LETYBO

What it is

LETYBO is supplied as a powder for injection containing 50 or 100 units of letibotulinumtoxinA, with albumin and sodium chloride as excipients in a sterile, freeze-dried form without a preservative. LetibotulinumtoxinA is a 900 kD molecular weight complex consisting of the *Clostridium botulinum* type A neurotoxin and several accessory proteins.

Approved indications

— Temporary improvement in the appearance of moderate to severe glabellar frown lines in adults.

Dosing overview

The standard dose is 20 units. This is administered as 4 units into each of 5 injection sites: two injections in each corrugator muscle and one injection in the procerus muscle. The intervals between treatments should be ≥ 12 weeks. The efficacy and safety of repeat injections of LETYBO beyond 48 weeks has not been evaluated.

Key safety warnings

Adverse reactions possibly related to the spread of toxin distant from the site of administration have been reported very rarely with botulinum toxin type A. Patients treated with therapeutic doses may experience exaggerated muscle weakness. Swallowing and breathing difficulties are serious and can result in death. Injection of LETYBO is not recommended in patients with a history of dysphagia and aspiration. Patients should be advised to seek immediate medical care if they experience any signs or symptoms consistent with the spread of botulinum toxin effect or if swallowing, speech or respiratory disorders arise. Patients with unrecognised neuromuscular disorders may be at increased risk of clinically significant systemic effects including severe dysphagia and respiratory compromise from typical doses of botulinum toxin type A. An anaphylactic reaction may occur very rarely after injection of botulinum toxin type A. Epinephrine (adrenaline) or any other anti-anaphylactic measures should therefore be available. There is a risk of eyelid ptosis following treatment. See dosing instructions for information on how to minimise this risk. Too frequent doses may increase the risk of antibody formation, which can result in treatment failure. The potential for antibody formation may be minimised by injecting with the lowest effective dose given at the longest feasible intervals between injections. Caution should be exercised when LETYBO is used in patients with bleeding disorders as injection may lead to bruising.

Contraindications

Hypersensitivity to the active substance or to any of the excipients. Generalised disorders of muscle activity including myasthenia gravis, Lambert-Eaton syndrome, and amyotrophic lateral sclerosis. Infection or inflammation at the proposed injection sites.

Regulatory history

LETYBO 50 U and 100 U were first registered on the ARTG on 28 November 2022. The TGA approved the registration on 23 November 2022 for the temporary improvement in the appearance of moderate to severe glabellar frown lines in adults. The approval was based on demonstrated efficacy and an acceptable safety profile.