Sam Khan, 34, has a £100-a-day drug habit. That is the cost of the prostacyclin that is pumped in a continuous infusion into her body through a tube in her side. It is her life-line.

She was diagnosed with primary pulmonary hypertension in her twenties and for many years her condition was stable. "I took tablets but no one knew about it. I carried on as normal. Then suddenly I went downhill. I couldn't breathe any longer and I went into hospital. The only solution was to have this drug or die."

She had to move in with her sister so she could be looked after. "I couldn't do anything for myself. I couldn't get dressed or go to the bathroom." But she craved independence - and wanted to continue her work as head of production at Kinnerton Confectionery in London.

She was started on prostacyclin 14 months ago. "Slowly but surely I got back to where I was. I have to drive to work instead of taking the Tube and I can't climb stairs or carry things. I work a full day and the job is very demanding but I don't want to give it up. I want to be independent."

When her treatment started she was living in Bedfordshire and the health authority agreed to fund the £37,000-a-year cost, but she has since moved to London and is unsure who is footing the bill now. "That is a worry," she said. "There is always a chance that the health authority could turn round and say they won't pay. It didn't happen to me. I was lucky."