LEVOTHYROXINE AND PHENOBARBITAL
An isolated report describes a reduction in the response to levothyroxine in a patient also given secobarbital with amobarbital. It seems possible that all barbiturates may interact in this way. Note that phenobarbital has been shown to reduce the serum levels of endogenous thyroid hormones in some studies.
The general importance of this interaction is almost certainly small, but be alert for any evidence of changes in thyroid status if barbiturates are added or withdrawn from patients taking levothyroxine.
The general importance of this interaction is almost certainly small, but be alert for any evidence of changes in thyroid status if barbiturates are added or withdrawn from patients taking levothyroxine.