My knowledge is limited with regard to regulated professions such as medicine.
Open work permit is not tied to an employer. So you do not need a prior job offer to apply for that. Neither does it indicate that you would work in your primary profession immediately. It just means being a spouse of a skilled temp worker / permanent resident etc. and possessing the xyz educational profile, you are authorized to work for any employer in Canada. Whether you actually work in medicine or not is not the concern.
For e.g. HR is also a regulated profession there i.e. it comes along with Knowledge and certification of legal requirements in Canada. So some one who has worked in HR in Pakistan needed to get all those certifications first in Canada to work in the same domain IF THEY ARE THE PRIMARY APPLICANT. However, my spouse possess a masters in HR and i did apply for an open work permit for her, since my twp allows it (i am the primary applicant with a job offer and LMO). It doesn't matter whether she works in HR or not. In fact we have no plans of her working at all in near future. However, the open work permit allows it and it will only be valid until my primary closed work permit is.
The point was that you showing your credentials as a doctor would present your case better as a more educated and capable profile as compared to all spousal sponsorship ones who apply for trv at the same time.
The above is just my opinion based upon what i have seen so far in regard to CIC. All the best.