Salbutamol Regimen for DOK7 Congenital Myasthenic Syndrome
For patients with DOK7 congenital myasthenic syndrome, salbutamol should be initiated at 2 mg orally three times daily (total 6 mg/day), which can be increased to 4 mg three times daily (total 12 mg/day) based on clinical response. 1, 2
Initial Dosing and Titration
- Start with 2 mg orally three times daily (total 6 mg/day) as the standard initial dose for all patients with DOK7 CMS 1, 3
- This dose can be increased to 4 mg three times daily (total 12 mg/day) in children and adults who require additional benefit 2
- Clinical improvement typically begins within the first month of treatment, with progressive improvement reaching a plateau at 12-18 months 2
Expected Clinical Response Timeline
- Within 1 month: Patients report functional benefit, with non-ambulant children often resuming walking with assistance 2
- At 3 months: Measurable improvement in QMG scores becomes evident, particularly in leg outstretched testing 1
- At 12-18 months: Maximum therapeutic benefit is typically achieved, with sustained improvement in ADL-MG scores and 6-minute walk test results 1, 2
Critical Management Considerations
- Avoid anticholinesterase therapy (pyridostigmine/Mestinon) in DOK7 patients, as it is ineffective and frequently worsens weakness, including head drop and limb weakness 4
- Salbutamol (albuterol in the United States) is the first-choice treatment option for DOK7 CMS, superior to other therapies 3, 5
- The medication is well tolerated with no major side effects reported in pediatric or adult populations 1, 2
Monitoring Parameters
- Assess functional improvement using QMG scores at baseline, 3,6,9, and 12 months 1
- Evaluate ADL-MG scores and 6-minute walk test at baseline and 12 months 1
- Monitor for specific improvements in limb-girdle strength, which is the predominant weakness pattern in DOK7 CMS 1, 3
- Track reduction in repetitive nerve stimulation decrement (may improve from 51% to 25% with treatment) 4
Common Pitfalls to Avoid
- Do not use immunosuppressive therapy for DOK7 CMS, as this is a genetic disorder affecting the neuromuscular junction, not an autoimmune condition like myasthenia gravis 4
- Do not discontinue salbutamol prematurely if initial response seems modest, as maximum benefit requires 12-18 months of continuous treatment 2
- Do not confuse DOK7 CMS with seronegative myasthenia gravis, as worsening with anticholinesterase therapy is a key distinguishing feature that should prompt genetic testing 4
Age-Specific Considerations
- Salbutamol is effective across all age groups, from young children (age 5.9 years) through adults (age 33 years at symptom onset) 3, 2
- The 2-4 mg three times daily dosing range applies to both pediatric and adult populations 2
- In the United States, albuterol (the same medication as salbutamol) is readily available and produces dramatic, persistent improvement in muscle strength within four weeks 5