It is not an uncommon scene: a waiting room filled with patients hoping to see a doctor. But the crowd of up to 100 people that gathered each day outside the Astramed clinic at 1228 Southern Boulevard in the Bronx, clamoring to get a prescription for the painkiller oxycodone, was a different story, the authorities say.

The clinic was controlled by drug traffickers, and the patients, doctors, prescriptions — and even urine samples — were part of a vast and elaborate scheme to divert oxycodone for sale on the street, the authorities said on Wednesday.

A federal indictment charges that in the operation, corrupt doctors were paid $300 in cash for fraudulent medical visits that lasted a minute or two, involved no physical examination and consistently led to the writing of prescriptions for large doses of oxycodone.

Over three years, Astramed doctors wrote about 31,500 medically unnecessary prescriptions for oxycodone, encompassing about 5.5 million oxycodone tablets with a street value of up to $550 million, a government court filing says.