Nick Bonnie, 30, collapsed at a nightclub in Manchester in the early hours of Saturday.
Mr Cameron said: "This is a tragic death. We've seen too many of these".
When asked if the Government has a grip on its drugs policy, he said: "The focus of Government has quite rightly been on education...and treatment".
He added that he disagreed with the Chief Constable of Durham's call for some drugs to be decriminalised as "it would make them more available and lead to more problems".
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"We are not afraid." Those were the defiant words of the Prime Minister this morning as she addressed the Commons.
Andreea Cristea, 29, remains in a critical condition after being rescued from the Thames after a terror attack along Westminster Bridge.
The Prime Minister has praised the former soldier's "huge professionalism" in trying to save the life of Pc Keith Palmer.