Medicines to reduce drooling in spinal muscular atrophy
Fact-checked by Drooling in spinal muscular atrophy (SMA) is often managed with a combination of medications and supportive care. Drooling medications for SMA can help improve comfort, oral health, and quality of life. Proper treatment may also reduce the risk of complications such as choking or lung infections.
While there are no treatments specifically approved for this SMA symptom, doctors can prescribe medications off-label to reduce saliva production and help control drooling.
Understanding drooling in SMA
Excessive drooling, or sialorrhea, is a symptom of many neuromuscular disorders, including SMA. Typically, the main problem isn’t that saliva is being overproduced — people with SMA make normal amounts of saliva, but they can’t effectively clear it from their mouths. This happens because mutations in the SMN1 gene, the underlying cause of SMA, lead to widespread weakness, including in the muscles needed for swallowing.
Saliva helps maintain oral health, protect the surfaces in the mouth from damage, initiate food digestion, and move food into the esophagus, but excessive saliva in SMA can interfere with these processes and have other negative health consequences.
People with sialorrhea are at risk of choking on saliva or inhaling saliva into their airways, which can lead to infections (aspiration pneumonia). Drooling can also have social or emotional consequences, such as stress or embarrassment, that reduce a person’s quality of life.
How medications work to reduce saliva
Saliva is produced by salivary glands near the mouth, which are controlled by a complex network of nerves. Many nerve cells in this network are cholinergic, meaning they communicate using the signaling molecule acetylcholine.
To help stop SMA drooling, doctors often prescribe medications that inhibit acetylcholine signaling, putting the brakes on the nerve signals that stimulate the salivary glands. Even though excessive saliva production isn’t the root cause of SMA drooling, this approach can help balance the amount of saliva that stays in the mouth when swallowing is difficult.
Most of the main SMA sialorrhea treatments work in one of two ways to inhibit acetylcholine signaling:
- preventing nerve cells from releasing acetylcholine (botulinim toxin-based treatments)
- blocking acetylcholine from binding to its receptor proteins (anticholinergic treatments)
Main medications for managing SMA drooling
None of the medications used to manage SMA drooling is specifically approved for SMA, although they are all approved by U.S. regulators for other medical uses. Medications that may be used off-label to manage SMA drooling include:
- amitriptyline: an oral antidepressant that has off-target effects as an anticholinergic
- atropine: an anticholinergic used to treat certain eye conditions and in hospital settings
- benztropine: an oral anticholinergic approved for Parkinson’s disease and other movement problems
- botulinum toxin: an injection treatment that prevents acetylcholine release, approved in the U.S. for treating muscle spasticity and a range of other medical and cosmetic uses
- glycopyrrolate: an oral anticholinergic used to manage peptic ulcers and drooling
- scopolamine: an anticholinergic administered using a skin patch, approved to treat certain types of nausea and vomiting
Botulinum toxin is toxic to the nervous system in large amounts. When used medically, these products are injected locally in small, targeted doses to avoid systemic exposure. Botulinum toxin products such as Botox for SMA drooling are injected into salivary glands — typically near the ears or below the jaw.
Though SMA is not specifically named in the prescribing label, Cuvposa is an oral solution formulation of glycopyrrolate approved to treat drooling associated with neurological conditions in children ages 3 to 16. Glycopyrrolate for SMA can be taken off-label as oral tablets; injectable formulations are mainly used in surgical settings.
Atropine for SMA drooling is often administered as drops placed directly under the tongue; injectable formulations are also available, though these are largely used in hospital settings.
Side effects of SMA drooling treatments
The side effects of SMA drooling medications vary depending on the specific therapy and mode of administration. Some possible side effects of medications with anticholinergic effects include:
- dry mouth
- constipation
- reduced sweating
- eye issues, including dry eyes, blurred vision, and pupil dilation
- inability to empty the bladder when urinating (urinary retention)
- fast heart rate
- fatigue or drowsiness
- cognitive changes, including confusion or hallucinations
- drowsiness
These effects are sometimes serious and may limit tolerability for some people with SMA.
The side effects of botulinum toxin depend on where the medication is injected. For drooling-related applications, possible side effects include:
- tooth extraction
- dry mouth
- diarrhea
- high blood pressure
- headache
- bronchitis, a type of respiratory tract inflammation
- nausea and vomiting
There is a small risk that botulinum toxin will spread beyond the injection area, leading to off-target side effects. People with neuromuscular disorders may also experience other side effects, because botulinum toxin can affect communication between nerves and muscles, but there is little data on its specific use in SMA.
Other treatments for SMA drooling
Beyond targeted sialorrhea medications, SMA drooling remedies may include:
- SMA treatments: the same medications that help ease other SMA symptoms may also strengthen mouth and throat muscles that control swallowing, potentially reducing drooling
- speech therapy: targeted speech therapy exercises can address difficulty with swallowing, making it easier to clear saliva
- surgery: procedures to alter the anatomy and connections of the salivary glands
There is limited direct evidence on whether SMA disease-modifying therapies affect drooling. Speech therapy may ease drooling in some children with neuromuscular conditions, but SMA-specific data is also limited.
Surgeries are an invasive option and typically only recommended if drooling isn’t responding to other treatments and is affecting quality of life.
SMA News Today is strictly a news and information website about the disease. It does not provide medical advice, diagnosis, or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.
