Knockoff versions of the company's weight-loss drug raise concerns, citing a "public health crisis."

Ahead of an approval filing, the drugmaker is amping up a fight against sellers who claim to offer versions of its highly anticipated “triple-G” weight loss medicine.

The drug company said Wednesday that it planned to file lawsuits against US businesses that sell retatrutide products illegally, and it’s asking regulators to do more to rein in…