The biotechnology company's adjusted profit fell 1% to $3.96 per share, which still beat the average analyst estimate of $3.88 per share, according to LSEG data.
Revenue rose 22% to $7.45 billion, in line with analysts' estimates of $7.44 billion.
The results were "essentially in-linish ... although not anything significant for the Street given that it is still early in the year," David Song, portfolio manager of the Tema Obesity & Cardiometabolic ETF said in an email.
Amgen shares, which rose a fraction to close at $278.39 in regular Nasdaq trading, were unchanged after hours.
Quarterly product sales were led by an 8% jump for osteoporosis drug Prolia to $999 million, and a 33% increase to $517 million for cholesterol drug Repatha. Sales of rheumatoid arthritis drug Enbrel fell 2% to $567 million.
Sales of eye drug Tepezza, which Amgen acquired through its Horizon purchase, rose about 5% to $424 million.
Excluding Horizon's medications, Amgen said year-over-year product sales grew 6%.
Investors are focused on Amgen's pipeline of experimental weight-loss drugs, and the company said it has completed a Phase 1 study of oral drug candidate AMG786.
Amgen said it anticipates data from a Phase 2 trial of its lead injectable weight-loss drug, MariTide, late this year and is planning "for a comprehensive Phase 3 program across multiple indications."
For full-year 2024, the company nudged up the lower end of its revenue outlook to between $32.5 billion and $33.8 billion from a previous view of $32.4 billion to $33.8 billion.
Amgen narrowed its 2024 adjusted earnings estimate and now expects a profit of $19.00 to $20.20 per share, from a previous view of $18.90 to $20.30.
Analysts have forecast 2024 earnings per share of $19.50 on revenue of $33 billion.
Amgen expects to hear by mid-June whether the U.S. Food and Drug Administration will grant accelerated approval to targeted immunotherapy tarlatamab for treating adults with advanced small cell lung cancer that has worsened despite chemotherapy.
Including one-time items, Amgen posted a first-quarter net loss of 21 cents a share.
