MPs have called on the government to clarify its plans to move to value-based pricing of drugs by 2014 and branded the delays in providing detauks about the new system "unacceptable".

Arrangements for implementing and using the value-based system – which would involve drugs being priced by efficacy rather than under the pharmaceutical price regulation scheme (PPRS) – had still not been settled and the health sector, patient groups and clinicians would have to work with the new system were unsure what the changes will mean in practice, said a report, published last week (January 8) by the Commons Health Committee.

After holding an inquiry into the work of Nice, the committee said decisions on how the system would work needed to be made without delay before the government introduced it across the UK in 2014, warning that it was "a source of concern that so little progress has been made on defining this nebulous concept".

"There is a lack of clarity around the whole issue, which has persisted for too long" Stephen Dorrell MP Health Committee

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The government needed to "bring uncertainty to an end" and clarify the situation by the end of March 2013, it added. "There is a lack of clarity around the whole issue, which has persisted for too long. Decisions need to be taken, and the details of the scheme made public to avoid problems with the transition to the new system at the beginning of 2014," said Health Committee chair Stephen Dorrell MP. ABPI chief executive Stephen Whitehead said the committee was right to highlight the impact of continuing uncertainty over future medicine pricing.

"The pharmaceutical industry and the NHS both need certainty to plan," he said. "Most importantly, patients need to be assured that government policy will enable them to get the medicines their clinicians recommend on the NHS."

Pharmacy Voice chief executive Rob Darracott agreed that more clarity and detail were needed.

"We have already warned the government to watch out for unintended consequences at the pharmacy end of the medicines supply chain," he said. "Any new system would need to make reference to international pricing and also be sensitive to the reimbursement mechanisms for pharmacies."

The value-based system is intended to give patients better access to medicines and to achieve value for money for the NHS. The government launched a consultation into the system in 2010 and the then health secretary Andrew Lansley gave it the go ahead in 2011.