Farrell had initially set the target at €400,000, but surpassed that amount after appearing on The Late Late Show last week.
The Irish actor is running the marathon in honour of his close friend Emma Fogarty, who is battling Epidermolysis Bullosa (EB), a rare genetic skin condition. Fogarty is Ireland's longest-surviving EB patient.
The disease which is also often referred 'Butterfly Skin', can cause blistering and open wounds, which can feel like third-degree burns, with patients often needing hours of daily bandaging to manage the condition.
While praising his friend Emma for her bravery in battling this illness, Colin Farrell also expressed his frustration with the lack of care available for treating EB in this country.
"I love Emma, I love her to bits. I couldn’t be any more proud of her," he said to Ray D'Arcy. "But I don’t think I could be any more frustrated knowing that Emma and all those in our country who suffer with EB aren’t getting the care they could".
Emma Fogarty will join Farrell in the final stretch of this marathon, which will see the actor push Fogarty in her wheelchair for the last four kilometres of the journey. Each kilometre will represent a decade in her life.
During the interview, Ray D'Arcy also confirmed that the HSE had pledged €125,000 in core funding for Debra.
Welcoming this funding, Farrell also spoke about the huge funding gap which still remains for EB sufferers.
"It’s hard to see the need and the suffering up close and personal through my relationship with my pal Emma and know that there’s a broader amount of suffering going on with a further 300 people living with EB in Ireland", he said. "If you have to leave a few potholes uncovered or not build a bridge, so be it… more needs to be done".
This was echoed by Emma Fogarty, who questioned how funding for EB patients can play second fiddle to infrastructure projects.
"How are the sick and more vulnerable not more important than a bike shed?", she asked.
You can also donate to Debra via their website: Debra.ie
