In Q1 2024, worldwide revenue was USD 8.77 billion, an increase of 26 percent compared with Q1 2023, driven by increases of 16 percent in volume and 10 percent due to higher realized prices. The volume increase was primarily driven by growth from Mounjaro, Zepbound, Verzenio and Jardiance, partially offset by declines in Trulicity.
Strong demand for the Lilly's incretin medicines outpaced supply increases. The company continues to expand manufacturing capacity, with the most significant production increases in 2024 expected in the second half of the year. Higher realized prices were driven by Mounjaro in the U.S. as Mounjaro saw net price positively impacted by savings card dynamics compared with Q1 2023.
In the second half of 2024, these savings card dynamics should cease to have a notable effect on realized price comparisons to base periods, as the USD 25 non-covered benefit expired June 30, 2023. New Products revenue grew by USD 1.79 billion to USD 2.39 billion in Q1 2024, led by Mounjaro and Zepbound. Growth Products revenue increased 2% to USD 4.66 billion in Q1 2024 as growth led by Verzenio, Jardiance, Taltz and Emgality was largely offset by lower Trulicity sales.
Revenue in the U.S. increased 28% to USD 5.69 billion, driven by a 16% increase in realized prices and a 12% increase in volume. The higher realized prices in the U.S. were driven by Mounjaro. The increase in U.S. volume was driven by Zepbound, Mounjaro and Verzenio, partially offset by a decrease in Trulicity. Exceptionally strong demand for the company's incretin medicines led to wholesaler backorders for these products at quarter end. The company expects tight supply to continue as growing production volume is outpaced by demand. In the short to mid-term, Lilly expects sales growth for incretin medicines to primarily be a function of the quantity the company can produce and ship.
In Q1 2024, research and development expenses increased 27% to USD 2.52 billion, or 29% of revenue, driven by higher development expenses for late-stage assets and additional investments in early-stage research, as well as a charge of approximately USD 75 million in Q1 2024 associated with the termination of the Verzenio prostate cancer program.
For Q1 2024, worldwide Trulicity revenue decreased 26% compared with Q1 2023 to USD 1.46 billion. U.S. revenue decreased 30% to USD 1.08 billion, driven by decreased sales volume primarily due to supply constraints and competitive dynamics. Revenue outside the U.S. decreased 13% to USD 374.4 million, driven by decreased volume and, to a lesser extent, lower realized prices.
