No evidence behind ADHD medication dosages

Matt Woodley

4/06/2019 2:24:18 PM

Researchers want clarity on maximum doses due to fears arbitrary guidelines are impacting the most ‘severely affected’ young people.

Child drawing
Some children and young people could benefit from higher doses than those that are being prescribed.

The recommendation comes after a University of Sydney meta-analysis of 49 international studies found wide variation in the reporting of dose ranges for stimulant medication, with the majority focusing on safety and efficacy rather than maximum doses.
Additionally, some studies did not report justification for the chosen dose range, while others used dosages inconsistent with their references or drew on information provided by the pharmaceutical manufacturer.
Dr James Best, Chair of the RACGP Child and Young Person’s Health Specific Interests network, told newsGP he supports the authors’ call for more research in this area.
‘It is a little surprising that the selected recommended maximum dosages have apparently been arbitrarily determined without an underpinning of rational clinical reasoning,’ he said.
‘It may well be that children and young people who would benefit from higher doses are not being prescribed them, and that a better understanding of what possible side effects could happen at different dosage levels would lead to better prescribing.’
Despite the lack of evidence or research, the study indicates that numerous guidelines specify ‘apparently arbitrary dose limitations’ that discourage clinicians from titrating to higher doses that could potentially be more efficacious for some patients.
The study’s senior author, University of Sydney paediatric lecturer Dr Alison Poulton, estimates 1% of Australian children use stimulant medication for attention deficit hyperactivity disorder (ADHD) and said while medication can improve symptoms, it needs to be better tailored to individual needs.
‘More carefully monitored studies are needed to understand the risks and benefits of using higher doses of ADHD stimulant medications for patients who are heavier, whose ADHD may be more severe or people whose bodies break down the drug more quickly,’ she said.
‘There are often conflicting recommended maximum levels across various jurisdictions and from different organisations, which leads to further confusion.
‘It concerns me that clinicians treating people with ADHD use these recommendations as a formal guide.’
According to Dr Poulton, there can be substantial personal and societal costs associated with not treating ADHD effectively.
‘Teenagers sometimes stop taking their stimulant medication because they outgrow the dose and it stops working,’ she said.
‘These are often the most severely affected young people who are at risk of dropping out of school and into drugs and delinquency.
‘Furthermore, if a doctor prescribes the recommended upper levels of stimulants and the patient is still experiencing problems, the doctor may start adding other drugs to the mix. Using a mix of drugs can increase the risk of side effects and drug interactions.’

New South Wales-based GP Associate Professor John Kramer, who has a special interest in treating ADHD, has been prescribing stimulants for around 25 years and told newsGP he also believes more research is required.
‘Most kids will respond within the dose range, but I think that’s more by good fortune than good management on the part of the recommended guidelines,’ he said.
However, he added that medication is one of only a number of multi-modal therapies that are utilised during treatment and that there are other options aside from increasing dosages.
‘When a patient isn’t responding to the maximum dosage that you can give you have to look for other medications and strategies,’ he said.
‘In parallel with [medication] you’re pursuing non-pharmacological strategies as well, such as counselling, behaviour management, occupational therapy, speech pathology – it’s not just medication in isolation.
‘Management of ADHD and related conditions is a real team effort. Parents, carers, teachers, GPs, allied health, grandparents – it’s a prime example of the big team.’

ADHD medication prescribing

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