Protriptyline

Pharmacogenomic Information in the Context of the FDA-Approved Drug Label*

Protriptyline hydrochloride is an antidepressant agent, while its mechanism of action in man is not known. Protriptyline belongs to the class of tricyclic antidepressants.

Excerpts from the Protriptyline drug label:

"The biochemical activity of the drug metabolizing isozyme cytochrome P450 2D6 (debrisoquine hydroxylase) is reduced in a subset of the Caucasian population (about 7% to 10% of Caucasians are so called "poor metabolizers")."
" Poor metabolizers have higher than expected plasma concentrations of tricyclic antidepressants (TCAs) when given usual doses."

"In addition, certain drugs inhibit the activity of this isozyme and make normal metabolizers resemble poor metabolizers. An individual who is stable on a given dose of TCA may become abruptly toxic when given one of these inhibiting drugs as concomitant therapy. The drugs that inhibit cytochrome P450 2D6 include some that are not metabolized by the enzyme (quinidine; cimetidine) and many that are substrates for P450 2D6 (many other antidepressants, phenothiazines, and the Type 1C antiarrhythmics, propafenone and flecainide)."

(For the complete drug label text with sections containing pharmacogenetic information highlighted, see the Protriptyline drug label PDF.)