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".
More top news
Medical charity worker relates how he and colleagues tried to save patients and staff following devastating air strike.
Union leaders and officials from a range of campaign groups will address demonstrators as Conservative party conference gets under way.
Teachers union says workload, pay and low morale drive educators away from the profession.