1. A 9-year-old boy with ADHD, combined type, has been trialed on methylphenidate ER 27 mg daily for 6 weeks with good attention improvement but persistent significant impulsivity and emotional dysregulation. His parents prefer to avoid amphetamine products. His pediatric psychiatrist considers adding or switching to atomoxetine. Which of the following most accurately identifies the pharmacological mechanism of atomoxetine, how it differs from methylphenidate, and whether the combination is pharmacologically rational?

• A) Atomoxetine is a selective serotonin reuptake inhibitor (SSRI) -- it was originally developed as a serotonergic antidepressant and its ADHD efficacy was discovered incidentally; its mechanism for ADHD is identical to SSRIs for depression: SERT blockade in the prefrontal cortex elevates synaptic serotonin, which activates 5-HT2A receptors that amplify noradrenergic signaling via a serotonin-norepinephrine cross-talk mechanism; because its mechanism is entirely serotonergic, atomoxetine and methylphenidate (which is dopaminergic and noradrenergic) are completely non-overlapping and highly synergistic when combined.
• B) Atomoxetine is a selective NET inhibitor (blocks NE reuptake without significant DAT or SERT inhibition at therapeutic doses); its ADHD mechanism is primarily noradrenergic -- by blocking NET in the prefrontal cortex, it increases synaptic NE and activates postsynaptic alpha-2A receptors on PFC dendritic spines (strengthening PFC network connectivity, improving working memory and attention regulation) and alpha-1 receptors (contributing to impulse control); it also has some effect on prefrontal dopamine (via a local NE-to-DA spillover mechanism, since PFC NET also clears prefrontal dopamine); unlike stimulants, atomoxetine does not significantly increase dopamine in the mesolimbic reward circuit (nucleus accumbens) because NET density is low there and the drug has no DAT activity, explaining its lower abuse potential and Schedule exemption; it is non-stimulant and not a controlled substance; the combination of methylphenidate (which blocks both NET and DAT, increasing PFC NE and DA) with atomoxetine (which blocks NET selectively) would produce additive NET blockade in the PFC without providing additional DAT blockade; this combination has limited pharmacological rationale because both drugs block NET (overlapping mechanism) without the methylphenidate providing any mechanism not shared by atomoxetine for the NE component; increasing the DAT blockade of methylphenidate's dose or switching to an amphetamine product (which adds NE and DA reverse efflux to the reuptake inhibition) would more rationally address the residual impulsivity.
• C) Atomoxetine blocks both NET and DAT with equal potency (similar to methylphenidate) but has a different pharmacokinetic profile -- it has a longer half-life (5-22 hours, CYP2D6-dependent) producing more sustained NE and DA elevation throughout the day without the peaks and troughs of immediate-release methylphenidate; the rationale for combining atomoxetine with methylphenidate is purely pharmacokinetic: atomoxetine provides the between-dose NE/DA baseline while methylphenidate provides the peak enhancement during peak school hours; the pharmacodynamic mechanisms are identical.
• D) Atomoxetine is a selective NET inhibitor with the primary mechanism of blocking NE reuptake in the prefrontal cortex, producing the noradrenergic PFC enhancement responsible for its ADHD efficacy; its impulsivity benefit specifically reflects increased NE at alpha-2A receptors on PFC interneurons that regulate inhibitory control networks; the emotional dysregulation improvement (a prominent feature of this boy's presentation) may reflect atomoxetine's NE-mediated enhancement of PFC regulation of amygdala reactivity; atomoxetine is non-stimulant and not scheduled; combining atomoxetine with methylphenidate would add selective NE enhancement to the dual NET+DAT blockade of methylphenidate, but since methylphenidate already blocks NET, the marginal NE benefit from adding atomoxetine may be limited; a more pharmacologically rational approach given the residual impulsivity and emotional dysregulation would be to add guanfacine ER (an alpha-2A agonist with direct PFC receptor activation) to the existing methylphenidate, as guanfacine acts downstream of NET (at the postsynaptic alpha-2A receptor) providing NE-receptor-level PFC enhancement complementary to methylphenidate's transporter-level mechanism.

2. A 31-year-old man presents to the emergency department with crushing substernal chest pain, diaphoresis, and dyspnea 30 minutes after insufflating cocaine at a party. His ECG shows 3 mm ST elevation in leads V1-V4. He is anxious and agitated. His BP is 188/112 mmHg and HR is 136 bpm. Troponin is pending. Which of the following most accurately identifies the immediate pharmacological management priorities and the agents to use and avoid?

• A) Immediate management of cocaine-associated STEMI: (1) Do NOT administer beta-blockers (propranolol, metoprolol): cocaine's NET blockade has produced a massive NE surge activating both alpha-1 (coronary vasospasm, peripheral vasoconstriction) and beta-2 (partial countering vasodilation); non-selective beta-blockers remove the beta-2 vasodilation while leaving alpha-1 vasoconstriction unopposed -- worsening coronary vasospasm and hypertension; even cardioselective beta-1 blockers (metoprolol) are generally avoided because the alpha-1-mediated vasospasm is the primary coronary mechanism and beta-1 blockade does not address it; (2) IV benzodiazepine (lorazepam 1-2 mg or diazepam 5-10 mg): first-line for agitation and reducing central sympathetic drive; reduces catecholamine release and may lower heart rate and blood pressure; (3) Aspirin 325 mg: platelet activation from cocaine's alpha-2 platelet effect contributes to thrombosis at vasospasm sites; antiplatelet therapy is indicated as in standard STEMI; (4) Sublingual or IV nitroglycerin: direct NO-mediated coronary vasodilation, directly reversing the alpha-1-mediated coronary vasospasm that is the primary mechanism of cocaine-associated MI; (5) Phentolamine IV (1-5 mg): alpha-1/alpha-2 blocker directly reversing the adrenergic vasoconstriction if nitroglycerin insufficient; (6) Emergent PCI: if STEMI pattern with ST elevation and clinical presentation consistent with acute MI, catheterization laboratory activation is indicated; cocaine-associated STEMI can involve both vasospasm and true thrombotic occlusion, requiring PCI; (7) Sodium bicarbonate: if QRS is widened on ECG (cocaine Na+ channel blockade producing conduction slowing), IV sodium bicarbonate 1-2 mEq/kg alkalinizes the sodium channel binding site (local anesthetic ionization-dependent binding decreases with alkalinization), reversing conduction abnormalities.
• B) Cocaine-associated STEMI should be managed identically to non-cocaine STEMI: aspirin, heparin, beta-blocker (metoprolol), statin, and emergent PCI; the cocaine exposure is irrelevant to the acute MI management because by the time STEMI has developed, the coronary occlusion is thrombotic rather than vasospastic and the cocaine has already been cleared; beta-blockers are not contraindicated in cocaine-associated MI and the historical concern is based on theoretical pharmacology rather than clinical outcomes data.
• C) The immediate pharmacological priorities in cocaine-associated STEMI with hypertension and tachycardia: (1) Avoid all beta-blockers including labetalol (unopposed alpha-1 vasoconstriction risk); (2) IV benzodiazepine first-line for agitation and sympathetic drive reduction; (3) Sublingual or IV nitroglycerin for coronary vasospasm; (4) Aspirin and antiplatelet therapy; (5) Phentolamine IV for refractory hypertension; (6) Sodium bicarbonate if QRS widened (cocaine Nav1 channel blockade reversal); (7) Emergent cardiac catheterization for STEMI; withold: propranolol and any sympathomimetics; hold: calcium channel blockers are also avoided in acute hypotensive phase but diltiazem or verapamil may be considered for cocaine-associated coronary vasospasm without hypotension or significant LV dysfunction after acute phase.
• D) The correct management of cocaine-associated STEMI prioritizes systemic vasoconstriction reversal over coronary reperfusion: phentolamine IV should be given before any attempt at cardiac catheterization because coronary vasospasm (the primary mechanism of cocaine MI in patients with normal coronary arteries) will prevent catheter passage through the vasospastic artery; once phentolamine reverses the vasospasm, spontaneous TIMI 3 coronary flow restoration occurs in greater than 80% of patients without PCI; emergent catheterization is therefore reserved only for patients who do not respond to phentolamine within 15 minutes; aspirin and benzodiazepines are adjunctive.

3. A 67-year-old woman with treatment-resistant depression has been on phenelzine 45 mg/day for 4 months. She needs elective total hip replacement surgery. The anesthesiologist asks the psychiatrist whether phenelzine should be discontinued before surgery and how long a washout is needed. Which of the following most accurately identifies the pharmacological reasons for and against preoperative MAOI discontinuation and the correct washout period?

• A) Phenelzine should be continued through surgery without any washout; MAOI-anesthesia interactions are theoretical concerns that have not been demonstrated in randomized controlled trials; modern anesthetic agents do not interact with MAO inhibitors; the historical recommendation for MAOI discontinuation was based on meperidine interactions from the 1960s when meperidine was the primary perioperative opioid; with contemporary anesthetic practice (propofol, sevoflurane, fentanyl, remifentanil), there is no pharmacological basis for MAOI discontinuation before elective surgery.
• B) Phenelzine requires a minimum 2-week washout before elective surgery because: phenelzine irreversibly inhibits MAO-A and MAO-B; recovery of MAO activity requires de novo enzyme synthesis (2-3 weeks after the last dose for full recovery); during MAOI activity, the following anesthetic agents pose specific risks: (1) Meperidine: absolute contraindication -- meperidine inhibits SERT, producing serotonin syndrome in combination with MAOI; other opioids (morphine, fentanyl, hydromorphone, remifentanil) are generally safer alternatives; (2) Indirect sympathomimetics used in anesthesia: ephedrine (commonly used for anesthesia-induced hypotension) causes massive NE release that cannot be inactivated by the inhibited intraneuronal MAO, producing hypertensive crisis; direct-acting vasopressors (phenylephrine, NE) should replace ephedrine for intraoperative hypotension management; (3) Succinylcholine: MAO inhibition prolongs succinylcholine duration by inhibiting plasma pseudocholinesterase (an off-target MAO effect at high drug concentrations) -- use non-depolarizing NMBs instead; surgical argument for early discontinuation: the patient has been on phenelzine for 4 months and discontinuation risks severe depression relapse and suicidality; this must be weighed against anesthetic risk and the psychiatric team must be closely involved; some expert anesthesiologists accept the MAOI risk with careful anesthetic technique modifications (avoiding meperidine, using direct vasopressors, avoiding indirect sympathomimetics) rather than risk depression relapse from discontinuation.
• C) Phenelzine should be discontinued 2 weeks before elective surgery; the 2-week washout corresponds to the time required for de novo MAO-A and MAO-B protein synthesis to restore normal enzyme activity after irreversible phenelzine inhibition; during this washout period, the patient should be bridged with a reversible MAOI (moclobemide) or a reversible MAO-B inhibitor (selegiline) to prevent depression relapse; at the 2-week washout timepoint, the anesthesia team may safely use the full range of anesthetic agents including ephedrine, meperidine, and all opioids without MAOI interaction risk.
• D) The correct perioperative management of a patient on phenelzine for elective surgery involves: 2-week washout before surgery (time for de novo MAO synthesis to restore enzyme activity from irreversible phenelzine inhibition); avoiding meperidine (absolute contraindication -- serotonin syndrome risk), tramadol, and dextromethorphan; if surgery cannot wait 2 weeks, proceeding with modified anesthetic technique: substituting phenylephrine or norepinephrine for ephedrine for intraoperative hypotension; avoiding meperidine; using morphine, fentanyl, or remifentanil for analgesia with caution (NOT meperidine); having phentolamine and cyproheptadine immediately available; noting that the benefit of continuing phenelzine (depression prevention in a 4-month responder) must be weighed carefully against anesthetic risk; close psychiatric-anesthesia collaboration is essential.

4. A 74-year-old man with hypertension, treated with reserpine 0.1 mg daily for many years as part of a fixed-dose combination product, is seen in the geriatric psychiatry clinic for worsening depression with suicidal ideation that developed gradually over the past 3 months. His internist had added the reserpine-containing product 4 months ago for additional blood pressure control. Which of the following most accurately identifies the diagnosis, mechanism, and appropriate pharmacological management?

• A) This is reserpine-induced depression from VMAT2 inhibition causing progressive depletion of central NE, dopamine, and serotonin stores; the 4-month timeline is consistent with gradual monoamine depletion -- VMAT2 inhibition by reserpine depletes vesicular stores over weeks, with maximal depletion occurring at 4-8 weeks and sustained thereafter; the depression reflects depletion of all three monoamines: NE and serotonin (mood, energy, vegetative symptoms), dopamine (anhedonia, motivational deficit); management: (1) Discontinue reserpine immediately -- recovery requires weeks as new VMAT2 protein is synthesized; switching to a non-VMAT2 antihypertensive (ACE inhibitor, calcium channel blocker, thiazide diuretic, or alpha-2 agonist if CNS depression is not a concern) for blood pressure management; (2) Initiate antidepressant therapy for the depression -- but with important agent selection considerations: since reserpine's effect persists for weeks after discontinuation (residual VMAT2 inhibition, depleted NE and serotonin stores), antidepressants that require intact presynaptic NE release for their mechanism (specifically agents that rely on releasing NE or that act on presynaptic autoreceptors to increase NE release) will have impaired efficacy until stores recover; TCAs or SNRIs that block NET (reuptake inhibitors) can be used and will amplify whatever residual NE is present; (3) Given suicidal ideation, urgent psychiatric assessment and likely hospitalization is indicated; reserpine is contraindicated in patients with any history of depression and this adverse effect, while historical, remains a real clinical risk in elderly patients on combination antihypertensive products still containing reserpine.
• B) The depression is caused by reserpine-induced alpha-2 receptor upregulation in the locus coeruleus -- reserpine's sympatholytic effect chronically reduces NE release, and the LC compensates by upregulating presynaptic alpha-2 autoreceptors; the hypersensitive autoreceptors then suppress even basal NE release more aggressively, producing a self-perpetuating monoamine deficit; the correct pharmacological treatment is yohimbine (an alpha-2 antagonist) which blocks the hypersensitive autoreceptors and restores NE release; SSRIs and SNRIs are ineffective because they require presynaptic NE availability that the hypersensitive autoreceptors prevent.
• C) The depression is an unrelated coincidence -- reserpine at 0.1 mg/day is a subtherapeutic dose that does not produce meaningful VMAT2 inhibition or monoamine depletion; the depression in a 74-year-old is more likely late-onset depression from white matter disease, vascular risk factors, or undiagnosed Parkinson's disease; reserpine should be continued for blood pressure management and a psychiatric evaluation for late-onset depression should proceed independently; the temporal relationship to reserpine initiation is coincidental.
• D) Reserpine-induced depression is an outdated concern from the 1950s that is not applicable to modern low-dose reserpine preparations (0.1 mg/day or less); modern pharmacological studies have shown that reserpine at doses below 0.25 mg/day does not produce clinically meaningful CNS monoamine depletion because the blood-brain barrier restricts reserpine's CNS penetration at low doses; the central adverse effects of reserpine (depression, extrapyramidal symptoms) occur only at doses above 0.5 mg/day, which are no longer used in clinical practice; the correct management is to continue reserpine at the current dose and initiate antidepressant therapy.

5. A 43-year-old man with HIV and an MRSA bloodstream infection is being treated with linezolid 600 mg IV twice daily. His psychiatric medications include sertraline 100 mg daily and bupropion XL 300 mg daily (prescribed for depression and smoking cessation). On day 3 of linezolid, the nursing staff reports he is acutely agitated, confused, has a temperature of 40.2 degrees C, and exhibits inducible ankle clonus on exam. Which of the following most accurately identifies the diagnosis, the specific drugs responsible, and the immediate management?

• A) This presentation represents serotonin syndrome from linezolid's MAO inhibitory property combined with sertraline (SERT inhibitor) and potentially bupropion (weak SERT inhibitor plus NET inhibitor); the clinical triad -- hyperthermia (40.2 degrees C from muscle hyperactivity plus direct thermoregulatory disruption), altered mental status (agitation, confusion), and clonus (pathognomonic neuromuscular abnormality from 5-HT2A receptor excess in the spinal cord) -- is classic serotonin syndrome; linezolid inhibits MAO-A (as a recognized off-target pharmacological property of this antibiotic), reducing serotonin degradation; sertraline simultaneously blocks SERT, preventing serotonin reuptake; bupropion additionally inhibits NET and weakly SERT, further contributing to monoamine excess; the combination produces massive serotonin excess at 5-HT2A receptors in the brainstem and spinal cord, generating the autonomic instability and neuromuscular hyperactivity; immediate management: (1) Discontinue linezolid immediately -- for the ongoing MRSA infection, switch to an alternative non-MAOI antibiotic (daptomycin IV for MRSA bacteremia if the organism is susceptible, or vancomycin); (2) Discontinue sertraline and bupropion; (3) IV benzodiazepines (lorazepam 1-2 mg IV) for agitation and to reduce muscle hyperactivity contributing to hyperthermia; (4) Cyproheptadine 12 mg orally or via NG tube (5-HT2A and 5-HT1A antagonist -- the specific pharmacological antidote for serotonin syndrome); (5) Active cooling measures for temperature 40.2 degrees C (evaporative cooling, ice packs to neck/axilla/groin); (6) Supportive ICU care; severe serotonin syndrome with extreme hyperthermia (greater than 41 degrees C) or muscle rigidity may require intubation and neuromuscular blockade (rocuronium) to prevent rhabdomyolysis, renal failure, and DIC from sustained hyperthermia.
• B) This presentation is neuroleptic malignant syndrome (NMS) from dopamine receptor blockade -- linezolid is a partial dopamine D2 receptor antagonist (an off-target property of its oxazolidinone ring structure); combined with bupropion's dopamine reuptake inhibition, the interaction produces dopaminergic dysregulation in the nigrostriatal pathway; NMS presentation includes hyperthermia, altered mental status, and muscle rigidity; treatment is bromocriptine (D2 agonist) and dantrolene (muscle relaxant reducing hyperthermia).
• C) The fever (40.2 degrees C), agitation, and clonus represent MRSA endocarditis with septic emboli to the CNS -- the linezolid has been insufficiently dosed for the severity of infection; the clinical picture is of CNS infection from seeding of brain parenchyma or meninges by MRSA; management is escalation of antibiotic therapy (add vancomycin and rifampin), emergent CT head, and lumbar puncture; clonus in this context is from cerebellar or corticospinal tract involvement from septic emboli rather than serotonergic excess.
• D) The clinical presentation is serotonin syndrome from linezolid-MAOI activity combined with sertraline (SERT inhibition) and bupropion (NET/SERT inhibition); treatment requires immediate discontinuation of linezolid (switching to daptomycin or vancomycin for MRSA), discontinuation of all serotonergic medications, IV benzodiazepines for agitation and temperature reduction, cyproheptadine for 5-HT2A antagonism, active cooling, and ICU monitoring; recognizing linezolid as an MAOI is the critical diagnostic step -- it is an oxazolidinone antibiotic whose MAO inhibitory activity is mechanistically distinct from its antibacterial mechanism but clinically dangerous when combined with any serotonergic or sympathomimetic drug.

6. A 38-year-old man with chronic sinusitis asks his pharmacist whether he can use oxymetazoline nasal spray (Afrin) or pseudoephedrine tablets for his congestion while he is taking his current medications: tranylcypromine (an irreversible non-selective MAOI) for depression, and phenylephrine nose drops he picked up at the pharmacy counter. Which of the following most accurately identifies which agents are contraindicated and explains the pharmacological basis for each restriction?

• A) Phenylephrine nasal drops and tranylcypromine: phenylephrine is a direct-acting alpha-1 agonist with no indirect NE-releasing mechanism; it activates alpha-1 receptors directly without entering the presynaptic terminal and without requiring NET transport; its vasoconstrictive effect does not depend on NE release or MAO-mediated NE inactivation; topical phenylephrine nasal drops applied at low doses with limited systemic absorption produce localized alpha-1 vasoconstriction of nasal submucosal vessels independent of the adrenergic nerve terminal; because phenylephrine does not rely on MAO-inactivated synaptic NE, its direct alpha-1 agonism is NOT significantly amplified by MAOI treatment at standard nasal decongestant doses; this is the pharmacological basis for the generally held view that direct-acting sympathomimetics are safer than indirect-acting agents in MAOI-treated patients, though all potent direct-acting agents (IV NE, IV epinephrine at higher doses) can still be dangerous if MAO-mediated metabolic clearance is also affected. Oxymetazoline nasal spray and tranylcypromine: oxymetazoline activates both alpha-1 and alpha-2 receptors; its alpha-2 agonism on presynaptic sympathetic terminals reduces endogenous NE release (the same mechanism as clonidine); this alpha-2 presynaptic effect at nasal mucosal nerve terminals actually reduces NE release and is self-limiting; systemic absorption at recommended decongestant doses is low; at topical nasal doses, oxymetazoline is generally considered to have a lower risk profile than systemic indirect sympathomimetics in MAOI patients, though the combination is still listed as requiring caution; rhinitis medicamentosa risk (rebound congestion with use beyond 3-5 days) is the primary clinical concern with oxymetazoline regardless of MAOI status. Pseudoephedrine and tranylcypromine: CONTRAINDICATED; pseudoephedrine is an indirect sympathomimetic (promotes NE release via NET reverse efflux); in tranylcypromine-treated patients, the released NE cannot be inactivated by intraneuronal MAO; massive NE accumulation in sympathetic synapses produces hypertensive crisis -- the same mechanism as the tyramine cheese effect; this is an absolute contraindication regardless of dose.
• B) All three agents (oxymetazoline, pseudoephedrine, and phenylephrine) are equally contraindicated with tranylcypromine -- all three are sympathomimetics, and all sympathomimetic agents are absolutely contraindicated with all MAO inhibitors regardless of mechanism; the pharmacological distinction between direct and indirect sympathomimetics is irrelevant to the MAOI interaction because tranylcypromine inhibits both the intraneuronal MAO that inactivates released NE AND the extraneuronal MAO that metabolizes directly administered sympathomimetics; since phenylephrine is partially metabolized by MAO after receptor activation, its effects are also amplified by MAOI.
• C) Pseudoephedrine and oxymetazoline are both safe with tranylcypromine at OTC decongestant doses because the gut wall MAO-A that normally metabolizes tyramine does not significantly metabolize pseudoephedrine or oxymetazoline (both lack the tyramine-like hydroxyphenyl structure required for MAO-A substrate activity); only tyramine and phenylephrine (which has the para-hydroxyphenyl structure identical to tyramine) are contraindicated with MAOIs; the prescribing information warning against all sympathomimetics with MAOIs is an overly broad extrapolation from the tyramine case.
• D) Only oxymetazoline is safe with tranylcypromine; pseudoephedrine and phenylephrine are both contraindicated; the pharmacological basis: oxymetazoline is an alpha-2 agonist (not alpha-1) and alpha-2 receptor activation reduces NE release from sympathetic terminals, which is pharmacologically opposite to what MAO inhibition potentiates; oxymetazoline's alpha-2-mediated NE suppression is actually protective against hypertensive crisis by reducing NE release; pseudoephedrine is contraindicated (indirect sympathomimetic); phenylephrine is contraindicated because its alpha-1 direct activity is amplified by MAO inhibition preventing NE metabolic clearance.