Drugs for Depression

Note: Serotonin, noradrenaline and dopamine are all chemical compounds in the body known as neurotransmitters that are all important for happiness and positive mood. This explains why these three neurotransmitters are the target for drugs to treat depression.

Drug How They Work Pros Side Effects and Risks
Selective serotonin uptake inhibitors (SSRIs)
  • Block the re-uptake of serotonin specifically in the brain rather than in other areas of the body -> increases the activity of serotonin in the brain
  • Used as first-line antidepressant
  • High efficacy
  • Low side effect profile
  • Tolerated better by patients compared to other anti-depressants
  • Can also be used to treat anxiety
  • Nausea, vomiting, agitation
  • Weight changes
  • Sexual dysfunction
  • For adolescents – anxiety and suicidal tendencies can occur when taking the drug for the first time
Serotonin/ noradrenaline reuptake inhibitors (SNRIs)
  • Block the re-uptake of serotonin and noradrenaline in the brain -> increases the activity of noradrenaline and serotonin in the brain
  • Most effective antidepressant for treating major depressive disorder
  • Nausea, dizziness, sweatiness
  • Headaches
  • Sexual dysfunction
Atypical antidepressants
  • Variable mechanism of action depending on the exact drug -> all drugs increase the activity of either serotonin, noradrenaline, dopamine or melatonin in the brain
  • Useful for patients who cannot tolerate the side effects of SSRIs or SNRIs, such as weight loss or disruption to sleep cycle
  • Nausea, dizziness, insomnia
  • Dry mouth
  • Weight gain
  • Seizures
Tricyclic antidepressants
  • Block the uptake of noradrenaline and serotonin in the brain -> increases the amount of noradrenaline and serotonin circulating in the brain
  • Additionally block histamine and cholinergic receptors in the brain -> very non-selective which can lead to adverse effects
  • Useful for patients who suffer from other psychiatric conditions such as panic attacks, anxiety, PTSD and bulimia nervosa
  • Hyperthermia
  • Muscle rigidity
  • Cardiovascular collapse
Monoamine-A oxidase inhibitors (MAOIs)
  • Block the action of the enzyme that breaks down serotonin, noradrenaline and dopamine -> ultimately increases the level of these neurotransmitters in the brain
  • Useful for patients who cannot tolerate the side effects of other antidepressant medications
  • Many drug-drug interactions and drug-food interactions
  • Hyperthermia
  • Muscle rigidity
  • Cardiovascular collapse