03.01 Antidepressants

Okay, let’s start talking about medications for various mental health conditions. In this first one we’re going to talk about Antidepressants. This is a bit of a beast because there are quite a few different categories. We’re going to try to demystify this a little bit for you for the 3 most common antidepressants and give you the most important points you need to know.

So, the big thing to know is that these medications work on various neurotransmitters in the brain to help improve mood. The three types we’ll talk about are Selective Serotonin Reuptake Inhibitors or SSRI’s, Tricyclic Antidepressants or TCA’s, and Monoamine Oxidase Inhibitors (MAOI’s). There are also SNRI’s which are serotonin and norepinephrine reuptake inhibitors.

So let’s review neurotransmitters quickly - they are chemicals within the nervous system that help to transmit certain signals throughout the central and peripheral nervous system. What you have to know here is that the more neurotransmitters ANY drug works on or influences, the more dangerous or risky the medication is. Some common neurotransmitters we’ll see being worked on are Serotonin, which I like to call the happy hormone, norepinephrine and epinephrine, which are involved in the fight or flight response, and Dopamine which is involved in motor movement and is the reward neurotransmitter.

So let’s review some general things you need to know and then we’ll break each of the 3 drug classes down. First, know that it could take 2-4 weeks to be at therapeutic levels, so make sure the patient knows they may not feel better right away. It’s also super important that they don’t stop abruptly but taper down when they are going to come off the meds, otherwise they can experience withdrawal symptoms. There are a LOT of drug interactions with antidepressants so make sure you’re reviewing the patient’s medication list. There’s also an increased risk for suicide after starting an antidepressant - why is that? Well they will start to feel better after a couple of weeks, but some of those thoughts of suicide may still be present. So now they have more energy and feel better, so it’s almost like they end up with MORE motivation to go ahead and end their lives, so make sure you’re looking out for signs of that - review the suicidal behavior lesson to learn more about that. These drugs can have some sedative like effects so caution with alcohol and driving and they could be a fall risk. And then remember that therapy in conjunction with medication is extremely beneficial.

So - SSRI’s - Selective Serotonin Reuptake Inhibitors - They Inhibit the Reuptake (or absorption and use) of Serotonin. So If the serotonin isn’t being taken up by the cells, then serotonin levels will be elevated in the circulation. Remember serotonin is the happy hormone, so that will help to elevate mood. Some possible side effects are weight changes, dependent on the patient, decreased libido, dizziness, and photosensitivity - a sensitivity to light. The big risk for SSRI’s is Serotonin Syndrome, which occurs when the serotonin gets to toxic levels. This has a rapid onset of tachycardia, shivering, hallucinations, and even coma and death. It’s important that you are aware of the risk and watching your patient for symptoms. The treatment is a serotonin antagonist. Now you’ll notice that SSRI’s only affect ONE neurotransmitter, so they tend to be first-line antidepressants because they’re a bit safer. This is things like Sertraline (Zoloft) and Fluoxetine (Prozac).

Moving up from here are TCA’s or Tricyclic Antidepressants. These drugs increase both serotonin AND norepinephrine levels - so TWO neurotransmitters, a little more risky, right? TCA’s have sedative effects, so use caution there. They can also have cardiac effects - remember norepinephrine is part of the fight or flight response, so watch for arrhythmias. And with TCA’s we also see anticholinergic effects. Remember cholinergic is rest and digest, so anticholinergic is don’t rest and don’t digest, or similar to fight or flight. The best way to remember anticholinergic effects is the 4 can’ts - Can’t pee - so urinary retention. Can’t see - blurry vision. Can’t spit - dry mouth. And Can’t shit - constipation. So you can imagine having serotonin the happy hormone, norepinephrine for fight or flight, and anticholinergic effects would perk someone up from depression, right? But, with multiple neurotransmitters it can be risky - they’re at risk for seizures and cardiac arrest, especially with overdose. And remember to look for drug interactions because that can potentiate this effect.

Okay last one is MAOI’s or monoamine oxidase inhibitors. These are our last resort antidepressant that we use if the others just don’t work because MAOI’s work on MULTIPLE neurotransmitters and have MULTIPLE drug interactions. We see alterations to serotonin, melatonin, epinephrine, norepinephrine, dopamine, tyramine, and more. If you give MAOI’s with opioids there’s a risk of coma, seizures, or blood pressure derangements. If you give them with vasoconstrictors, nasal decongestants, dopamine, other antidepressants, amphetamines or tyramine-containing foods - there’s a risk for hypertensive crisis. Now I’ve highlighted this for you - tyramine-containing foods. This is big and you’ll see it on tests as well as in real life. Foods that contain tyramine tend to be cured meats, cultured foods like cheese or yogurt, or fermented foods like sauerkraut. I’ve put a longer list in your outline so make sure you check it out. This is so significant that we recommend patients taking MAOI’s wear a medical alert bracelet to alert first responders and healthcare providers.

So let’s recap - the more neurotransmitters a drug impacts, the more dangerous the medication. For SSRI’s you need to know about the risk of serotonin syndrome, which can be life threatening. For TCA’s recognize that they have cardiac and anticholinergic effects, so know the 4 Can’ts and get an EKG before administering. And for MAOI’s remember that there are a LOT of interactions and they’re usually last line - and remember Tyramine containing foods can cause hypertensive crisis. Finally just remember that it takes time for them to work, so we need to keep monitoring for suicidal ideations and that they shouldn’t be stopped abruptly - we taper them down over weeks.

Okay that’s it for antidepressants. Make sure you check out all the resources attached to this lesson. Now, go out and be your best selves today. And, as always, happy nursing!!