Known interactions between the following drugs: Didrex, Perphenazine and Amitriptyline

Amitriptyline is broken down into both active and inactive by-products by the liver--a process referred to a "drug metabolism". Perphenazine may interfere with the liver's ability to metabolize amitriptyline. As a result, blood levels of amitriptyline may become elevated and this could increase the risk for side effects. Potential side effects include drowsiness, dizziness, a dry mouth, and blurred vision. Other, more serious side effects include changes in blood pressure, seizures, and an abnormal heart rhythm. Your doctor may want to monitor you closely while these drugs are used together to make sure that you are not getting too much amitriptyline. If you are experiencing problems, it may be necessary to adjust the dose of amitriptyline. You may want to ask your healthcare provider about this potential interaction if you think you are having problems.

Although the cause of this potential interaction is not clearly understood, the effects of either drug may be diminished when benzphetamine and perphenazine are used at the same time. If this happens, you may experience weight gain and an increase in psychotic symptoms including unusual speech or behavior, feelings of distrust, or believing that you can hear, see, smell, or taste things that are not really there. If possible, avoid using benzphetamine and perphenazine together. Discuss this potential interaction with your healthcare provider at your next appointment, or sooner if you think you are having problems.