Investigations by the state boards of medicine and pharmacy have turned up no evidence that the controversial drug Ritalin has been abused by physicians or patients in Idaho.

"This substance is being properly prescribed with appropriate examination and followup," Board of Medicine Chairman J.V. Drost said. "This treatment receives serious attention. It appears that patients who need it are being referred for treatment."The investigations were prompted by statistical reports showing that in early 1987 Idaho ranked fifth nationally in per capita use of Ritalin, or methylphenidate hydrochloride, a drug used to control a form of hyperactivity in children called attention deficit disorder. Six years earlier, Idaho ranked 31st in per capita use of the drug.

The boards, their findings included in statements released Friday, reviewed medical records of 13 Idaho doctors who most frequently prescribed the drug and more than 17,000 prescriptions issued to their 387 patients over 21 months through December 1987. More than 1.4 million Ritalin tablets, ranging from five to 20 milligrams, were issued through those prescriptions.

The doctors, who voluntarily cooperated with the investigations and were each personally interviewed, were not identified. But the Board of Medicine said their practices were in Coeur d'Alene, Boise, Twin Falls, Ketchum, Pocatello and Idaho Falls.

The boards did not attempt to determine why per capita use of Ritalin had risen so dramatically in Idaho. But they pointed out that the same statistical information showed neighboring Utah ranked first nationally and Wyoming ninth - both sparsely populated states.

"Relevant factors could include the population balance," Drost said. "Idaho ranks high among the states in birthrate and in the ratio of children to adults. Other geographic and demographic factors could affect the findings."

The Board of Pharmacy, in closing its inquiry, said the study of prescriptions "indicated no abuse, such as patients going to more than one physician for the same medication, physicians prescribing more frequently than needed or patients using false names and identification."

While the pharmacy board made no attempt to evaluate doctors' prescribing practices, the Board of Medicine said its review "indicated thorough evaluations are consistently done, including physical examinations. Parents are informed about the difficulties of learning disabilities and the effects of the drug. Other possible physical problems are considered."

Drost said records indicated physicians and school officials discussed children under treatment with parents and educators involved in monitoring progress. Referral to trained specialists was considered, he said.

"The study points to the conclusion that children are being carefully and appropriately treated," Drost said. "It does not suggest the substance is used excessively."

The inquiries were aided by the state's triplicate system for prescribing controlled substances. Idaho is one of just seven states using that system, which allowed the boards to pinpoint prescriptions by doctor and patient.