New treatment to benefit millions suffering from kidney stones by making it faster and less painful
Millions of people who suffer from kidney stones could benefit from a new treatment that is faster and less painful. The proposed treatment, which involves a combination of two drugs, could relax the body and ease the difficult process of removing kidney stones, according to researchers at MIT and Massachusetts General Hospital.
These drugs are muscle relaxants, which relax the walls of the ureter -- the tube that connects the kidneys to the bladder. By relaxing the ureter, MIT scientists believe, passing of the stones from the kidney could be less stressful. This is because most of the pain arises from cramps and inflammation in the ureter, as the stones pass through the narrow tube, explain researchers.
In addition to treating kidney stones, this approach could also be useful for relaxing the ureter to help doctors insert a stent or an endoscope in the ureter.
"If you look at how kidney stones are treated today, it hasn't really changed since about 1980, and there's a pretty substantial amount of evidence that the drugs given don't work very well," says lead author Christopher Lee, a recent PhD recipient in the Harvard-MIT Division of Health Sciences and Technology. Lee adds that the volume of how many people the treatment could potentially help is really exciting.
Kidney stone disease, which affects millions of people, is caused due to the accumulation of hard crystals in the organ. These crystals are formed when there is too much solid waste in the urine and not enough liquid to wash it out. It is estimated that about one in 10 people will have a kidney stone at some point in their lives. Each year, more than half a million people go to emergency rooms for kidney stone problems and the prevalence of kidney stones in the US increased from 3.8% in the late 1970s to 8.8% in the late 2000s.
To come up with new treatment strategies, the researchers decided to look at muscle relaxants. They screened 18 drugs for their ability in relaxing the cells that line the ureter: smooth muscle cells.
They narrowed down the search to two drugs that worked especially well, and found that they worked even better when given together. One of these is nifedipine, a calcium channel blocker used to treat high blood pressure, and the other is used to treat glaucoma, known as a ROCK (rho kinase) inhibitor. Following this, the team tested these drugs on pigs, who showed positive effects. The treatment nearly eliminated ureteral contractions in the animals, making them more relaxed.
The treatment has another benefit too. It may have few side effects: the team could not detect the drugs in the animals' bloodstream as they were delivered directly to the ureter.
However, there are still a few questions that need answers, says the team. More studies are needed to determine how long the muscle relaxing effect lasts and how much relaxation would be needed to expedite stone passage, the researchers say.
They are now launching a startup company, Fluidity Medicine, to continue developing the technology for possible testing in human patients.
The study has been published in Nature Biomedical Engineering.