We'll have a pyjama party on Kilimanjaro

But this won't deter three city businessmen from wearing only their pyjamas as they stand at the top of Africa.

The men are not only climbing Mount Kilimanjaro in an attempt to raise 25,000 for the new Sick Kids hospital, but will take the photograph to hand maximum publicity to the New Pyjamas campaign.

They will set off next month on the five-day climb in Tanzania, and have already exceeded the 8,000 mark despite "not really getting started" on the fundraising campaign.

Organiser Mark Little, 46, who is managing director of Barclays Wealth in Scotland and Northern Ireland, has previously raised more than 120,000 for the hospital and sits on the board of the Sick Kids Friends Foundation.

He said while he was anxious about the climb and the acclimatisation that would have to take place, there was one other issue causing him concern.

"We'll be going up over Valentine's Day and one of the things we have been told to take which will help us adjust is Viagra," said the Colinton man.

"I am a bit worried about spending 14 February in a tent with two other fat blokes who've taken it."

He encouraged friends Colin McKay, 50, managing director of Eversheds, and 42-year-old John Macdonald, a senior sales manager at medical company PPI to take part in the 19,000ft hike over a pint, listing it as one of the things he hoped to do before he died.

"I've raised money for the hospital in the past," he said. "Any parent that lives in the Lothians or Fife will have used it at some point.

We know we have to do it now. There are so many people supporting us. I've been massively impressed by how many people have given."

He added that, given the huge number of high-flying business contacts each participant has, raising serious money for the campaign was a realistic target.

The New Pyjamas Campaign aims to generate 15 million for the new hospital when it moves to Little France in 2013. That money will pay for equipment above and beyond what is provided for in standard NHS budgets.

David Mitchell, creative director of the campaign, said: "Mark Little and his two friends have set themselves a formidable task, inspiring others to sponsor their self-imposed challenge in support of the New Pyjamas campaign.

"We are very grateful to all three men for facing this supreme test of mental and physical fitness in aid of sick kids."

Donations can be made either through the New Pyjamas website – www.newpyjamas.org – or at www.justgiving.com/SKFFoldboyskiliclimb.