of 38.1 years. Significant improvements were observed in the WHOQOL-BREF scores across all domains from baseline to 12 months (physical domain: 49.4 ± 10.5 to 70.2 ± 10.6, p < 0.001; mental domain: 34.8 ± 11.2 to 61.9 ± 11.5, p < 0.001). SF-36 scores also showed significant enhancements in physical and mental health components (physical: 44.3 ± 7.5 to 56.9 ± 5.9, p < 0.001; mental: 41.1 ± 7.2 to 54.4 ± 6.3, p < 0.001). Additionally, significant improvements were noted in patient perception on quality of life from the perspective of various aspects including physical discomfort, pain management, and mood and emotional well-being. The study demonstrated that Botox injections significantly improved the quality of life in patients with chronic anal fissures, with sustained benefits observed over a year. These findings suggest Botox as an effective treatment modality for enhancing life quality in patients with this condition, highlighting the potential for broader applications in managing chronic anal fissures.

The pluripotential evolution and journey of Botox (onabotulinumtoxinA)

Clinical use of onabotulinumtoxinA evolved based on strategic, hypothesis-driven applications, as well as serendipitous observations by physicians and patients. The success of onabotulinumtoxinA in blepharospasm and strabismus led to its study in other head and neck dystonias, followed by limb dystonia, tremor, and spasticity. The aesthetic use of onabotulinumtoxinA followed initial reports from patients of improved facial lines after injections for facial dystonias and hemifacial spasm. Although patients with dystonias and spasticity regularly reported that their local pain improved after injections, onabotulinumtoxinA was not systematically explored for chronic migraine until patients began reporting headache improvements following aesthetic injections. Clinicians began assessing onabotulinumtoxinA for facial sweating and hyperhidrosis based on its inhibition of acetylcholine from sympathetic cholinergic nerves. Yet another line of research grew out of injections for laryngeal dystonia, whereby clinicians began to explore other sphincters in the gastrointestinal tract and eventually to treatment of pelvic sphincters; many of these sphincters are innervated by autonomic nerves. Additional investigations in other autonomically mediated conditions were conducted, including overactive bladder and neurogenic detrusor overactivity, achalasia, obesity, and postoperative atrial fibrillation. The study of onabotulinumtoxinA for depression also grew out of the cosmetic experience and the observation that relaxing facial muscle contractions associated with negative emotions may improve mood. For approved indications, the safety profile of onabotulinumtoxinA has been demonstrated in the formal development programs and post-marketing reports. Over time, evidence has accumulated suggesting clinical manifestations of systemic effects, albeit uncommon, particularly with high doses and in vulnerable populations. Although onabotulinumtoxinA is approved for approximately 26 indications across multiple local regions, there are 15 primary indication uses that have been approved in most regions, including the United States, Europe, South America, and Asia. This review describes many uses for which AbbVie has not sought and/or received regulatory approval and are mentioned for historical context only.