Yeah, it depends what you want to teach. A pharmacy calculation class for nursing students? Probably. Anything at a Pharm D school? Probably not.
Well...that depends.
PharmD route: There are quite a few adjunct PharmD instructors at PharmD programs as well with their PharmD. They are considered "Volunteer Faculty" by some schools and may not be taken as seriously as their residency-trained counterparts. Sad, but true.
For example, USFCOP (FL) had quite a few adjunct instructors: one who taught leadership from the NAVY and another who taught gout from a corporate hospital; both instructors did not gain residency or post-graduate training, but they did have experience. Some clinical pharmacists who had PGY-1 and/or PGY-2 training prepared lectures and sent them online to the Course Coordinator. One instructor I know from Albany College of Pharmacy and Health Sciences (ACPHS) taught nursing pharmacology, not calculations, after working 2 years at Rite-Aid. He eventually attained an MSL position after 20 years of experience: some clinical, some retail.
PhD route: Most Adjunct Instructors in UNC Chapel Hill's PharmD program have PhDs, but a few have PharmDs. The internal requirements vary depending on where you decide to apply and where your scholarly contributions lie: pharmacy or something else. Some schools, like UF, put it to a vote after reviewing your application. One instructor I met in GA had to obtain a PhD when going into Health Outcomes Research for 4-6 years. This instructor already had a PharmD. They transitioned from retail to that type of research.
Fellowship route: Some PharmD or PhD fellowships have a teaching component with it, which requires you to be on or near campus. The Oncology fellowship program through Novartis in NJ is like this as well as Duke University's Drug Information Fellowship. Usually these post-doctoral fellowships last 1-2 years depending on the program. Gaining a position, however, is not always guaranteed. Candidates who get into these pharmaceutical or HEOR fellowships with a PharmD usually have a stellar academic record and what I call true publications with very strong letters of recommendation.
Here is my question: Are you obligated to go to your alma mater for teaching opportunities and to get the ASHP Teaching Certificate or can you find a mentor somewhere else to gain the expected training and experience online? I prefer to go somewhere else and find another mentor from another school: personal and professional reasons. The ASHP Teaching Certificate PREFERs you find a mentor at your practice site, but that is not always feasible. You can't do the ASHP Teaching Certificate online, which is INSANE considering educational delivery is mostly online anyways.