Dr. Summers has served as an advisor and speaker for several pharmaceutical companies including:
- Forest Pharmaceuticals
- Abbott Laboratories
- AstraZeneca Pharmaceuticals
- Eli Lilly & Co.
- GlaxoSmithKline
- Janssen Pharmaceutica
- Pfizer Pharmaceuticals
- Wyeth Pharmaceuticals
- Bristol Myers Squibb
- Angelini Laborpharm