Problem:
The PMHNP is working with a 25 year old client that has the diagnosis of Bipolar 1 and being treated with Zyprexa 15mg with good symptom management for the last year. The client has had multiple adequate dose and time trials of other medications to include Lithium, Depakote, Risperdal, and Seroquel with minimal to negative results. The client has returned to work as a data processer and works 5 days a week. The client reports good relationship with boss and coworker and enjoys her job. Her hobbies include scrapbooking, watching movies, and hanging with her friends and boyfriend. The client is in a stable relationship with their partner of 5 years. Has no children and is currently on Sprintec and also uses condoms "just in case". The client comes in for a 2 month follow up and states that she has been adherent to treatment and takes her meds at night regularly. She reports that her only complaint is that she is gaining weight and read that metformin can be used to help with weight management and asks the NP to prescribe this at this time. Recent labs last month reveal all WNL (CMP, CBC, Lipid panel, TSH, free T4, and A1C). AIMS=0 at appointment.
As a PMHNP is metformin within your prescribing scope of practice? Support your stance with appropriate evidence, educational preparation, and experience.