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Myobloc®
(rimabotulinumtoxinB) Injection
Distant Spread of Toxin Effect
Postmarketing reports indicate that the effects of MYOBLOC (botulinum toxin type b) and all botulinum toxin products may spread from the area of injection to produce symptoms consistent with botulinum toxin effects. These may include asthenia, generalized muscle weakness, diplopia, blurred vision, ptosis, dysphagia, dysphonia, dysarthria, urinary incontinence, and breathing difficulties. These symptoms have been reported hours to weeks after injection. Swallowing and breathing difficulties can be life threatening and there have been reports of death. The risk of symptoms is probably greatest in children treated for spasticity but symptoms can also occur in adults treated for spasticity and other conditions, particularly in those patients who have underlying conditions that would predispose them to these symptoms. In unapproved uses, including spasticity in children and adults, and in approved indications, cases of spread of effect have occurred at doses comparable to those used to treat cervical dystonia and at lower doses.
MYOBLOC ® (rimabotulinumtoxinB) injection is a sterile liquid formulation of a purified neurotoxin that acts at the neuromuscular junction to produce flaccid paralysis. The neurotoxin is produced by fermentation of the bacterium Clostridium botulinum type B (Bean strain) and exists in noncovalent association with hemagglutinin and nonhemagglutinin proteins as a neurotoxin complex. The neurotoxin complex is recovered from the fermentation process and purified through a series of precipitation and chromatography steps.
MYOBLOC (botulinum toxin type b) is provided as a clear and colorless to light-yellow sterile injectable solution in 3.5-mL glass vials. Each single-use vial of formulated MYOBLOC contains 5,000 Units of botulinum toxin type B per milliliter in 0.05% human serum albumin, 0.01 M sodium succinate, and 0.1 M sodium chloride at approximately pH 5.6.
One unit of MYOBLOC (botulinum toxin type b) corresponds to the calculated median lethal intraperitoneal dose (LD50) in mice. The method for performing the assay is specific to Solstice Neurosciences' manufacture of MYOBLOC (botulinum toxin type b) . Due to differences in specific details such as the vehicle, dilution scheme and laboratory protocols for various mouse LD50 assays, units of biological activity of MYOBLOC (botulinum toxin type b) cannot be compared to or converted into units of any other botulinum toxin or any toxin assessed with any other specific assay method. Therefore, differences in species sensitivities to different botulinum neurotoxin serotypes preclude extrapolation of animal dose-activity relationships to human dose estimates. The specific activity of MYOBLOC (botulinum toxin type b) ranges between 70 to 130 Units/ng.
MYOBLOC (botulinum toxin type b) is indicated for the treatment of adults with cervical dystonia to reduce the severity of abnormal head position and neck pain associated with cervical dystonia.
The recommended initial dose of MYOBLOC (botulinum toxin type b) for patients with a prior history of tolerating botulinum toxin injections is 2,500 to 5,000 Units divided among affected muscles (see Clinical Studies). Patients without a prior history of tolerating botulinum toxin injections should receive a lower initial dose. Subsequent dosing should be optimized according to the patient's individual response. MYOBLOC (botulinum toxin type b) should be administered by physicians familiar and experienced in the assessment and management of patients with CD.
The method described for performing the potency assay is specific to Solstice Neurosciences' manufacture of MYOBLOC (botulinum toxin type b) . Due to differences in the specific details of this assay such as the vehicle, dilution scheme and laboratory protocols for various potency assays, Units of biological activity of MYOBLOC (botulinum toxin type b) cannot be compared to or converted into units of any other botulinum toxin or any toxin assessed with any other specific assay method. Therefore, differences in species' sensitivities to different botulinum neurotoxin serotypes preclude extrapolation of animal dose-activity relationships to human dose estimates.
The duration of effect in patients responding to MYOBLOC (botulinum toxin type b) treatment has been observed in studies to be between 12 and 16 weeks at doses of 5,000 Units or 10,000 Units (see Clinical Studies).
MYOBLOC (botulinum toxin type b) is provided as a clear and colorless to light-yellow sterile injectable solution in single-use 3.5-mL glass vials. Each single-use vial of formulated MYOBLOC contains 5,000 Unitsa of botulinum toxin type B per milliliter in 0.05% human serum albumin, 0.01 M sodium succinate, 0.1 M sodium chloride at approximately pH 5.6.
MYOBLOC (botulinum toxin type b) is available in the following three presentations.
| Dosage Strength | Volume Per Vial | Single-Vial Carton |
| 2,500 Units | 0.5 mL | NDC 10454-710-10 |
| 5,000 Units | 1 mL | NDC 10454-711-10 |
| 10,000 Units | 2 mL | NDC 10454-712-10 |
Store under refrigeration at 2°- 8°C (36°- 46°F).
DO NOT FREEZE. DO NOT SHAKE.
Protect from light. No U.S. Standard of Potency.
Ready to use; no reconstitution required. The recommended storage condition for MYOBLOC (botulinum toxin type b) is refrigeration at 2°-8°C.
MYOBLOC (botulinum toxin type b) may be diluted with normal saline. Once diluted, the product must be used within 4 hours as the formulation does not contain a preservative.
All vials of expired MYOBLOC (botulinum toxin type b) and equipment used in the administration of MYOBLOC (botulinum toxin type b) should be carefully discarded according to standard medical waste practices.
Do not use after the expiration date stamped on the vial.
Discard unused portion. Single-use vial.
a See DOSAGE AND ADMINISTRATION
Manufactured By: Solstice Neurosciences, Inc., South San Francisco, CA 94080. Rev. 07/09
The most commonly reported adverse events associated with MYOBLOC (botulinum toxin type b) treatment in all studies were dry mouth, dysphagia, dyspepsia, and injection site pain. Dry mouth and dysphagia were the adverse reactions most frequently resulting in discontinuation of treatment. There was an increased incidence of dysphagia with increased dose in the sternocleidomastoid muscle. The incidence of dry mouth showed some dose-related increase with doses injected into the splenius capitis, trapezius and sternocleidomastoid muscles.
Only nine subjects without a prior history of tolerating injections of type A botulinum toxin have been studied. Adverse event rates have not been adequately evaluated in these patients, and may be higher than those described in Table 3.
Adverse reaction rates observed in the clinical trials for a product cannot be directly compared to rates in clinical trials for another product and may not reflect the rates observed in actual clinical practice. However, adverse reaction information from clinical trials does provide a basis for identifying the adverse events that appear to be related to drug use and for approximating rates.
MYOBLOC (botulinum toxin type b) was studied in both placebo controlled single treatment studies and uncontrolled repeated treatment studies; most treatment sessions and patients were in the uncontrolled studies. The data described below reflect exposure to MYOBLOC (botulinum toxin type b) at varying doses in 570 subjects, including more than 300 patients with 4 or more treatment sessions. Most treatment sessions were at doses of 12,500 Units or less. There were 57 patients administered a dose of 20,000 or 25,000 Units. All but nine patients had a prior history of receiving type A botulinum toxin and adequately tolerating the treatment to have received repeated doses.
The rates of adverse events and association with MYOBLOC (botulinum toxin type b) are best assessed in the results from the placebo controlled studies of a single treatment session with active monitoring. The data in Table 3 reflect those adverse events occurring in at least 5% of patients exposed to MYOBLOC (botulinum toxin type b) treatment in pooled placebo controlled clinical trials. Annual rates of adverse events are higher in the overall data which includes longer duration follow-up of patients with repeated treatment experience. The mean age of the population in these studies was 55-years-old with approximately 66% being female. Most of the patients studied were Caucasian and all had cervical dystonia that was rated as moderate to severe in severity.
Table 3: Treatment-Emergent AEs Reported by at Least 5% of
MYOBLOC (botulinum toxin type b) Treated Patients by Dose Group, Following Single Treatment Session in
Controlled Studies 09, 301 and 302
| Adverse Event (COSTART Term) |
Dosing Groups | |||
| Placebo (N=104) |
2,500 Units (N=31) |
5,000 Units (N=67) |
10,000 Units (N=106) |
|
| Dry Mouth | 3 (3%) | 1 (3%) | 8 (12%) | 36 (34%) |
| Dysphagia | 3 (3%) | 5 (16%) | 7 (10%) | 27 (25%) |
| Neck Pain related to CD* | 17 (16%) | 0 (0%)† | 11 (16%) | 18 (17%) |
| Injection Site Pain | 9 (9%) | 5 (16%) | 8 (12%) | 16 (15%) |
| Infection | 16 (15%) | 4 (13%) | 13 (19%) | 16 (15%) |
| Pain | 10 (10%) | 2 (6%) | 4 (6%) | 14 (13%) |
| Headache | 8 (8%) | 3 (10%) | 11(16%) | 12 (11%) |
| Dyspepsia | 5 (5%) | 1 (3%) | 0 (0%) | 11(10%) |
| Nausea | 5 (5%) | 3 (10%) | 2 (3%) | 9 (8%) |
| Flu Syndrome | 4 (4%) | 2 (6%) | 6 (9%) | 9 (8%) |
| Torticollis | 7 (7%) | 0 (0%) | 3 (4%) | 9 (8%) |
| Pain Related to CD/Torticollis | 4 (4%) | 3 (10%) | 3 (4%) | 7 (7%) |
| Arthralgia | 5 (5%) | 0 (0%) | 1 (1%) | 7 (7%) |
| Back Pain | 3 (3%) | 1 (3%) | 3 (4%) | 7 (7%) |
| Cough Increased | 3 (3%) | 1 (3%) | 4 (6%) | 7 (7%) |
| Myasthenia | 3 (3%) | 1 (3%) | 3 (4%) | 6 (6%) |
| Asthenia | 4 (4%) | 1 (3%) | 0 (0%) | 6 (6%) |
| Dizziness | 2 (2%) | 1 (3%) | 2 (3%) | 6 (6%) |
| Accidental Injury | 4 (4%) | 0 (0%) | 3 (4%) | 5 (5%) |
| Rhinitis | 6 (6%) | 1 (3%) | 1 (1%) | 5 (5%) |
| * Not a COSTART term † Not collected in Study 09 by special COSTART term |
||||
In the overall clinical trial experience with MYOBLOC (botulinum toxin type b) (570 patients, including the uncontrolled studies), most cases of dry mouth or dysphagia were reported as mild or moderate in severity. Severe dysphagia was reported by 3% of patients. Severe dry mouth was reported by 6% of patients. Dysphagia and dry mouth were the most frequent adverse events reported as a reason for discontinuation from repeated treatment studies. These adverse events led to discontinuation from further treatments with MYOBLOC (botulinum toxin type b) in some patients even when not reported as severe.
The following additional adverse events were reported in 2% or greater of patients participating in any of the clinical studies (COSTART terms, by body system):
Body as a Whole: allergic reaction, fever, headache related to injection, chest pain, chills, hernia, malaise, abscess, cyst, neoplasm, viral infection; Musculoskeletal: arthritis, joint disorder; Cardiovascular System: migraine; Respiratory: dyspnea, lung disorder, pneumonia; Nervous System: anxiety, tremor, hyperesthesia, somnolence, confusion, pain related to CD/torticollis, vertigo, vasodilation; Digestive System: gastrointestinal disorder, vomiting, glossitis, stomatitis, tooth disorder; Skin and Appendages: pruritis; Urogenital System: urinary tract infection, cystitis, vaginal moniliasis; Special Senses: amblyopia, otitis media, abnormal vision, taste perversion, tinnitus; Metabolic and Nutritional Disorders: peripheral edema, edema, hypercholesterolemia; Hemic and Lymphatic System: ecchymosis.
The following adverse event has been reported during postmarketing use for approved and unapproved indications: constipation.
A two-stage assay was used to test for immunogenicity and neutralizing activity induced by treatment with MYOBLOC (botulinum toxin type b) . In order to account for varying lengths of follow-up, life-table analysis methods were used to estimate the rates of development of immune responses and neutralizing activity. During the repeated treatment studies, 446 subjects were followed with periodic ELISA based evaluations for development of antibody responses against MYOBLOC (botulinum toxin type b) . Only patients who showed a positive ELISA assay were subsequently tested for the presence of neutralizing activity against MYOBLOC (botulinum toxin type b) in the mouse neutralization assay (MNA). 12% of patients had positive ELISA assays at baseline. Patients began to develop new ELISA responses after a single treatment session with MYOBLOC (botulinum toxin type b) . By six months after initiating treatment, estimates for ELISA positive rate were 20%, which continued to rise to 36% at one year and 50% positive ELISA status at 18 months. Serum neutralizing activity was primarily not seen in patients until after 6 months. Estimated rates of development were 10% at one year and 18% at 18 months in the overall group of patients, based on analysis of samples from ELISA positive individuals. The effect of conversion to ELISA or MNA positive status on efficacy was not evaluated in these studies, and the clinical significance of development of antibodies has not been determined.
The data reflect the percentage of patients whose test results were considered positive for antibodies to MYOBLOC (botulinum toxin type b) in both an in vitro and in vivo assay. The results of these antibody tests are highly dependent on the sensitivity and specificity of the assays. Additionally, the observed incidence of antibody positivity in an assay may be influenced by several factors including sample handling, concomitant medications, and underlying disease. For these reasons, comparison of the incidence of antibodies to MYOBLOC (botulinum toxin type b) with the incidence of antibodies to other products may be misleading.
Co-administration of MYOBLOC (botulinum toxin type b) and aminoglycosides or other agents interfering with neuromuscular transmission (e.g., curare-like compounds) should only be performed with caution as the effect of the toxin may be potentiated.
The effect of administering different botulinum neurotoxin serotypes at the same time or within less than 4 months of each other is unknown. However, neuromuscular paralysis may be potentiated by co-administration or overlapping administration of different botulinum toxin serotypes.
Included as part of the PRECAUTIONS section.
Postmarketing safety data from MYOBLOC and other approved botulinum toxins suggest that botulinum toxin effects may, in some cases, be observed beyond the site of local injection. The symptoms are consistent with the mechanism of action of botulinum toxin and may include asthenia, generalized muscle weakness, diplopia, blurred vision, ptosis, dysphagia, dysphonia, dysarthria, urinary incontinence, and breathing difficulties. These symptoms have been reported hours to weeks after injection. Swallowing and breathing difficulties can be life threatening and there have been reports of death related to spread of toxin effects. The risk of symptoms is probably greatest in children treated for spasticity, but symptoms can also occur in adults treated for spasticity and other conditions, and particularly in those patients who have underlying conditions that would predispose them to these symptoms. In unapproved uses, including spasticity in children and adults, and in approved indications, symptoms consistent with spread of toxin effect have been reported at doses comparable to or lower than doses used to treat cervical dystonia.
The potency units of MYOBLOC are specific to the preparation and biological activity assay method utilized. Due to differences in the aspects of this assay such as the vehicle, dilution scheme, and laboratory protocols for various potency assays, potency units are not interchangeable with other preparations of botulinum toxin products and, therefore, units of biological activity of MYOBLOC cannot be compared to or converted into units of any other botulinum toxin products assessed with any other specific assay method [see DESCRIPTION].
Serious hypersensitivity reactions have been reported with botulinum toxin products. Angioedema, urticaria, and rash have occurred with MYOBLOC treatment [see ADVERSE REACTIONS]. Hypersensitivity reactions can also include anaphylaxis, serum sickness, soft tissue edema, and dyspnea. If serious and/or immediate hypersensitivity reactions occur, discontinue further injection of MYOBLOC and institute appropriate medical therapy immediately. The use of MYOBLOC in patients with a known hypersensitivity to any botulinum neurotoxin or to any of the excipients (human albumin, sucrose), could lead to a life-threatening allergic reaction [see CONTRAINDICATIONS, ADVERSE REACTIONS].
Treatment with MYOBLOC and other botulinum toxin products can result in swallowing or breathing difficulties. Patients with pre-existing swallowing or breathing difficulties may be more susceptible to these complications. In most cases, this is a consequence of weakening of muscles in the area of injection that are involved in breathing or swallowing. When distant effects occur, additional respiratory muscles may be involved.
Deaths as a complication of severe dysphagia have been reported after treatment with botulinum toxin. Dysphagia may persist for several months and require use of a feeding tube to maintain adequate nutrition and hydration. Aspiration may result from severe dysphagia and is a particular risk when treating patients in whom swallowing or respiratory function is already compromised.
Treatment of cervical dystonia with botulinum toxins may weaken neck muscles that serve as accessory muscles of ventilation. This may result in a critical loss of breathing capacity in patients with respiratory disorders who may have become dependent upon these accessory muscles. There have been postmarketing reports of serious breathing difficulties, including respiratory failure, in cervical dystonia patients. Patients treated with botulinum toxin may require immediate medical attention should they develop problems with swallowing, speech or respiratory disorders. These reactions can occur within hours to weeks after injection with botulinum toxin [see ADVERSE REACTIONS].
Individuals with peripheral motor neuropathic diseases, amyotrophic lateral sclerosis, or neuromuscular junctional disorders (e.g., myasthenia gravis or Lambert-Eaton syndrome) should be monitored particularly closely when given botulinum toxin. Patients with neuromuscular disorders may be at increased risk of clinically significant effects including severe dysphagia and respiratory compromise from typical doses of MYOBLOC [see ADVERSE REACTIONS].
This product contains albumin, a derivative of human blood. Based on effective donor screening and product manufacturing processes, it carries an extremely remote risk for transmission of viral diseases and variant Creutzfeldt-Jakob disease (vCJD). There is a theoretical risk for transmission of Creutzfeldt-Jakob disease (CJD), but if that risk actually exists, the risk of transmission would be considered extremely remote. No cases of transmission of viral diseases, CJD, or vCJD have ever been identified for licensed albumin or albumin contained in other licensed products.
Advise the patient to read the FDA-approved patient labeling (Medication Guide).
Advise patients to inform their healthcare provider if they develop any unusual symptoms, including difficulty with swallowing, speaking or breathing, or if any existing symptom worsens [see BOX WARNING and WARNINGS AND PRECAUTIONS]. Inform patients of the risk of aspiration.
Counsel patients that if loss of strength, muscle weakness, or impaired vision occur, they should avoid driving a car or engaging in other potentially hazardous activities.
No long-term carcinogenicity studies in animals have been conducted.
No genetic toxicology studies have been conducted.
Intramuscular administration of MYOBLOC (0, 300, 1000, or 3000 Units/kg/day) to male and female rats prior to and throughout the mating period and continuing in females to gestation day 6 resulted in decreases in implantation sites and viable fetuses at the high dose of 3000 Units/kg/day, which was associated with maternal toxicity. The no-effect dose for reproductive toxicity (1000 Units/kg/day) is 12 times the maximum recommended human dose for cervical dystonia (5000 Units) on a body weight (Units/kg) basis.
There are no adequate data on the developmental risks associated with the use of MYOBLOC in pregnant women. No developmental toxicity was observed in pregnant rats administered MYOBLOC by intramuscular injection during gestation and lactation, at doses producing maternal toxicity.
In the U.S. general population, the background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2% to 4% and 15% to 20%, respectively. The background risk of major birth defects and miscarriage for the indicated population is unknown.
Animal Data
When MYOBLOC was administered by intramuscular injection to pregnant rats (0, 300, 1000, or 3000 Units/kg/day) or rabbits (0, 0.03, 0.1, 0.3, or 1.0 Units/kg/day) throughout gestation, no adverse effects on embryofetal development were observed. The highest dose tested in rat, which was associated with maternal toxicity, was 36 times the maximum recommended human dose (MRHD) for cervical dystonia (5000 Units) on a body weight (Units/kg) basis.
The highest dose tested in rabbit was substantially less than the MRHD for cervical dystonia on a Units/kg basis; maternal toxicity was observed at all but the lowest dose tested.
There are no data on the presence of MYOBLOC in human milk, the effects on the breastfed infant, or the effects on milk production. The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for MYOBLOC and any potential adverse effects on the breastfed infant from MYOBLOC or from the underlying maternal condition.
Safety and effectiveness in pediatric patients have not been established.
In the controlled studies for MYOBLOC in patients with cervical dystonia, 152 (75%) were under the age of 65, and 52 (26%) were 65 years of age or older [see Clinical Studies]. For these age groups, the most frequently reported adverse reactions occurred at similar rates in both age groups. Efficacy results did not suggest any large differences between these age groups.
Very few patients age 75 or older were enrolled; therefore, no conclusions regarding the safety and efficacy of MYOBLOC within this age group can be determined.
Of the 166 MYOBLOC-treated patients in the placebo-controlled studies for treatment of chronic sialorrhea [see Clinical Studies], 105 (63%) were 65 years of age or older, and 43 (26%) were 75 years of age or older. No overall differences in safety or effectiveness were observed between patients over 65 years of age and younger patients, but greater sensitivity of some older patients cannot be ruled out.
Excessive doses of MYOBLOC may be expected to produce neuromuscular weakness with a variety of symptoms. Respiratory support may be required where excessive doses cause paralysis of respiratory muscles. In the event of overdose, the patient should be medically monitored for symptoms of excessive muscle weakness or muscle paralysis [see WARNINGS AND PRECAUTIONS]. Symptomatic treatment may be necessary.
Symptoms of overdose are likely not to be present immediately following injection. Should accidental injection or oral ingestion occur, the person should be medically supervised for several weeks for signs and symptoms of excessive muscle weakness or muscle paralysis.
In the event of overdose, antitoxin raised against botulinum toxin is available from the Centers for Disease Control and Prevention (CDC) in Atlanta, GA. However, the antitoxin will not reverse any botulinum toxin-induced effects already apparent by the time of antitoxin administration. In the event of suspected or actual cases of botulinum toxin poisoning, please contact your local or state Health Department to process a request for antitoxin through the CDC. If you do not receive a response within 30 minutes, please contact the CDC directly at 770-488-7100. More information can be obtained at http://cdc.gov/ncidod/srp/drugs/drug-service.html.
MYOBLOC is contraindicated in patients with:
The seven serologically distinct botulinum neurotoxins, designated A through G, share a common structural organization consisting of one Heavy Chain and one Light Chain polypeptide linked by a single disulfide bond. These toxins inhibit acetylcholine release at the neuromuscular junction via a three stage process: 1) Heavy Chain mediated neurospecific binding of the toxin, 2) internalization of the toxin by receptor-mediated endocytosis, and 3) ATP and pH dependent translocation of the Light Chain to the neuronal cytosol where it acts as a zinc-dependent endoprotease cleaving polypeptides essential for neurotransmitter release. MYOBLOC (botulinum toxin type b) specifically has been demonstrated to cleave synaptic Vesicle Associated Membrane Protein (VAMP, also known as synaptobrevin) which is a component of the protein complex responsible for docking and fusion of the synaptic vesicle to the presynaptic membrane, a necessary step to neurotransmitter release.
Using currently available analytical technology, it is not possible to detect MYOBLOC (botulinum toxin type b) in the peripheral blood following intramuscular injection at the recommended doses.
Two phase 3, randomized, multi-center, double-blind, placebo controlled studies of the treatment of cervical dystonia were conducted. Both studies enrolled only adult patients who had a history of receiving botulinum toxin type A in an open label manner, with a perceived good response and tolerable adverse effects. Study #301 enrolled patients who were perceived as having an acceptable response to type A toxin, while Study #302 enrolled only patients who had secondarily lost responsiveness to type A toxin. Other eligibility criteria common to both studies were that all subjects had moderate or greater severity of cervical dystonia with at least 2 muscles involved, no neck contractures or other causes of decreased neck range of motion, and no history of any other neuromuscular disorder. Subjects in Study #301 were randomized to receive placebo, 5,000 Units or 10,000 Units of MYOBLOC (botulinum toxin type b) , and subjects in Study #302 were randomized to receive placebo or 10,000 Units of MYOBLOC (botulinum toxin type b) . Study agent was administered to subjects in a single treatment session by investigators who selected 2 to 4 muscles per subject from the following: Splenius capitis, Sternocleidomastoid, Levator scapulae, Trapezius, Semispinalis capitis, and Scalene muscles. The total dose was divided between the selected muscles, and from 1 to 5 injections were made per muscle. There were 109 subjects enrolled into Study #301, and 77 into Study #302. Patient evaluations continued for 16 weeks post injection.
The primary efficacy outcome variable for both studies was the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS)-Total Score (scale range of possible scores is 0–87) at Week 4. TWSTRS is comprised of three sub-scales which examine 1) Severity—the severity of the patient's abnormal head position; 2) Pain—the severity and duration of pain due to the dystonia; and 3) Disability— the effects of the abnormal head position and pain on a patient's activities. The secondary endpoints were the Patient Global and Physician Global Assessments of change at Week 4. Both Global Assessments used a 100-point visual-analog scale (VAS). The Patient Global Assessment allows patients to indicate how they feel at the time of their evaluation compared to the pre-injection baseline. Likewise, the Physician Global Assessment indicates the physician's assessment of a patient's change from baseline to Week 4. Scores of 50 indicate no change, 0 much worse, and 100 much better. Results of comparisons of the primary and secondary efficacy variables are summarized in Table 1.
Table 1: Efficacy Results From Two Phase 3 MYOBLOC (botulinum toxin type b) Studies
| Assessments* | STUDY 301 | STUDY 302 | |||
| Placebo n = 36 |
5,000 Units n = 36 |
10,000 Units n = 37 |
Placebo n = 38 |
10,000 Units n = 39 |
|
| TWSTRS Total | |||||
| Mean at Baseline | 43.6 | 46.4 | 46.9 | 51.2 | 52.8 |
| Change from Baseline | -4.3 | -9.3 | -11.7 | -2.0 | -11.1 |
| 95% Confidence Interval | (-8.9, -1.2) | (-11.1, -3.3) | (-12.2, -5.2) | ||
| P value | 0.012 | 0.0004 | 0.0001 | ||
| Patient Global | |||||
| Mean at Week Four | 43.6 | 60.6 | 64.6 | 39.5 | 60.2 |
| 95% Confidence Interval | (7.0, 26.9) | (11.3, 31.1) | (11.2, 29.1) | ||
| P value | 0.001 | 0.0001 | 0.0001 | ||
| Physician Global | |||||
| Mean at Week Four | 52.0 | 65.3 | 64.2 | 47.9 | 60.6 |
| 95% Confidence Interval | (5.5, 21.3) | (3.9, 19.7) | (7.4, 18.1) | ||
| P value | 0.001 | 0.004 | 0.0001 | ||
| TWSTRS-Subscales | |||||
| – Severity | |||||
| Mean at Baseline | 18.4 | 20.2 | 20.2 | 22.1 | 22.6 |
| Change from Baseline | -2.3 | -3.2 | -4.8 | -1.2 | -3.7 |
| 95% Confidence Interval | (-2.5, 0.6) | (-4.0, -1.0) | (-3.9, -1.0) | ||
| P value | 0.22 | 0.002 | 0.001 | ||
| – Pain | |||||
| Mean at Baseline | 10.9 | 11.8 | 12.4 | 12.2 | 11.9 |
| Change from Baseline | -0.5 | -3.6 | -4.2 | -0.2 | -3.6 |
| 95% Confidence Interval | (-4.7, -1.1) | (-5.1, -1.4) | (-5.0, -2.1) | ||
| P value | 0.002 | 0.0008 | 0.0001 | ||
| – Disability | |||||
| Mean at Baseline | 14.3 | 14.4 | 14.4 | 16.9 | 18.3 |
| Change from Baseline | -1.6 | -2.5 | -2.7 | 0.8 | -3.8 |
| 95% Confidence Interval | (-2.7, 0.7) | (-2.8, 0.6) | (-4.1, -1.0) | ||
| P value | 0.26 | 0.19 | 0.002 | ||
| * 95% Cl are for the differences between the active and placebo groups. The P values are for the comparison of active dose and placebo. For TWSTRS-Total and TWSTRS-subscale scores, P values are from ANCOVA for each variable with center and treatment in the model and the baseline value of the variable included as a covariate. For the Patient Global and Physician Global Assessments, P values are from ANOVA for each variable with center and treatment in the model. | |||||
There were no statistically significant differences in results between the 5,000 Units and 10,000 Units doses in Study #301. Exploratory analyses of these two studies suggested that the majority of patients who showed a beneficial response by Week 4 had returned to their baseline status between Weeks 12 to 16 post injection. Although there was a MYOBLOC (botulinum toxin type b) associated decrease in pain, there remained many patients who experienced an increase in dystonia-related neck pain irrespective of treatment group (see ADVERSE REACTIONS). TWSTRS Total Score at Week 4 and Patient Global Assessment among subgroups by gender or age showed consistent treatment-associated effects across these subgroups (see also PRECAUTIONS: Geriatrics). There were too few non-Caucasian patients enrolled to draw any conclusions regarding relative efficacy in racial subsets.
MYOBLOC (botulinum toxin type b) was studied in two phase 2 dose ranging studies, Studies #08 and #09, which preceded the phase 3 studies. Studies #08 and #09 had a study design similar to the phase 3 studies, including eligibility criteria. Study #08 enrolled 85 subjects randomized between doses of placebo, 400 Units, 1,200 Units, or 2,400 Units (21 or 22 subjects per group). Study #09 enrolled 122 subjects and randomized between doses of placebo, 2,500 Units, 5,000 Units, and 10,000 Units (30 or 31 subjects per group). These studies demonstrated efficacy on the TWSTRS-Total, baseline to Week 4, at doses of 2,400 Units, 2,500 Units, 5,000 Units, and 10,000 Units. Study #08 showed mean improvement from baseline on the Week 4 TWSTRS for placebo and 2,400 Units of 2.0 and 8.5 points respectively (from baselines of 42.0 and 42.4 points). Study #09 showed mean improvement from baseline to Week 4 for placebo, 2,500 Units, 5,000 Units, and 10,000 Units of 3.3, 11.6, 12.5, and 16.4 points, respectively (from baselines of 45.5, 45.6, 45.2, and 47.5 points). Study #08 also indicated there is less response for doses below 2,400 Units.
Study #352 was an open label, intrapatient dose-escalation study of 3 treatment sessions where each patient with cervical dystonia sequentially received 10,000 Units, 12,500 Units, and 15,000 Units, at periods of 12 to 16 weeks between treatment sessions irrespective of their response to their previous dose. This study enrolled 145 patients, of whom 125 received all three treatments. Although this was an open label design where investigators and patients knew the dose at each treatment session, there were similar mean improvements on the TWSTRS-Total, from baseline to Week 4, for all three doses.
In the MYOBLOC (botulinum toxin type b) injected patients (n=112) of the phase 3 studies, 19% had 2 muscles injected, 48% had 3 muscles injected, and 33% had 4 muscles injected. Table 2 indicates the frequency of use for each of the permitted muscles, and the fraction of the total dose of the treatment injected into each muscle, for those patients in whom the muscle was injected.
Table 2: Studies 301 and 302 Combined Data Fraction of Total
Dose Injected into Involved Muscles
| Muscle Injected | Percent Frequency Injected* | Fraction of Total Dose Injected by Percentiles | ||
| 25th | 50th | 75th | ||
| Splenius Capitis | 88 | 0.30 | 0.40 | 0.50 |
| Sternocleidomastoid | 80 | 0.20 | 0.25 | 0.30 |
| Semispinalis Capitis | 52 | 0.30 | 0.36 | 0.50 |
| Levator Scapulae | 46 | 0.13 | 0.20 | 0.20 |
| Trapezius | 38 | 0.20 | 0.25 | 0.35 |
| Scalene Complex | 13 | 0.20 | 0.25 | 0.30 |
| * Percent frequency of patients in whom each muscle was injected | ||||
MYOBLOC®
(My-o-block)
(rimabotulinumtoxinB) injection, for intramuscular or
intraglandular use
What is the most important information I should know about MYOBLOC?
MYOBLOC may cause serious side effects that can be life threatening. Call your doctor or get medical help right away if you have any of these problems after treatment with MYOBLOC:
These symptoms can happen hours to weeks after you receive an injection of MYOBLOC.
These problems could make it unsafe for you to drive a car or do other dangerous activities. See “What should I avoid while receiving MYOBLOC?”
What is MYOBLOC?
MYOBLOC is a prescription medicine used in adults that is injected into:
It is not known whether MYOBLOC is safe or effective in children.
Do not receive MYOBLOC if you:
Before receiving MYOBLOC, tell your doctor about all your medical conditions, including if you have:
Tell your doctor if you:
Tell your doctor about all the medicines you take, including prescription and over-the-counter medicines, vitamins and herbal supplements. Talk to your doctor before you take any new medicine after you receive MYOBLOC.
Using MYOBLOC with certain other medicines may cause serious side effects. Do not start any new medicines until you have told your doctor that you have received MYOBLOC in the past. Especially tell your doctor if you:
Ask your doctor if you are not sure if your medicine is one that is listed above.
Know the medicines you take. Keep a list of your medicines with you to show your doctor and pharmacist each time you get a new medicine.
How should I receive MYOBLOC?
What should I avoid while receiving MYOBLOC?
MYOBLOC may cause loss of strength or general muscle weakness or vision problems within hours to weeks of receiving MYOBLOC. If this happens, do not drive a car, operate machinery or do other dangerous activities. See “What is the most important information I should know about MYOBLOC?”
What are the possible side effects of MYOBLOC?
MYOBLOC can cause serious side effects including:
See “What is the most important information I should know about MYOBLOC?”
The most common side effects of MYOBLOC in people with cervical dystonia include:
The most common side effects of MYOBLOC in people with sialorrhea include dry mouth and trouble swallowing (dysphagia).
These are not all the possible side effects of MYOBLOC. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088. You may also report side effects to US WorldMeds at 1-888461-2255.
General information about the safe and effective use of MYOBLOC.
Medicines are sometimes prescribed for purposes other than those listed in a Medication Guide. You can ask your doctor or pharmacist for information about MYOBLOC that is written for healthcare professionals.
What are the ingredients in MYOBLOC?
Active ingredient: botulinum toxin type B
Inactive ingredients: albumin human, sodium chloride and sodium succinate.
This Medication Guide has been approved by the U.S. Food and Drug Administration.
