CATEGORY AUSTRALASIAN DENTIST65 Daxxify, and Relfydess – undergo further filtration to remove these proteins, leaving only the 150 kDa active neurotoxin. However, among these, Xeomin is the only truly pure botulinum toxin, containing only botulinum toxin A, sucrose, and human albumin. Both Daxxify and Relfydess include polysorbate as a stabiliser instead of human albumin. While polysorbate is commonly used in detergents and emulsifiers, it has been shown to elicit an immune response and promote antibody formation. Thus, although all formulations can be clinically effective, complexing proteins and polysorbate additives may increase the likelihood of immunogenicity over time, rendering the pharmaceutical ineffective. Understanding antibody formation Antibody formation remains one of the most under-recognised yet critical considerations when selecting a botulinum toxin. Repeated exposure to foreign proteins – particularly those that are complexed or immunogenic — can trigger the body to form neutralising antibodies (nAbs). These antibodies bind to the toxin molecule, preventing it from attaching to nerve terminals and rendering treatment ineffective. This effect is most frequently observed with Dysport, which also contains bacterial flagellin, an additional immune stimulant. Studies suggest that up to 3.9 percent ofpatients develop measurable antibodies when treated with this formulation. Polysorbate-containing products may present a similar immunogenic risk, with Daxxify recording an antibody rate of 2.0% in patients. Why this matters Once a patient develops neutralising antibodies, they may experience: X Reduced duration of effect X Incomplete response or treatment failure X Cross-resistance to other botulinum toxins Studies show that antibody-related treatment failure can persist for up to five years, with efficacy restored only when patients completely avoid exposure to complexed or immunogenic toxins during that period. This issue is particularly relevant for patients receiving frequent or high-dose treatments, or for those undergoing therapy for both medical and aesthetic purposes (for example, bruxism, migraine, cervical dystonia). Risk factors for antibody formation X Highly complexed or impure formulations X Frequent treatment intervals (< 3 months) X High cumulative dose exposure X Use in antigen-rich areas (e.g., skin, neck, or masseter regions near lymph nodes) Although true immunogenic resistance remains relatively uncommon, its effects are often profound and irreversible. For this reason, many injectors now prefer high-purity formulations such as Xeomin, especially for younger patients or those likely to receive ongoing treatment. Comparing clinical behaviour across brands While all botulinum toxins share the same core mechanism, their clinical performance can vary depending on formulation. 1. Diffusion and spread X Dysport tends to spread more widely, which may be beneficial in large areas but increases the risk of unintended diffusion. X Botox, Nuceiva, Letybo, and Xeomin demonstrate more predictable diffusion, making them suitable for smaller or more defined muscles, such as the glabella or perioral zone. X A higher molecular weight produces a “heavier” feel, while smaller molecules provide a more natural, lighter result. 2. Onset and duration Botulinum toxin begins its onset within 2–14 days, reaching full effect by two weeks. Additional dosing should only occur after this period to avoid complications. All formulations have similar durations of action, and longevity is dose-dependent, despite marketing claims suggesting otherwise. 3. Reconstitution and Storage Most products require storage between 2–8 °C and reconstitution before use. Xeomin and Daxxify are room-temperature stable prior to reconstitution, improving convenience for high-volume or mobile practices. Relfydess is supplied as a readyto-inject formulation, eliminating reconstitution altogether. Selecting the right Botulinum Toxin Choosing the ideal product depends on several clinical and practical considerations: X Patient history and goals: For firsttime patients, start with a standard, predictable formulation such as Xeomin, which minimises antibody risk. Explain to patients why this product was selected for them. X Treatment area: Areas rich in dendritic cells (e.g., skin) or lymph nodes (e.g., masseter, parotid region) are more prone to immune stimulation; therefore, antigens should be avoided in these zones. X Allergies and sensitivities: Match patients carefully if they are allergic to lactose or polysorbate. X Logistics and storage: Clinics without dedicated refrigeration may benefit from shelf-stable options such as Xeomin or Daxxify. Dentists and the expanding role of muscle relaxants Dentists have a unique anatomical understanding of the face, giving them an exceptional foundation for safe, precise injectable treatments. From managing bruxism and balancing the lower face to enhancing aesthetic harmony, muscle relaxants allow dentists to extend their care beyond the smile. However, scope of practice and CLINICAL
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