antidepressants

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Introduction

Antidepressants are medications used in the treatment of depression, but many can also be used in conditions such as anxiety disorders and obsessive compulsive disorder. Most antidepressants are taken orally.

What we already know

To understand antidepressants, it is important to understand the key biological theory of what causes depression. Although not fully clear, depression may be caused by a deficit of monoamine neurotransmitters (e.g serotonin, noradrenaline, dopamine) at certain sites in the brain and so most antidepressants aim to restore this deficit.

Antidepressants can be divided into six groups, based on their mechanism of action:

  1. Selective Serotonin Reuptake Inhibitors (SSRIs)“ e.g. Citalopram, Sertraline
  2. Serotonin-Noradrenaline Reuptake Inhibitors (SNRIs)“ e.g. Venlafaxine, Duloxetine
  3. Noradrenergic and Specific Serotonergic Antidepressants (NaSSAs) e.g. Mirtazapine
  4. Tricyclic Antidepressants (TCAs)“ e.g. Amitriptyline, Imipramine
  5. Monoamine Oxidase Inhibitors (MAO-Is) e.g. Phenelzine, Moclobemide
  6. Miscellaneous“ e.g. Bupropion, Trazodone, Reboxetine

Side effects depend on the mechanism of action and can vary from person to person.

NICE guidelines suggest use of antidepressants in moderate or severe cases of depression only. The risks of antidepressant medication use in mild depression outweigh the risks, so other forms of therapy are recommended in these cases.

Areas of uncertainty

  • The exact mechanisms of action – we are yet to find out exactly why and how many of the antidepressants work (there are inconsistencies in the monoamine theory of depression)
  • How to limit side effects associated with antidepressant use
  • Using antidepressants in special groups -“ limited data exists for which antidepressants (if any) are best to use in pregnant women, children and the elderly

What’s in the pipeline

  • Ketamine has been shown to have promising antidepressant effects, although further randomised placebo-controlled trials are needed (Coyle and Laws, 2015)
  • Research is ongoing into the biological causes of depression and it is hoped that when this is better understood, therapy can be targeted towards the exact cause
  • Further research is also being conducted into the long term effects of antidepressants

References

NICE guidelines CG90 (2009) ‘Depression in adults: The treatment and management of depression in adults’ [PDF]

Semple, D. and Smyth, R. (eds.) (2013) Oxford Handbook of Psychiatry. 3rd ed. Oxford: Oxford University Press. (Publisher)

Coyle, C. M. and Laws, K. R. (2015), ‘The use of ketamine as an antidepressant: a systematic review and meta-analysis.’ Hum. Psychopharmacol Clin Exp, doi: 10.1002/hup.2475 [Abstract]

Our antidepressants Blogs

Combined methylphenidate and citalopram may help older people with depression recover faster

Depressed older man

Lisa Burscheidt summarises a recent randomised controlled trial of combined methylphenidate and citalopram for depression in older people, which presents promising but limited findings.

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Antidepressants for depression in cancer: Cochrane review highlights lack of evidence

Female cancer patient

Kirsten Lawson reports on a recent Cochrane systematic review, which highlights a lack of high quality trials about the efficacy and safety of antidepressants for depression in cancer.

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Medication for self-harm: new Cochrane review finds very limited evidence to support its use

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Dochka Hristova reports on a new Cochrane review of pharmacological interventions for self-harm in adults, which looks at the treatment effect on repetition of self-harm of antidepressants, antipsychotics, mood stabilisers and dietary supplements.

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Psychotropic medications: scale and patterns of prescribing to people with learning disabilities

shutterstock_38537203 two bottles of drugs

In this blog, John Northfield considers a study of rates and patterns of prescribing psychotropic medications by GPs to people with learning disabilities and/or autism.

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Antidepressants during pregnancy and risk of persistent pulmonary hypertension of the newborn

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Meg Fluharty examines the findings of a recent study, which looks at the risk of persistent pulmonary hypertension of the newborn (PPHN) when mothers take antidepressants during pregnancy.

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Pharmacotherapy for anxiety and comorbid alcohol use disorders

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Natasha Clarke summarises a recent Cochrane review of pharmacotherapy for anxiety and comorbid alcohol use disorders, which found only very low quality evidence about the effectiveness of medication (buspirone, paroxetine, sertraline) for treating patients with both conditions.

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Dose equivalents of antidepressants: standardising prescribing between different drugs

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Andrew Shepherd summarises a meta-analysis, which looks at the dose equivalents of antidepressants by bringing together data from 83 trials of 23 different antidepressants.

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Pharmacotherapy for PTSD: an update on the evidence finds some efficacy but small effect sizes

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Patrick Kennedy-Williams summarises a recent systematic review of pharmacotherapy for PTSD, which compares antidepressants with placebo for post-traumatic stress disorder. [Please note: this blog was amended on 7/5/15].

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Mindfulness-based cognitive therapy to prevent depression

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André Tomlin presents the results of the PREVENT RCT published today in The Lancet, which investigates the effectiveness and cost-effectiveness of mindfulness-based cognitive therapy compared with maintenance antidepressant treatment in the prevention of depressive relapse or recurrence.

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