With sales drops in several of Allergan's (AGN - Get Report) core products, analysts will scrutinize the performance of its recent acquisitions and strength of the company's pipeline when it reports first quarter earnings prior to the market's opening Tuesday.

Analysts estimate that Allergan's total revenue will fall 6.9% to $3.53 billion in in the quarter, according to FactSet, due to the loss of patent exclusivity of Asacol HD, which is used to treat adults with moderately active ulcerative colitis, and two products in its Namenda Alzheimer's franchise. Revenue growth were also hit by the divestitures of the company's global generics business and its ANDA distribution business to Teva Pharmaceuticals TEVA in 2016.

Analysts following Allergan have a range of forecasts, depending on how well they think the company is replacing the lost revenue.

Credit Suisse analyst Vamil Divan is one of the most positive on the stock and in an April 4 note gave a target price of $281 for the shares, which closed Friday at 244.94. Royal Bank of Canada said on April 12 it has a $279 target. The firm currently has a buy rating on the stock.

"While the base business is facing challenges, we remain bullish on the stock," Divan wrote.

More cautious are David Amsellem of Piper Jaffray and Andrew Finkelstein of Susquehanna Financial, who both have holds on Allergan and price targest in the $236-$237 range.

Allergan shares were down $3.2, or 1.33%, through late afternoon Monday to $241.68.

Real Money's Doug Kass said there's no apparent reason for the drop in Allergan shares.

The company's drug pipeline is critical too.

Among the most-watched products in Allergan's development queue are acne medication sarecycline, which showed positive results relative to a placebo in a Phase 3 trial. A New Drug Application submission for sarecycline is anticipated for the second half of 2017. Allergan has predicted annual sales for sarecycline could top $300 million.

The company's highest-profile drug, Botox, turned out disappointing results for a mid-stage study as a treatment for patients with major depressive disorder. Allergan is putting the drug into a Phase 3 study for depression anyway and insists it won't give up on the drug.

One of the drugs Allergan has coming through the pipeline is abicipar pegol, a potential rival to Regeneron's (REGN - Get Report) Eylea franchise, for wet age-related macular degeneration. Regeron generated about $3.3 billion in product sales and $710MM in royalty revenue from the Eylea franchise last year.

Allergan is still enrolling phase 3 trials of the drug while Novartis (NVS - Get Report) is expected to complete phase 3 trials of its wetAMD treatment, RTH258, in May.

Analysts also are likely to grill company execs on the chances for major M&A. With tax reform as top priority of the Trump Administration, the White House in April unveiled an executive order instructing the Treasury Department to find and review tax regulations since the beginning of 2016 and make recommendations on modifying or repealing any they see as overly complex and burdensome. The Deal reported that the order could potentially open the door for Pfizer (PFE - Get Report) and Allergan to take another stab at the proposed merger squashed by Obama regulations in 2016.

New York-based Pfizer and Dublin-based Allergan announced in November 2015 they would merge in a transaction valued at $160 billion. Then in April of last year, the companies scrapped the deal after a clampdown on inversions by the Treasury Department. At the moment most are watching to see if Pfizer merges with Bristol Myers Squibb (BMY - Get Report) .

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