FOI release

Freedom of Information request on Yellow Card reports received related to withdrawal after stopping baclofen (FOI 21/862)

Published 20 January 2022

17th August 2021

FOI 21/862

Dear

Thank you for your recent correspondence on 19th July asking if the Yellow Card scheme has received any reports relating to patients experiencing withdrawal effects after stopping baclofen.

Following a search of our database up to and including 9th August 2021, we have received 58 UK spontaneous ADR reports of baclofen with a minimum of one reaction related to withdrawal reactions. It is important to note that we are unable to accurately provide case details pertaining to baclofen being stopped abruptly, as the Yellow Card scheme does not contain a specific question on whether a drug has been stopped abruptly, making it difficult to identify such cases. A reporter can provide this information in the reaction summary section of a Yellow Card on a voluntary basis, as well as providing the start and stop dates for both the reactions experienced and for the use of the suspect medication itself. However, this information is not mandatory or required to make a report valid. Hence, there may be instances where the duration of use of a suspect drug is not reported, and unless otherwise explicitly stated, it is not known if a drug is stopped suddenly.

Whilst we are unable to accurately provide the data for reports where baclofen has been stopped abruptly, if you require it, a type 1b line listing of the 58 cases where a withdrawal reaction has been reported can be provided. A type 1b line listing concerns a list of data from Yellow Card reports, which exclude any information that can identify the patient/reporter and therefore can be released without the need for consideration from the Pharmacovigilance Expert Advisory Group (PEAG) under the FOI act.

In the Summary of Product Characteristics (SmPCs) for baclofen, section 4.4 describes features of abrupt withdrawal as the following:

‘Anxiety and confusional state, delirium, hallucination, psychotic disorder, mania or paranoia, convulsion (status epilepticus), dyskinesia, tachycardia, hyperthermia, rhabdomyolysis and temporary aggravation of spasticity have been reported with abrupt withdrawal of baclofen, especially after long term medication. Drug withdrawal reactions including postnatal convulsions in neonates have been reported after intrauterine exposure to oral baclofen.’

Further to your request, from the 58 UK cases received by the MHRA, please see Table 1 below detailing the number of reports associated with the listed withdrawal effects mentioned in the above SmPC extract. Also, please note that more than one reaction can be reported in association with baclofen use per ADR report; therefore, the total number of reports from table 1 will not necessarily be equal to the 58 ADR reports held within our database.

Table 1: Number of UK spontaneous suspected ADR reports associated with baclofen and the withdrawal symptoms listed in the SmPCs

Reaction	Number of ADR Reports
Anxiety	4
Acute psychosis	1
Confusional state	10
Delirium tremens	1
Drug withdrawal convulsions	1
Dyskinesia	1
Generalised tonic-clonic seizure	3
Hallucination	19
Hyperthermia	1
Muscle spasticity	7
Neonatal seizure	2
Paranoia	6
Psychotic disorder	4
Rhabdomyolysis	1
Status epilepticus	1
Tachycardia	5

I can also confirm that the Yellow Card scheme has not received any reports of mania associated with withdrawal effects for reports of baclofen.

When assessing the data provided, it is important to note that a report of a suspected reaction to the Yellow Card scheme does not necessarily mean that the medicine caused it, only that the reporter has a suspicion it may have. Therefore, not all events have been medically confirmed or diagnosed, as we encourage patients and healthcare professionals to report on the basis of suspicion alone. Reports submitted to MHRA may be due to concurrent diagnosed or undiagnosed illness, other medicines or purely coincidental events that would have occurred anyway in the absence of therapy.

Furthermore, the number of reports received should not be used to determine the incidence of a reaction as neither the total number of reactions occurring nor the number of patients receiving the drug is included in this data. Hence the data provided may not provide an accurate representation of what is occurring in the clinical setting. Any emerging evidence relating to possible risks associated with medicines and vaccines is carefully reviewed, and, if appropriate, regulatory action would be taken.

If you require any Yellow Card data on medicines in the future, you may be interested to know that you can view all our ADR data on our Yellow Card website. Interactive Drug Analysis Profiles (iDAPs) list all spontaneously reported adverse drug reactions on the MHRA database associated with a drug substance (considered category 1a data).

I hope the information provided is helpful, but if you are dissatisfied with the handling of your request, you have the right to ask for an internal review. Internal review requests should be submitted within two months of this response’s date and can be addressed to this email address.

Yours sincerely,

FOI Team,

Vigilance and Risk Management of Medicines Division