AtroPen (Atropine)

AtroPen (atropine) is a medication approved by the U.S. Food and Drug Administration (FDA) for the treatment of nerve agent and insecticide poisonings. It also is used to decrease saliva production, and reduce muscle spasms of the gastrointestinal tract, and the urinary and gallbladder systems. In spinal muscular atrophy (SMA) patients, it is used to reduce excessive saliva production and drooling.

How AtroPen works

AtroPen is an anticholinergic medication, which means it interferes with the action of acetylcholine. Acetylcholine is a neurotransmitter (cell-signaling molecule) that is released by the nerve cells to pass on a signal to an adjacent cell. Acetylcholine binds to receptors found on the surface of the adjacent cell. This cell can be another nerve cell, a muscle cell, or a gland cell. AtroPen blocks the activity of acetylcholine by binding to acetylcholine receptors instead of acetylcholine.

When injected into salivary glands or applied under the tongue, AtroPen blocks acetylcholine receptors in the glands that secrete saliva and consequently reduces drooling.

Studies with AtroPen

AtroPen has not been tested in randomized clinical trials specifically in SMA patients. There is, however, a small study with Parkinson’s disease patients that suggests AtroPen has the potential to reduce drooling.

The study included seven participants with a complaint of drooling. Six of the participants had Parkinson’s disease and one patient had progressive supranuclear palsy, an uncommon brain disorder. They received one drop of AtroPen solution that contained 0.5 mg of the medication, administered under the tongue. Participants self-reported a significant decline in drooling compared to baseline within 180 minutes of AtroPen administration. The treatment was continued for one week twice daily. After one week, objectively measured saliva production decreased significantly compared to baseline.

Additional information

Side effects of AtroPen include dryness of the mouth, constipation, blurred vision, dizziness, headaches, and nausea.


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