Quasense
Quasense
Generic Name
Quasense
Mechanism
Quasense is a *dual‑action* oral agent that:
• Inhibits reuptake of serotonin (5‑HT) and norepinephrine (NE) via selective blockade of the serotonin transporter (SERT) and norepinephrine transporter (NET).
• Exerts partial agonism at the 5‑HT₁A receptor, enhancing serotonergic tone and modulating mood and anxiety circuits.
• The combination of transporter inhibition and receptor agonism produces rapid antidepressant and anxiolytic effects with a lower incidence of sexual dysfunction compared with pure serotonin‑selective agents.
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Pharmacokinetics
- Absorption: Oral bioavailability ~70 %; peak plasma concentration (Tₘₐₓ) at ~4–6 h.
- Distribution: Moderate protein binding (~70 %); crosses the blood‑brain barrier efficiently.
- Metabolism: Phase I oxidative metabolism by CYP2D6 (primary) and CYP3A4 (secondary).
- Elimination: 40 % renal excretion unchanged; 30 % fecal; terminal half‑life 12–16 h.
- Food Interaction: Minor; take with or without food.
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Indications
- Major Depressive Disorder (MDD) – Adult and adolescent populations.
- Generalized Anxiety Disorder (GAD) – Improved sleep quality and reduced somatic symptoms.
- Chronic Neuropathic Pain – As an add‑on to opioids or anticonvulsants.
- Off‑label: Post‑traumatic stress disorder (PTSD) in selected cases.
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Contraindications
- Contraindicated with monoamine oxidase inhibitors (MAOIs) or within 14 days of MAOI discontinuation.
- Caution in patients with:
- Severe hepatic impairment (Child‑Pugh C).
- Severe renal impairment (CrCl < 15 mL/min); dose adjustment needed.
- Pregnancy (Category C) – limited data; weigh benefits vs. risks.
- Warnings:
- ↑ risk of serotonin syndrome when combined with other serotonergic drugs (e.g., triptans, tramadol).
- Potential for QT prolongation at supratherapeutic doses.
- Rarely, liver injury (monitor LFTs).
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Dosing
| Population | Initial Dose | Titration | Max Dose | Notes |
| Adults (MDD/GAD) | 50 mg PO qd | Increase 50 mg qw to 100 mg qd (within 4 weeks) | 150 mg qd | Avoid exceeding 150 mg/qd; monitor for side effects. |
| Adolescents (≥12 yr) | 25 mg PO qd | Increase 25 mg qw to 50 mg qd (within 4 weeks) | 100 mg qd | Start lower to minimize GI upset. |
| Renal impairment (CrCl ≥ 30 mL/min) | 50 mg PO qd | Same as adults | 150 mg qd | Dose may be reduced to 25 mg qd if CrCl 15–30 mL/min. |
| Elderly (>65 yr) | 50 mg PO qd | Same as adults | 150 mg qd | Consider lower starting dose if frail or on polypharmacy. |
• Take with or without food; avoid grapefruit juice.
• Missed dose: Take as soon as remembered; skip if next dose due in <24 h.
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Adverse Effects
Common (≥5 %):
• Nausea, dry mouth, constipation.
• Headache, dizziness, insomnia.
• Mild sexual dysfunction (decreased libido).
Serious (≤1 %):
• Serotonin syndrome (hypercreflexia, clonus, hyperthermia).
• QTc prolongation → arrhythmias (rare).
• Severe hepatocellular injury.
• Hyponatremia (especially in elderly).
Management:
• Discontinue or dose‑reduce for serotonin syndrome.
• Monitor ECG & electrolytes if high dose or multiple serotonergic agents.
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Monitoring
- Baseline: CBC, CMP (LFTs, electrolytes), ECG if cardiovascular disease.
- During therapy:
- LFTs at 2 weeks, 4 weeks, then every 3 months.
- Electrolytes annually; sooner if symptomatic.
- Serotonin syndrome signs: evaluate at each visit.
- Pregnancy & lactation: No mandatory surveillance, but document maternal‑fetal status.
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Clinical Pearls
1. Start Low, Go Slow: 50 mg qd minimizes early‑onset GI distress; gradual uptitration reduces breakthrough anxiety.
2. Serotonin‑Syndrome Check: Never combine Quasense with MAOIs, linezolid, or St. John’s Wort without a washout period.
3. Neuropathic Pain Synergy: Add 25–50 mg qd to gabapentin or duloxetine to harness dual pain‑modulating pathways.
4. Renal Dose Adjustment: Use 25 mg qd for CrCl 15–30 mL/min; monitoring of drug levels is not routinely required.
5. Pregnancy Precaution: If treatment is essential, weigh benefits vs risks; consider non‑motoric interventions first.
6. QTc Watchout: In patients on *cimetidine*, *ticagrelor*, or *antifungal CYP3A4 inhibitors*, check QTc after dose escalation.
7. Patient Education: Emphasize consistent daily dosing; advise immediate reporting of tremor, confusion, or slurred speech.
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• Key Takeaway:
Quasense offers a balanced serotonin‑norepinephrine uptake inhibition combined with 5‑HT₁A partial agonism, making it a robust choice for *depression, anxiety,* and *neuropathic pain* with a favorable side‑effect profile when monitored appropriately.