Sir Charles, MP for Cheltenham for 18 years, confirmed that he had twice been interviewed by detectives investigating the case against Dr Clive Froggatt, who was one of the Government's advisers on changes in the National Health Service.
The former MP, who retired from Parliament in 1992, has been a close personal friend and political associate of the 46-year-old doctor for many years.
In a statement to his local newspaper, the Gloucestershire Echo, Sir Charles said he had never received diamorphine from Dr Froggatt. 'I thought it was a brand of whisky,' he joked. 'Whatever medication has been prescribed for me I have received and had it. If anyone else would like to try it, they are welcome.'
Speaking of Dr Froggatt, he said: 'I am certain he is innocent. He is my best friend and has been for a long time.' Sir Charles confirmed he had spoken to police last week after his return from a brief holiday at his apartment in Tangier, Morocco.
'We had a chat, a friendly casual chat,' he said. 'There was nothing in it at all.
'I am a patient of his and CID officers have seen a number of his patients. As far as I know they have also received the medication they were entitled to or needed and I really don't know any more than that.'
Dr Froggatt is on bail until 10 November, having been remanded by Gloucester magistrates on six charges of possessing, supplying, and illegally obtaining heroin.
He is alleged to have obtained a total of 295mg of diamorphine - the technical name for heroin - from pharmacists and supplied it to another unnamed person.