Quillivant XR
Quillivant XR
Generic Name
Quillivant XR
Mechanism
Quillivant XR is an oral, extended‑release solution of quetiapine fumarate.
• Dopamine D₂/D₃ antagonist – reduces hyperdopaminergic activity in mesolimbic and mesocortical pathways.
• Serotonin 5‑HT₂A antagonist – modulates serotonergic tone, dampening anxiety and psychosis.
• Additional receptor profile – partial agonist at 5‑HT₁A, antagonist at H₁, M₁, and α₁‑adrenergic sites, contributing to anxiolytic, antihistaminic, anticholinergic, and antihypertensive effects.
• Extended‑release formulation provides steady plasma levels, minimizing peak‑trough fluctuations and improving tolerability versus immediate‑release quetiapine.
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Pharmacokinetics
- Absorption: Rapid oral uptake; C_max achieved 3–4 h post‑dose.
- Bioavailability: ~30–35 % (first‑pass metabolism).
- Distribution: High V_d (~4–6 L/kg); crosses blood‑brain barrier.
- Metabolism: Primarily *CYP3A4* mediated to N‑hydroxyquetiapine (active metabolite).
- Elimination: Renal (30 %) and biliary (70 %) excretion; half‑life ~6–8 h, prolonged by active metabolite (~13 h).
- Special populations:
- *Elderly*: ↑ exposure by ~30 % – start at lower dose.
- *Renal/hepatic impairment*: Adjust cautiously; monitor levels.
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Indications
- Schizophrenia (adult and pediatric 10–17 y) – as monotherapy or adjunct.
- Bipolar I disorder – acute manic or mixed episodes; maintenance therapy.
- Off‑label: Adjunctive for major depressive disorder, panic disorder, generalized anxiety disorder (clinical judgment required).
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Dosing
| Population | Starting Dose | Titration | Maintenance Range |
| Adults (Schizophrenia/Bipolar) | 150 mg once daily | ↑ 50–100 mg increments every 3–5 days | 300–800 mg/day (max 1,200 mg/day) |
| Pediatric (10–17 y, Schizophrenia) | 112.5 mg once daily | ↑ 50–100 mg per week | 112.5–337.5 mg/day |
| Pediatric (10–17 y, Bipolar) | 112.5 mg once daily | ↑ 50–100 mg per week | 112.5–300 mg/day |
• Form: Oral solution (100 mg/5 mL).
• Swallowing: Dose shaken; can be titrated by volume (e.g., 5 mL increments) for pediatric titration.
• Timing: Once daily in the evening to mitigate daytime sedation.
• Compliance: Educate on importance of dose timing to maintain therapeutic troughs.
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Adverse Effects
| Category | Examples |
| Common (≥ 10 %) | Somnolence, dry mouth, dizziness, weight gain, increased appetite, orthostatic hypotension. |
| Moderate (≥ 1 %–10 %) | Hyperlipidemia, hyperglycemia, constipation, blurred vision, mild extrapyramidal symptoms. |
| Serious (≤ 1 %) | QTc prolongation, NMS, severe sedation, metabolic derangements, orthostatic hypotension leading to syncope, severe allergic reactions. |
• Adverse event monitoring: Baseline and periodic ECG, fasting glucose, lipids, liver function, ophthalmic screening (visual acuity, intra‑ocular pressure) as indicated.
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Monitoring
| Parameter | Frequency | Rationale |
| Weight & BMI | Baseline, 1 month, then every 3 months | Metabolic risk |
| Fasting glucose & HbA1c | Baseline, 1 month, then every 6 months | Diabetes screening |
| Lipid panel | Baseline, 1 month, then yearly | Dyslipidemia |
| Electrocardiogram (QTc) | Baseline (if risk factors), at dose escalation | QT prolongation |
| Blood pressure & orthostatic vitals | Baseline, 1 month, then quarterly | Hypotension |
| LFTs & CBC | Baseline, 1 month, then at 3 month intervals | Hepatic/hematologic toxicity |
| Clinical response | Every 2–4 weeks initially | Efficacy & tolerability |
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Clinical Pearls
- Extended‑release advantage: Use Quillivant XR to avoid peak‑peak highs that can precipitate akathisia or sedation seen with immediate‑release quetiapine; crucial in inpatient stabilization or transition to steady outpatient care.
- Pediatric dosing strategy: Because the solution allows precise volumetric titration, use half‑dose increments (25 mg / 5 mL) in 10–14 yr olds; avoid abrupt upward steps that increase QTc risk.
- Polypharmacy caution: Co‑administration with potent *CYP3A4* inhibitors may necessitate a 25–50 % dose reduction; *CYP3A4* inducers can require a 30–50 % increase, but monitor for toxicity.
- Sedation & sleep hygiene: Initiate therapy in late afternoon; counsel patients on sleep‑safe environments (reduce caffeine, avoid alcohol).
- Weight monitoring: If > 5 % weight gain in 6 months, reassess diet and consider adjunctive agents (e.g., metformin) or switch to a lower‑weight‑gain antipsychotic.
- Vaccination: Live vaccines contraindicated while on *Quillivant XR* due to immunomodulatory effects.
- Discontinuation: Drop dose gradually (10 % reductions every 2–3 weeks) to minimize withdrawal psychosis or rebound mania.
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