Parkinson’s UK is demanding and answers and action from Merck Sharp & Dohme on the ongoing shortages of its Parkinson’s disease drug Sinemet, which look set to remain until next year.

The charity is urging patients to join its campaign calling on Merck Sharp & Dohme and its parent company Merck to put an end to the waning supply of the drug and, in the meantime, better communicate with both PD patients and pharmacists in the UK to help clear up the current confusion and provide information on how supplies will be released and where they will be sent to.

Limited global availability of Sinemet (carbidopa-levodopa) and the controlled release version Sinemet CR is expected to continue into 2011, because of a change in the source of supply for the drug and “the necessary timelines needed to obtain regulatory approvals for this supply change”, according to MSD.

In a statement to the Association of British Neurologists, MSD warned that, because of the change in arrangements, which reportedly involve a switch to a single wholesaler, it is likely that “some markets will get their full needs met, many will experience a significant shortfall in their supply, and many will not get any supply of these products”.

“Many countries are being asked to take reduced allocations so that Merck and MSD can supply product to patients in countries that have no or limited alternative treatment options”, the company said, but has not given any further clarification on the situation.

While other formulations of the active ingredient are available, it can take a long time for patients to find the combination of drugs suitable for them and get to grips with new dosing regimens or the timing necessary to treat symptoms of the disease most effectively, a spokesperson for the charity told PharmaTimes UK News online.

In addition, some people may experience side effects to new medication, as while the active ingredient is the same different substances can be used in different products to ‘bulk up’ the pill.

“The shortage of Sinemet has caused anxiety and deep distress for people who are already trying to cope with the impact of Parkinson’s,” said Steve Ford, Parkinson’s UK’s chief executive. “We’ve heard of cases where people with Parkinson’s are being told by their pharmacist that there is no Sinemet available so this means they have to look elsewhere. This is unacceptable,” he added.

“Waiting until 2011 is simply not good enough. This shortage should end now,” Ford stressed.

MSD could not be reached in time for comment.