Sherry Johnston was charged in December with six felony drug counts involving a prescription painkiller.
In a deal with prosecutors, Johnston planned to plead guilty Friday and be sentenced on one count of possession with intent to deliver.
Defense attorney Rex Butler asked for a delay to work out a specialized medical treatment plan with the Alaska Department of Corrections if Johnston is imprisoned.
He says Johnston suffers chronic pelvic pain from prior medical surgeries.
Johnston is the mother of 19-year-old Levi Johnston. Levi Johnston and 18-year-old Bristol Palin, the daughter of former Alaska Gov. Sarah Palin, broke off their engagement after the Dec. 27 birth of their son.
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