is a combination of 2 tricyclic antidepressants popularly known as the TCAs. This drug is not approved in many countries cause of absence of clear clinical efficacy . Moreover TCAs as such are unpolular cause of the various cardiac complications caused by them. Considering that you are on a TCA and have a tachycardia
(increased heartrate), first thing is you should get an ECG done and get your self examined by a physician. There are much safer anti depressants in the market and you should consider starting them from now on.
hope i am able to solve your query.