Focalin XR
Focalin XR
Generic Name
Focalin XR
Mechanism
- Selective dopamine‑reuptake inhibitor (DRI): blocks the dopamine transporter (DAT) on presynaptic neurons, increasing synaptic dopamine levels.
- α‑Adrenergic (moderate) activity: enhances noradrenergic tone, contributing to improved attention and impulse control.
- The XR formulation employs a *controlled‑release microsphere* technology that prolongs plasma concentration and maintains therapeutic levels for 8–12 h.
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Pharmacokinetics
| Parameter | Typical Value (Adults) | Notes |
| Absorption | Peak plasma ~3 h after dosing | First‑order, linear with dose |
| Bioavailability | ~53 % | Influenced by food (slight reduction) |
| Distribution | Volume of distribution ~4 L/kg | Highly protein‑bound (~95 %) |
| Metabolism | Extensively metabolized by CYP2D6 → 3‑hydroxylated metabolites (inactive) | Polymorphisms affect clearance |
| Excretion | Renal (≈ 60 %) | Urinary pH 4–8; unchanged drug ~10 % |
| Half‑life | ~10 h (steady‑state) | XR yields a biphasic elimination profile |
| Onset | 30–60 min (immediate) | Sustained effect with XR form |
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Indications
- Attention‑Deficit/Hyperactivity Disorder (ADHD)
- Children ≥6 yr, adolescents ≥12 yr, adults ≥18 yr.
- Off‑label: Some practitioners use for adult attention, but FDA indication is limited to ADHD.
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Contraindications
Contraindications
• Severe cardiovascular disease (sudden cardiac death risk)
• Untreated narrow‑angle glaucoma
• Known hypersensitivity to dexmethylphenidate or excipients
Warnings
• Cardiovascular: ↑systolic/diastolic BP, tachycardia; monitor baseline and periodic vitals.
• Psychiatric: potential for anxiety, mania, or aggression; watch for suicidal ideation.
• Growth Suppression: ↓height velocity in pediatric patients; review growth charts quarterly.
• Rhabdomyolysis/Torsades: rare but serious in patients with QT prolongation.
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Dosing
| Age Group | Initial Dose | Titration | Maintenance | Max Daily Dose |
| Children 6–12 yr | 5 mg once daily (XR) | Increase 5 mg every 1–2 wks, 4 h before bedtime | 10–20 mg/day | 30 mg |
| Adolescents 13–17 yr | 10 mg once daily | Increase 5–10 mg every 1–2 wks | 20–30 mg/day | 30 mg |
| Adults ≥18 yr | 10 mg once daily | Increase 10 mg weekly | 20–40 mg/day | 40 mg |
• Administration: With or without food, avoid late‑day dosing to prevent insomnia.
• Missed dose: Skip; don’t double‑dose the next day.
• Medication holidays: Discuss with supervising physician; typical for weekend/holiday breaks.
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Adverse Effects
Common (≥ 5% in trials)
• Insomnia
• Loss of appetite / weight loss
• Dry mouth
• Palpitation, tachycardia
• Irritability, agitation
Serious (≥ 1% and/or life‑threatening)
• Hypertension or severe tachycardia
• Suicidal ideation or behavior in children/adolescents
• Cardiac arrhythmias (QT prolongation, torsades)
• Rhabdomyolysis (rare)
• Growth retardation (pediatric)
• Severe psychiatric breakthrough (mania, psychosis)
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Monitoring
| Parameter | Frequency | Rationale |
| BP & HR | Baseline, 1 week, 1 month, then quarterly | Detect cardiovascular toxicity |
| Weight & Height (peds) | Every 3 months | Monitor growth suppression |
| Growth velocity | Clinically if slowed | Early sign of long‑term effect |
| Psychiatric screening | Baseline, then bi‑annually | Identify emergent mood/anxiety disorders |
| QTc interval | Baseline in patients with heart disease | Risk of torsades |
| Metabolic panel (renal, electrolytes) | Baseline, annually | Safety for renal clearance |
| Adherence | Clinical interview | XR formulation may mask non‑adherence if taken late |
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Clinical Pearls
- XR vs. Immediate‑Release: XR has a *biphasic*, extended release that reduces dose‑frequency and mitigates “peak‑trough” side effects common with IR methylphenidate.
- Switching Strategy: For patients with GI upset on IR, switch to XR *at the same total daily dose* to maintain therapeutic exposure while minimizing nausea.
- CYP2D6 Poor Metabolizers: Consider starting on the lower end of the dosing range; they often need a lower maintenance dose due to slower clearance.
- Growth Monitoring: Even if weight stabilizes, a *height velocity drop >20 %* relative to pre‑treatment growth charts is concerning; consider dose adjustment or treatment holiday.
- Cardiovascular Precautions: For patients with a history of arrhythmias, keep the *maximum daily dose ≤ 30 mg* and arrange an ECG before initiation.
- Stool Color Change: A green discoloration may occur; reassure patients if no other GI complaints.
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• *This drug card provides evidence‑based, concise information for medical students and clinicians seeking quick reference regarding Focalin XR. For comprehensive patient guidance, consult the prescribing information and institutional protocols.*