Using an antidepressant: SNRIs, mirtazapine and 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).

Fluoxetine wasn’t effective for Peter, but when he started…

Age at interview 28

Gender Male

Age at diagnosis 22

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Charlotte experienced initial side effects from venlafaxine…

Age at interview 34

Gender Female

Age at diagnosis 20

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Roisin said that venlafaxine saved my life’ but it had taken several…

Age at interview 45

Gender Female

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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.

Venlafaxine is the antidepressant that worked best for Stuart…

Age at interview 52

Gender Male

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Hannah had been feeling increasingly distressed while on…

Age at interview 28

Gender Female

Age at diagnosis 23

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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.

t 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 antidepressantsTelling the difference between depression symptoms and antidepressant side effectsTaking other medicines with antidepressants and Treatment in hospital).

Mirtazapine

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 she “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).

Lucy Y was functioning’ on fluoxetine but mirtazapine made…

Age at interview 23

Gender Female

Age at diagnosis 18

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Sonia was prescribed mirtazapine to help her sleep, because…

Age at interview 31

Gender Female

Age at diagnosis 17

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Thomas took mirtazapine but the sedative effects disrupted his…

Age at interview 34

Gender Male

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Collette changed from mirtazapine to duloxetine, which…

Age at interview 28

Gender Female

Age at diagnosis 19

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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.

Sonia felt some benefits from taking mirtazapine but gained…

Age at interview 31

Gender Female

Age at diagnosis 17

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Catherine was put on mirtazapine and felt it helped alleviate…

Age at interview 41

Gender Female

Age at diagnosis 14

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Monoamine oxidase inhibitors (MAOIs)

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.

Flora had tried other antidepressants that hadn’t worked for her…

Age at interview 43

Gender Female

Age at diagnosis 21

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Using an antidepressant: tricyclics (TCAs)

Tricyclic antidepressants (TCAs) are an older type of antidepressant. They are no longer regarded as a first-line treatment for depression because an overdose can be...

Coping with antidepressant side effects

Not everyone gets side effects, but side effects of antidepressants can cause problems particularly when people start taking a new one. It can take several...