Topeka ? A judge blocked a state regulation Thursday that would have prevented most doctors from injecting chemicals into their patients to melt body fat.

The State Board of Healing Arts, which regulates doctors, approved the regulation last month, and it was supposed to take effect today. Kansas is the first state to attempt to regulate such treatments.

But the board’s action prompted a lawsuit in Shawnee County District Court by Fig, a St. Louis company that operates 15 clinics in seven states, including one in Overland Park.

The board’s regulation would have prohibited doctors from injecting the chemicals unless they were participating in a clinical trial. Such a trial would impose additional rules, screen potential patients and reduce or even eliminate the payment to the doctor.

“There is nothing in the agency record to explain the board’s rationale,” Judge David Bruns wrote in his 15-page pretrial order.

Fig provides a treatment known as Lipodissolve. Its officials said the board’s regulation would have forced it to close the Overland Park clinic and refund up to $12 million to patients who couldn’t finish their treatments. The company also said patients would be forced to consider other, riskier treatments, such as liposuction or abdominal surgery.

Tom Lemon, a Topeka attorney representing Fig, called the order “the right result,” adding, “We’re pleased with the work the court did to analyze a very complicated issue and very complicated facts in a short period of time.”

The board argued it was trying to protect consumers from potential health problems caused by an unproven drug. The federal Food and Drug Administration has not approved Lipodissolve’s key combination of chemicals.