The cost per item paid by the NHS to manufacturers for special order medicines, or 'specials', fell by 25% after the new tariff took effect in November 2011.
Figures from NHS Prescription Services show the average price paid by the NHS was £182.76 between June 2010 and October 2011. This dropped to an average of £136.17 between November 2011 and June 2012.
The NHS spent £28.2m on specials in April-June 2012, marginally down from £28.7m the quarter before. But since the tariff was introduced, average monthly NHS spend fell from £10.8m to £9.3m.
Specials are prescribed by GPs when patients cannot tolerate cheaper licensed products, but can add thousands of pounds to primary care budgets. Examples include capsules for vitamin D deficiency and liquid medicines to treat convulsions in children.
The new drug tariff, agreed by the DH last year, saw pharmacies paid a fixed amount for 60 commonly prescribed products.
Previously, various approaches were attempted to stem rising prices, including new guidance on prescribing and legislation allowing price lists to be shared, but none were successful.
A spokeswoman from the Association of Pharmaceutical Specials Manufacturers (APSM) said: 'We concur that the cost has reduced slightly and the number of specials prescribed has increased.'
She added: 'However, there are cautions about the long-term effects of cost cutting, which is largely being driven by pressure from PCTs, not the tariff. Patient need and patient safety must always be the overriding criteria in any decision about prescribing or dispensing a special prescription.'
Use the interactive chart below to examine how specials costs have fallen.
Each point on the above chart represents one PCT's spending on specials for a given month. Red colours mean higher spend per item, with blue denoting lower spend.
Click the 'Play' button to see the evolution of costs from June 2010 to June 2012. Track individual PCTs by selecting them in the right hand column. Different ways of illustrating the data can be seen by selecting the tabs to the upper right of the chart.
Note how over time, and particularly after November 2011, the colours trend towards the blue end of the spectrum, showing cost per item has fallen dramatically.
NHS Manchester is the outlier to the right of the chart, and shows clinicians in the PCT prescribed far more specials than other areas, reaching a high of 3,285 items per month in March 2011.
When asked last year why it purchased so many specials, an NHS Manchester spokeswoman said: 'The rise in special order products can be attributed to colecalciferol (vitamin D) which because it is not a licensed product, is classed as a ‘special’.
'A high number of Manchester residents have tested positive for being deficient in Vitamin D and have therefore been prescribed colecalciferol products.'