Five Manhattan doctors were paid more than $800,000 by a pharmaceutical company to prescribe a spray version of the highly potent and addictive opioid fentanyl to more and more patients whether they needed it or not, according to an indictment handed up Friday in federal court.

The money was earmarked as "speaker fees" for educational lectures on the drug that the doctors had agreed to give to medical professionals. In reality, according to federal prosecutors, the "lectures" were just booze-fueled social gatherings, and the fees were kickbacks paid to prescribe the drug, Subsys.

And doctors who went along with the arrangement got other perks, prosecutors say: tickets to sporting events, free meals delivered to their office workers, casino and nightclub outings and an evening of lap dances at a strip club -- all paid for by the drugmaker, Insys Therapeutics.

32 PHOTOS Opioid and drug crisis in America See Gallery Opioid and drug crisis in America Meth is most common drug in overdose deaths in chunk of US Craig Box, whose son Austin Box died of an opioid overdose, pauses during testimony during the second day of a trial of Johnson & Johnson over claims they engaged in deceptive marketing that contributed to the national opioid epidemic in Norman, Oklahoma, U.S. May 29, 2019. Sue Ogrocki/Pool via REUTERS FILE - This Thursday, Jan. 31, 2019 file photo shows a display of the fentanyl and meth that was seized by Customs and Border Protection officers at the Nogales Port of Entry, during a news conference in Nogales, Ariz. According to a report released by the Centers for Disease Control and Prevention on Friday, Oct. 25, 2019, fentanyl is driving drug overdose deaths in the U.S. overall, but in nearly half of the country, it’s a different story. Meth is the bigger killer. (Mamta Popat/Arizona Daily Star via AP) Alarm bells sounding across Monterey County in the wake of an alarming increase in opiod overdose deaths. 29 so far this year, compared with just nine in all of last year Opioid painkillers like these are linked to thousands of overdose deaths in the US Discarded needles are seen at a heroin encampment in the Kensington neighborhood of Philadelphia, Pennsylvania, on April 7, 2017. In North Philadelphia, railroad gulch as it is knowen, is ground zero in Philadelphia?s opioid epidemic. Known by locals as El Campanento, the open air drug market and heroin encampment is built with the discarded materials from the gulch and populated by addicts seeking a hit of heroin to keep their dope sick, or withdrawal symptoms, at bay. In one area, near the 2nd Avenue overpass, empty syringe wrappers blanket the refuse like grass the used needles they once contained poking through like thistles. / AFP PHOTO / DOMINICK REUTER (Photo credit should read DOMINICK REUTER/AFP/Getty Images) NEW YORK, NY - JUNE 07: 'Surfer' shoots heroin in a park in the South Bronx on June 7, 2017 in New York City. Like Staten Island, parts of the Bronx are experiencing an epidemic in drug use, especially heroin and other opioid based drugs. More than 1,370 New Yorkers died from overdoses in 2016, the majority of those deaths involved opioids. The Mott Haven-Hunts Point area of the Bronx borough of New York currently leads the city in heroin overdose deaths. According to the Deputy Attorney General, drug overdose are now the leading cause of death for Americans under the age of 50. (Photo by Spencer Platt/Getty Images) NEW YORK, NY - JUNE 07: A man leans against the wall appearing to be under the influence of drugs on a street in the South Bronx on June 7, 2017 in New York City. Like Staten Island, parts of the Bronx are experiencing an epidemic in drug use, especially heroin and other opioid based drugs. More than 1,370 New Yorkers died from overdoses in 2016, the majority of those deaths involved opioids. The Mott Haven-Hunts Point area of the Bronx borough of New York currently leads the city in heroin overdose deaths. According to the Deputy Attorney General, drug overdose are now the leading cause of death for Americans under the age of 50. (Photo by Spencer Platt/Getty Images) WASHINGTON, DC - SEPTEMBER 18: Family members of those who died of opioid overdoses attend the 'Fed Up!' rally to end the opioid epidemic on at the National Mall on September 18, 2016 in Washington, DC. Activists and family members gathered on the National Mall to march to the Capitol Building. Some 30,000 people die each year due to heroin and painkiller pill addiciton. Speakers called for Congress to provide $1.1 billion for the Comprehensive Addiction and Recovery Act, which Congress passed in July without funding. (Photo by John Moore/Getty Images) NEW YORK, NY - JUNE 07: A man rests against a wall appearing to be under the influence of drugs on a street in the South Bronx on June 7, 2017 in New York City. Like Staten Island, parts of the Bronx are experiencing an epidemic in drug use, especially heroin and other opioid based drugs. More than 1,370 New Yorkers died from overdoses in 2016, the majority of those deaths involved opioids. The Mott Haven-Hunts Point area of the Bronx borough of New York currently leads the city in heroin overdose deaths. According to the Deputy Attorney General, drug overdose are now the leading cause of death for Americans under the age of 50. (Photo by Spencer Platt/Getty Images) NEW YORK, NY - JUNE 07: Brian smokes a synthetic drug called K2 on the street in the South Bronx on June 7, 2017 in New York City. Like Staten Island, parts of the Bronx are experiencing an epidemic in drug use, especially heroin and other opioid based drugs. More than 1,370 New Yorkers died from overdoses in 2016, the majority of those deaths involved opioids. The Mott Haven-Hunts Point area of the Bronx borough of New York currently leads the city in heroin overdose deaths. According to the Deputy Attorney General, drug overdose are now the leading cause of death for Americans under the age of 50. (Photo by Spencer Platt/Getty Images) NEW YORK, NY - JUNE 07: 'Surfer' shoots heroin in a park in the South Bronx on June 7, 2017 in New York City. Like Staten Island, parts of the Bronx are experiencing an epidemic in drug use, especially heroin and other opioid based drugs. More than 1,370 New Yorkers died from overdoses in 2016, the majority of those deaths involved opioids. The Mott Haven-Hunts Point area of the Bronx borough of New York currently leads the city in heroin overdose deaths. According to the Deputy Attorney General, drug overdose are now the leading cause of death for Americans under the age of 50. (Photo by Spencer Platt/Getty Images) WASHINGTON, DC - SEPTEMBER 18: Activists and family members of loved ones who died in the opioid/heroin epidemic take part in a 'Fed Up!' rally at Capitol Hill on September 18, 2016 in Washington, DC. Protesters called on legistlators to provide funding for the Comprehensive Addiction and Recovery Act, which Congress passed in July without funding. Some 30,000 Americans die each year due to heroin and painkiller pill addiciton in the United States. (Photo by John Moore/Getty Images) Quincy Massachusetts Police Detective Lt. Patrick Glynn holds a nasal injection containing the overdose-reversing drug naloxone at the police headquarters in Quincy, Mass., June 13, 2014. Quincy, Massachusetts, in 2010 became the first U.S. city to make the drug standard equipment for its police officers, who have used it to reverse some 275 overdoses, a significant number in a city of 93,000 people. Police forces nationwide are starting to follow suit. The state program has now moved far beyond police, training some 25,747 people in Massachusetts how to recognize the signs of opioid drug overdoses and administer naloxone. June 13, 2014. REUTERS/Gretchen Ertl (UNITED STATES - Tags: DRUGS SOCIETY HEALTH CRIME LAW) A woman suspected of acting under the influence of heroine shows arms to police on April 19, 2017 in Huntington, West Virginia. Huntington, the city in the northwest corner of West Virginia, bordering Kentucky, has been portrayed as the epicenter of the opioid crisis. On August 15, 2016, from 3:00 pm to 9:00 pm, 28 people in the city overdosed on heroin laced with fentanyl, a synthetic opioid far more powerful and dangerous than heroin. The economic incentives are powerful: one kilogram of fentanyl costs $5,000, which can make a million tablets sold at $20 each for a gain of $20 million. 'This epidemic doesn't discriminate,' Huntington Mayor Steve Williams said. 'Our youngest overdose was 12 years old. The oldest was 77.' / AFP PHOTO / Brendan Smialowski / TO GO WITH AFP STORY by Heather SCOTT, US-health-drugs-WestVirginia (Photo credit should read BRENDAN SMIALOWSKI/AFP/Getty Images) Paraphernalia for smoking and injecting drugs is seen after being found during a police search on April 19, 2017 in Huntington, West Virginia. Huntington, the city in the northwest corner of West Virginia, bordering Kentucky, has been portrayed as the epicenter of the opioid crisis. On August 15, 2016, from 3:00 pm to 9:00 pm, 28 people in the city overdosed on heroin laced with fentanyl, a synthetic opioid far more powerful and dangerous than heroin. The economic incentives are powerful: one kilogram of fentanyl costs $5,000, which can make a million tablets sold at $20 each for a gain of $20 million. 'This epidemic doesn't discriminate,' Huntington Mayor Steve Williams said. 'Our youngest overdose was 12 years old. The oldest was 77.' / AFP PHOTO / Brendan Smialowski / TO GO WITH AFP STORY by Heather SCOTT, US-health-drugs-WestVirginia (Photo credit should read BRENDAN SMIALOWSKI/AFP/Getty Images) Paraphernalia for smoking and injecting drugs is seen after it was found during a police search on April 19, 2017, in Huntington, West Virginia. Huntington, the city in the northwest corner of West Virginia, bordering Kentucky, has been portrayed as the epicenter of the opioid crisis. On August 15, 2016, from 3:00 pm to 9:00 pm, 28 people in the city overdosed on heroin laced with fentanyl, a synthetic opioid far more powerful and dangerous than heroin. The economic incentives are powerful: one kilogram of fentanyl costs $5,000, which can make a million tablets sold at $20 each for a gain of $20 million. 'This epidemic doesn't discriminate,' Huntington Mayor Steve Williams said. 'Our youngest overdose was 12 years old. The oldest was 77.' / AFP PHOTO / Brendan Smialowski / TO GO WITH AFP STORY by Heather SCOTT, US-health-drugs-WestVirginia (Photo credit should read BRENDAN SMIALOWSKI/AFP/Getty Images) Paraphernalia for injecting drugs is seen after being found during a police search on April 19, 2017 in Huntington, West Virginia. Huntington, the city in the northwest corner of West Virginia, bordering Kentucky, has been portrayed as the epicenter of the opioid crisis. On August 15, 2016, from 3:00 pm to 9:00 pm, 28 people in the city overdosed on heroin laced with fentanyl, a synthetic opioid far more powerful and dangerous than heroin. The economic incentives are powerful: one kilogram of fentanyl costs $5,000, which can make a million tablets sold at $20 each for a gain of $20 million. 'This epidemic doesn't discriminate,' Huntington Mayor Steve Williams said. 'Our youngest overdose was 12 years old. The oldest was 77.' / AFP PHOTO / Brendan Smialowski / TO GO WITH AFP STORY by Heather SCOTT, US-health-drugs-WestVirginia (Photo credit should read BRENDAN SMIALOWSKI/AFP/Getty Images) Jessica, a homeless heroin addict, shows her kit of clean needles, mixing cap and tourniquet in the Kensington neighborhood of Philadelphia, Pennsylvania, on April 14, 2017. In North Philadelphia, railroad gulch as it is known, is ground zero in Philadelphia's opioid epidemic. 80 percent of us want to get out,' said Jessica, before outlining the numerous ways she has tried to get treatment for her addiction. In one case, she said, there weren't any available beds. In another, a treatment provider required a positive drug test before delivering aid, meaning if she hadn't used recently she'd be denied. Instead of getting treatment, she spends her nights trying to keep warm on a mattress under a bridge, the very spot where she was raped and infected with HIV. People come from throughout the city, and some as far away as the Midwest, for heroin that is remarkably cheap and pure at the largest heroin market on the East coast. / AFP PHOTO / DOMINICK REUTER (Photo credit should read DOMINICK REUTER/AFP/Getty Images) Drug paraphernalia and other garbage litter a vacant house on April 19, 2017 in Huntington, West Virginia. Huntington, the city in the northwest corner of West Virginia, bordering Kentucky, has been portrayed as the epicenter of the opioid crisis. On August 15, 2016, from 3:00 pm to 9:00 pm, 28 people in the city overdosed on heroin laced with fentanyl, a synthetic opioid far more powerful and dangerous than heroin. The economic incentives are powerful: one kilogram of fentanyl costs $5,000, which can make a million tablets sold at $20 each for a gain of $20 million. 'This epidemic doesn't discriminate,' Huntington Mayor Steve Williams said. 'Our youngest overdose was 12 years old. The oldest was 77.' / AFP PHOTO / Brendan Smialowski / TO GO WITH AFP STORY by Heather SCOTT, US-health-drugs-WestVirginia (Photo credit should read BRENDAN SMIALOWSKI/AFP/Getty Images) A man injects himself in the foot with heroin near a heroin encampmentin the Kensington neighborhood of Philadelphia, Pennsylvania, on April 14, 2017. In North Philadelphia, railroad gulch as it is known, is ground zero in Philadelphia's opioid epidemic. At the camp, and throughout the nearby area, a user can buy a bag of high-grade heroin at a low price and even pay to have another person inject them if for any reason they are unable to inject themselves. For several individuals, the addiction process was a slow one that started with a doctor's prescription for pain pills after an accident or surgery, and by the time the medication was finished, a dependency was born. After seeking black-market pills to feed their addiction, the simple economics of heroin won out: the price of a single pill could fetch anywhere between 2 and 10 bags of heroin, a savings that's hard to ignore when an insurance company is no longer underwriting the cost. / AFP PHOTO / DOMINICK REUTER (Photo credit should read DOMINICK REUTER/AFP/Getty Images) WASHINGTON, DC - SEPTEMBER 18: Michael Botticelli, U.S. National Drug Control Policy Director, speaks at the 'Fed Up!' rally to end the opioid epidemic on September 18, 2016 in Washington, DC. Activists and family members of people who have died in the opioid and heroin epidemic gathered on the National Mall to march to the Capitol Building. Some 30,000 people die each year due to heroin and painkiller pill addiciton. Speakers called for Congress to provide $1.1 billion for the Comprehensive Addiction and Recovery Act, which Congress passed in July without funding. (Photo by John Moore/Getty Images) A man uses a syringe to gather the last drops from a scavenged water bottle to mix up a shot of heroin near a heroin encampment in the Kensington neighborhood of Philadelphia, Pennsylvania, on April 14, 2017. In North Philadelphia, railroad gulch as it is known, is ground zero in Philadelphia?s opioid epidemic. The tracks and the surrounding property are owned and operated by the Consolidated Rail Corporation, a joint subsidiary of Norfolk Southern and CSX. People come from throughout the city, and some as far away as the Midwest, for heroin that is remarkably cheap and pure at the largest heroin market on the East coast. According to the city Health Commission, Philadelphia is on track to see 33 percent more drug overdose deaths in 2017 over last year. / AFP PHOTO / DOMINICK REUTER (Photo credit should read DOMINICK REUTER/AFP/Getty Images) A Philadelphia Police officer patrols under a bridge near a heroin encampment in the Kensington neighborhood of Philadelphia, Pennsylvania, on April 14, 2017. In North Philadelphia, railroad gulch as it is known, is ground zero in Philadelphiaï¿½ï¿½s opioid epidemic. The tracks and the surrounding property are owned and operated by the Consolidated Rail Corporation, a joint subsidiary of Norfolk Southern and CSX. Last month, Philadelphia Mayor Jim Kenney announced citations against the Consolidated Rail Corporation for what the mayor, in a release, said was Conrail's failure to clean and secure their own property.' Visitors and homeless residents of the gulch say the trash isn't their fault, and that they are only there because they have nowhere else to go. According to the city Health Commission, Philadelphia is on track to see 33 percent more drug overdose deaths in 2017 over last year. / AFP PHOTO / DOMINICK REUTER (Photo credit should read DOMINICK REUTER/AFP/Getty Images) SANFORD, ME - FEBRUARY 16: Milo Chernin, who lost her son Sam to a heroin overdose on Jan. 16, 2017, looks at photos at her home in Sanford. She says that Sam, who died at age 25, struggled with his addiction and could not stay away from heroin despite getting treatment. (Photo by Derek Davis/Portland Press Herald via Getty Images) WASHINGTON, DC - SEPTEMBER 18: Activists and family members of loved ones who died in the opioid/heroin epidemic take part in a 'Fed Up!' rally at Capitol Hill on September 18, 2016 in Washington, DC. Protesters called on legistlators to provide funding for the Comprehensive Addiction and Recovery Act, which Congress passed in July without funding. Some 30,000 Americans die each year due to heroin and painkiller pill addiciton in the United States. (Photo by John Moore/Getty Images) GROTON, CT - MARCH 23: A box of the opioid antidote Naloxone, also known as Narcan, sits on display during a family addiction support group on March 23, 2016 in Groton, CT. The drug is used to revive people suffering from heroin overdose. The group Communities Speak Out organizes monthly meetings at a public library for family members to talk about how their loved ones' addiction affects them and to give each other emotional support. Communities nationwide are struggling with the unprecidented heroin and opioid pain pill epidemic. On March 15, the U.S. Centers for Disease Control (CDC), announced guidelines for doctors to reduce the amount of opioid painkillers prescribed nationwide, in an effort to curb the epidemic. The CDC estimates that most new heroin addicts first became hooked on prescription pain medication before graduating to heroin, which is stronger and cheaper. (Photo by John Moore/Getty Images) NEW LONDON, CT - MARCH 23: A heroin user injects himself on March 23, 2016 in New London, CT. Communities throughout New England and nationwide are struggling with the unprecidented heroin and opioid pain pill epidemic. On March 15, the U.S. Centers for Disease Control (CDC), announced guidelines for doctors to reduce the amount of opioid painkillers prescribed nationwide, in an effort to curb the epidemic. The CDC estimates that most new heroin addicts first became hooked on prescription pain medication before graduating to heroin, which is stronger and cheaper. (Photo by John Moore/Getty Images) GROTON, CT - MARCH 23: Family members of people addicted heroin and opioid pain pills share stories during a support group on March 23, 2016 in Groton, CT. The group Communities Speak Out organizes monthly meetings at a public library for family members to talk about how their loved ones' addiction affects them and to give each other emotional support. Communities nationwide are struggling with the unprecidented heroin and opioid pain pill epidemic. On March 15, the U.S. Centers for Disease Control (CDC), announced guidelines for doctors to reduce the amount of opioid painkillers prescribed nationwide, in an effort to curb the epidemic. The CDC estimates that most new heroin addicts first became hooked on prescription pain medication before graduating to heroin, which is stronger and cheaper. (Photo by John Moore/Getty Images) NEW LONDON, CT - MARCH 14: Jackson, 27, who said he is addicted to prescription medication, lies passed out in a public library on March 14, 2016 in New London, CT. Police say an increasing number of suburban addicts are coming into the city to buy heroin, which is much cheaper than opioid painkillers. On March 15, the U.S. Centers for Disease Control (CDC), announced guidelines for doctors to reduce the amount of opioid painkillers prescribed nationwide. The CDC estimates that most new heroin addicts first became hooked on prescription pain medication before graduating to heroin, which is stronger and cheaper. (Photo by John Moore/Getty Images) ST. JOHNSBURY, VT - FEBRUARY 06: 'Buck' who is 23 and addicted to heroin, shoots up Suboxone, a maintenance drug for opioid dependence that is also highly addictive on February 6, 2014 in St. Johnsbury, Vermont. Vermont Governor Peter Shumlin recently devoted his entire State of the State speech to the scourge of heroin. Heroin and other opiates have begun to devastate many communities in the Northeast and Midwest leading to a surge in fatal overdoses in a number of states. As prescription painkillers, such as the synthetic opiate OxyContin, become increasingly expensive and regulated, more and more Americans are turning to heroin to fight pain or to get high. Heroin, which has experienced a surge in production in places such as Afghanistan and parts of Central America, has a relatively inexpensive street price and provides a more powerful affect on the user. (Photo by Spencer Platt/Getty Images) Up Next See Gallery Discover More Like This HIDE CAPTION SHOW CAPTION of SEE ALL BACK TO SLIDE

On Friday, the five physicians, several of whom are affiliated with prestigious hospitals, were indicted on conspiracy and other charges that carry up to 20 years in prison. Drs. Gordon Freedman, Jeffrey Goldstein, Todd Schlifstein, Dialecti Voudouris and Alexandru Burducea all pleaded not guilty and were released on $200,000 bond each.

At the same time, prosecutors unsealed the guilty pleas of two former Insys executives, Jonathan Roper and Fernando Serrano, who were charged last year and are now cooperating. The company's billionaire founder, John Kapoor, and other Insys officials and employees are also under indictment in a scandal that has been unfolding since 2014.

The 75-page indictment, unsealed Friday in New York, alleges that as the doctors pocketed more money from Insys, the more Subsys they prescribed.

An email from one sales representative to Freedman gave explicit instructions on how many new patients were needed to help meet a company target, according to the indictment.

"I'd rather you put 20 (or more, of course LOL) new patients (commercially insured of course, as always) on it in April even if we wind up getting only 10-14 approved, rather than only have you go with the safe 6-7 that you think will all get approved," the email said.

Freedman replied: "Got it."

Prosecutors said Freedman received approximately $308,000 in "speaker program fees" and by the last quarter of 2014 was the fourth-highest prescriber of Subsys in the nation, accounting for more than $1 million in sales.

The indictment says that when Goldstein began prescribing a lot of a competing product, Insys put pressure on him and he began recommending Subsys more often. After a bitter argument with a company executive, he convinced Insys to send him a $9,800 check for a home security system and then dummied up an invoice without buying one, prosecutors alleged.

Burducea married an Insys sales rep and then lied to federal investigators about how long they had been dating so their relationship couldn't be linked to his high prescription rate, the indictment says. Voudouris had Insys' Serrano take an exam for her so she would be eligible to prescribe Subsys, prosecutors said.

When she didn't write enough prescriptions, the indictment says, Insys got upset. An email from Roper to sales reps said they had "invested way too much" to be satisfied with just a few patients.

"1 new PT [patient] a day is what was agreed upon," the email said. "Don't let the doctor sell you, you sell the doctor!"

In a statement, Manhattan U.S. Attorney Geoffrey Berman noted that the doctors had sworn a "solemn oath" to put their patients' care above all else.

"Instead, they engaged in a malignant scheme to prescribe fentanyl, a dangerous and potentially fatal narcotic 50 to 100 times more potent than morphine, in exchange for bribes in the form of speaker fees," he said.

"Payments from pharmaceutical companies should not influence how doctors prescribe — especially when a potent and dangerous drug like fentanyl is involved."

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