express concern

You know that any setbacks in treatment are opportunities to discuss with the patient the specifics of treatment and progress in recovery, and to re-visit the treatment agreement that was signed by the patient, prescriber and you at beginning of treatment.

You also want to make sure that Cathy understands the rationale for the course of treatment. Remember that being open and honest is the best (and only) way to communicate with Cathy.

You express your concern for her safety: 

"Hi, Cathy, you don't seem your usual self. Are you ok? You seem a bit sleepy, and down, you even have some difficulty speaking. Because of the way you present, I am concerned about the risk of serious breathing problems and overdose if you take methadone right now. There's a risk of death too. For your safety, I'm obligated to send you to see your methadone doctor before you can receive your dose."

Cathy grudgingly agrees, realizing that she will not receive her dose now, and leaves.

What else would like to do at this point?