Dr. Rachel Okonkwo
Medicinal Chemist
Pfizer Research & Development
About
Dr. Rachel Okonkwo develops new pharmaceutical compounds at one of the world's largest drug companies. Her work has contributed to treatments for autoimmune diseases. She holds a PhD in Chemistry from Yale University and co-founded ChemSisters, a mentorship program connecting women chemists with high school students.
“Chemistry is the central science — it connects biology, physics, and engineering. If you like understanding how things work at the molecular level, chemistry opens doors to countless careers.”
Interview
What does a medicinal chemist do?
A medicinal chemist designs and synthesizes molecules that could become medicines. We work at the intersection of chemistry and biology, creating compounds that interact with specific targets in the body to treat diseases. It's like being a molecular architect — you design molecules with specific shapes and properties to do a specific job. When a compound you designed moves from the lab to clinical trials, it's an incredibly rewarding feeling.
What was your educational journey like?
I was a curious kid who loved science experiments. In college, I started as a biology major but switched to chemistry after taking organic chemistry — a class many people dread, but I loved the puzzle-like nature of it. I went straight to a PhD program at Yale, where I focused on synthetic organic chemistry. After graduating, I joined Pfizer as a research scientist and have been here for eight years, working my way up to lead my own drug discovery team.
Tell us about ChemSisters and why you started it.
I noticed that by the time women got to college, many had already decided chemistry "wasn't for them." I wanted to intervene earlier. ChemSisters pairs women chemists in industry and academia with high school students for year-long mentorship. We also host hands-on chemistry workshops and lab tours. Seeing a 15-year-old light up when she successfully runs her first reaction — that's why I do it. We've served over 500 students in three years.
What would you say to students who find chemistry challenging?
Chemistry is challenging — that's what makes it valuable. The key is to build strong foundations. Make sure you understand the basics before moving to advanced topics. Use models, videos, and hands-on experiments to make abstract concepts concrete. Form study groups. And remember that struggling with chemistry doesn't mean you're bad at it — even professional chemists encounter reactions that don't work. Persistence and curiosity matter more than getting everything right the first time.