Here is a long and ongoing discussion of the issue:
https://connect.mayoclinic.org/discussion/7-saline-prescription-and-medicare-part-b-payment-quandry/
The answer is "Yes!" However, in order for it to be covered the pharmacist must code it correctly. Here is the official document explaining what must be done:
https://www.cms.gov/medicare-coverage-database/view/article.aspx?articleId=52466
I have since learned something interesting from CVS Mail Order - if a pharmacy sells nebulizers (even if they must order one for you) and takes Medicare, they are able to do this. Apparently most CVS stores choose not to do so. Many Walgreens do...

Where I live right now there are as many independent pharmacies as corporate ones - only those who handle durable medical equipment also handle saline and many other inhaled meds. It makes life crazy, I am fortunate that CVS Mail Order, part of my supplemental insurance coverage, also provides my saline & other inhalables.
Sue