With Merck and Pfizer reporting earnings today, let's take a look at some of the best pharmaceutical companies TheStreet Quant Ratings says you should add to your portfolio right now. While you might already know about big pharma companies to buy, here are three mid-cap drug makers that are a bit more under-the-radar and worth taking a look at. Mid-cap pharmaceutical companies can be good investments due to their potentially higher returns, the amount of mergers and acquisitions in their industry, and their patents allow them to recoup their research and development investments. Number 3 is Impax Laboratories. With a 'B' rating, the company's strengths can be seen in its robust revenue growth and increase in net income. 2nd is, Prestige Brands. This rating is an 'A-.' Prestige thrives in its solid stock price performance and reasonable valuation levels. Number 1 is Lannett. With an 'A' rating the company flourishes in its notable return on equity and expanding profit margins. TheStreet Ratings are algorithmic stock picks based on 32 major data points. S&P 500 stocks rated 'buy' yielded a 16.5% return in 2014, beating the S&P 500 Total Return Index by more than 300 basis points. For the full reports on these stocks, you can visit TheStreet.com/QuantRatings.