What medications are available to treat  AADC Deficiency?

Each affected AADC child reacts differently to medications used to treat the disorder.  Below is some information that may help you understand a little more about their benefits when treating this disease.  Please do not use this information to self diagnose or self medicate your child and discuss in detail with your child’s treating physician/consultants the potential benefits to your child. 

Dopamine Receptor Agonists

Dopamine is normally released from the end of a nerve. It crosses the gap (synapse) between this nerve and the next one where it binds to receptors causing the receptors to ‘fire’. This process allows signals to transfer from one nerve to another. In AADC deficiency, dopamine levels are insufficient to allow this passage of signals to occur. Dopamine agonists are an artificial form of naturally produced dopamine.  The agonists mimic the action of the naturally produced dopamine and they act by attaching and stimulating dopamine receptors in the brain.

Dopamine agonists used to treat AADC deficiency include ergot and non-ergot derived forms. Recently it has been reported that ergot forms of dopamine agonists, such as pergolide and bromocriptine can cause a serious fibrotic reaction. The newer forms of non-ergot dopamine agonists, pramipexole and ropinirole, are now more favoured in the treatment of AADC deficiency but do not necessarily have the same benefits as the ergot forms.  This should be discussed in more detail with your affected child’s treating physician/consultant and with the help of an AADC medical expert.

Monoamine Oxidase Inhibitors (MAOI)

In AADC deficiency there is always a very small amount of dopamine and serotonin that is produced. MAO inhibitors are used to inhibit the monoamine oxidase enzyme that would normally break down dopamine and serotonin. In the presence of MAOI’s the small amounts of dopamine and serotonin can accumulate and hence improve the neurotransmission process.

Usually whilst taking MAO inhibitors you are advised to avoid certain foods and medications.  Although, we do know of at least one child affected by AADC, on an MAO inhibitor, who continues to eat all food groups without adverse reaction.

Vitamin B6 – Pyridoxine
 

Vitamine B6 – otherwise known as pyridoxine is a precursor that the body converts into pyridoxal -5’ phosphate.  This pyridoxal 5’-phosphate is required for the normal functioning of AADC.   By increasing the amount of B6 it is hoped that it may help stimulate AADC function to facilitate some production of natural dopamine and serotonin.  In AADC deficiency the benefit of high doses of B6 is unknown.

Anticholinergic Agents

Theoretically anticholinergics agents such as Trihexyphenidyl are used to improve the imbalance between the acetylcholine and dopamine.  In children with AADC deficiency, these medications have been reported to help reduce the increased sweating and possibly ameliorate the limb dystonia.

It has been reported that it may help in the smoothing out of motor fluctuations.

Antiepilectics

Used for the treatment of seizures – seizures are rarely present in AADC deficiency. 

Serotinergic Medications

Selective Serotonin Re-uptake Inhibitors (SSRI) or Serotonin Agonists may be used to treat AADC deficiency.  Serotonergic medications may cause an adverse reaction if used in conjuction with MAO inhibitors.  This should be discussed in more detail with your affected child's treating physician/consultant and with the help of an AADC medical expert.

Gastrointestinal Medications
 

There are many gastrointestinal medications and interventions, once your child has been fully assessed for gastrointestinal symptoms and treatments or procedures recommended, try and resource all the information you can about their benefits and risks.

Folate
 

In AADC deficiency there is accumulation of L-dopa. The removal of this L-dopa requires methylfolate. For every molecule of L-dopa that accumulates you need one molecular of methylfolate. For this reason, if the intake of folate in the diet is inadequate a patient with AADC deficiency can slowly become folate deficient.  It is recommended that you discuss this with your physician and regularly check your child’s folate status.

Note
 

This list is not an exhausted list of medications and we encourage you to use the medline link provided to explore more about each medication and its potential benefit and risk when being used to treat your child.  This can prove difficult, as some of the medications above are not routinely used to treat children.

If you have specific concerns about medications used to treat your affected child then it may be useful to refer your child’s treating physician/consultant to an AADC medical expert to find out more.