Hi There, Thanks for asking. With this switching, the dopamine receptor
occupancy in his brain has increased, because he is taking 50 mg XR of Vyvance which is substantially more effective than 20 mg of Focalin
. Experiencing shortness of breath
in the first days of dosage increment is a common side effect which is seen. Most of the time it is improved with gradual increase in the dose. The chance of arrythmia
is really low and you should not worry about it, but it is bothersome for the patient and parents. Since he is taking Zoloft
as well, which can also cause shortness of breath, this side effect is exaggerated. The formula of Start low, Go Slow would probably work for him initiating Vyvance. I wish for him the best health and performance at school.