Switching medication and polypharmacy
Switching from a stimulant to atomoxetine
There are currently no published clinical studies specifically looking at the optimal way to switch from a stimulant medication to atomoxetine although results from ongoing trials should be published in 2005.
From the information that is available, it seems that there are no significant concerns if both medications are coadministered simultaneously (in particular the cardiovascular side effects i.e. increased heart rate and increased blood pressure are not additive).
Until an optimum regime is recommended, there are 3 basic choices:
- Stop the stimulant and start atomoxetine the next day (or after a longer wash out period if thought more suitable),
- Start the atomoxetine and cross taper (i.e. gradually decrease the dose of stimulant whilst simultaneously increasing the dose of atomoxetine),
- Start the atomoxetine, titrate up to the full dose, then stop the stimulant (either abruptly or by weaning down gradually).
Switching from clonidine to atomoxetine.
The clonidine should first be slowly tappered down and not withdrawn suddenly due to the risk of rebound hypertension and tics. Once the clonidine has been completely withdrawn, atomoxetine can be started as per earlier recommendations. It is not advised that both medications are co-administered.
Polypharmacy
This may be necessary in certain situations, especially where co-morbidity is a feature, but should be supervised by a specialist with expertise in this area.
In general combining drugs will increase the risk of potential adverse side effects and consideration should be given to potential drug interactions.
Combining atomoxetine with a stimulant
It can be seen from the above that it is thought to be safe to combine the use of atomoxetine with a stimulant for the purposes of switching medications. There have been individual case reports of children and young people who have continued to experience significant and problematic symptoms when treated with either a stimulant or atomoxetine alone, who have then been treated with combinations of stimulant plus atomoxetine. In the absence of adequate research, decisions to utilize such combinations should be made on a case-by-case basis with full disclosure of the limited research-base to the patient or parents and with ongoing monitoring for effectiveness and possible adverse effects.
Combining clonidine with a stimulant
Clonidine has been combined with methylphenidate to reduce aggression and to provide better control of ADHD symptoms after the stimulant has worn off and to counteract the insomnia that can occur with stimulants. If the combination is to be used, the starting dose of clonidine is 50 microgrammes at bedtime, increasing the dose gradually to an absolute maximum of 300 microgrammes/day. Clonidine is given at night time for sleep or 2-3 times daily if the aim is to control aggressive behaviour. N.B. For children on clonidine and drug combinations which include clonidine, blood pressure, pulse and ECG should be monitored regularly because of the potential for the development of bradycardia.
