Medsafe requests Ritalin SR be made available
27 September 2007
Medsafe requests Ritalin SR be made available
Following Medsafe concerns about the safety profile of the medicine Rubifen SR, Pharmac has announced it will make Ritalin SR available to people who experience serious side-effects following use of Rubifen SR, the subsidised brand of slow-release methylphenidate.
Medsafe requested Ritalin SR be made available after a number of reports to the Centre for Adverse Reactions Monitoring (CARM) of serious reactions in patients following the change from Ritalin SR to Rubifen SR. About 6000 patients are prescribed methylphenidate in New Zealand.
Medsafe Interim Manager Dr Stewart Jessamine said between February and 21 September this year CARM received 88 reports of adverse reactions. More than half of these reports were of reduced therapeutic effect. This finding was not unexpected as it is well known that for some patients the way they respond to a medicine changes when the brand of the medicine supplied changes, even though the active ingredient, in this case methylphenidate, remains the same.
However, in this case, a number of patients, in particular children aged under 17, developed unusual and severe side effects, including mood disorders and irritability, following the change to Rubifen SR.
"Due to the number and severity of the adverse reactions reported to Rubifen SR, and the absence of any reports of a similar nature for Ritalin SR, Medsafe's Medicines Adverse Reactions Committee has asked Pharmac to make Ritalin available to those patients who experience serious side-effects, Dr Jessamine said."
Since the first reports of aggression as a side effect of Rubifen SR were made to the CARM Medsafe has been collecting data and investigating Rubifen SR to determine what might cause these side effects.
Dr Jessamine said:â€To date there is no evidence to suggest that these side effects are due to a manufacturing problem or an issue with Rubifen SR delivering the wrong dose of methylphenidate or delivering it too quicklyâ€œ.
Anyone who was taking Rubifen SR and who developed behavioural, psychiatric or other serious side-effects should contact their GP to talk about the best ADHD treatment option for them.
Prescribers are asked to report all side effects to methylphenidate to the Centre for Adverse Reaction Monitoring at the New Zealand Pharmacovigilance Centre, PO Box 913, Dunedin.
The Centre for Adverse Reactions Monitoring has provided details of the reports of side effects in 56 children to Medsafe. The data reports that 75% reported loss of effect (42 children), 55% reported unusual psychiatric events (31 children), including mood disorders, irritability, reported hallucinations (1 case) and suicidal ideation (2 cases), and 55% reported aggressive and oppositional defiant types of behaviour (20 children). A number of children reported more than 1 of the above adverse effects. All of these side effects occurred a few hours to days after patients switched over to Rubifen SR.
A literature review of the safety of methylphenidate confirms that these types of psychiatric and severe behavioural side effects have been reported in children, and less commonly in adults. All brands of methylphenidate can cause these side effects and their occurrence and severity are not related to the dose of medication being taken. As in the New Zealand reports, most patients who develop these side effects do not exhibit this type of behaviour before being started on methylphenidate.
Medsafe has also reviewed the global adverse reactions data for methylphenidate including a report listing side effects for Rubifen SR from Argentina, the only other country that markets this product. The global data confirms that serious adverse reactions to methylphenidate occur however the data from Argentina does not include any reports of aggressive behaviour or mood disorders.
Medsafe has extensively reviewed the manufacturing process, formula and testing performed on Rubifen SR before it came onto the market to determine if the side effects may be due to the quality of Rubifen SR.
Medsafe is continuing to investigate this product and is conducting its own testing of Rubifen SR. It has also asked AFT Pharmaceuticals, the manufacturer of Rubifen SR to urgently provide more data about the quality and safety of this medicine.
It will take Medsafe several weeks to complete its investigations to allow it to determine what is the likely underlying cause of the increased rate of reporting of serious side-effects.