Wichita ? A retired Oklahoma doctor has appealed his prison sentence for illegally distributing prescription drugs through an Internet pharmacy, claiming federal prosecutors coerced his guilty plea when they offered to dismiss charges against his cancer-stricken wife in exchange for it.

U.S. District Judge Wesley Brown on Friday granted a request by Wilbur D. Hilst, 76, to remain free pending his appeal. Earlier this month, Brown sentenced Hilst to 33 months in prison and ordered him to forfeit $20,129 from a bank account after he pleaded guilty to conspiracy in a scheme to unlawfully distribute controlled substances.

His attorneys argued in court documents filed Thursday that the government put Hilst in an “untenable position” by prosecuting his frail wife along with him in the government’s case over the operation of Red Mesa Pharmacy in Wichita.

Margaret Hilst, 77, is undergoing chemotherapy for breast cancer and suffers from osteoporosis, his attorneys said. She already had undergone one hip replacement surgery and will likely need a total replacement of her other hip.

“At the time defendant Hilst entered his guilty plea, he knew that his wife was facing two serious medical conditions, one a life-threatening illness and the other a potentially crippling condition,” his attorneys argued in court documents.

The couple, who now live in Wewoka, Okla., have been married for 52 years.

The U.S. attorney’s office declined Friday to comment, saying it would respond in court filings.

Defense attorney Dan Monnat referred questions to Oklahoma attorney John W. Coyle, the lead attorney in the case. Coyle did not immediately respond to a message left at his office.

As part of the plea deal, Wilbur Hilst pleaded guilty to one count of conspiracy, and the government dismissed three other drug-related counts. Prosecutors also recommended a sentence of probation for the retired doctor, while noting in the plea agreement that the judge was not bound by their recommendation.

Hilst agreed in the plea deal not to appeal any sentence within the federal guideline range. The 33-month sentence he received was below the statutory maximum of 36 months.

But in his appeal, the doctor argued that under the circumstances the government effectively forced him to enter his guilty plea by agreeing to dismiss charges against his wife.

Attorneys for Wilbur Hilst also contended in court filings that any prison sentence he received was likely to result in his death, given his own poor health and need for specialized medical monitoring and access to emergency care.

Pharmacist Jerry L. Lovern and computer technician Robert J. Barron were convicted by a jury in February of one count of conspiracy and three counts of unlawfully distributing controlled substances in the Internet pharmacy case.

Last week, Brown sentenced Lovern to 18 months in prison and Barron to two years probation. They also are appealing.