For blepharospasm, reconstituted Siax (see Table 2 in Cautions for Usage) is injected using a sterile, 27 - 30 gauge needle without electromyographic guidance. The initial recommended dose is 1.25 - 2.5 U (0.05 mL to 0.1 mL volume at each site) injected into the medial and lateral pre-tarsal orbicularis oculi of the upper lid and into the lateral pre-tarsal orbicularis oculi of the lower lid. In general, the initial effect of the injections is seen within three days and reaches a peak at one to two weeks post-treatment. Each treatment lasts approximately three months, following which the procedure can be repeated. At repeat treatment sessions, the dose may be increased up to two-fold if the response from the initial treatment is considered insufficient-usually defined as an effect that does not last longer than two months. However there appears to be little benefit obtainable from injecting more than 5.0 U per site. Some tolerance may be found when the drug is used in treating blepharospasm if treatments are given any more frequently than every three months, and is rare to have the effect be permanent.
The cumulative dose of Siax treatment in a 30-day period should not exceed 200 U.
Pediatric cerebral palsy:
For the pediatric cerebral palsy, reconstituted Siax (see Table 2 in Cautions for Usage) is injected using a sterile, 26-30 gauge needle. It is recommended to inject to each of the medial and lateral heads of the gastrocnemius muscles. A total dose of 4U/kg bodyweight is recommended for the affected gastrocnemius muscle in patients with hemiplegia. And in patients with diplegia, the recommended dose is 6U/kg bodyweight divided between both legs. The maximum dose administered must not exceed 200U/patient at a time. After injection, patient should be monitored for at least 30 minutes for any presence of acute adverse event.
Siax is reconstituted to make 100U/2.5mL (4U/0.1 mL) with 0.9% nonpreserved sterile saline.
Using a 30 gauge needle, 20U of Siax is injected to two places on the corrugators muscle for each eye and one place on the procerus muscle, total of 5 sites with 0.1 mL per site. To reduce complications of drooping (ptosis) eyelids, injection is avoided in the levator palpebrae superioris vicinity, especially for patients with large corrugators muscles. When administering injection in the medial end of corrugators muscle and in the midpoint between each eyebrow, it must be done in a place at least 1 cm apart from supraorbital ridge. Siax is injected with caution so that it does not enter the blood vessel, and to prevent effusion from the area below the orbital ridge, firmly place a thumb or an index finger on the area below the orbital ridge prior to injection. During injection, the needle should point upward toward the center and injection dose must be measured accurately. The corrugators muscle and orbicularis oculi muscle move the center of the forehead and generate the glabellar facial wrinkles. The procerus muscle and depressor supercilii muscle pull the forehead down. Frowning or glabellar wrinkles are produced by these muscles. Because the position, size, and use of these muscles are different for individuals, an effective dose is determined based on general observations on the patient's ability to move the injected superficial muscles. The treatment effect of Siax for glabellar wrinkles lasts approximately 3-4 months. Frequent injection of Siax has not been clinically evaluated for safety and effectiveness, and it is not recommended. In general, the first Siax injection induces chemical denervation in the injected muscles 1 to 2 days after injection and its intensity increases during the first week.
The exact dosage and the number of injection should be tailored to the individual based on the size, the number and location of the muscles involved, the severity of spasticity, presence of local muscle weakness, and the patient's response to previous treatment. Clinical improvement in muscle tone is seen four to six weeks following treatment.
In controlled clinical trials, the following doses are administered: See Table 1.
Click on icon to see table/diagram/image
In the clinical trial, doses are not over 360U, injected into individual muscles.
Reconstituted Siax is injected using a sterile 24~30 gauge needle for superficial muscles, and a longer needle may be used for deeper musculature. Localization of the involved muscles with electromyographic guidance or nerve stimulation techniques is recommended.