SAN DIEGO (AP) — Federal border inspectors are not only seizing drugs coming into the country from Mexico, but are also making arrests for drug smuggling that is going the other way.

A doctor from the Los Angeles area and 14 other people have been charged in a conspiracy to smuggle prescription drugs into Mexico from California, the authorities said on Friday.

The operation sent opiates to pharmacies in Tijuana in exchange for bundles of cash that were brought back into the United States. American addicts crossing the border from San Diego were able to buy the pills over the counter in Tijuana, investigators said.

Officials speculated that it was easier for smugglers to unload large amounts of pills at loosely regulated Mexican pharmacies than to distribute them in small amounts to street dealers in this country.