YEKATERINBURG, Russia — The treatment center does not handcuff addicts to their beds anymore. But caged together on double-decker bunks with no way out, they have no choice but to endure the agonies of withdrawal, the first step in a harsh, coercive approach to drug treatment that has gained wide support in Russia.

“We know we are skirting the edge of the law,” said Sergei Shipachev, a staff member at the center, which is run by a private group called City Without Drugs. “We lock people up, but mostly we have a written request from their family. The police couldn’t do this, because it’s against the law.”

A thick silence fills the little room crammed with tall metal beds, obscuring the fact that there are 37 men lying shoulder to shoulder, each lost in a personal world of misery.

Outside the chamber, known as the quarantine room, 60 men who have emerged — after as long as a month with only bread and water or gruel — work at menial jobs, lift weights or cook in a regimen of continued isolation from the world that staff members said usually takes a year.