Monoamine oxidase inhibitors :

These act by inhibiting the monoamine oxidase, therefore increasing the noradranergic transmission. 2 isoforms of the enzymes exist,  MAOa (e.g. moclobemide) & MAOb. These are NON-SELCTIVE IRREVERSIBLE INHIBITORS

Cheese contains the substance  tyramine:  if this gets into the blood stream it is highly toxic,therefore  this must be metabolised . We would assume that if we block one of these enzymes, the other could resume to metabolise tyramine, later it was realised it required the irreversible binding i.e. the type of binding i.e. competitive inhibition.

 

Selective Serotonin and Noradrenaline Reuptake Inhibitors (SNRIs)

• These are known as dual action antidepressants

• SNRIs include : venlafaxine and duloxetine 

• They are a newer class of antidepressants compared to SNRIs

• Act in a similar way to SSRIs 

• As the name suggests, they inhibit the reuptake of serotonin and noradrenaline

• Side effects of SNRIs are also similar to SSRIs, particularly gastrointestinal adverse effects

 

Venlafaxine

• Was the first drug to come to the market (1994)

• Indicated for major depression and generalised anxiety disorder 

• Most commonly used from this class 

• May affect tasks e.g. driving, so patients must be warned about this prior to using it 

• Posesses less sedative and antimucarinic effects compared to TCAs  

• Known to have a higher risk of withdrawal symptoms compared to other antidepressants 

• Most common withdrawal symptoms of venlafaxine include : 

 

 

 

 

 

 

 

 

 

Duloxetine 

• Duloxetine is indicated for major depressive disorder, generalised anxiety disorder, diabetic neuropathy, stress urinary incontinence

• Brand name for duloxetine indicated for  major depressive disorder, generalised anxiety disorder, diabetic neuropathy, stress urinary incontinence is Cymbalta®. 

• The Yentreve® brand is reserved for the treatment of stress urinary incontinence 

• In no circumstance should either brands be used together 

• Each brand should be used solely for the purpose intended 

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Selective noradrenaline reuptake inhibitor 

• This specifically blocks the reuptake of noradrenaline 

• Reboxetine 

• Not routinely used in the UK 

• NICE recommends the use of reboxetine when SSRIs are not well tolerated 

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Noradrenergic an specific serotonergic antidepressant

 

Mirtazapine:  

• MIrtazapine is a tetracyclic antidepressant 

• This is a presynaptic alpha2 -adrenoceptor antagonist, increasing noradrenaline and serotonergic transmission 

• MIrtazapine intially causes sedation during the early staes of treatment but has FEW sedative effects

•  Associated 

Supposedly blocks 5-HT and NA reuptake this also includes TETRACYCLIC ANTIDEPRESSANTS. E.g. MIRTAZAPINE this noradrenergic specific serotonergic antidepressants – these blocks presynaptic alpha 2 inhibitory autoreceptor and some 5HT receptor subtypes.