Longevity scientists are investigating a generic drug that may slow the aging process. Biologist Matt Kaeberlein used rapamycin himself to treat a frozen shoulder that did not respond to physical therapy. Within 10 weeks, the pain was gone, he says.

According to NPR, Kaeberlein, the former director of the Healthy Aging and Longevity Research Institute at the University of Washington is also the co-founder of the Dog Aging Project that is studying how rapamycin may extend the lifespan of canines. His theory is that the drug helps reduce inflammation by inhibiting a pathway in the body called mTOR, one of the regulators of lifespan and aging.

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This pathway is known to accumulate protein aggregates and degenerated mitochondria leading to age-related disorders such as cardiovascular disease, says research.

Rapamycin was approved by the Food and Drug Administration (FDA) in the late 1990s to help suppress immune response in transplant patients in high doses. In low doses, the drug appears to lower inflammation. Many doctors prescribe the drug for pain and anti-aging, although it hasn’t been approved by the FDA for that purpose. Kaeberlein says that patients who take low doses of the drug often report benefits.

Dr. Jonathan An, an assistant professor in the department of oral health sciences at the University of Washington School of Dentistry, has FDA approval to study rapamycin’s effectiveness in treating gum disease, which is more common as people age. The study of people with gum disease over the age of 50 will evaluate the safety and efficacy of taking rapamycin for 8 weeks.

An tells NPR that if the drug is effective it could help target the “biology of aging.” Gum disease can lead to a host of other medical problems such as damage to blood vessels that can lead to heart disease. If rapamycin is successful in treating gum disease, it may also help reduce the risk of other conditions leading to problems with the heart or brain.

Because rapamycin is a generic drug, it’s hard to get research funding. Several private companies are raising funds to do their own studies.

According to The Washington Post, it is unlikely that the FDA will approve the drug for longevity as the agency doesn’t classify aging as a disease. However, dozens of medical practices prescribe rapamycin as an anti-aging treatment and telehealth companies are supplying thousands of patients nationally. Prices vary, but typically an online purchase costs $10 a week or less. One physician in New York, Dr. Alan Green, has treated nearly 1,500 patients with the drug calling it “the most important drug in the history of medicine.”

Kaeberlein agrees.

“I would say that rapamycin is the current best-in-class for a longevity drug that we have,” he said.

However, Dr. Eric Verdin, chief executive of the Buck Institute on Aging, cautions that while there is a strong case to be made for rapamycin as an anti-aging drug, “we should not as a field recommend use on people.” Verdin, along with other experts, says the drug is no substitute for exercise and a healthy diet.

However, 67-year-old Verdin admits he takes the drug, but acknowledges he doesn’t feel any different one way or another.