Glycopyrrolate for spinal muscular atrophy

Last updated March. 3, 2025, by Andrea Lobo, PhD
Fact-checked by Jose Lopes, PhD

What is glycopyrrolate for SMA?

Glycopyrrolate is an anticholinergic, a class of medications that block the action of the neurotransmitter acetylcholine.

It is approved to treat chronic, severe, excessive drooling in children ages 3 to 16 with neurologic conditions such as cerebral palsy, and for indications including reducing airway or gastric secretions, blocking heart inhibitory reflexes during induction of anesthesia and intubation, counteracting arrhythmias (abnormal heart rhythms) during surgery. It is also approved as an add-on therapy for peptic ulcers (open sores on the inner lining of the stomach and the upper part of the small intestine) in certain cases.

The treatment may also reduce excessive drooling, a condition known as sialorrhea, in people with spinal muscular atrophy (SMA).

Glycopyrrolate was originally developed by the pharmaceutical company Shionogi under the name Robinul, which has been discontinued in the U.S. The formulation approved to treat severe drooling is sold under the brand name Cuvposa, marketed by Merz Pharmaceuticals. Several generic versions are available.

Therapy snapshot

How does glycopyrrolate work?

SMA is caused mainly by mutations in the SMN1 gene, which result in low or no production of the survival motor neuron (SMN) protein. The loss of this protein leads to the dysfunction and loss of motor neurons, or the nerve cells that control voluntary movements, resulting in muscle weakness and wasting.

People with SMA may experience excessive drooling as weak muscles in the mouth and throat cause jaw spasms and difficulty swallowing.

Saliva is produced as nerve signals are sent from the brain to the salivary glands. Nerve cells release a signaling molecule called acetylcholine that binds to receptors on the gland cells, triggering saliva secretion.

As an anticholinergic medication, glycopyrrolate binds to the same receptors as acetylcholine in the salivary glands, preventing their activation and reducing the production of saliva and excessive drooling.

How is glycopyrrolate administered?

Glycopyrrolate is available in oral and injectable formulations, although the oral solution is the only approved formulation to treat chronic severe drooling:

• 1 mg/5 mL oral solution
•  1 to 2 mg oral tablets
• 0.2 mg/mL solution for intravenous (into-the-vein) or intramuscular (into-the-muscle) injection.

As an oral solution, the treatment is initiated at a dose of 0.02 mg/kg of body weight three times a day. That can be increased every five to seven days, based on therapeutic response and adverse reactions, up to a maximum recommended daily dose of 0.1 mg/kg or 3 mg, whichever is less. It should be given at least one hour before or two hours after a meal.

Common side effects of glycopyrrolate

The most common side effects of glycopyrrolate reported in people treated for excessive drooling, though not specific to SMA, include:

• dry mouth
• constipation
• vomiting
• nasal congestion
• flushing (sudden reddening of the face, neck, or upper chest due to increased blood flow).

Use in patients with certain conditions or taking potassium chloride

Use of glycopyrrolate for excessive drooling is contraindicated (not recommended) in patients with conditions that preclude anticholinergic therapy, such as glaucoma (an eye condition that damages the optic nerve), severe ulcerative colitis (an inflammatory bowel disease), and myasthenia gravis. It is also contraindicated for patients taking solid oral forms of potassium chloride, as their passage through the digestive tract may be affected by taking glycopyrrolate.

Gastrointestinal reactions

Glycopyrrolate may lead to constipation, intestinal pseudo-obstruction (when the intestine is not able to effectively push food through) and diarrhea.

Treatment should be discontinued if intestinal obstruction is suspected.

Prostration at high temperatures

At high temperatures, people taking glycopyrrolate may experience fever and heatstroke due to decreased sweating. Patients taking the medication should avoid exposure to high temperatures.

Driving or operating machinery

Glycopyrrolate may cause drowsiness and blurred vision. Patients taking the medication should not drive or operate machinery that requires them to be alert.

Anticholinergic effects

Glycopyrrolate should be used with caution in people with conditions that may be made worse by the use of anticholinergic drugs. These include kidney disease, ulcerative colitis, autonomic neuropathy (damage of the nerves that control involuntary body functions, like blood pressure and digestion), hyperthyroidism (production of high levels of thyroid hormone), certain heart conditions, and hiatal hernia (when a part of the stomach bulges into the chest).

Use in children and older adults

Glycopyrrolate’s use has not been established in children younger than 3. Clinical studies of glycopyrrolate for excessive drooling have not included patients 65 and older.

Use in pregnancy and breastfeeding

There are no available data about the risk associated with the use of oral formulations of glycopyrrolate in pregnant patients. Limited data on the use of injected glycopyrrolate in pregnant patients, particularly after the first trimester and usually at the time of cesarean section delivery, have not identified risks of birth defects or miscarriage.

In animal studies, glycopyrrolate did not affect maternal or offspring survival, although maternal and fetal weight were reduced.

There are no data about the presence of glycopyrrolate in human milk, or the effects on breastfed infants or milk production.

The health benefits of breastfeeding for infants should be considered along with the mother’s need for the medication and potential adverse effects on the breastfed infant or from the underlying maternal condition.

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.