The SNP leader faced criticism from opponents at Holyrood on Thursday over cuts to rehabilitation and support services after figures this week revealed 1,200 people died from drugs-related issues last year – the highest annual total since records began.
But the First Minister accepted the criticism was “valid and legitimate” and pledged the issue would now be an urgent priority for the Scottish Government.
She said: “The figures that were published this week were completely unacceptable and therefore you will not hear political answers from me on this.
"We have much to do to sort this out and sorting it out is our responsibility and it is a serious responsibility.
"Behind every single one of these statistics is a human being whose life mattered – someone’s son or daughter, mother, father, brother or sister..
"And I am sorry to every family who has suffered grief. Every person who dies an avoidable death from drugs use is being let down.”
The First Minister told MSPs the issue was “difficult and complex”.
But she added: “That is not an excuse.
“These figures tell us that we need to do more and we need to do it quickly.”
Ms Sturgeon will attend the next meeting of Scotland’s drugs deaths taskforce next month to “take stock” and consider what “immediate steps” can be taken to address the issue.
She will then make a statement to MSPs before the end of next month setting out the action the Government will take.
But Ms Sturgeon admitted there may be a need for more funding to boost drugs services.
"I think many of the criticisms are valid and legitimate,” Ms Sturgeon conceded.
"I’m not gong to stand here and try to defend the indefensible.”
Tory leader Ruth Davidson had raised concerns over the rehabilitation provision in Scotland, pointing to the example of Castle Craig Hospital in Peebleshire where 256 NHS patients were admitted in 2002 – but this fell to five last year.
She also pointed to rehab facilities in Glasgow and Dundee, which were struggling through a lack of funding.
"Back in 2006 Nicola Sturgeon stood where I am – right on this spot – berating the-then Scottish Government for cutting rehab funding,” she said. “In fact, she went further. She said it showed why Scotland needed a new government.”
Ms Davidson added: "Scotland’s drugs deaths rate is not just the worst recorded in Europe, but in large parts of the rest of the world too.”
Labour leader Richard Leonard repeated his party’s calls for public health minister Joe Fitzpatrick, who oversees the government’s approach on drugs, to be sacked.
Scots don't expect “shortcuts” on the drugs issue, Mr Leonard said.
But he said: “They do expect the government to do its job.
"Instead they’ve seen cuts – cuts to funding for rehabilitation beds, cuts to the funding of alcohol and drugs partnerships, cuts to third sector support and rehabilitation organisations and an abject failure to integrate mental health and substance use and recovery services.”