The US Food and Drug Administration’s approval of a controversial Alzheimer’s drug has prompted calls for its commissioner to be removed amid criticism that the medicines regulator is too close to Big Pharma.

This month, the FDA approved the first new Alzheimer’s drug in nearly two decades, offering hope to the roughly 35m people worldwide who live with the disease. But the decision has angered scientists who say the treatment does not work and should not have been approved, and that the regulator ignored scientific advice.

“The agency has long held this esteemed position in the world of drug regulators . . . That is threatened with this case,” said Peter Lurie, president of the Center for Science in the Public Interest, an independent advocacy group.

Aducanumab, which costs $56,000 a year, is the first drug claiming to slow the progression of the disease itself rather than treat its symptoms.

Three members of the FDA’s advisory panel quit in rapid succession following the decision, saying the regulator’s decision lowered its standards. Last year the panel unanimously opposed approval of aducanumab.

Aaron Kesselheim, one of the members who resigned, said it was “probably the worst drug approval decision in recent US history”.

The contentious endorsement is reminiscent of similar decisions made by the FDA in recent years where medicines with questionable efficacy were given the go-ahead. In 2016, the regulator faced criticism for its approval of eteplirsen, a treatment for people with Duchenne muscular dystrophy — a debilitating illness where muscles waste away over time.

In 2015, the FDA authorised pink Viagra, a libido enhancer for women, despite twice rejecting it over concerns that the benefits did not outweigh the side effects.

“This is very reminiscent of [eteplirsen],” said Bruce Ovbiagele, a member of the FDA’s advisory committee who opposed the approval of both the Alzheimer’s and muscular dystrophy drugs. He said both decisions relied on weak scientific evidence.

“The FDA might have caved to the pressure from community advocates and the fact that these devastating diseases have no even modestly effective treatments,” he added.

Several members of the scientific group point to an unusually close collaboration between Biogen and the FDA as an example of the regulator becoming too entwined with the companies it oversees.

The FDA and Biogen released a joint briefing document for the company’s application, a curious move between a regulator and its regulated company. “Little by little the barriers start to drop and pretty soon you’re co-authoring a briefing document together,” said Lurie, adding that “in small increments” the agency has grown too close to the pharmaceutical industry.

The agency said: “The FDA often works closely with industry to help foster drug development, understand emerging data, and advise on best approaches to development plans, especially in areas where there is a significant need for treatments for devastating diseases.”

Some critics have blamed Janet Woodcock, the head of the FDA, for allowing this close relationship to be cultivated. She also oversaw the approval of many painkillers while the opioid epidemic raged across the US.

Woodcock was appointed acting commissioner this year while the search for a permanent head continued. She is considered a shoe-in for the role and some believe that such a major drug approval would not have been made without a nod from her.

“A decision of this magnitude with this kind of potential controversy would ultimately have to be greenlighted at a higher level than Dunn,” said Ovbiagele, referring to Billy Dunn, head of the FDA’s neuroscience unit.

The FDA said the data submitted for aducanumab “was very complex, and our review has been thorough.” All drug reviews “are a team effort. No one person makes decisions in isolation on any approval, policy or safety matters,” it added.

Woodcock did not respond to a request for comment on calls for her removal or claims that she is too close to the industry.

One healthcare investor, who declined to be named said: “In the industry, everyone is keeping their mouth shut. The Big Pharma companies have been totally quiet on it, because they know if they say something in support of Janet, she would be toast. But everybody’s like: ‘Listen, you know with Janet at least we know what to expect’.”

On Thursday, Joe Manchin, the senator from West Virginia, wrote a letter to president Joe Biden urging him not to appoint Woodcock as permanent head of the regulator. “Dr Woodcock is not the right person to lead the FDA,” he wrote, adding that she “repeatedly ignored public health concerns” regarding the opioid epidemic.

Michael Carome, director of the health research group at Public Citizen, said the agency “is too often making decisions that are in the best interest of pharma companies and their shareholders rather than the best interest of public health and their patients.”

Last week, Carome wrote to the US health secretary urging the removal of Woodcock, as well as Patrizia Cavazzoni, director of the Center for Drug Evaluation and Research and Dunn, director of the FDA’s Office of Neuroscience.

“The damage caused by the FDA’s reckless approval of aducanumab to the agency’s credibility as a science-based regulatory agency . . . cannot be overstated,” he wrote, adding that “regulatory capture of the agency by the industry” had occurred.

The FDA was accused of fostering a revolving door environment this month when it emerged that former commissioner Stephen Hahn would take a job at Flagship Pioneering, the investor that founded Moderna. Hahn was head of the FDA when Moderna’s Covid-19 vaccine was approved last year.

The green light for aducanumab may set a precedent for future drug approvals and comes as the FDA seeks to regain trust in itself and its science following controversies during the pandemic — such as the endorsement then rejection of using hydroxychloroquine to treat Covid-19 patients.

“This was a chance for the agency to say we got pushed around during Trump but it’s back to business as usual, meaning the FDA is the gold standard for scientific rigour,” said Lurie. “This [approval] sets the agency back . . . they dropped the ball.”