Understanding The Different Types Of Antidepressants

Antidepressants are a popular choice of medication used to treat depression. Depression affects or happens due to chemical imbalances in the brain. Antidepressants can help correct the anomalies and treat depression by curbing the symptoms slowly.

5 Major Types of Antidepressant Are:

Most antidepressants can be classified broadly into 5 major classes. They are Selective Serotonin Reuptake Inhibitors (SSRIs), Serotonin and Norepinephrine Reuptake Inhibitors (SNRIs), Tricyclic Antidepressants (TCAs), Monoamine Oxidase Inhibitors (MAOIs) and Atypical Antidepressants.

• Selective Serotonin Reuptake Inhibitors (SSRIs)
• Serotonin and Norepinephrine Reuptake Inhibitors (SNRIs)
• Tricyclic Antidepressants (TCAs)
• Monoamine Oxidase Inhibitors (MAOIs)
• Atypical Antidepressants

1. Selective Serotonin Reuptake Inhibitors (SSRIs)

These are the most commonly used type of antidepressants. Selective Serotonin Reuptake Inhibitors prevent reabsorption (reuptake) of neurotransmitters in the body. By inhibiting the reabsorption in the body, these types of antidepressants make sure that there are more available in the brain. SSRIs are devised to inhibit the uptake of serotonin mostly. That is how they increase serotonin levels in the brain and help it to function better. Selective Serotonin Reuptake Inhibitors were first developed during the 1970s.

Side Effects of Selective Serotonin Reuptake Inhibitors (SSRIs)

These types of antidepressants have fewer side effects than others. SSRIs also have fewer drug interactions and are much less likely to be associated with suicide.

• Headache
• Nausea
• Diarrhoea
• Vomiting
• Insomnia
• Nervousness, tremors
• Agitation, restlessness
• Sexual dysfunction
• Unwanted weight gain or loss

Use of Selective Serotonin Reuptake Inhibitors (SSRIs)

SSRIs are used to treat the following illnesses:

• Depression
• Obsessive-Compulsive Disorder (OCD)
• Generalized Anxiety Disorder (GAD)
• Premature ejaculations
• Eating disorders

2. Serotonin and Norepinephrine Reuptake Inhibitors (SNRIs)

SNRIs work precisely in the same way except for one thing. Serotonin and Norepinephrine Reuptake Inhibitors inhibit the reabsorption of both serotonin and norepinephrine. SNRIs help to make serotonin and norepinephrine more abundant around the nerve tissues. The first Serotonin and Norepinephrine Reuptake Inhibitor was approved by the Food and Drug Association (FDA) in December 1993.

Side Effects of Serotonin and Norepinephrine Reuptake Inhibitors (SNRIs)

Drug interactions and side effects of SNRIs are:

• Unwanted weight loss or gain
• Agitation, restlessness
• Insomnia
• Sexual dysfunction
• High blood pressure
• Nausea
• Drowsiness, fatigue
• Constipation
• A dry mouth

Use of Serotonin and Norepinephrine Reuptake Inhibitors (SNRIs)

SNRIs are used to treat the following illnesses:

• Depression
• Generalized Anxiety Disorder (GAD)
• Post Traumatic Stress Disorder (PTSD)
• Social Anxiety Disorder (SAD)
• Panic Disorder
• Nerve pain associated with fibromyalgia
• Chronic pain

Breakthrough depression or worsening depression happens in 1/3 of people taking anti-depressants when the medications stop working and do not show any benefits and the symptoms worsen, it would be essential to follow up with your doctor if you experience worsening symptoms of depression.

Dr. Ashish Bajaj, M.B.B.S., M.D. in Clinical Pharmacology and Toxicology

3. Tricyclic Antidepressants (TCAs)

TCAs are an older class of drugs. They were first discovered in the 1950s. Tricyclic Antidepressants are made up of three interconnected rings of atoms. The drug gets its name from its structure. Tricyclic antidepressants block the absorption of serotonin, norepinephrine and acetylcholine into nerve cells. Acetylcholine helps to regulate the movement of skeletal muscles. Some Tricyclic Antidepressants are also antihistamines. They work by blocking the action of histamine in the body.

Side Effects of Tricyclic Antidepressants (TCAs)

Side effects of TCAs are:

• A dry mouth
• Constipation
• Urinary retention
• Visual disturbances
• Sexual dysfunction
• Sedation
• Unwanted weight gain
• Orthostatic Hypotension (low blood pressure when standing)
• Abnormal heart rhythms
• Dizziness leading to falls and fractures

Use of Tricyclic Antidepressants (TCAs)

TCAs are used to treat illnesses like:

• Depression
• Chronic pain from various illnesses
• ADHD (Attention Deficit Hyperactivity)

Tricyclic Antidepressants were used to treat ADHD in children before but has now been replaced with more effective drug agents that have fewer side effects than TCAs.

Also Read: Physical and Mental Signs of Depression

While antidepressants are beneficial in treating depression and its other indications, many patients fail to receive adequate treatment. To effectively manage depression, a clinician must employ an interprofessional team-centered approach to effectively detect and diagnose the depression, provide patient education, use evidence-based pharmacotherapy, provide close-follow up for compliance, identify side effects, and determine treatment effectiveness.

Dr. M.G. Kartheeka, MBBS, MD(Pediatrics)

4. Monoamine Oxidase Inhibitors (MAOIs)

MAOIs were first discovered in the 1950s and were the first class of antidepressants to be ever developed. They inhibit an enzyme known as monoamine oxidase, whose role, in turn, is to break down monoamines. Monoamine Oxidase breaks down serotonin, norepinephrine and dopamine, thus decreasing their concentration. Monoamine Oxidase Inhibitors elevates the level of mood-regulating neurotransmitters by blocking the action of monoamine oxidase.

Side Effects of Monoamine Oxidase Inhibitors (MAOIs)

The side effects of MAOIs are:

• Headache
• Insomnia
• Nausea
• Vomiting
• Sweating
• Decreased libido
• Dilated pupils
• Hypertension
• Heart palpitation
• Chest pain
• Neck stiffness or soreness
• Brain haemorrhage (Bleeding in or around the brain)
• Orthostatic hypotension
• Peripheral oedema (swelling of lower legs and ankles)

Use of Monoamine Oxidase Inhibitors (MAOIs)

MAOIs are used to treat illnesses like:

• Agoraphobia
• Social phobia
• Bulimia
• Borderline personality disorder
• PTSD
• Bipolar depression

However, the use of Monoamine Oxidase Inhibitors is reserved only when other antidepressant options have failed.

5. Atypical Antidepressants

There are some antidepressants that do not fit into any of the above categories. They are broadly described as Atypical Antidepressants, and they affect serotonin, dopamine, and norepinephrine in unique ways.

Side Effects of Atypical Antidepressants Include

• Constipation
• A dry mouth
• Dizziness
• Nausea
• Insomnia
• Blurry vision
• Weight gain
• Sexual dysfunction

Antidepressants should never be taken without consulting a doctor first. It is best to talk about the side effects and solve them together with your doctor.

Also Read: How to Help Someone With Depression?

How Do Antidepressants Work?

There are three principal neurotransmitters in the brain that regulate your mood. They are:

1. Serotonin: This neurotransmitter regulates mood, sleep, appetite, memory, sleep, social behavior and libido.

2. Norepinephrine: This neurotransmitter influences motor function, and alertness and helps to regulate heart rate and blood pressure in case of a lot of stress.

3. Dopamine: This neurotransmitter plays a pivotal role in motivation, decision-making, signalling of pleasure and reward and arousal.

Antidepressants Dosage

How much, how often and what is the best antidepressant for your case are questions only your doctor will be able to shed light on. In this context, your doctor will be a psychiatrist. Since antidepressants come in tablet form, your doctor will advise you on what strength tablets you need and how often you need to take them (such as weekly, bi-weekly, daily, etc). You will experience most of your symptoms within the first couple of weeks as your body adjusts to the new medicine, but these will mostly disappear eventually.

Completing Your Course

It is very important to stick to your antidepressant regime for the entire course prescribed by your doctor. Stopping suddenly or not completing it can result in many issues from stronger depression recurrence to other psychological and physical problems (like withdrawal from antidepressant drugs). Your doctor will slowly reduce the dosage and frequency of your medication over weeks or months when it is time for you to stop.  

People with depression suffer from low availability of these neurotransmitters. Antidepressants help by increasing the level of these neurotransmitters. Different classes of antidepressants act on various neurotransmitters. Psychiatrists usually prescribe antidepressants to patients, along with talk therapy.

Read More:  Treatment for Depression – Medication, Therapy & Other Ways

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