A FBI hot line was flooded with calls Thursday after concerned cancer patients learned that a Kansas City, Mo., pharmacist had been accused of diluting chemotherapy drugs.

FBI investigators pored over pharmacist Robert R. Courtney's records to find which patients may have been affected by weakened prescriptions of Taxol and Gemzar.

Taxol is a second-line therapy for advanced ovarian or breast cancer and is used against AIDS-related Kaposi's sarcoma and lung cancer. Gemzar is used to treat pancreatic cancer and some types of lung cancer. 

The drugs were allegedly diluted before being given to patients at Courtney's Research Medical Tower Pharmacy in Kansas City. Federal authorities say some intravenous drug bags mixed at the pharmacy contained less than 1 percent of the dosages ordered by doctors. 

After surrendering Wednesday to the FBI, Courtney, 48, was ordered held without bond by a federal magistrate on a felony charge of misbranding and adulteration of a drug. 

"This is a nightmare, a real nightmare," said Chris Whitley, a spokesman for the U.S. attorney's office in Kansas City. "We're searching for needles in a pharmaceutical haystack." 

Federal investigators said there could be hundreds of patients who received improper dosages. 

By Wednesday afternoon, the FBI hot line set up to find potential victims had received more than 150 calls. 

Courtney's attorney, Jean Paul Bradshaw, said he expected his client to plead innocent. 

Bradshaw declined to discuss his client's side of the story Wednesday, saying it would be inappropriate given Courtney has not entered a plea. He said he and Courtney were cooperating with the government to address some of its concerns, specifically the issue of the number of patients that may be involved. 

"Any patients the government would be concerned about is a much smaller number than has been suggested in recent media reports," Bradshaw said. He declined to elaborate. 

If convicted, Courtney faces up to three years in prison without parole and a $250,000 fine. 

Authorities have refused to discuss a motive. But they've pointed to the hundreds of dollars that could be saved per dose if expensive cancer drugs are diluted. 

In one instance, prosecutors said, an order of Gemzar would normally have cost $1,021, but the amount allegedly provided by Research Medical Tower Pharmacy would have cost just $242. 

Courtney is worth more than $10 million in stock and property, according to the court order declaring the pharmacist a flight risk. 

Federal agents seized records from Courtney's pharmacy on Monday. 

Courtney's pharmacy license was placed on probation for one year beginning in July 1992 for practicing after his license had expired, said Kevin Kinkade, executive director of the Missouri State Pharmacy Board. 

Courtney is also licensed in Kansas. He owns a pharmacy in that state, but Whitley said it's not under scrutiny because it doesn't dispense Gemzar or Taxol. 

According to the U.S. attorney's office, the dilution was discovered by a sales representative for Eli Lilly and Co., which makes Gemzar. 

The representative noticed a discrepancy between the amount of Gemzar the pharmacy ordered and the amount it had billed an unidentified Kansas City-area doctor. 

Last month, the FBI and Food and Drug Administration tested samples of the drugs from the doctor's pharmacy and found some bags of Gemzar contained only 17 percent to 39 percent of the amount that had been prescribed. Tests on later samples showed Taxol at 28 percent of the prescribed strength, the U.S. attorney's office said. 

Dr. Howard McLeod, an oncologist with Barnes Jewish Hospital in St. Louis, said it's important to administer chemotherapy drugs at a dose strong enough to hurt the cancer, but not the patient. 

"It's likely that anything less will be a disservice to the patients," he said. 

The Associated Press contributed to this report.