Tolcapone Norepinephrine

LEVODOPA, SELEGILINE, POSSIBLY RASAGILINE, ENTACAPONE, TOLCAPONE MAOIs Risk of adrenergic syndrome -hypertension, hyperthermia, arrhythmias - and dopaminergic effects with selegiline Levodopa and related drugs are precursors of dopamine. Levodopa is predominantly metabolized to dopamine, and a smaller proportion is converted to epinephrine and norepinephrine. Effects are due to inhibition of MAOI, which breaks down dopamine and sympathomimetics Avoid concurrent use. Onset may be 6-24 hours after ingestion. Carbidopa and benserazide, which inhibit dopa decarboxylase that converts L-dopa to dopamine, is considered to minimize this interaction. However, MAOIs should not be used in patients with Parkinson s disease on treatment with levodopa. Imipramine and amitriptyline are considered safer by some clinicians... 

Entacapone and imipramine did not interact adversely in a single-dose study. Similarly, tolcapone and desipramine did not interact adversely. Nevertheless, the manufacturers of entacapone and tolcapone recommend caution if they are used with tricyclic antidepressants or other drugs that inhibit noradrenaline (norepinephrine) uptake, such as maprotiline or venlafaxine. 

In these pharmacological studies, no important interaction between enta-capone and imipramine or between tolcapone and desipramine was detected. Nevertheless, the manufacturer of entacapone says there is limited clinical experience of the use of entacapone with tricyclic antidepressants, and they therefore recommend caution. Similarly, the manufacturers of tolcapone suggest that caution should be exercised with desipramine and any drugs that are potent noradrenaline (norepinephrine) uptake inhibitors such as maprotiUne and venlafaxine. ... 

---