Have you ever worried that the little pill you just popped in your mouth is going to interact poorly with another one already in your system?

You aren't alone. Thousands of Utahns have the same concern - one that Osco Drug is trying to alleviate.Osco, a division of American Drug Stores, has installed a computerized drug interaction screening system in more than 635 of its Osco Drug stores nationwide.

The system, based on a drug interaction database containing more than 7,000 drug products and approved by the Utah Pharmaceutical Association, enables pharmacists to screen prescriptions automatically for potentially harmful drug-to-drug interactions, drug overlaps and allergies.

Donald Hoscheit, vice president of pharmacy operations for Osco Drug, said a study conducted in 1983 monitored the prescriptions of more than 23,000 patients presenting prescriptions to retail pharmacies. The study showed that 17.3 percent of all prescriptions monitored were found to have some potential for drug interaction, and 5.7 percent of the interactions were considered highly to moderately significant.

The computer reduces the risk by comparing a newly prescribed drug with the drugs in a patient's medication history. As the new prescription is processed, the chemicals in that drug are automatically cross-checked, through the database, against the chemicals in previous prescriptions dispensed at that drugstore for that patient.

If one or more of the chemicals in the new prescription are found to interact or overlap with any chemicals already in the patient's profile, a warning flashes on the computer screen, said Maude Norman, a pharmacist at Osco Drug in Murray.

"If it is a serious interaction, we call the doctor so he will be aware of it."

In addition to drug interaction screening, the system has an allergy screening function that works in a similar way. By completing a patient allergy form, customers can advise their pharmacist of any known allergies.