The 5 Major Classes of Antidepressants
Depression is a growing concern of healthcare in the 21st century and it’s a second-leading disability in the world, right behind cardiovascular diseases.
More and more people are falling prey to this insidious illness and opinions on its causes and treatments differ as we are still unable to treat it with 100% efficiency.
Doctors agree that the causes for depression are physiological, psychological and environmental in nature.
Psychiatrists usually start treating patients by determining if there are physiological causes for depression.
Even when there are no such causes, psychological distress alone can destabilize physiology and antidepressants may come in handy to bring back the homeostatic balance before the psychotherapy enters the scene.
However, many doctors are quick to pull the trigger with antidepressants even though some of these medicaments aren’t to be trifled with.
After all Big Pharma earns a significant amount of money from antidepressants and you can imagine how the good doc gets his slice of cake as well.
Moreover, many patients with self-diagnosed depression jump straight to treating themselves with happy pills so knowing your drugs may prove to be useful seeing how their popularity grows.
CLASSES OF ANTIDEPRESSANTS
We all know that antidepressants help mechanically articulate the dysfunction of our brain-chemistry and neurotransmitters trafficking through the nerve routes to and from the brain.
Antidepressants group to form classes depending on the way they affect our central nervous system.
Drugs belonging to the same class usually have somewhat similar mechanisms of action or side effects.
The difference in the chemical structure of the drugs can decide on how well our body will absorb, tolerate and disseminate the drug.
There are 5 major classes of these drugs and a few others that are not that frequently used.
Each class has its own advantages, disadvantages and appropriate uses.
Provided that your doctor is conscientious and not just mechanically prescribing, he/she will closely examine your symptoms, medical history, and coexisting disorders to determine the right kind of a drug for you.
The 5 classes they usually choose from are SSRIs, SNRIs, TCAs, MAOIs, and Atypical Antidepressants. You’re enlightened now, huh?
Kidding, we’ll get right to what they are, but first of all, an explanation of what they do is in order.
HOW DO ANTIDEPRESSANTS WORK
Your mood regulation seems to come down to 3 basic molecules that go by the name of monoamines.
They primarily function as neurotransmitters which means they literally transmit signals from the nerves to their matching receptors in the central nervous system.
Antidepressants usually have a great impact on the function of the mentioned neurotransmitters.
It’s usually the case with people suffering from depression that the levels of the mentioned neurotransmitters in their brains are low.
Antidepressants usually work by increasing the levels of one or several neurotransmitters in different ways.
Now, before we jump to specific classes of antidepressants, let’s see which neurotransmitters are the antidepressants dealing with.
Nota bene: If you don’t want to get into the boring neurochemical data, you may as well skip the next chapter and jump straight to “SSRIs”.
THE MAIN NEUROTRANSMITTERS IN CHARGE OF MOOD REGULATION
Serotonin – or 5-hydroxytryptamine or 5-HT is composed of tryptophan (protein chain) and tryptophan hydroxylase (a chemical reactor).
It regulates mood (duh), memory, sleep-wake cycles, internal clock, appetite, digestion, sexual desire (or libido as they call it), social behavior and such.
An interesting thing about serotonin is that it occurs evenly throughout the body and it doesn’t only influence psychological functions in the brain like the release of melatonin and circadian rhythm.
It also has an impact on the function of smooth muscles, bowel movements, gastrointestinal tract, etc. That’s why some consider it a hormone and not just neurotransmitter.
Nota bene: Serotonin doesn’t cross the blood-brain barrier so all serotonin used by the brain, must be produced somewhere in the central nervous system as well.
Dopamine – (DA, a contraction of 3,4-dihydroxyphenethylamine) influences decision-making, arousal, pleasure-reward signals, and motivation.
Dopamine functions both as a neurotransmitter and a hormone and plays important roles in the body and the brain alike.
It’s synthesized in the brain and kidneys as well as plants and most animals.
The brain has several different dopamine pathways. One of its most popular pathways plays a role in reward-motivated behavior.
Other dopamine pathways influence motor control and release of various other hormones.
Dopamine is popularized as the main chemical of pleasure, but the current pharmacological opinion is that it confers motivational salience rather than pleasure directly.
Important things to note about dopamine are that its levels are affected by other mental disorders as well, such as schizophrenia (heightened dopamine) and ADHD.
Same as serotonin, dopamine can’t reach the brain from the bloodstream. Except for the blood vessels, dopamine is synthesized locally in all peripheral systems where it exerts effect and near the releasing cells.
It’s interesting that dopamine inhibits the release of the next important neurotransmitter – norepinephrine.
Norepinephrine – NE also called noradrenalin NA is an organic chemical in the family of catecholamine. It functions in both body and brain as a hormone and a neurotransmitter.
It influences alertness, blood pressure, motor functions, heart rate, etc. The name “noradrenaline” is derived from Latin which means “alongside kidneys” and that suggests the place where it’s synthesized.
Its general function is to mobilize the organism (brain and body) for action. Its levels are lowest during sleep, they rise when we wake and are at their peak during stress where they impact the fight-or-flight response.
Norepinephrine increases arousal, vigilance, alertness, memory retrieval, attention as well as anxiety.
It increases blood pressure, heart rate, the release of glucose, blood flow to skeletal muscles, pupil dilation by contracting the iris.
It can be released directly into the bloodstream by adrenal glands to combat low blood pressure in the state of medical emergencies.
Now you know what the antidepressants are dealing with here, at least to an extent.
The following are the 5 major classes of antidepressants prescribed by the psychiatrists:
1. Selective Serotonin Reuptake Inhibitors (SSRIs)
So this is how it works:
Neurotransmitters get attached for the matching receptors in the brain but after a while, they get reabsorbed and their function dissipates.
Reuptake inhibitors block or prevent that absorption from happening so that they prolong the effect of serotonin in your central nervous system or your body.
Selective serotonin reuptake inhibitors work by specifically preventing the reabsorption of serotonin which prolongs the effects of serotonin and by now you surely know what they are.
SSRIs are a newer class of antidepressants that developed in 1970.
Examples of such antidepressants include:
- Prozac (fluoxetine)
- Paxil (paroxetine)
- Zoloft (sertraline)
- Celexa (citalopram)
- Luvox (fluvoxamine)
- Lexapro (escitalopram)
- Viibryd (vilazodone)
They usually have fewer contraindications and side effects than other antidepressants.
However, some of their side effects may include nausea, insomnia, anxiety, nervousness, diarrhea, weight gain or loss, sweating, dizziness, and tremors.
Symptoms of depression are sometimes known to worsen before the positive impact of SSRIs is noticed, but that should only go for the first month of treatment.
SSRIs don’t start working before the period of 2-4 weeks has passed and their side effects should decrease in that time as well.
The FDA requires for all antidepressants to have a black-box warning about the suicidal ideation during initial stages of treatment, especially in adolescents and children.
All of that doesn’t really scream “depression treatment” right? Still, these are some of the best drugs that the market offers.
SSRIs don’t just treat depression, but OCD, anxiety disorders, premature ejaculations, eating disorders, etc.
They are known to help during recovery from strokes as well.
There is a possibility of SSRIs causing excessive stimulation of the 5-HT receptors. That is called serotonin syndrome or serotonin toxicity and it usually occurs when a person takes more than one serotonin-boosting drugs at the same time.
Acute serotonin syndrome can be life-threatening in 2 to 12% of examined cases.
Its symptoms include seizures, unconsciousness, high fever, and, in some cases, irregular heartbeats.
Discontinuation of the medication is usually enough to reverse the symptoms.
2. Serotonin and Norepinephrine Reuptake Inhibitors (SNRIs)
These antidepressants work do basically the same thing as SSRIs do, with the addition of inhibiting the reuptake of norepinephrine as well. That is why they are called “dual-action antidepressants”.
The first SNRI was approved by the FDA in December 1993 and they are considered the second generation of antidepressants.
People suffering from stupor or a catatonic depression may be prescribed these types of drugs as they enhance physical movement and the speed of thought.
Patients with psychomotor ailments are treated with SNRIs as well.
Some of the SNRIs include:
- Effexor (venlafaxine)
- Cymbalta (duloxetine)
- Pristiq (desvenlafaxine)
- Savella (milnacipran)
- Fetzima (levomilnacipran)
Side effects of SNRIs include constipation, dry mouth, nausea, drowsiness, insomnia, etc.
Some SNRIs like duloxetine are known to treat chronic pain which is a condition closely related to the development of clinical depression.
They are also used to treat anxiety, social anxiety disorders (SADs), PTSD or post-traumatic stress disorder, panic disorder and nerve pain and fibromyalgia.
Contrary to popular belief, reuptake inhibitors do not cause addiction, but some withdrawal symptoms are still known to occur.
SNRIs among themselves differ to an extent as they harbor different pharmacological properties. It is still unknown whether these differences will become clinically relevant or not.
3. Trycyclic Antidepressants (TCAs)
Trycyclic Antidepressants belong to an older class of antidepressants first discovered and approved in the 1950s. Their chemical structure of three interconnected atom rings is what gave them their name.
They function somewhat similarly to previously mentioned reuptake inhibitors since they block the absorption of serotonin and norepinephrine into presynaptic nerve cells.
They also block or inhibit the reabsorption of another neurotransmitter called acetylcholine (ACh).
Acetylcholine mainly regulates the movement of skeletal muscles. Motor neurons of the nervous system use ACh to activate muscles.
That means that drugs that deal with cholinergic systems may have dangerous effects ranging from convulsions to paralysis.
In the brain, ACh has many effects on plasticity, reward as well as arousal. ACh plays an important role in alertness enhancement when we wake up. It also helps sustain attention and learning or memorizing.
Examples of TCAs include:
- Elavil (amitriptyline)
- Norpramin (desipramine)
- Asendin (amoxapine)
- Anafranil (clomipramine)
- Pamelor (nortriptyline)
- Tofranil (imipramine)
- Vivactil (protriptyline)
- Surmontil (trimipramine)
- Sinequan (doxepin)
Sometimes ludiomil or maprotiline is mentioned next to TCAs, although it belongs to the TeCas (tetracyclic antidepressants) seeing how it has a fourth atomic ring.
Common symptoms of TCAs include blurry vision, dizziness, weight gain, drowsiness, dry mouth.
In fewer occasions, they can cause low blood pressure, irregular heartbeats or even seizures.
Besides depression treatment, tricyclic antidepressants can help alleviate chronic pain.
They were once frequently used in treating ADHD (attention deficit hyperactivity disorder) in kids, but they have been replaced with more effective drugs with fewer contraindications.
4. Monoamine Oxidase Inhibitors (MAOIs)
One of the oldest and first classes of antidepressants were monoamine oxidase inhibitors. This class was first discovered in the 1950s.
MAOIs inhibit the functioning of an enzyme called monoamine oxidase. This enzyme’s function is to break down monoamines. By blocking the whole process, MAOIs allow more neurotransmitters to engage in mood regulation.
They are considered as effective as SSRIs and TCAs, but they are less frequently in use due to necessary dietary precautions as well as risks of adverse effects when mixed with other types of drugs.
Some of MAOIs in the market include:
- Nardil (phenelzine)
- Parnate (tranylcypromine)
- Marplan (isocarboxazid)
- Emsam (selegiline)
It’s important to note that MAOI treatment necessarily involves specific dietary restrictions.
Despite its obvious risks like nausea, anxiety, insomnia, drowsiness, convulsions, etc. it is a useful drug in battling PTSD, personality disorders and bipolar depression.
As with the TCAs, its use is prescribed usually when other antidepressant options fail.
5. Atypical Antidepressants
There are many other antidepressants that don’t really fit into any of the above-described categories.
These are described as atypical antidepressants as their mechanism of action greatly differs even though they also affect serotonin, norepinephrine or dopamine levels in our organisms.
Examples of atypic antidepressants include:
- Wellbutrin (bupropion) which is classified as a dopamine reuptake inhibitor. It’s used to treat the seasonal affective disorder and other mood disorders resembling depression as well as depression itself. It’s a great smoking cessation aid as well.
- Remeron (mirtazapine) is a noradrenergic antagonist used to treat major clinical depression by blocking stress hormone receptors of the brain.
- Oleptro (trazodone) and Brintellix (vortioxetine) are serotonin antagonist and reuptake inhibitors used to treat depression by inhibiting serotonin reuptake and blocking the adrenergic receptors.
- Symbax combines the Selective serotonin reuptake inhibitor fluoxetine with the antipsychotic fluoxetine in order to treat bipolar depression disorders or depression. which is generally treatment-resistant
Side effects of these antidepressants vary to a great degree, but the golden antidepressant classics such as dry mouth, insomnia, sexual dysfunction, blurry vision, convulsions, nausea, etc. are present.
THE EFFICIENCY OF ANTIDEPRESSANTS AND CONTROVERSIES
Some data suggest that 5 to 6 people out of every 10 will experience a certain improvement in mood regulation after 3 months of antidepressant use.
People who experience improvement should continue medicating for at least 6 months after the initial improvement. Patients who stop before 8 months of medicating often suffer recursive symptoms.
There’s data that suggests that long-term use of these drugs might worsen the symptoms in some patients.
It should be noted that antidepressants during pregnancy are not advised.
It’s a theory about the causes of depression being purely physiological and relating to the neurotransmitter imbalance in the nervous system.
Since it’s a hypothesis, it’s not yet scientifically proven and yet it’s the number 1 market supported therapy.
Some scientists are questioning whether the neurotransmitters indeed have a role in triggering depression.
Such examinations are, of course, not given attention by the global media or institutional practices as they undermine the business so to speak.
There’s also a growing concern that use of antidepressants could result with a natural serotonin depletion with long-lasting adverse effects.
The other problem of the whole pharmacotherapy is that it’s not possible to measure serotonin levels in the brain since serotonin doesn’t cross the blood-brain barrier and since it is produced in the brain and the gut as well. Same goes for dopamine and norepinephrine.
Researchers can’t know for a fact that the levels of neurotransmitters or hormones reflect their presence in the brain.
Moreover, there’s a possibility that the hormonal and neurotransmitter imbalance in the organism is not a cause, but the effect of the psychological ailment of depression.
There were animal studies that suggested that serotonin i.e. may not play a role in causing depression. The researches were done with mice with absolutely incapacitated serotonergic centers in their brains. They showed no signs of depression even when placed under severe stress.
However, other studies have proven that mice that lacked serotonin were more susceptible to social stressors. Talk about science being exact and up to the point, huh?
The situation with depression, its causes, nature, and effects is complex, to say the least. Science is still baffled by it and many theories try to explain its origin and suggest the ways of battling it.
Such diversity has opened the market for many agents that promise cures and successful treatments of the ailment.
Life coaches offer training on the streets, different modalities of psychotherapy have their own charms and there are spiritualists offering ceremonies and illegal, but natural remedies that oddly work in a similar manner as antidepressants, with the exception of being a couple of million years older than artificial drugs.
There is a great threat of laymen and crooks exploiting the affected, but then again… there’s a threat of the more institutionalized forms of treatment being equally illegitimate as well.
One should study all the different manners of therapy before opting for one.
The mere fact that there are two different callings and trainings, one psychiatric and the other psychological and psychotherapeutic, speak for themselves.
In theory, those two should work together in order to help those in need, but due to vanity, power relations and such, it’s rarely the case in real life.
Before seeing the doctor or diagnosing yourself with depression, you should make sure that your sleeping patterns aren’t imbalanced simply because of your social life.
Make sure that you exercise enough, have a healthy diet and sleep well… then check your surroundings for toxicity and stupidity.
As the popular meme goes: Before you diagnose yourself with depression, make sure you’re not surrounded by complete as**oles.
There’s a theory of depressive realism that suggests the possibility of depressed people actually having a better picture of the nature of our society.
Antipsychiatric movements of the late 1960s lead by some of the 20th century best philosophers like Foucault have pleaded against mental health industry since it doesn’t recognize the causes of mental disorders and rather induces them instead of treating them.
Authors like Deleuze have suggested that society, economy, and social psychology are to blame for the mental disorders that are normal people’s reaction to the negative state of the world we’ve created for ourselves.
Spiritualists and clergy claim that depression is a symptom of communication breakdown between man and divinity or sacred nature.
On the other hand, there’s a couple of thousand-year-old class of MDs specializing in therapy and devoting their lives to the science of medicine.
All of these branches suggest their own major classes of antidepressants, so choose pick your poison.
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