The red pills, worth around £2000, were recovered from houses in Coatbridge, North Lanarkshire, in two separate raids on Monday.
While the seizures were not part of the investigation into the death of Regane MacColl, 17, it is believed that the pills are of the type she is thought to have taken before she collapsed.
The teenager fell ill at Glasgow nightspot The Arches at the weekend after taking a tablet known as Mortal Kombat, which has an image of a dragon on it.
There are fears over the content of the drug after four other young people were hospitalised after taking what is thought to be the same type of pill.
Police arrested a 19-year-old man in connection with the seizure of 200 tablets at a property in Tantallon Drive at around 2.40pm on Monday.
Thomas McGuiness appeared in private at Airdrie Sheriff Court in connection with the haul of tablets yesterday.
Mr McGuiness, of Bannockburn, Stirling, faces two charges of being in possession of a controlled drug with intent to supply. He made no plea or declaration and was released on bail. He is expected to return to court at another date.
A second 19-year-old was arrested after a police operation at around 5.20pm on Monday. A total of 160 ecstasy tablets worth an estimated street value of £1600 were seized from a property in Drummore Avenue, Coatbridge. The teenager has been released and is expected to appear at court at a later date.
A 19-year-old woman received treatment in Glasgow and two 18-year-old men and a 27-year-old man were hospitalised in Kilmarnock at the weekend after taking what are thought to be the same kind of pills.
One of the teenagers has been transferred to Hairmyres Hospital in East Kilbride where he is in a serious but stable condition.
Police Scotland said two men aged 18 and 20 were arrested at The Arches in the early hours of Sunday morning in connection with alleged drugs offences.
A 19-year-old woman was also arrested in Clydebank. It is understood the arrests are not being linked to the death of Ms MacColl.
Ms MacColl, from Clydebank in West Dunbartonshire, was a pupil at the town's St Peter the Apostle High School and head teacher Linda Booth has paid tribute to the "popular, hardworking and enthusiastic" student.
Ms Booth said: "This is a real tragedy for a girl who worked so hard and I'm sure would have gone on to achieve so much in her life.
"Everyone feels a deep sense of grief and our thoughts and prayers are with Regane's family and friends at this devastating time."
Lawrence O'Neill, a local councillor and family friend, had said her parents Alastair and Vickie were "devastated".
He said: "It's one of those things that always happens to someone else and never you or your children. The two of them are shattered this has happened to their daughter who was a bright light in their lives and for her family and friends and those who knew her. That light has now gone out."