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What are the depression medications and how do they work?

How do depression medications work?

The depression medications work through their effect on the biochemistry of the brain which then affects our thinking processes. Our thoughts, actions and moods are activated by the nerve cells in the brain which are referred to as neurons. The thoughts, actions and moods that we experience in our daily lives involve neurons in specific areas of the brain being activated and then communicating with other neurons using a biochemical referred to as a neurotransmitter. These neurons frequently work together with other neurons, which then form networks in specific areas of the brain which allows us to complete specific actions and thought processes.

Some of the main biochemical messengers (neurotransmitters) which communicate with other neurons when completing thoughts and actions are of specific biochemical types including norepinephrine and serotonin. There are other neurotransmitters that are very important to our lives and functioning such as dopamine, which is involved in various mental processes such as when you feel pleasure or happiness. However, the neurotransmitters norepinephrine and serotonin have been found to correlate highly with how a person thinks and feels and experiences specific moods. Depression medications tend to primarily increase these two neurotransmitters. Medications of these types are usually referred to as SSRI’s or selective serotonin reuptake inhibitors. The SSRI’s are believed to focus on increasing the level of serotonin even though their selectivity is now somewhat controversial. Some of the newer antidepressant medications are known to increase both serotonin and norepinephrine and are referred to as serotonin norepinephrine reuptake inhibitors or SNRI’s.

There are some depression medications that have been around for a long time including the tricyclic antidepressants and monoamine oxidase inhibitors or what are referred to as MAOI’s. These medications are believed to affect several of the neurotransmitters in the brain rather than selectively affecting just serotonin and norepinephrine.

Antidepressant Medication: Selective Serotonin Reuptake Inhibitors:

As previously mentioned, these depression medications are believed to selectively affect the neurotransmitter serotonin in the brain. This selectivity however is currently in debate among researchers and doctors. The description of selective serotonin reuptake inhibitors may not be an accurate description due to this debate of their selectivity. However, although this issue is somewhat controversial they are still referred to in conventional medicine and by physicians as belonging to the SSRI class of medications. The SSRI depression medications follow.

Selective Serotonin Reuptake Inhibitors:


Additional depression medications also have some effect on the serotonin level of the brain but are not usually referred to as selective serotonin reuptake inhibitors. These include:

trazodone (Desyrel)
vilazodone (Viibryd)
etoperidone (Axiomin, Etonin)
vortoxetine (Brintellix)
buspirone (BuSpar)

These medications are also included in this section due to their similar side effect profile.

The SSRI’s seem to be generally well tolerated but do have some common side effects which include drowsiness, difficulty achieving an orgasm and heartburn. More specific side effects are included in relation to specific medications on their respective pages. They can also affect a loss of appetite at times and have been known to also interact poorly with other medications. You should always consult your pharmacist or physician prior to mixing these medications with any other drugs.

Serotonin Norepinephrine Reuptake Inhibitors (SNRI):

One of the more recent depression medications which are marketed for their effect on both norepinephrine and serotonin are the serotonin norepinephrine reuptake inhibitors. The medications which fall within this category follow.

Serotonin Norepinephrine Reuptake Inhibitors:

venlafaxine (Effexor)
tofenacin (Elamol, Tofacine)
dezvenlafaxine (Pristiq)
duloxetine (Cymbalta)
levomilnacipran (Fetzima)
milnacipran (Ixel, Savella)

Additional depression medications that affect primarily serotonin along with norepinephrine are also not included in the category of SSRI’s including:

setiptline (Tecipul)
mirtazapine (Remeron)

There are many critics of the medication classification system which state that medications seem to be classified in a rather arbitrary way possibly to switch patients from one drug class to another if their previous medication does not seem to work.

Many of the same negative side effects listed for the SSRIs can also be included in the side effect profile for SSRI’s. These may include withdrawal symptoms and possible tardive dysphoria. Duloxetine (Cymbalta) and venlafaxine (Effexor) have both been included in the top five medications reported to the FDA MedWatch associated with very serious concerns such as violence including injuries to self, suicidal tendencies and possible homicidal ideation.

Depression Medication: The tricyclics

The tricyclic antidepressant medications are some of the older depression medications going back several decades. Their name is derived from their chemical structure and are still believed to be effective in combating depression for some people. Unfortunately, they have some side effects which are troublesome for some people that are not shared by the newer SSRI’s and SNRI medications. Some of the primary side effects which seem to be of concern to many people are dry mouth, constipation and drowsiness. Once again, more specific side effects associated with each medication are identified on the individual antidepressant medication pages.

Tricyclic Antidepressant Medications:


All of the tricyclic depression medications are now in generic forms and produced by additional manufacturers.

The Monoamine Oxidase Inhibitors (MAOI’s):

Another classification of medications that have been around for several decades and are still in use are the monoamine oxidase inhibitors or the MAOI’s. They are still found to be effective for some types of depression. However, one of the primary concerns with MAOI’s is that they have very serious, even potentially life-threatening concerns for interaction with other drugs. Your doctor needs to be very involved when taking these medicines in helping you to avoid foods that may interact poorly with these medications resulting in life-threatening consequences.

Monoamine Oxidase Inhibitors (MAOIs):

Parnate (tranylcypromine).
Nardil (phenelzine)

Miscellaneous Antidepressants:

A final category of depression medications that really do not fit well in other specific categories include the following:

Serzone (nefazodone)
Wellbutrin (bupropion
Remeron (mirtazapine)

Depression Medications: Conclusion

Depression medications have evolved significantly over the last several decades with the introduction of newer medications including the selective serotonin reuptake inhibitors and the selective norepinephrine reuptake inhibitors. These medications are frequently selected for their effectiveness for specific symptoms as well as well as their respective side effect profiles. Although these medications are marketed according to specific categories as previously mentioned, these categories do not always represent the selectivity and specificity of the neurotransmitters that are affected. Also, older antidepressants such as the tricyclic antidepressants have had a long history and continue to demonstrate effectiveness for some mood disorders, although the side effect profile seems to be more troublesome for some individuals.

By Paul Susic Ph.D. Licensed Psychologist

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