Selective serotonin reuptake inhibitor
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Selective serotonin reuptake inhibitors (commonly abbreviated as SSRIs) are a class of pharmaceutical antidepressant medications. They are commonly prescribed for the treatment of major depressive disorders. Other conditions include anxiety disorders, obsessive-compulsive disorder, migraine, attention-deficit hyperactivity disorder (ADHD), addiction/dependence, and sleep disorders. The exact pharmacological mechanism of action SSRIs is unknown. They are believed to increase the extracellular level of the neurotransmitter serotonin, eventually leading to improved mood.[clarification needed]
SSRIs can be dangerous when used in combination with other substances that increase or modulate serotonin such as MDMA and Monoamine Oxidase Inhibitors (MAOIs). A combination with these substances can lead to serotonin syndrome and potentially be fatal. SSRIs do not work for everyone and take 3-6 weeks to start having noticeable effects.[clarification needed]
SSRIs are reported to have fewer side effects than older antidepressants like monoamine oxidase inhibitors and tricyclic antidepressants. Monoamine oxidase inhibitors also interact with many other medications and foods, leading to a hypertensive crisis that can potentially be fatal. SSRIs can cause sexual dysfunction and compulsive yawning as side effects. Discontinuation of SSRIs can lead to withdrawal symptoms which include flu-like symptoms, as well as brain zaps.
Mechanism of action
SSRIs are believed to increase the extracellular level of the neurotransmitter serotonin by limiting its reuptake into the presynaptic cell, increasing the level of serotonin in the synaptic cleft available to bind to the postsynaptic receptor. They have varying degrees of selectivity for the other monoamine transporters. Pure SSRIs show only weak affinities for the norepinephrine and dopamine transporters.
SSRIs also lead to an increased level of cAMP (cyclic adenosine monophosphate), brain-derived neurotrophic factor, and several other regulatory neuromodulators. Different SSRIs have different binding profiles, which may lead to different effects.
- Anxiety suppression
- Appetite enhancement or Appetite suppression
- Cognitive fatigue
- Focus suppression
- Decreased libido
- Dream potentiation
- Ego inflation
- Emotion suppression
- Orgasm suppression - this effect is usually mild.
- Physical fatigue
- Suicidal ideation (upon first introduction) 
- Brain zaps
- Cognitive disconnection
- Focus suppression
- Motivation suppression
Citalopram is an SSRI sold under the brand name Celexa in the United States. Citalopram is indicated for the treatment of a major depressive disorder. Citalopram was approved in 1998 by the Food and Drug Administration for the treatment of major depressive disorder. Citalopram is almost exclusively found as the hydrobromide salt, which is the only form approved by the FDA.
Escitalopram is an SSRI sold under the brand name Lexapro in the United States. Escitalopram is indicated for the treatment of major depressive disorder and anxiety disorders. It is the s-enantiomer of citalopram, and both have similar efficacy. Escitalopram was FDA approved in 2002.
Fluoxetine is an SSRI commonly sold under the brand name Prozac. Fluoxetine is indicated for the treatment of major depressive disorder, bulimia nervosa, obsessive-compulsive disorder, panic disorder, and premenstrual dysphoric disorder. Fluoxetine is sometimes used in conjunction with olanzapine (an atypical antipsychotic) to treat bipolar I disorder as well as treatment-resistant depression.A single pill medication called Symbyax is a combination of olanzapine and fluoxetine.Fluoxetine is on the World Health Organization's list of essential medicines, a list of medicines needed for a basic and effective health system.Fluoxetine was first FDA approved in 1987.
Fluvoxamine is an SSRI that is used to treat obsessive-compulsive disorder. Fluvoxamine was first approved by the FDA in 1994.Fluvoxamine has the greatest affinity for the σ1 (sigma-1) receptor, where it acts as an agonist, which may contribute to its biological effects.
Paroxetine is an SSRI that is sold under the brand name Paxil. Paroxetine is used to treat major depressive disorder, obsessive-compulsive disorder, post-traumatic stress disorder, anxiety disorders, premenstrual dysphoric disorder, and under the brand name Brisdelle, it is used to treat hot flashes related to menopause. Paroxetine was first approved by the FDA in 1992.
Sertraline is an SSRI that is sold under the brand name Zoloft. Sertraline is used to treat major depressive disorder, obsessive-compulsive disorder, post-traumatic stress disorder, anxiety disorders, panic disorder, and premenstrual dysphoric disorder. Sertraline was first FDA approved in 1991.Unlike most SSRIs, sertraline, has somewhat significant activity at the dopamine transporter protein and could be considered a serotonin-dopamine reuptake inhibitor.
Several other SSRIs have been developed and marketed. Dapoxetine is used in some countries to treat premature ejaculation. Indalpine and zimelidine were originally marketed but later withdrawn because of the development of Guillain–Barré syndrome. Cericlamine and panuramine were developed but never marketed.
A wide array of substances is contraindicated with SSRIs. substances that increase extracellular serotonin may increase the risk of serotonin syndrome, particularly substances like MDMA, dextromethorphan, tramadol and pethidine. Independent research should be done before taking any substances while on an SSRI to ensure there is no drug interaction. Some dietary supplements such as 5-HTP and St. John's Wort can lead to serotonin syndrome if taken by someone currently medicated with an SSRI.
Some NSAID analgesics may increase the risk of excess bleeding in those who take SSRIs. NSAIDs include acetaminophen (paracetamol), ibuprofen, aspirin, and naproxen.
Most SSRIs inhibit the function of certain cytochrome P450 enzymes that metabolize other substances so that SSRIs may lead to an increased or decreased serum level of certain medications.
If hallucinogenic substances are taken while under the influence of an SSRI, the user may not experience any visual hallucinations (with few exceptions).
- http://pi.lilly.com/us/prozac.pdf page 20
- Kolb, Bryan and Wishaw Ian. An Introduction to Brain and Behavior. New York: Worth Publishers 2006, Print.
- Björkenstam, C., Möller, J., Gunilla Ringbäck, G., Salmi, P., Hallgvist, J., & Ljung, R. (2013, September 9). An Association between Initiation of Selective Serotonin Reuptake Inhibitors and Suicide - A Nationwide Register-Based Case-Crossover Study. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3767591/
- Nemeroff, CB (2012). Management of Treatment-Resistant Major Psychiatric Disorders. USA: Oxford University Press. p. 30.
- Citalopram | https://www.drugs.com/citalopram.html
- Escitalopram | https://www.drugs.com/cdi/escitalopram.html
- Fluoxetine | https://www.drugs.com/fluoxetine.html
- Symbyax Prescribing Information | http://pi.lilly.com/us/symbyax-pi.pdf
- WHO List of Essential Medicines | http://www.who.int/medicines/publications/essentialmedicines/EML2015_8-May-15.pdf
- Fluvoxamine | https://www.drugs.com/cdi/fluvoxamine.html
- Sigma-1 receptors and selective serotonin reuptake inhibitors: clinical implications of their relationship. | https://www.ncbi.nlm.nih.gov/pubmed/20021354
- Paroxetine | https://www.drugs.com/paroxetine.html
- Sertraline | https://www.drugs.com/sertraline.html
- Second generation SSRI: human monoamine transporter binding profile of escitalopram and R-fluoxetine | https://www.ncbi.nlm.nih.gov/pubmed/12232544