Every antidepressant item on the PMHNP exam looks the same once you have seen enough of them. A patient meets criteria for a depressive or anxiety disorder. Somewhere in the stem there is one extra fact - an age, a comorbidity, a previous response, a concurrent medication, a symptom that is not part of the core diagnosis. That fact is the question.
Efficacy is not the discriminator. Across the major classes, first-line antidepressants perform comparably in the average patient with major depressive disorder. What separates them is tolerability, safety in specific populations, and side effects that happen to be useful or dangerous in the patient in front of you.
The default, and why it is the default
SSRIs are first-line for major depressive disorder and for most anxiety disorders because they are effective, broadly tolerable and comparatively safe in overdose. If a stem gives you an uncomplicated adult with a first episode of moderate depression and no complicating detail, an SSRI is the answer and the exam is testing whether you know that.
SNRIs are also first-line, particularly where comorbid pain is present. Bupropion and mirtazapine are reasonable first-line options in the right patient. Tricyclics and MAOIs are effective but have moved to later lines because of tolerability, interaction burden and overdose risk.
Reading the complicating detail
Here is the mapping that answers most items.
| Detail in the stem | What it points toward | Reasoning |
|---|---|---|
| Prominent insomnia and weight loss | Mirtazapine | Sedation and appetite stimulation are useful here rather than adverse |
| Distressed by sexual side effects, or wants to stop smoking | Bupropion | Minimal sexual dysfunction; also indicated for smoking cessation |
| Comorbid neuropathic pain or fibromyalgia | Duloxetine | SNRI with an analgesic indication |
| History of poor adherence, misses doses | Fluoxetine | Long half-life blunts the effect of missed doses and discontinuation symptoms |
| Complex medication list, interaction concern | Sertraline, escitalopram | Comparatively fewer cytochrome interactions |
| Seizure disorder, or current or past eating disorder with purging | Avoid bupropion | Lowers seizure threshold; contraindicated in these populations |
| Poorly controlled hypertension | Caution with venlafaxine | Dose-dependent increase in blood pressure |
| Older adult, falls, hyponatraemia, anticholinergic burden | Avoid paroxetine and tricyclics | Anticholinergic effects, orthostasis, SIADH risk |
| Any history suggesting mania or hypomania | Do not start an antidepressant alone | Risk of precipitating a manic switch; treat as bipolar depression |
The screen you do before you prescribe
If there is one habit the exam rewards above all others in this content area, it is screening for a history of mania or hypomania before starting an antidepressant. A stem describing a depressed patient who once had a period of several days of reduced need for sleep, elevated mood and uncharacteristic activity is not a major depressive disorder item. It is a bipolar item wearing a disguise, and the correct answer is almost never "start an SSRI".
Depression is a presentation, not a diagnosis. The exam wants to see you ask what else has happened to this patient's mood.
Starting, and the first weeks
Counselling points that appear as answer options constantly: mood response takes weeks rather than days; physical side effects often precede benefit; early gastrointestinal upset and activation frequently settle; do not stop abruptly; and, in patients under twenty-five, the boxed warning regarding suicidal thinking requires close early monitoring rather than avoidance of treatment.
That last point is worth stating carefully because the exam tests the nuance. The warning is not an instruction to withhold antidepressants from young people. It is an instruction to monitor closely, particularly in the first weeks and after dose changes.
Adequate trial before you call it a failure
An adequate trial means an adequate dose for an adequate duration - conventionally several weeks at a therapeutic dose, not two weeks at a starting dose. Items often present a patient who is "not better" after ten days and ask what to do; the answer is usually to continue and reassess rather than to switch.
When the first one fails
After a genuinely adequate trial with partial or no response, the standard options are optimising the dose, switching within or between classes, or augmenting. Which one the exam wants usually depends on whether there was partial response - partial response tends toward augmentation or optimisation, no response at all tends toward switching.
Switching requires attention to washout and interaction. Moving to or from an MAOI demands a washout period, and that period is longer when the other agent has a long half-life such as fluoxetine. Combining serotonergic agents - including with tramadol, triptans, linezolid or St John's wort - raises serotonin syndrome risk.
Stopping
Discontinuation syndrome appears often enough to be worth memorising. It is most likely with short half-life agents - paroxetine and venlafaxine are the classic examples - and least likely with fluoxetine. Symptoms are flu-like and sensory: dizziness, electric-shock sensations, irritability, nausea, vivid dreams, starting within days of stopping or reducing. The management is to taper gradually, and the teaching point is to warn the patient at the time of prescribing rather than at the time of stopping.
Doses, warnings and washouts change
Ceiling doses, boxed warnings, interaction lists and washout intervals are revised as labelling and evidence change. Confirm every specific figure against current prescribing information and current clinical practice guidelines before relying on it.
Key points
- Antidepressant items are decided by the one complicating detail in the stem, not by comparative efficacy.
- Screen for prior mania or hypomania before starting an antidepressant; a disguised bipolar stem is a common trap.
- Match side-effect profile to the patient: mirtazapine for insomnia and weight loss, bupropion for sexual side effects and smoking, duloxetine for comorbid pain.
- Discontinuation syndrome tracks half-life - highest with paroxetine and venlafaxine, lowest with fluoxetine.