A blood pressure medicine that is being tested as a baldness cure worked on one third of the men participating in a Texas study.

Doctors first started testing minoxidil after patients reported hair growth while taking the medicine orally to control hypertension, its original purpose. In the hair-growing experiments, it is applied directly to the scalp.

In the experiment at San Antonio's Texas Health Science Center, 56 men were treated. The drug worked best on those who had been bald for less than 10 years and whose bald spots measured less than 10 centimeters across.

"I think it's going to be an excellent medicine to grow hair on people," said Dr. Richard L. De Villez in a telephone interview, "and an incredible money-maker for the drug company."

The drug, made by Upjohn, will not be submitted to the Food and Drug Administration for approval until late this year at the earliest, according to an Upjohn spokeswoman. Larger studies are still being evaluated, and approval could take two more years. De Villez, who reported the results of his study in the February Archives of Dermatology, said the drug has no side effects and is "incredibly safe."

It will cost about $35 a bottle, which will last a month, and will have to be applied as long as people want hair, he said.

Meanwhile, in Dundee, Scotland, scientists are working on a way to mass produce certain skin cells that control hair growth. The cells, called papillae, sit at the base of the hair follicles.

Science Digest reports that cells produced in the laboratory were as effective in producing hair growth as the natural ones are. In rats, that is.