The latest results were impacted by a US$6.1bn charge related to the new US tax laws, which led to a quarterly net loss of US$4.26bn, or US$5.89 per share,
Lower Enbrel sales and higher expenses to blame
Adjusted earnings-per-share came in at US$2.89, compared with consensus of US$3.03.
Revenue fell to US$5.80bn from US$5.97bn, compared with consensus of US$5.85bn.
Weighing on the numbers was a decline in the sales of blockbuster rheumatoid arthritis drug Enbrel and higher-than-expected expenses.
For 2018, Amgen is forecasting adjusted earnings per share (EPS) of between US$12.60 and US$13.70 and revenue of US$21.8bn to US$22.8bn.
Analysts had been forecasting US$12.71 per share and US$22.8bn in revenue.