BY WILL CONNORS

LAGOS, Nigeria”Biofem Pharmaceuticals Ltd., a Nigerian medicine distributor, wanted to arrest a slide in sales after a counterfeit ring targeted its best-selling drug. Sproxil Inc., a start-up founded by a Ghana-born Ph.D. student at Dartmouth, promised to do what Nigerian authorities could not: help companies and consumers detect fake pharmaceuticals.

Sproxil’s founder, 28-year old Ashifi Gogo, overcame initial skepticism and a lack of funding to persuade investors to back a technology that offers a quick counterfeit-drug test. The technology could pave the way for wary foreign drug makers to enter the huge African market. The market includes Nigeria, Africa’s biggest …