Serotonin and norepinephrine reuptake inhibitors (SNRIs) are a class of antidepressants that work by blocking serotonin and norepinephrine reuptake in the synapse (as the name suggests). 🗒️ It is important to educate patients that there is an increased risk of suicidal thinking and behavior in children, adolescents, and young adults during the first few months of therapy and it may take up to 8 weeks before therapeutic effects are recognized.
💊 Selective serotonin reuptake inhibitors (SSRIs) work by inhibiting 5-HT reuptake by the presynaptic cleft, thus increasing serotonin levels in the synapse. It is commonly used to treat depression, a condition thought to be linked to low levels of serotonin, dopamine, and norepinephrine. ⭐ As you can see, this mnemonic is similar to the mnemonic on the side effects of SNRIs. Since they both block serotonin reuptake, they exhibit very similar side effect profiles except SNRIs can also impact blood pressure (increase or decrease) due to the norepinephrine reuptake inhibition. SSRIs do not affect blood pressure. In addition, SSRIs can cause weight gain in adults on long-term therapy, while SNRIs cause less of this long-term weight gain and are more associated with weight loss.
Tricyclic antidepressants (TCAs) are drugs used to treat depression, bipolar disorder, and other conditions such as chronic pain and insomnia. They primarily work by blocking norepinephrine and serotonin (5HT2) reuptake. They also block acetylcholine and histamine receptors which contribute to their side effect profile. 👉🏻 Muscarinic M1 block: anticholinergic side effects including dry mouth, blurry vision, constipation, and urinary retention 👉🏻 Histamine 1 receptor block: sedation and weight gain 👉🏻 Adrenergic alpha block: postural hypotension, tachycardia, and erectile disfunction 👉🏻 Sodium channel block: QTc prolongation, arrhythmias 👉🏻 Serotonin uptake block: weight gain