U.S. biotech Amgen Inc (AMGN.O) on Tuesday said its first-quarter sales and profit fell due to a 7% drop in its net drug prices and the COVID-19 pandemic, which continued to limit patient interactions with healthcare providers. Amgen shares were down 3.4% at $246.50 after hours. The company"s quarterly adjusted earnings per share fell 12% from a year earlier to $3.70, short of the $4.04 forecast by Wall Street analysts, as calculated by Refinitiv. Revenue for the quarter fell 4% to $5.9 billion - also below analyst estimates of $6.26 billion. Net profit fell 8% to $2.83 per share. "They are typically weakest in the first quarter due to seasonality in patient volumes and then bounce in Q2 on a recovery in buying patterns and patient volumes," Jefferies analyst Michael Yee said in an email. For the full year, Amgen said it still expects adjusted earnings of $16.00 to $17.00 per share on revenue of $25.8 billion to $26.6 billion, but lowered its net EPS forecast to a range of $9.11 to $10.71 from a previous $12.12 to $13.17. The company said it now expects a 2021 net tax rate of 14% to 15.5% - up from a previous estimate of 11% to 12.5%. Its adjusted tax rate is now forecast at 13.5% to 14.5%, compared with the previous 13% to 14%. "We felt the impact of the pandemic in January and February, and we began to see a recovery in March, a trend that seems to be holding in April as well," Amgen Chief Executive Robert Bradway said on a conference call with investors. Company officials said Amgen continues to expect 2021 net selling prices for its drugs to fall by a rate in the mid-single digits due to increased competition, including cheaper generics and biosimilars. First-quarter sales of its rheumatoid arthritis drug Enbrel fell 20% to $924 billion, shy of analysts" estimate of $1.1 billion. Sales of newer migraine drug Aimovig fell 7% from a year earlier to $66 million for the quarter, well short of the $95.7 million projected by analysts. But sales of cholesterol fighter Repatha rose 25% to $286 million, beating Wall Street estimates of $251 million. The U.S. Food and Drug Administration in February granted priority review status to sotorasib, Amgen"s experimental lung cancer drug. The company on Tuesday said it is studying different doses of the drug and expects to have data from combination studies in the second half of this year.