This Saturday is "National Prescription Drug Take-Back Day." This is a program originated by the U.S. Drug Enforcement Administration to fight drug abuse by adults and teenagers in the United States. Studies show that people who abuse these types of drugs get them by raiding the medicine cabinets of their friends and family members. To keep unused or unwanted prescription drugs out of the hands of drug abusers, on Saturday, between 10 a.m. and 2 p.m., people can safely throw away their unused prescription drugs at designated collection sites around the country.
I see a further value in that this offers a safe disposal regime for return of unused antibiotics. If you throw unused antibiotics down the toilet, they can end up entering the ecosystem, where they can help create disease resistant bacteria or, even thought less likely, harm fish and wildlife. In this program, they will be properly destroyed.
Also, of course, expired drugs may be ineffective or even harmful. For example, taking expired tetracycline (an antibiotic) can cause serious kidney problems.
You can find a local collection site on this webpage.