WASHINGTON — Lawmakers accused Valeant Pharmaceuticals of gouging patients to reward Wall Street investors during a hearing Wednesday scrutinizing the embattled drugmaker’s pricing tactics.

The blistering criticisms from Senate Republicans and Democrats came as Valeant’s outgoing CEO expressed regrets for the most egregious price increases, and a billionaire hedge fund investor defended the company’s business model.

Valeant’s stock price surged for years, fueled by a strategy of gobbling up smaller companies and raising prices on niche drugs – bypassing the huge research and development investments typical of the drug industry. But the company’s approach has drawn scrutiny from federal prosecutors, Congress and its own investors.

At the hearing, members of the Senate Committee on Aging laid into the Canadian drugmaker’s strategy of acquiring companies, slashing spending and jacking up prices. “Valeant’s monopoly model operates at the expense of real people,” said Sen. Susan Collins, R-Maine.