The marathon covers 156 miles in southern Morocco over six days, where runners will trek across white-hot salt plains in temperatures of up to 50 degrees Celsius.
Water is rationed during the marathon and if runners exceed the ration, they receive a time penalty.
What makes the challenge even more staggering for the brothers, is neither of them have employed professional personal trainers or running coaches ahead of the event, nor are they even members of a gym.
Nick explains: “We couldn’t justify paying for expensive gym memberships or expert trainers, when that money could instead go towards our chosen charities.”
They have therefore got into a rigorous training regime and between them have amassed 1,700 miles from 120 runs, each, since December 2015.
The pair typically run three times a week, covering between 20 and 50 miles.
As part of their marathon preparations the brothers competed in the Cotswolds Ultra Marathon in September 2016, which took place over two days and covered 57 miles, and they came in joint tenth place.
The brothers were looking for a way to raise significant funds for local cancer charity the Nicola Corry Support Foundation and the World Cancer Research Fund, after both their parents and Alex’s partner Sally Westmacott, 38, were afflicted by the disease.
Sally is currently undergoing treatment for breast cancer at Cheltenham Royal Infirmary.
Alex, who is known to many as the general manager of The Porch House Inn, in Stow-on-the-Wold said: “We wanted to raise a significant amount of money for these two, fantastic charities and felt the best way to do that would be to attempt something genuinely extraordinary.
“[The Nicola Corry Foundation] were amazing.
“They came out of nowhere and offered financial support for our children's nursery costs, which was a huge help while Sally went through chemotherapy for six months.
“Then at Christmas, a cheque to help with children's presents came through the post, which was unforgettable in terms of a gesture of utter kindness.”
Nick and Alex have already raised nearly £10,000 towards their £40,000 target and are looking for further sponsorship or donations that can be put towards a charity auction they are planning for later in the year.
For more information, visit their website madns.co.uk