(6) Unit 1 - Drug therapy (antidepressants)

What is the purpose of antidepressant drugs?

Used to tackle the symptoms of unipolar depression (the most common form of depression).

How mant types of antidepressants are there?

Three: MAOIs, SSRIs and tricyclics.

When does depression occur?

When there are low levels of serotonin in the brain.

What are MAOIs?

Monoamine oxidase inhibitors.

How do MAOIs work?

By blocking the enzymes that break down serotonin in the brain. Depressed individuals have very low levels of this biochemical; therefore, it is not beneficial for a depressive to have any more serotonin broken down. By blocking the MAO enzymes that decrease serotonin production, serotonin levels are increased, and the depressed person begins to feel happier.

What is an example of an MAOI?

Phenelzine.

What are SSRIs?

Selective serotonin reuptake inhibitors.

How can depression sometimes occur?

One reason for such low levels of serotonin is that the reuptake of serotonin back into the presynaptic neuron occurs too soon. This means that there is a lack of appropriate communication between presynaptic and postsynaptic neurons.

How do SSRIs work?

Aim to increase levels of serotonin by binding onto the presynaptic neuron in order to prevent the serotonin in the synapse from reabsorbing back into it. This increases the amount of serotonin in the synapse, which will then pass onto the postsynaptic neuron. This increases communication between the two neurons and will eventually lessen, or eradicate, the symptoms of depression.

What are some examples of SSRIs?

Fluoxetine and citalopram.

How do tricyclics work?

These tablets work in a similar way to SSRIs, but they block noradrenaline and serotonin whereas SSRIs only block serotonin.

What are some examples of tricyclics?

Amitriptyline and doxepin.