The men, aged between 33 and 55, were detained as part of a Scotland-wide crackdown on serious and organised crime over the past two weeks.
Detectives were investigating the seizure of £950,000 worth of diamorphine between August last year and January.
The men have been charged under the Misuse of Drugs Act and are due to appear in court at a later date.
Detective Chief Inspector Colin Boyle said: "As a result of the investigation, almost £1 million worth of diamorphine was seized before it could cause untold harm on our communities.
"Our enquiries have resulted in eight men subsequently being charged with drug offences and these arrests should send a clear message that Police Scotland will continue to act on information from the public to tackle serious and organised crime whenever it arises."