Serotonin and norepinephrine reuptake inhibitors

Serotonin norepinephrine reuptake inhibitors, or SNRIs, are mainly used to treat major depressive disorder. This disorder causes a persistent feeling of sadness and loss of interest in everyday activities.

Even though the exact cause of depression is still unknown, there's some evidence that suggests it’s related to low levels of neurotransmitters like serotonin, norepinephrine, and dopamine.

Serotonin norepinephrine reuptake inhibitors work by increasing the levels of serotonin and norepinephrine to alleviate the symptoms of depression.Alright, now within the brain, there are many different types of neurons, but we’re going to focus only on two: serotonergic neurons which produce serotonin, and noradrenergic neurons which produces norepinephrine.

Each of these neurons synthesizes and stores their neurotransmitters in small vesicles. So, when an action potential reaches the presynaptic membrane, these vesicles fuse with the membrane, releasing neurotransmitters in the synaptic cleft.

Once released, serotonin or 5-HT binds to 5-HT2 receptors on the postsynaptic membrane, thereby increasing neural stimulation and regulating mood, feeding, and reproductive behavior.

On the other hand, norepinephrine binds to norepinephrine receptors on the postsynaptic membrane, boosting alertness. As long as there’s a high enough concentration of neurotransmitters in the synaptic cleft, the postsynaptic neurons will continue to fire.

Now, serotonergic neurons on their presynaptic membrane have serotonin transporters or SERT, while noradrenergic neurons have norepinephrine transporters or NET.

These membrane proteins transport the serotonin and norepinephrine in the synaptic cleft back into presynaptic neurons. This leads to decreased neurotransmitter concentration within the synaptic cleft, causing the postsynaptic neurons to stop firing.

So, in conditions such as major depressive disorder, where there are low levels of serotonin and norepinephrine, SNRIs can be used.

Common medications in this class include duloxetine, venlafaxine, and desvenlafaxine, which is actually an active metabolite of venlafaxine, milnacipran, and levomilnacipran.

SNRIs bind to serotonin and norepinephrine transporters and inhibit them, leading to increased levels of these neurotransmitters within their synaptic clefts.

Other conditions that can be treated with SNRIs include anxiety and neuropathic pain like peripheral neuropathy. For medication specific indications, duloxetine can be used to treat urinary incontinence, which is an uncontrollable leakage of urine; and fibromyalgia, which is a condition characterized by chronic muscle pain, fatigue, and sleep problems.

On the other hand, venlafaxine is indicated in social anxiety, panic disorders, post-traumatic stress disorder or PTSD and obsessive-compulsive disorder or OCD.

Lastly, venlafaxine can treat postmenopausal hot flashes, which are sudden feelings of heat, usually most intense over the face, neck, and chest.Side effects of SNRIs include insomnia, nausea and sexual dysfunctions.

Also, due to increased levels of norepinephrine, SNRIs can cause high blood pressure, sweating, and headaches. The most dangerous, however, are suicidal ideations, especially in individuals under 25, and serotonin syndrome, which is a life-threatening condition caused by serotonin accumulation and over stimulation of the nervous system.

This syndrome is characterized by skin flushing, hyperthermia, agitation, muscle rigidity, seizure, and coma. It usually occurs in individuals treated with a combination of SNRIs and other antidepressants that increase serotonin level, such as monoamine oxidase inhibitors.

Treatment of serotonin syndrome consists of administration of benzodiazepines and supportive care, and in severe cases administration of cyproheptadine, which is an antihistamine that can also block 5HT2 receptors.

If SNRIs are discontinued abruptly, some people can experience withdrawal syndromes like irritability, headaches, and insomnia.

For medicine specific side effects, venlafaxine is an inhibitor of cytochrome P450 enzymes. These liver enzymes are responsible for the metabolism of a variety of drugs and toxins in our body.

So, when combined with other drugs that are metabolized by cytochrome P450 enzymes, such as benzodiazepines, SSRIs will reduce their rate of elimination and cause them to build up in the body.

Lastly, duloxetine can potentially cause liver damage, so it’s hepatotoxic.Now, we want to make a simple and fun mnemonic that’ll help you efficiently memorize and retain all these pharm facts!

For the medications, let’s have a dull, bored ox pulling a cart for duloxetine. In the cart is a greasy, nasty, frying pan for milnacipran, and levomilnacipran.

On the frying pan is a fax machine for venlafaxine and desvenlafaxine. For indications of SNRIs let’s have a medical student who’s anxious about taking care of her first patient.

The patient is a sad looking man in a wheelchair representing depression. He can’t move because his arms and legs are bandaged up, representing peripheral neuropathy.

For drug specific indications, let’s have the dull ox wait eagerly outside a porta potty to help you remember duloxetine can treat urinary incontinence.

Inside the porta potty is a tired janitor with aching muscles, who fell asleep on the job because duloxetine also treats fibromyalgia.

For venlafaxine, let’s have the fax machine print out a speech for a soldier with PTSD. His practicing his big speech obsessively, for obsessive compulsive disorder, because he’s got a fear of public speaking and social anxiety.

Cheering him on, is his mother who’s got hot flashes and is fanning herself. For side effects let’s have a sweaty man sitting up in bed representing insomnia.

He can’t sleep because his feeling nauseous, and there’s some vomit on the floor. He didn’t even feel like putting on his sexy boxer with little hearts on them tonight and they are on his bedsheet.

Next to the boxers, is a blood pressure cuff since his doctor told him his blood pressure is on the high side. For the two dangerous side effects of SNRIs, serotonin syndrome will be represented by a dead knight who’s about to be cremated.

He’s stiff, so there’s muscle rigidity, the hot fire represents hyperthermia, and the armor is glowing red for flushing.

The knight was only faking his death, so he starts squirming from the heat to represent agitation and seizure. No one believed he's alive though since he left behind a suicide note for suicidal ideation.

For medication specific side effects, the dull ox, or duloxetine, was so bored he decided to try eating meat, and is digging into a plate of liver, representing hepatotoxicity.

Next, venlafaxine is a cytochrome p450 inhibitor so, let’s have the fax machine suck in a chrome colored cell through the paper loader.

All right, as a quick recap. Serotonin-norepinephrine reuptake inhibitors, or SNRIs, are antidepressant medications that prevent serotonin and norepinephrine reuptake from the synaptic cleft, thus enhancing the effect of both neurotransmitters on the postsynaptic neuron.

Aside from major depressive disorder, SNRIs can also treat anxiety and neuropathic pains. In addition, duloxetine can also treat urinary incontinence and fibromyalgia, while indications for venlafaxine include social anxiety, PTSD and OCD and postmenopausal hot flashes.

These medications have a few dangerous side effects like increased risk of suicide and the life-threatening serotonin syndrome.

reuptake inhibitors or are antidepressant medications that prevent serotonin and norepinephrine reuptake from the synaptic cleft is is the the the the the effect of of both neurotransmitters on the postsynaptic neuron Aside from major depressive disorder SNRIs can also treat anxiety and neuropathic pains In addition DULoxetine can also treat urinary incontinence and fibromyalgia While indications for venlafaxine include social anxiety PTSD and OCD and postmenopausal hot flashes Patients exhibit of the me have a have a few dangerous side effects like increased risk of suicide and a life-threatening serotonin syndrome But wait there's more here's a mind map with all the mnemonics from the video Go ahead and pause the video So you can test yourself to see what you