Wells Fargo analyst David Maris points out that Amphastar Pharmaceuticals' Primatene Mist is the only FDA approved asthma inhaler available without a prescription in the United States, and used for the temporary relief of mild symptoms of intermittent asthma in people ages 12 and above. Primatene Mist could have peak sales over $65M, Maris tells investors in a research note. Given Amphstar's 2018 sales base is approximately $265M, the approval "could be transformative" for the company, says Maris. He believes the approval could add at least $210M to $280M in value to Amphastar, or $4 to $6 per share. Maris has an Outperform rating on the stock with a $26 price target. Amphastar in morning trading is up 9%, or $1.72, to $20.97.