Novartis is significantly boosting its marketing spending — by at least $200 million — for Entresto, a heart-failure drug with blockbuster ambitions and lukewarm sales.

The drugmaker has cited a number of reasons for Entresto’s sluggish sales, including high rates of prior authorization and physicians reluctant to switch patients from other medications.

During a call with investors, Novartis executives said Tuesday that two factors prompted the boost in spending: new clinical guidelines released by the American College of Cardiology, the American Heart Association, and two other medical societies in May that recommended Entresto as the standard of care for some heart-failure patients; and a study published last month in JAMA Cardiology that found the drug can lower the risk of death in certain heart-failure patients with reduced ejection.

“We made the decision to increase spending in the second half of the year significantly versus our original budget,” Novartis CEO Joseph Jimenez said during the investor call. “This will be to support the U.S. field force primary care buildout as well as additional medical support.”

See also: Novartis: Cardiologists slow to advocate on behalf of new drugs

Entresto, which was approved in July 2015, is viewed as a booster to Novartis’ bottom line. The company hopes it will offset generic competition for the drugmaker’s best-selling drug Gleevec, which lost patent protection in February.

But Entresto hasn’t performed as expected. The drug generated $32 million in sales in the second quarter of 2016, up from $17 million in the first quarter of the year. That means the therapy needs to bring in $151 million in sales within six months to meet projections of $200 million for 2016.

The slow uptake has worried analysts. “Chronic underperformance of the Alcon eye care business and the slow uptake of Entresto have damaged sentiment and reminded investors how the company periodically snatches defeat from the jaws of victory,” Sanford Bernstein analyst Tim Anderson wrote in a research note in June. “Alcon performance, Gleevec generics, and continued heavy investment in Entresto (which is ramping slower than slow!) make 2016 a ‘reset’ year with essentially no growth and no ‘story.’”

See also: Novartis launches DTC campaign for Entresto

One oft-cited challenge to Entresto’s adoption has been limited insurance coverage that requires prior authorization before a patient can begin taking the drug.

Novartis believes that marketing to primary-care physicians as well as cardiologists will help solve that problem, in part because primary-care doctors are more familiar than cardiologists when it comes to filling out prior-authorization forms. Primary-care physicians have “have better or more well-developed skills … that have been on this journey themselves before in helping overcome these barriers,” said Paul Hudson, the new CEO of Novartis Pharmaceuticals.

In addition, the company expects to see a “gradual softening” of prior-authorization requirements in the U.S., based on talks executives have had with payers, Hudson noted. During the week ending July 1, there were 5,851 prescriptions for Entresto, more than half of which (3,079) were new.

“The U.S. is at least beginning to create a break in the trendline,” Jimenez said. “This gives us additional confidence that now is the time to pull that spending forward.”

See also: New cardiovascular drugs raise concerns about pricing, efficacy

In April, Novartis launched a direct-to-consumer ad campaign for Entresto, which featured seniors singing “Tomorrow” from the musical “Annie.” It spent $5.5 million to advertise Entresto during the first three months of the year, according to Kantar Media.

Novartis has also worked with Greater Than One on the Keep it Pumping campaign, a global social campaign that includes a donate-your-heartbeat app. Greater Than One CEO Elizabeth Izard Apelles described the purpose of the campaign as creating “awareness among people who might not know they have heart problems, and then engaging as many people as possible in the program.”