Experiences of antidepressants

Using an antidepressant: SNRIs, Mirtazapine & MAOIs

Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs)
We talked to some people who had been prescribed antidepressants from other groups including Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs) such as duloxetine and venlafaxine. These work in a similar way to SSRIs. It is thought that they can help the symptoms of depression by changing the levels of chemical messengers (neurotransmitters) used to communicate between brain cells. They block the reuptake of the neurotransmitters serotonin and norepinephrine (previously known as noradrenaline) in the brain. They also affect certain other neurotransmitters. It is thought that changing the balance of these chemicals helps the brain to send and receive messages, which can then improve mood. Some people are prescribed SNRIS if they have not responded to SSRIs, which are usually the first treatment choice, or where there is a history of serious depressive illness. As with all antidepressants, people will respond differently and what works well for one person may not have the same effect on somebody else.
Several people we spoke to had taken venlafaxine. Charlotte and Roisin both found that venlafaxine suited them best when compared with other antidepressants they had tried. Roisin was frustrated that it had taken many years of trying other antidepressants before she was prescribed venlafaxine by a psychiatrist in hospital.
Venlafaxine should not be used by those with a serious heart problem. It can also increase blood pressure, so this may need to be monitored. Venlafaxine does not cause sedation but has is more likely to cause withdrawal effects than most other antidepressants (see ‘Changing antidepressants’ and ‘Stopping taking antidepressants’).
Stuart had tried several antidepressant medicines, and felt that venlafaxine may have been the most effective in alleviating his symptoms, but the effect on his sex life was bad. Hannah had taken venlafaxine and mirtazapine at different times, but thought neither of them helped her symptoms, and she lost all hope that anything would work. The mental health team became increasingly worried about her because she had overdosed several times. 
A few of those who had been prescribed one or more of these other antidepressants had also been diagnosed with other mental health problems for which they were taking additional medicines such as antipsychotics, or mood stabilising drugs. In most cases they are prescribed by a psychiatrist rather than the GP. Sometimes these antidepressants were prescribed to people whilst they were in hospital and it was understandably hard to remember which medicines they had taken. Some had been diagnosed with other complex conditions such as bipolar, personality disorders or forms of psychosis. It can be difficult for people to separate out the effects of each. It can also sometimes be difficult to distinguish the effects of antidepressants or other medicines for depression from the symptoms of the illness. People described how their doctor or psychiatrist had at various times changed them from one antidepressant to another, or altered the dose. (See ‘Changing antidepressants’,‘Stopping taking antidepressants'Telling the difference between depression symptoms and antidepressant side effects' and ‘Taking other medicines with antidepressants’ and ‘Treatment in hospital’).

Some people had been prescribed mirtazapine, a presynaptic alpha 2 adrenoreceptor antagonist unrelated to SSRIs or SNRIs. It is thought that this medicine acts on receptors in the brain, increasing the amounts of the chemical messengers noradrenaline and serotonin and can improve mood. It often causes sedation during initial treatment. Typically people in our interviews who had been prescribed mirtazapine had not responded to other antidepressants such as SSRIs or tricyclics. It is more usually prescribed to people with serious depressive symptoms but is sometimes given to help with insomnia. For insomnia people will be advised to take it at night.
Lucy Y found that mirtazapine helped her sleep and that after a few months ‘I felt like a completely new person’. Thomas had been prescribed mirtazapine, but found the sedation difficult to cope with at work. ‘I have to use my head, to talk to people... and I just couldn’t function’. The sedative effects helped Hannah because she had trouble sleeping but were so powerful that it was hard to get up in the morning and go to work, or be able to do anything. Collette was alarmed by uncharacteristic aggressive feelings whilst taking mirtazapine and her doctor changed her to a different antidepressant. Decisions about stopping or changing a medicine should be planned together with the doctor who will give advice about how to minimise discontinuation effects (see also ‘Changing antidepressants’,‘Stopping taking antidepressants’ and ‘Managing antidepressants’).
Several people said that mirtazapine seemed to make them crave sugar or increased their appetite, and they had gained weight over the time they had taken it. Both Sonia and Dina explained how this side effect can be difficult for people with depression who may also have an eating problem. Some felt that psychiatrists ought to be more cautious with people with eating disorders when prescribing medicines that can do this. 
MAOI’s (Monoamine Oxidase Inhibitors)
Monoamine Oxidase Inhibitors (MAOI) are used much less than other antidepressants because they interact dangerously with some foods and drugs. They are usually only prescribed by specialists because they can cause high blood pressure when taken with certain foods. The enzyme monoamine oxidase is involved in removing the neurotransmitters noradrenaline, serotonin and dopamine from the brain. MAOIs prevent this from happening, which makes more of these brain chemicals available, boosting mood. A significant drawback of MAOIs is the need to avoid certain foods and drinks, such as red wine, Marmite and pickled fish, which contain an amino acid called tyramine; consuming tyramine while taking an MAOI can cause a dangerous rise in blood pressure.

Flora had recurrent serious depressive episodes and felt that none of the antidepressants she had taken had been effective, or she couldn’t tolerate the side effects. A relative had been helped by an MAOI, so Flora asked her doctor if he would prescribe one for her to try. Flora was told a lot about the medicine before she started taking it, did not experience any undue effects, and has found that it worked well for her. 

Last reviewed June 2016.
​Last updated June 2016.


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