LOS ANGELES — The gig: Andrew Ritter, the 34-year-old founder of Ritter Pharmaceuticals in Los Angeles, created the original form of the firm’s lead experimental drug by testing it on himself when he was in eighth grade.

Ritter has been working on the project — which he says could be the first government-approved treatment for lactose intolerance — ever since.

Last year, Ritter’s company sold its first shares to the public. In October, the company completed a key clinical trial that could help the drug eventually win approval by the Food and Drug Administration. The first results from that trial are expected early next year.

• A personal passion: At age 9, Ritter was diagnosed with lactose intolerance. He said he suffered pain and cramps if he ate even a tablespoon of ice cream or another dairy product. “What is really driving me is that I know how painful and embarrassing this condition can be,” he said. “When you’re a kid and you go to birthday parties, there’s nothing worse than not being able to eat ice cream and pizza.”

• Power of old-fashioned library research: At age 13, Ritter began researching lactose intolerance and looking for a solution. “This was before Google, so you had to use the index cards at the library,” he said. “I started tinkering with the theories I had gathered.”

• Disbelieving adults: Ritter said that as a middle school student, he called and wrote letters to academic experts named in the research papers he read. Often he got no reply.

A pharmacist was also skeptical when he tried to purchase supplies for his experiments. “I had to get a note from my science teacher,” he said, “because the pharmacy would not give me the materials.”

• Experimenting on himself: Ritter said he mixed the powder in water and drank a glassful each day for about month while still in the eighth grade. “Every day I would take it and think, ‘How did it go? Should I do it again tomorrow?’” He said he’s been able to eat dairy products ever since without pain. In 1997, he won a prize at the California State Science Fair for the project.

•College startup: While studying political science and business at USC, Ritter founded the company, then called Ritter Natural Sciences.

•Aiming even higher: Rather than continuing to sell his supplement, Lactagen, over the counter, Ritter decided to try to get an improved version of the drug approved by the FDA. To help fund the necessary trials, Ritter went public last year, raising $20 million and another $5 million this summer. “I went from science fair poster board to Nasdaq,” he said. “Kind of cool.”