- In patients with Sjögren's syndrome, the primary clinical concern is the significant reduction in exocrine gland function, leading to symptoms such as dry mouth (xerostomia) and dry eyes.
- To alleviate dry mouth symptoms, medications that stimulate salivary secretion are commonly prescribed.

- Cevimeline is a muscarinic receptor agonist that specifically targets M3 muscarinic receptors on exocrine glands. This selective activation leads to increased saliva production, making it highly effective in managing xerostomia in Sjögren's syndrome patients. Its oral bioavailability and efficacy in increasing salivary flow have been well demonstrated.

- Although pilocarpine (Option 1) is also a muscarinic agonist used for the same purpose, it is less selective and may have a broader stimulation of muscarinic receptors, which can sometimes lead to more side effects. However, both pilocarpine and cevimeline are FDA-approved for treating dry mouth in Sjögren's syndrome.

- Atropine (Option 3) and glycopyrrolate (Option 4) are anticholinergic agents. These medications actually inhibit muscarinic receptors and reduce secretions, so they would worsen dry mouth rather than alleviate it.

In summary, cevimeline is primarily prescribed to alleviate dry mouth in Sjögren’s syndrome due to its selective agonist action on M3 receptors, leading to increased salivary gland secretion.

Reference: Harrison's Principles of Internal Medicine, 20th Edition, Volume 2, Chapter 330 - Sjögren’s Syndrome