In this episode, we explore monoamine oxidase inhibitors (MAOIs), one of the oldest yet most effective classes of antidepressants. We discuss how MAOIs such as phenelzine, tranylcypromine, isocarboxazid, and selegiline work by increasing serotonin, norepinephrine, and dopamine levels in the brain. The episode reviews their unique role in treatment-resistant and atypical depression, key adverse effects, important dietary considerations involving tyramine-containing foods, and potentially serious drug interactions. We also highlight practical clinical pearls to help pharmacists and healthcare professionals safely and effectively use these powerful but often underutilized medications.
In this episode, we explore four unique antidepressants that do not fit neatly into the traditional SSRI or SNRI categories: trazodone, nefazodone, vilazodone, and vortioxetine. Trazodone and nefazodone are classified as serotonin antagonist and reuptake inhibitors (SARIs), working primarily through blockade of 5-HT2 receptors while also inhibiting serotonin reuptake. Trazodone’s strong antihistamine and alpha-1 blocking properties make it highly sedating and commonly used off-label for insomnia, whereas nefazodone causes less sedation but is rarely prescribed today because of its association with severe and potentially fatal liver toxicity. Both agents are notable for producing less sexual dysfunction than many traditional SSRIs.
We also discuss two newer multimodal antidepressants: vilazodone (Viibryd) and vortioxetine (Trintellix). Vilazodone combines serotonin reuptake inhibition with partial agonism at the 5-HT1A receptor, a mechanism often compared to combining an SSRI with buspirone. Vortioxetine has an even more complex pharmacology, acting as a serotonin reuptake inhibitor while modulating multiple serotonin receptor subtypes through agonist, partial agonist, and antagonist actions. This multimodal activity may contribute to benefits in cognitive symptoms associated with major depressive disorder. Throughout the episode, we compare receptor pharmacology, clinical applications, adverse effect profiles, and the unique characteristics that distinguish these medications from more commonly prescribed antidepressants.
Serotonin-norepinephrine reuptake inhibitors (SNRIs) are a class of antidepressants that increase serotonin and norepinephrine levels in the brain. Common agents include venlafaxine (Effexor XR), desvenlafaxine (Pristiq), duloxetine (Cymbalta), levomilnacipran (Fetzima), and milnacipran (Savella). In addition to treating depression and anxiety disorders, several SNRIs have important pain indications, making them especially useful in patients with neuropathy, fibromyalgia, or chronic musculoskeletal pain. Common adverse effects include nausea, sweating, insomnia, sexual dysfunction, and elevated blood pressure. Clinicians should also remember the significant discontinuation risk associated with shorter half-life agents like venlafaxine and desvenlafaxine.
Mirtazapine is a unique antidepressant often chosen when depression occurs alongside insomnia or poor appetite. Its antihistamine activity makes it sedating, particularly at lower doses, and it commonly increases appetite and weight. Unlike many SSRIs, mirtazapine has a lower risk of sexual dysfunction and gastrointestinal side effects because it blocks 5-HT2 and 5-HT3 receptors. It is frequently dosed at bedtime and can be especially useful in older adults or medically ill patients who need both mood improvement and help with sleep or weight gain.
Bupropion is an activating antidepressant that works by increasing norepinephrine and dopamine activity rather than serotonin. It is often preferred in patients with fatigue, low motivation, hypersomnia, or concerns about sexual dysfunction and weight gain. Bupropion is also approved for smoking cessation. Common adverse effects include insomnia, anxiety, dry mouth, and headache. A major clinical pearl is its dose-related seizure risk, making it contraindicated in patients with seizure disorders or eating disorders such as anorexia nervosa or bulimia.
Welcome to today’s episode on the tricyclic antidepressants, commonly known as TCAs — one of the foundational medication classes in psychopharmacology. Although newer antidepressants like SSRIs often dominate modern prescribing, TCAs remain highly relevant in clinical practice because of their effectiveness in treatment-resistant depression, chronic pain syndromes, migraine prevention, insomnia, and certain anxiety disorders. In this episode, we’ll break down the pharmacology behind these medications, discuss how tertiary amines differ from secondary amines, review major adverse effects and drug interactions, and highlight the key clinical pearls that healthcare professionals and students need to know. Whether you’re a medical, pharmacy, nursing, or PA student preparing for exams, or a practicing clinician looking for a practical refresher, this episode will give you a solid framework for understanding this classic but still clinically important medication class.
SSRI adverse effects are critical to know. In part 2 of this 2-part series on SSRIs, we cover the most important adverse effects to know, in addition to putting a nice bow on the most important clinical practice pearls on each SSRI. Enjoy the show!
In this episode, we break down the pharmacology of selective serotonin reuptake inhibitors (SSRIs) with a focus on the high-yield clinical pearls pharmacists, medical students, and healthcare professionals need to know. We compare the major SSRIs—including fluoxetine, sertraline, paroxetine, citalopram, escitalopram, and fluvoxamine—based on adverse effects, drug interactions, pharmacokinetics, and board exam relevance. Topics include serotonin syndrome, discontinuation syndrome, CYP450 interactions, QT prolongation, sexual dysfunction, weight changes, and SSRI selection in special populations such as older adults and pregnancy. Whether you are preparing for exams, clinical rotations, or looking to sharpen your psychopharmacology knowledge, this episode provides practical and memorable insights into one of the most commonly prescribed medication classes. This is Part 1 of 2.
Alprazolam is a short-acting benzodiazepine that enhances the inhibitory effects of gamma-aminobutyric acid (GABA) at the GABA-A receptor. Clinically, this results in anxiolytic, sedative, muscle-relaxant, and anticonvulsant effects.
After oral administration, alprazolam is rapidly absorbed, with onset of action typically within 30–60 minutes. It undergoes extensive hepatic metabolism primarily via CYP3A4 to inactive metabolites, and has an elimination half-life of approximately 11 hours, which may be prolonged in elderly patients or those with hepatic impairment.
Common adverse effects include sedation, dizziness, impaired coordination, and cognitive slowing. More serious risks include respiratory depression, especially when combined with opioids, alcohol, or other CNS depressants.
Clinically, alprazolam should be used at the lowest effective dose for the shortest possible duration. Abrupt discontinuation should be avoided; gradual tapering is essential to reduce withdrawal risk. It is a controlled substance that carries the risk of addiction and dependence.
Pimavanserin is an atypical antipsychotic approved for the treatment of hallucinations and delusions associated with Parkinson’s disease psychosis. Unlike traditional antipsychotics, it does not block dopamine receptors, making it a unique option for patients with Parkinson’s disease who are highly sensitive to dopamine antagonism.
Mechanism of Action
Pimavanserin works primarily as a selective serotonin 5-HT2A inverse agonist and antagonist, with minor activity at 5-HT2C receptors. This dopamine-sparing effect is the key reason it does not worsen motor symptoms in Parkinson’s disease.
Adverse Effects
The most commonly reported side effects include peripheral edema, nausea, confusion, and hallucinations. QT interval prolongation is a clinically important concern, especially in patients with existing cardiac risk factors. Somnolence may occur but is generally less prominent compared with dopamine-blocking antipsychotics.
Warnings and Precautions
Pimavanserin carries a boxed warning for increased mortality in elderly patients with dementia-related psychosis, consistent with other antipsychotics. It should not be used in patients with known QT prolongation, a history of ventricular arrhythmias, or in combination with other QT-prolonging agents when possible.
Drug Interactions
Strong CYP3A4 inhibitors, such as ketoconazole or clarithromycin, can significantly increase pimavanserin concentrations and require dose reduction. Strong CYP3A4 inducers, such as rifampin or carbamazepine, may reduce efficacy and should generally be avoided. Additive QT prolongation may occur when combined with other QT-prolonging medications, including certain antiarrhythmics, fluoroquinolones, and macrolide antibiotics.
Vilazodone (brand name Viibryd) is an antidepressant with a unique pharmacologic profile compared to most other agents in the SSRI class. While not a first-line choice for every patient, understanding its mechanism, adverse effects, and interaction profile is essential for optimizing therapy and preventing downstream prescribing problems.
Mechanism of Action Vilazodone is classified as a selective serotonin reuptake inhibitor (SSRI) and a partial agonist at the 5-HT1A receptor. The SSRI activity increases synaptic serotonin by blocking the serotonin transporter, while partial agonism at 5-HT1A receptors may contribute to antidepressant effects and potentially reduce certain SSRI-associated adverse effects (though clinical evidence for this benefit is mixed).
Adverse Effects
GI effects – diarrhea, nausea, and vomiting are frequent early in therapy. Taking the medication with food can help minimize these.
Insomnia – often dose-related; morning dosing may help.
Sexual dysfunction – may be slightly lower than with some SSRIs but still present.
Serotonin syndrome – rare but serious, particularly if combined with other serotonergic drugs.
Discontinuation syndrome – abrupt cessation can lead to dizziness, irritability, and flu-like symptoms.
Drug Interactions Vilazodone is primarily metabolized by CYP3A4. This means:
CYP3A4 inhibitors (e.g., ketoconazole, clarithromycin, ritonavir) can increase vilazodone concentrations, potentially worsening side effects—dose reductions may be required.
CYP3A4 inducers (e.g., carbamazepine, rifampin, St. John’s Wort) can lower drug levels, reducing effectiveness.
Other serotonergic agents (e.g., triptans, SNRIs, MAOIs, tramadol, linezolid) increase the risk of serotonin syndrome.
Antiplatelets and anticoagulants – SSRIs can impair platelet aggregation, increasing bleeding risk when combined with aspirin, NSAIDs, or warfarin.
Prescribing Cascade Examples Vilazodone’s adverse effects can easily lead to unnecessary prescriptions if side effects aren’t recognized:
GI upset → Acid suppression therapy – Diarrhea or nausea prompts the addition of proton pump inhibitors or antiemetics, instead of adjusting vilazodone dose or timing.
Insomnia → Hypnotic initiation – Trouble sleeping results in adding zolpidem or trazodone, without reassessing morning dosing or vilazodone’s role.
Sexual dysfunction → PDE5 inhibitor prescription – Erectile dysfunction leads to sildenafil use, when the root cause is vilazodone’s serotonergic activity.
Vilazodone’s combination of SSRI and 5-HT1A partial agonist activity makes it somewhat distinct, but its side effect profile and interactions require the same careful monitoring as other antidepressants. Healthcare professionals can play a key role in catching early signs of adverse effects, preventing prescribing cascades, and ensuring drug–drug interactions are managed appropriately.
