PMHNP Antidepressant Master Cheat Sheet
Antidepressants carry a boxed warning for increased suicidal thoughts/behaviors in young adults and require careful patient screening for conditions like bipolar disorder, psychosis, and substance use before initiation.
Core Principles
- Universal Antidepressant Rules: Always screen for bipolar disorder, suicide risk, psychosis, substance use, pregnancy/lactation, drug interactions, baseline vitals, QT risk, seizure risk, serotonergic polypharmacy, and discontinuation risk before prescribing.
- SSRI First-Line: SSRIs are workhorses, with Fluoxetine offering a long half-life for adherence issues, Sertraline as a versatile default, Escitalopram for its clean profile, Citalopram requiring QT monitoring, Paroxetine for its significant withdrawal and side effects, and Fluvoxamine being potent for OCD but interaction-prone.
Action Steps
- Screen all patients for bipolar disorder, suicide risk, psychosis, substance use, pregnancy/lactation, and potential drug interactions before initiating antidepressants.
- Obtain baseline weight/BMI, BP/HR, and consider ECG for QT risk, especially with citalopram and TCAs, and assess seizure risk with bupropion and TCAs.
- Monitor patients of all ages for worsening depression, agitation, akathisia, and behavioral changes, particularly during dose changes.
- Initiate SSRIs at low doses (e.g., Fluoxetine 10-20 mg, Sertraline 25-50 mg, Escitalopram 5-10 mg, Citalopram 10-20 mg, Paroxetine 10-20 mg, Fluvoxamine 25-50 mg) and titrate to typical/target doses (e.g., Fluoxetine 20-40 mg, Sertraline 50-150 mg, Escitalopram 10 mg, Citalopram 20 mg, Paroxetine 20-40 mg, Fluvoxamine 100-200 mg).
Key Terms
- Boxed Warning: A prominent warning on a drug's label alerting prescribers and patients to serious or potentially life-threatening risks, such as increased suicidal thoughts with antidepressants in young adults.
- t½ (Half-life): The time it takes for the amount of a drug in the body to be reduced by half, influencing dosing frequency and withdrawal duration (e.g., Fluoxetine's long half-life vs. Paroxetine's short half-life).
- CYP Inhibitor: A substance that blocks the activity of cytochrome P450 enzymes, affecting the metabolism of other drugs and increasing their potential for interactions (e.g., Fluoxetine inhibits CYP2D6, Fluvoxamine inhibits CYP1A2 and CYP2C19).
- QT Prolongation: A delay in the heart's electrical recharging phase, which can increase the risk of dangerous arrhythmias; Citalopram is particularly associated with this risk.
- Akathisia: A movement disorder characterized by a feeling of inner restlessness and a compelling need to be in constant motion, which should be monitored for when starting antidepressants.
Pro Tips
- Fluoxetine's long half-life (2-4 days, norfluoxetine 7-15 days) makes it ideal for patients with poor adherence or when switching antidepressants due to its pharmacokinetic self-tapering.
- Sertraline is often favored in cardiac disease and is a good choice when weight gain is a concern, despite potential GI side effects.
- Escitalopram has few CYP interactions and is often well-tolerated, making it an excellent first-line option for MDD/GAD.
- Paroxetine's short half-life (~21 hours) leads to significant withdrawal symptoms upon abrupt discontinuation.
- Fluvoxamine is particularly useful for OCD due to its potency, but requires careful management of its numerous drug interactions, especially with CYP1A2 and CYP2C19 inhibition.
Pitfalls to Avoid
- Starting antidepressants without screening for bipolar disorder can precipitate mania or hypomania.
- Failing to monitor patients for increased suicidal thoughts/behaviors, especially those under 24, can lead to tragic outcomes.
- Abruptly discontinuing Paroxetine causes significant withdrawal symptoms due to its short half-life.
- Exceeding 40 mg/day of Citalopram is generally avoided due to QT prolongation risk, especially in patients over 60 or with hepatic impairment/CYP2C19 poor metabolism.
Myth vs Reality
- Antidepressants are only for severe depression.: SSRIs like Fluoxetine, Sertraline, and Escitalopram are indicated for a range of conditions including MDD, OCD, panic disorder, GAD, PTSD, and PMDD, not solely severe depression.
- All SSRIs have similar side effect profiles.: SSRI side effect profiles vary significantly; Paroxetine is known for sedation and weight gain, Fluvoxamine for drug interactions, and Citalopram for QT prolongation, while Sertraline can cause GI issues and Fluoxetine can be activating.
Real World Examples
- A patient with a history of mania is prescribed an antidepressant.: This is a critical error; antidepressants can trigger mania/hypomania in bipolar patients, necessitating a thorough bipolar screening beforehand.
- A patient with poor adherence is started on an antidepressant.: Fluoxetine is a good choice due to its long half-life, which provides a pharmacokinetic buffer if doses are occasionally missed.
- A patient is taking multiple serotonergic drugs.: This increases the risk of serotonin syndrome; careful review for drug interactions is essential before and during treatment.
Statistics
- Increased suicide cases per 1,000 patients <18 on antidepressants vs. placebo: ~14
- Increased suicide cases per 1,000 patients aged 18-24 on antidepressants vs. placebo: ~5
People
- FDA: Food and Drug Administration, responsible for drug safety warnings like the boxed warning on antidepressants.
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