Pharmaceuticals giant Pfizer (PFE) on Tuesday unveiled a promising first quarter despite having one of the most mature portfolios of drugs in the industry.

New York-based Pfizer reported a 32% increase in adjusted earnings per share to 67 cents from the year-ago period, beating estimates of 55 cents. The drugmaker generated revenue of $13 billion, up 20% from a year ago. Analysts had forecast $12 billion.

Pfizer shares were up about $1.02 per share, or 3%, midday Tuesday to $33.81. The company has a market cap of $209 billion.

At Pfizer, the 20% revenue increase from the prior year reflects operational growth of $2.9 billion, or 26%, partially offset by the unfavorable impact of foreign exchange of $729 million, the company said.

Not counting the impact of legacy Hospira operations of $1.2 billion and foreign exchange, Pfizer-standalone revenues grew by $1.7 billion operationally, representing a 15% rise. Pfizer acquired Hospira, a provider of injectable drugs and infusion technologies and a major manufacturer of biosimilars, in a deal that closed in September.

In the first quarter of this year, there were five additional selling days in the U.S. and four additional selling days in international markets, contributing around $900 million of revenue.

"Excluding this impact, operational [year-over-year] revenue growth comes as ~8%, which is still very good growth for Pfizer with its relatively mature portfolio of products," said Evercore ISI analyst Mark Schoenebaum in a note.

For his part, Leerink Partners analyst Seamus Fernandez noted that the majority of Pfizer's revenue beat was fueled by older products, "with Lipitor beating our forecast by $76M, Lyrica beating us by $99M, and Sutent beating our estimate by $33M."

Fernandez also wrote that Ibrance and Xeljanz "continued to perform well, with Ibrance sales of $429M beating our above consensus forecast by $19M, and Xeljanz beating us by $27M."

Pfizer on Tuesday raised its guidance for the year. It now expects full-year reported revenues of $51 to $53 billion, compared with $49 billion to $51 billion previously. Pfizer now expects adjusted diluted EPS to be in the $2.38 to $2.48 range, up from $2.20 to $2.30 previously.

Pfizer's Q1 results came nearly a month after the company announced it was scrapping its $160 billion merger with Allergan (AGN) after a new clampdown on so-called inversions by the Treasury Department.

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Also reporting results Tuesday morning was pharma company Mylan (MYL) . Mylan reported adjusted earnings per share of 76 cents, up 9% from a year earlier and surpassing analysts' expectations of 74 cents. Revenue was $2.19 billion, up 17% year-over-year. Analysts had expected $2.22 billion.

Also on Tuesday, Mylan named Kenneth S. Parks as chief financial officer effective June 6. Parks is currently CFO at Wesco International (WCC) and previously spent the majority of his career at United Technologies (UTX) . At Mylan, Parks succeeds John Sheehan, who in January announced plans to retire in April.

The release of Mylan's first quarter numbers come as the company is in the process of acquiring Meda. Mylan in February announced a proposed $9.9 billion deal to buy the Swedish drugmaker.