CNS Stimulants and Drugs used to treat ADHD

• Attention deficit hyperactivity disorder (ADHD) is a persistent pattern of inattention and/or hyperactivity and impulsivity that is more frequent and severe than is typically observed in individuals at a comparable level of development.
• Management options include social, psychological and behavioural interventions, support of the parents and patients, and drugs.
• This record deals with the drug management of ADHD.
• NICE recommend three drugs for ADHD: methylphenidate, atomoxetine and dexamfetamine, all of which are CNS stimulants. All are intended for initiation by specialists but GPs may be asked to provide repeat prescriptions once the patient is stabilised.¹

• Methylphenidate is licensed as part of a comprehensive treatment programme for severe ADHD, where remedial measures alone prove insufficient. It is a schedule 2 controlled drug.
• It is not licensed for children under the age of 6, and there are various other contraindications.
• Prescribing by general practitioners should only be undertaken under the auspices of shared care guidelines drawn up by local secondary care specialists in collaboration with healthcare agencies and other key partners, including GPs. Such guidelines should include:
  • Details of dosage, side effects, drug interactions and monitoring
  • A clear statement of the responsibilities of the specialist and the GP
  • Who the GP should approach for advice and support

Prescribing Unlicensed Medicines

• GPs should be aware that once they sign a prescription they are taking full medicolegal responsibility for subsequent adverse events and for reporting them to the Medicines and Healthcare products Regulatory Agency (MHRA).
• They should only prescribe if they are fully conversant with the monitoring requirements and have enough confidence, if they are unable to access specialist support, to alter dosage and stop the drug if required.
• The decision to participate in shared care should not therefore be taken lightly.

• Licensed for children 3 years and older
• A schedule 2 controlled drug
• Adverse effects similar to methylphenidate
• Tends to be reserved for children who do not respond to methylphenidate

• Licensed for children 6 years and older
• Useful for ADHD in adolescents and adults

NICE were unable to draw conclusions on the relative cost-effectiveness of the different drug treatments based on the evidence presented to it, and has suggested further research.
Its current recommendations are that treatment should be tailored to individual patients bearing in mind the following considerations:

• The presence of comorbid conditions (atomoxatime is better for children with Tourette's or tic disorders)
• The different adverse effects of the drugs
• Compliance (e.g. methylphenidate is available in slow-release form, which may obviate the need for taking a mid-day dose at school)
• The potential for drug diversion and/or misuse (dexamfetamine is a well-known street drug)
• The preferences of the child or adolescent and/or his or her parent or guardian
• Cost

Since the NICE report, the MHRA has issued alert concerning atomoxetine (Strattera), highlighting a potential increase in suicidal thoughts/behaviour, the potential for producing seizures, and the risk of QT interval prolongation.⁵
It advises:

• That patients taking atomoxetine should be monitored for signs of depression, suicidal thoughts or suicidal behaviour and referred for appropriate treatment if necessary.
• That patients and parents should be advised to watch for any clinical worsening, irritability or agitation, suicidal thoughts or behaviour or other unusual changes in behaviour.
• That it should be introduced with caution in patients with a history of seizures.
• That it should be used with caution in patients with congenital or acquired history or a family history of QT interval prolongation.

The MHRA recognises that methylphenidate may also worsen depression.