ANCHORAGE, Alaska — Alaska authorities say the mother of Bristol Palin's boyfriend sent text messages to two police informants discussing drug transactions before her arrest on felony drug charges.

An affidavit filed Wednesday says Sherry L. Johnston sent text messages referring to "coffee" as a code for the drug OxyContin.

The 42-year-old Johnston was arrested last week after state troopers served a search warrant at her Wasilla home. She is out on bail.

Johnston is the mother of 18-year-old Levi Johnston. Gov. Sarah Palin announced in September that her 18-year-old daughter Bristol was pregnant and Johnston was the father.