Firdapse for Post-BOTOX Vocal Weakness

NCT05123053 | Completed Phase 2 FDA Drug

• 1 other identifier: SD-DAP-01
• Study Type: interventional
• Target: 18
• Locations: 1 country
• Sites: 1

Brief Summary

Botox injections into the thyroarytenoid muscle are a predictable and effective treatment for SD, but typically result in transient symptoms of voice weakness and breathiness during the first 2-3 weeks after injection. Investigators hypothesize that voice weakness and breathiness after Botox treatment can be alleviated using amifampridine.

Conditions

Vocal Weakness(Post-BOTOX Injection)

Keywords

BOTOX; Onabotulinumtoxin; Spasmodic Dysphonia

Outcome Measures

Primary Outcomes (1)

• Voice Handicap Index-10

  VHI-10 is a scale used to assess the severity of problematic symptoms associated with the voice. It is a series of 10 questions. Each questions is answered using numbers 0-4, with 0 meaning the patient never has a problem with that symptom; and, 4 meaning the patient always has a problem with that symptom.

  over 2 months

Study Arms (1)

Treatment Arm

EXPERIMENTAL

subjects will be given active drug and titrated up in 10mg increments (with max single dose being 30mg) until a change or drug side effect is noticed.

Drug: Amifampridine

Interventions

Amifampridine DRUG

10mg tablet

Also known as: Firdapse

Treatment Arm

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Male or female ≥18 years of age.
• Capable of providing informed consent.
• Confirmed physician diagnosis of spasmodic dysphonia.
• Receives onabotulinumtoxinA for treatment of their spasmodic dysphonia.
• Experiences significant breathiness ± 5 days following their injection.
• If sexually active and of childbearing potential, willing to use an acceptable method of contraception (as noted below) from screening visit until 3 months after the last dose of investigational product.
• A.NOTE: No adequate clinical data on exposed pregnancies are available for amifampridine. No nonclinical safety data are available regarding the effects of amifampridine on reproductive function. Amifampridine phosphate should not be used during pregnancy. It is unknown whether amifampridine is excreted in human breast milk. The excretion of amifampridine in milk has not been studied in animals. Amifampridine phosphate should not be used during breastfeeding. Acceptable methods of birth control include:
• Hormonal contraception (e.g., oral contraceptive, transdermal contraceptive, contraceptive implant, or injectable hormonal contraceptive) for at least 3 months prior to study drug administration, throughout the study, and for 3 months after the last dose of study drug.
• Double-barrier birth control (e.g., a combination of male condom with either cap, diaphragm, or sponge together with spermicide) starting at the Screening visit, throughout the study, and for at least 4 weeks after the last dose of study drug. NOTE: Use of a male and female condom simultaneously is NOT an acceptable method of double-barrier birth control.
• Intrauterine contraception/device starting at the Screening visit, throughout the study, and for 3 months after the last dose of study drug.
• Total abstinence from sexual intercourse (only acceptable if it is the preferred and usual lifestyle of the subject) for at least 1 complete menstrual cycle prior to the Screening visit, throughout the study, and for 3 months after the last dose of study drug.
• Maintenance of a monogamous relationship with a male partner who has been surgically sterilized by vasectomy.
• B. NOTE: Periodic abstinence (calendar, symptothermal, postovulation methods), withdrawal (coitus interruptus), spermicides only, and lactational amenorrhea method are not acceptable methods of contraception.

You may not qualify if:

• History of epilepsy and/or on medication/treatment for seizures (such as but not limited to valproic acid, lamotrigine, topiramate, carbamazepine, and phenytoin); or, on certain medications that may lower seizure threshold, such as:
• anaesthetic drugs (propofol),
• antibiotics (penicillins, cephalosporins, imipenem),
• some antidepressants (clomipramine, bupropion, and maprotiline),
• antipsychotics (clozapine, chlorpromazine),
• bronchodilators (aminophylline, theophylline),
• Immunomodifiers (cyclosporine), and
• Narcotic analgesics (pethidine, fentanyl).
• Any SGOT, SGPT that are more than 3x upper limit of normal; and, creatinine that is greater than 2.1
• Women who are pregnant, expecting to get pregnant, or breastfeeding.
• Any condition that, in the view of the Principal Investigator, places the subject at risk, or subjects with poor treatment compliance.

Sponsors & Collaborators

• Augusta University: lead

Study Sites (1)

Augusta University

Augusta, Georgia, 30912, United States

Location

MeSH Terms

Conditions

Dysphonia

Interventions

Amifampridine

Condition Hierarchy (Ancestors)

Voice Disorders; Laryngeal Diseases; Respiratory Tract Diseases; Otorhinolaryngologic Diseases; Neurologic Manifestations; Nervous System Diseases; Signs and Symptoms; Pathological Conditions, Signs and Symptoms

Intervention Hierarchy (Ancestors)

4-Aminopyridine; Aminopyridines; Amines; Organic Chemicals; Pyridines; Heterocyclic Compounds, 1-Ring; Heterocyclic Compounds

Study Officials

• Michael H Rivner, MD

  Charbonnier Professor Emeritus of Neurology

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: interventional
• Phase: phase 2
• Allocation: NA
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: SINGLE GROUP
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: November 5, 2021
• First Posted: November 17, 2021
• Study Start: October 28, 2021
• Primary Completion: May 27, 2025
• Study Completion: September 23, 2025
• Last Updated: October 3, 2025

Record last verified: 2025-02

Data Sharing

• IPD Sharing: Will not share

Locations

US (1)