SSRIs (Selective Serotonin Reuptake Inhibitors) Antidepressants NCLEX Nursing Review

SSRIs (Selective Serotonin Reuptake Inhibitors) are medications that are used as antidepressants. This review will discuss the mechanism of action of SSRIs, what conditions they treat, nursing implications, side effects, and patient education.

Don’t forget to watch the SSRIs lecture and to take the SSRIs NCLEX questions quiz  after reviewing this material.

Selective serotonin reuptake inhibitors (SSRIs): are a group of medications that inhibit the reuptake of the neurotransmitter serotonin. This helps increase serotonin levels in the brain.

This action makes these medications helpful in treating depression (most often used). They also treat:

• Anxiety and Panic disorders
• Compulsion disorders
• PTSD

How to recognize them? Generic name gives some clues on if it is an SSRI, but this isn’t the case with all the medications. Below are ones used here in the U.S.

• Paroxetine
• Fluoxetine
• Fluvoxamine
• Sertraline
• Citalopram
• Escitalopram
• Vilazodone

How do SSRIs work…mechanism of action?

Goal: Block the reuptake of the neurotransmitter serotonin by the releasing neuron so more is available to be used at the synaptic cleft for the receptor site on the post-synaptic neuron.

Since SSRIs help increase levels of serotonin in the brain, and they may be helpful in treating depression and other disorders.

Why does depression occur? There are many theories as to why depression occurs. One theory is that it’s caused by an imbalance in neurotransmitters and one of those neurotransmitters may be a decrease in serotonin.

In order to understand the mechanism of action of SSRIs, let’s review the role of neurons and neurotransmitters, specifically serotonin.

Neurons are the functional part of the brain that allows our brain to function. They have a special job of sending and transmitting information to other neurons, glands, and muscles.

However, in order to get their message across or communicate it, they must release specific neurotransmitters.

Neurotransmitters are chemical agents that give the details on what type of message is being sent. There are different types of neurotransmitters in the body and each has its own function.

Some neurotransmitters have the ability to send exciting messages (excitatory neurotransmitters), and this message will stimulate the brain. While others have the ability to inhibit messages (inhibitory transmitters), and this calms the brain. Then some neurotransmitters can be both excitatory and inhibitory.

Serotonin is an inhibitory neurotransmitter. It calms the brain and makes us experience happiness.

Serotonin type neurons are found in the brain stem in the raphe nucleus. Serotonin has a major influence on our:

• mood (allowing you to feel happy and gives you mental stability)
• emotions
• memory
• sleeping schedule
• appetite
• GI digestion

So in other words, in order for us to function properly, we need a balance of serotonin (not too high or too low….either side of this spectrum leads to adverse effects).

Now let’s look at how serotonin is released from the neuron and how SSRIs work to enhance the availability of serotonin in the brain.

Above is an example of a serotonin receptors and how it is communicating with another neuron. The pre-synaptic neuron receives a signal and to communicate that signal/message to the other structures (hence the post-synaptic neuron) it releases a chemical agent (the neurotransmitter) called serotonin.

Serotonin enters the synaptic cleft (this is just a fancy term to describe the space between the pre and post synaptic neuron) and locks onto its receptor on the post-synaptic neuron, which causes a generation of signals (calms the brain).

However, there is left over serotonin in the synaptic cleft and it needs to be cleared out of this space so this process can continue smoothly. Plus, the body likes to be resourceful and minimize its waste of neurotransmitter.

To accomplish this, certain processes can be done to remove the left behind neurotransmitter and recycle it from further use. One way some of the serotonin is removed from this space is through the help of a protein transporter called serotonin-transporter (SERT). SERT helps transport the serotonin back into the pre-synaptic neuron that released it.

But how does this process change when a SSRIs is onboard?

The SSRI is going to block the serotonin-transporter (SERT) from transporting serotonin back into the pre-synaptic neuron. In turn, more stays in the synaptic cleft and is available for use at the receptor site. This can help the patient who is experiencing low serotonin levels with depression.

SSRIs Nursing responsibilities, Side effects, and Patient Education

Remember “SSRIs”

Symptoms start to improve around a month to six weeks

• Educate: takes time to work, don’t stop taking, and if experiencing side effects they usually start to ease after this time
• Assess baseline signs and symptoms and re-evaluate if the medication is helping the patient’s signs and symptoms.

Slowly taper off with assistance of prescriber…don’t quit suddenly (some patients feel better and don’t want to take the medication anymore and others don’t like the side effects)

• Why taper off? The body is use to the amount of neurotransmitter it’s receiving and must slowly be readjusted to the change in the amount.
  • Discontinuation syndrome can happen and last for a week or so (very uncomfortable for the patient):
    • “STOP”
    • Stomach pain with diarrhea/nausea
    • Trouble sleeping
    • Off balance (dizzy, ataxia)
    • Peculiar sensations (electrical shocks, tingling, numbness)

Risk for suicidal thoughts in young adults and possible adverse effects in pregnancy and breastfeeding (depends on the SSRI)

• Assess for thoughts of suicide or self-harm
• Assess patient’s plans on having a baby, if pregnant (associated with heart defects and persistent pulmonary hypertension of the newborn (PPHN), or breastfeeding

Interaction w/ other medications

• Serotonin Syndrome: occurs when serotonin levels increase too high. Tends to happen when SSRIs are combined with other medications or substances that increase serotonin levels too.
  • Education: Avoid MAOIs, certain opioids, OTC cold medications “dextromethorphan”, alcohol, migraine medications “triptans” St. John’s Wort, Cocaine
  • SEROTONIN (HIGH)
• Sweating (shivers)
• Elevated Temperature and Heart rate
• Rigidity of muscles
• Overactive reflexes
• Tremors/twitching (seizures)
• Ophthalmic changes (pupil dilation)
• Nausea/vomiting (diarrhea)
• Irritable/confused
• Nervousness (anxiety)

Side effects of SSRIs (main)

• Tend to ease off overtime
• GI disturbances (n/v…take with food…remember serotonin influences the GI system, diarrhea), low libido or erectile dysfunction, weight gain, insomnia (take in the morning), dry mouth (sugarless gum, good dental care)

References: