Predictions that scrapping prescription charges would cause an explosion in demand for medicines have been proved wrong, according to Health Secretary Nicola Sturgeon.

In her first major interview since the May election, Ms Sturgeon said the figures prove abolishing the charges was the right decision.

She also spoke of her pride in the National Health Service and her belief it is affordable and sustainable.

Government experts thought phasing out charges might lead at most to a 3% annual rise in the number of prescriptions issued, but critics argued that it could go up far more sharply.

In fact as the price of prescriptions fell, the number issued rose by 2.2% in 2008/09, 2.7% the following year, and last year the increase was just 1%.

This meant the cash allocation to health boards for prescriptions was just over the amount needed in the first year, £1 million over in the second year and £2m over last year.

This year, after the charges were abolished completely in April, it is expected to be £3m to £4m over the sum needed, allowing boards to spend the surplus on problem areas such as rising energy bills.

Ms Sturgeon said: "It's not led to some explosion in demand, with people abusing the system. We're comfortably within budget."

Ms Sturgeon also said the Scottish Government was to consider how to merge health and social care for the elderly, saying the aim was for the cost of free personal care to be offset by a fall in unplanned hospital stays.

She said: "When you look at the optimal way of delivering older people's care, it's completely wrong to focus it all on the free personal care element."