WASHINGTON—Drugmakers Valeant Pharmaceuticals International Inc. and Turing Pharmaceuticals AG boosted the prices of newly acquired drugs to meet preset profit targets, congressional investigators wrote in memos that summarized internal company documents they obtained.

The price increases by Valeant and Turing spurred public outrage and prompted congressional investigations.

Executives from both companies are expected to testify Thursday at a hearing of the House Oversight and Government Reform Committee. Democrats on the panel released the memos Tuesday.

A number of pharmaceutical companies have raised the prices of drugs after acquiring the rights to sell them in the U.S., a tactic that some Wall Street analysts say is contributing to higher spending on prescription medicines and has prompted criticism of price gouging.

From 2014 to 2015, Valeant raised the price of more than 20 prescription products by more than 200%, the Democrats’ memos say. The company increased the prices of several of these products in some cases by as much as 800%, according to the memos.