The tablets, mostly pain killers and pregnancy termination tablets, were found packed in 150 cartons.
The police acting on a tip-off about the illegal transportation of the medicines arrested the 35-year-old suspect. He was later remanded in judicial custody.
The police said the tablets should be sold only by an authorized medical dealer, on doctors' prescriptions.
Interrogation revealed that the medicines were dispatched in the private bus by one Khader in Chennai. He had asked the suspect to receive the consignment and hand it over to a Sri Lankan Tamil in Rameswaram.
The Sri Lankan, who was planning to smuggle the medicines through the sea route to Sri Lanka, was absconding, the police said.