Montgomery County District Attorney Risa Vetri Ferman and Lehigh County District Attorney James Martin, along with local police, released the details at a news conference on Thursday.
Those officials said the network was discovered after a year-long operation to crack down on synthetic drugs.
The drugs targeted included so-called "bath salts" and imitation marijuana.
"These items are packaged in a way to appeal to young people," Ferman said, holding up a package with the cartoon character Scooby-Doo. "I was particularly taken this morning to see 'Scooby Snacks." Authorities say the investigation led them to J and L Wholesale in Allentown, Pa. The owners were allegedly supplying gas stations and convenience stores in the two counties with the synthetic drugs.
Ferman said $900,000 in cash and enough evidence to fill two tractor trailers was seized.
Synthetic drugs were banned by Pennsylvania law last year.
"Bath salts are considered one of the most dangerous of synthetic drugs. They provide a high similar to that of methamphetamine and cocaine. The drug has resulted in many deaths," said Martin.
Those arrested include Kenneth Grossman, the proprietor of J and L Wholesale, along with partners Jason Grossman, Rajwant Thind and Malwinder Mangat. All four were part of a subsidiary which shipped the synthetic drugs from Delaware.
Grossman's lawyer, Jake Griffin, said J and L Warehouse was largely on the level.
"There was a number of items that were sold in that warehouse," said Griffin. "Whatever this alleged activity, it certainly not indicative of this being 100% of the business."
Those arrested also include local store owners.