Congratulations on deciding to complete a PhD in pharmaceutical engineering, I'm sure that this will represent an amazing portion of your academic life.

It is absolutely possible to pursue a PhD five years after your Masters degree. In fact, it not only possible, but you may be at somewhat of an advantage, given that during those five years your academic horizons were no doubt expanded, and you may have gained industry experience.

That being said, there will be a couple of challenges given the fact that you are currently not in education, so may not being receiving academic support during your application. If this is the case, I could offer a couple of suggestions:

1. Reach out to the lecturers or other staff from your Masters. Your past lecturers will no doubt want to help you, whether that be with some advice, suggestions of contacts, or letters of recommendations.
2. Reflect on and refine your research interests. After a five-year gap, it's useful to reflect on your current interests in the field, especially since your passions or areas of focus may have changed during the time away from education. Having a clear and focused research interest is important for a strong PhD proposal. Perhaps it would be useful to read through some academic journals in order to understand any evolution in the field since your Masters.
3. Leverage your professional experience. Sit down and relfect on all the professional experience you have had in the time out of education, because PhD programs will value candidates with practical insights. Write down all of the skills that you aquired so that you have something to talk about in your application and interview.
4. Brush up on your academic skills. Science gets rusty after a while, and so it may benefit you to brush up on some learning. Perhaps there are some texbtooks laying around which you could flick through, some problems to work through online, or even a lectuer series on YouTube. It's worth brushing up on now, as in the interview section of a PhD application, you may be asked specific questions concerning your field of study.
5. Reach out to potential supervisors. Identify potential supervisors at unviersities whose corresponding department aligns with your interests. Write an email expressing your interest in the potential of carrying out a PhD there. You could even ask for their advice. They may remember your name when they are looking through the applications, and they will remember that you were proactive.

Congratulations on deciding to complete a PhD in pharmaceutical engineering. Speaking from the perspective of a current graduate student, I'm sure that this will represent an amazing portion of your life!

It is absolutely possible to pursue a PhD five years after your Masters degree. In fact, you may be at somewhat of an advantage, given that during those five years, your academic horizons were no doubt expanded, and you may have gained industry experience.

That being said, there will be a couple of challenges given the fact that you are currently not in education, so may not being receiving academic support during your application. If this is the case, I could offer a couple of suggestions:

1. Reach out to the lecturers or other staff from your Masters. Your past lecturers will no doubt want to help you, whether that be with some advice, suggestions of contacts, or letters of recommendations.
2. Reflect on and refine your research interests. After a five-year gap, it's useful to reflect on your current interests in the field, especially since your passions or areas of focus may have changed during the time away from education. Having a clear and focused research interest is important for a strong PhD proposal. Perhaps it would be useful to read through some academic journals in order to understand any evolution in the field since your Masters.
3. Leverage your professional experience. Sit down and relfect on all the professional experience you have had in the time out of education, because PhD programs will value candidates with practical insights. Write down all of the skills that you aquired so that you have something to talk about in your application and interview.
4. Brush up on your academic skills. Science gets rusty after a while, and so it may benefit you to brush up on some learning. Perhaps there are some texbtooks laying around which you could flick through, some problems to work through online, or even a lectuer series on YouTube. It's worth brushing up on now, as in the interview section of a PhD application, you may be asked specific questions concerning your field of study.
5. Reach out to potential supervisors. Identify potential supervisors at unviersities whose corresponding department aligns with your interests. Write an email expressing your interest in the potential of carrying out a PhD there. You could even ask for their advice. They may remember your name when they are looking through the applications, and they will remember that you were proactive.