‘Devastating effects’ caused by switching between branded and generic Parkinson’s disease medication

Charity Parkinson's UK said patients had experienced pain and other symptoms after being switched between branded and generic medications.
older patient's hands

Patients with Parkinson’s disease (PD) who had their medication switched because of shortages have been detrimentally affected by the change, a leading UK charity has said.

In a press release, published on 30 January 2023, Parkinson’s UK said patients had been left with “devastating effects” after being given prescriptions for a mixture of both Sinemet (Carbidopa/levodopa; Organon Pharma UK) and its generic version, co-careldopa; with some patients not consulted about the change before it happened.

The charity cited the example of one patient, who had lived well with PD for 17 years, developed slow speech, and was left in pain and with an uncontrolled tremor after his normal branded medication was switched to generic co-careldopa.

Janine Barnes, a neurology specialist pharmacist at the Dudley Group NHS Foundation Trust and founder of the Parkinson’s Disease Specialist Pharmacy Network (PDSPN), said that “numerous people” with PD had informed her that they had lost control of their symptoms when their branded medication was switched to generic. 

“Medical colleagues often believe that this is not the case as the active drug received by the patient remains constant but, in my experience, the change in drug diluent, absorption characteristics etc., can have a dramatic effect on symptom control,” she said.

“We advise people with [PD] to request a specific brand on their prescription, if they find that it works better for them, and then legally this brand will be dispensed by their pharmacist.”

Barnes said changes should not be made without discussion with the patient and the original medication brand should be supplied as soon as it becomes available again.

“I do not believe that the specialist needs to be involved in these conversations as the pharmacist can manage these discussions and ensure that a patient is prescribed the same product as previously or returned to the initial product as soon as it becomes available again,” she added.

“I think that involving a specialist in these decisions will slow the process down considerably in view of current NHS pressures and is unnecessary.”

Stephanie Bancroft, a community pharmacist and chair of the PDSPN, said that past shortages in supply of Sinemet — most recently in 2020 — were “challenging for everyone” and a change from branded to generic had sometimes been necessary to avoid the patient going without medication.

“Cost savings is [another] possible reason that medications may be switched from branded to generic,” she added.

“There is an NHS policy in place to do this, where possible, but in the case of [PD] medications, the cost savings are not as evident as with some other drugs.” 

However, she added: “If a patient has been stabilised on Sinemet by their consultant, this should not be changed to a generic version by their GP without discussing the change with the consultant and patient.”

Last updated
The Pharmaceutical Journal, PJ, February 2023, Vol 310, No 7970;310(7970)::DOI:10.1211/PJ.2023.1.173781


  • Michael Hannay

    Interesting article which raises questions over bio equivalence testing for PD medicines

    • Robert Wise

      I agree. I looked at bioequivalence requirements a long time ago (2014) & was surprised to see the wide tolerances permitted (80% - 125%) between test & reference product. For narrow therapeutic index meds (decided on a case by case basis) between 90% - 111.11%. This was the Bioequivalence Guidance document published by CHMP/EMA in 2010. I haven't checked to see if this has been updated since, but IMHO the bioequivalence tolerances should be tighter.

  • Pareshkumar Modasia

    Janice Barnes should perhaps understand Community Pharmacy remuneration and Drug Tariff before making a statement like "legally this brand will be dispensed by pharmacist"
    Community Pharmacists will only dispense what they get paid by NHS. Also, some PCN pharmacy advisors tend to muddy the waters by switching to "cheaper " brands to justify their existence of making savings. We notice that even in other clinical categories.
    Paresh Modasia

    • Janine Barnes

      I stand by my comment that pharmacists must dispense a medication brand if specified by the prescriber on the patient's prescription.
      If the brand e.g., Sinemet is written on a prescription, the pharmacist must dispense Sinemet unless it is unavailable. If it is unavailable the pharmacist can
      • ask the GP to alter the prescription to a generic product which may be easier to source
      • signpost the patient to another pharmacy that has the branded product in stock
      • in some circumstances where there is an ongoing stock shortage problem, NHSE issues a Serious Shortage Protocol (SSP) then the pharmacist can dispense an alternative product against a branded Rx and endorse accordingly (SSP reference number, date, brand and price of product supplied).
      Whilst, I fully understand the current cost pressures and funding inequalities within community pharmacy, my role is to manage people with Parkinson's disease who have been stabilised on a specific brand of medication and a change of brand could have deleterious consequences on their symptom control.
      Janine (not Janice) Barnes

    • Tim Webb

      Hi Paresh

      I completely agree with the remuneration issue you describe. However, I think Janine is stating that patients ask the prescriber to write the brand on the prescription rather than demand that the a brand is supplied against a generic prescription.


You may also be interested in