Simulations Plus Inc. has been adding customers and staff, resulting in blowout earnings that made investors optimistic about its chief executive’s plan to continue to aggressively grow the business.

Shares of the Lancaster software maker jumped 8 percent during the week ended July 9 to close at $5.92, making it one of the biggest gainers on the LABJ Stock Index. (See page 32.)

Simulations Plus plans to grow the business both internally and externally. It recently added four Ph.D.s to the team, and with a good deal of cash on its balance sheet, its boss says the company is in the market to scoop up other businesses.

“We added to our talent in this quarter, hiring new scientists and engineers to grow organically and we continue to seek accretive acquisition possibilities,” Chief Executive Walt Woltosz said in a press release accompanying its earnings report.

Simulations Plus did not respond to a request for comment for this article.

Simulations Plus on July 3 reported net income of $1.3 million (8 cents a share) in the three months ended May 31, up 31 percent from the same quarter a year earlier. Revenue soared 21 percent to $3.7 million. Both numbers beat expectations. The company also reported a robust $7.8 million in cash on hand.

The Lancaster firm makes software for pharmaceutical research that helps researchers predict the way drugs and chemicals are absorbed by plants or animals. The company added 20 customers last quarter, including the Environmental Protection Agency, which purchased multiple licenses of two of its programs.

Simulations Plus also stands to benefit from a deal it cut in the last quarter with Therapeutic Systems Research Laboratories. It will pay the Ann Arbor, Mich., company $6 million over 10 years to terminate a license agreement signed in 1997. Simulations Plus used software developed by Therapeutic Systems in one of its products, GastroPlus. Royalty payments on GastroPlus had cost Simulations Plus as much as $626,000 a year.

“We anticipate this agreement will have a significant positive impact on future earnings, as we will no longer be paying royalties on GastroPlus, but will have a fixed amortization expense of $150,000 per quarter,” Chief Financial Officer John Kniesel said in the press release.

Howard Halpern, who covers Simulations Plus for New York brokerage Taglich Bros., maintains a “speculative buy” rating on the company. In his April 28 report, Halpern wrote that downward pressure on pharmaceutical company budgets should benefit research software firms.

“Simulation software should be in the forefront of reducing the costs and increasing productivity as R&D budgets shrink,” he wrote.