A research associate performs a buffer exchange for protein formulation at AMGEN, a drug research and development laboratory.

Shares of Amgen fell 3 percent in extended trading after the company issued weak 2019 guidance, which overshadowed its better-than-expected fourth-quarter earnings, after the market close on Tuesday.

The biotech company said it expects adjusted 2019 earnings per share between $13.10 and $14.30. That range is well below Wall Street projections for full-year earnings of $14.61 per share, according to a Refinitiv consensus estimate.

For 2019, Amgen said it expects revenue between $21.8 billion and $22.9 billion. That range is also below Wall Street's estimate for revenue of $22.91 billion.

Amgen's 2019 outlook represents a year-over-year decline in both earnings and revenue. For 2018, the company reported adjusted earnings of $14.40 per share on revenue of $23.75 billion.

The biotech company, however, reported fourth-quarter earnings and revenue that topped analyst expectations.

Here's how the company did compared with what Wall Street expected:

Earnings per share: $3.42, vs. $3.27, forecast by Refinitiv

Revenue: $6.23 billion, vs. $5.84 billion, forecast by Refinitiv

In the year-ago quarter, Amgen reported adjusted earnings of $2.89 per share on $5.80 billion in revenue.

Amgen's second-largest drug, Neulasta, posted fourth-quarter sales of $1.17 billion, topping expectations for $1 billion in sales. The company's largest drug, Enbrel, also posted better-than-expected sales of $1.32 billion, compared with projections of $1.30 billion.

Amgen's results follow similar news from Pfizer earlier Tuesday, which also posted strong fourth-quarter results but issued weak 2019 guidance.

Shares of Amgen have fallen about 3 percent over the past year.

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