Focalin
Focalin
Generic Name
Focalin
Mechanism
Focalin selectively inhibits dopamine (DA) reuptake via the dopamine transporter (DAT), increasing synaptic dopamine concentration.
• Dopamine modulation: Enhances dopaminergic signaling in the prefrontal cortex, basal ganglia, and limbic system—regions implicated in attention and impulse control.
• Serotonin contribution: Exhibits weaker, partial serotonin reuptake inhibition, which may mitigate some psychiatric side effects compared with racemic methylphenidate.
• Resultant effect: Greater attentional focus, reduced hyperactivity, and improvement in executive function.
Pharmacokinetics
- Absorption: Rapid oral uptake; ~70 % bioavailability for immediate‑release (IR) formulation.
- Onset: 30–60 min post‑dose.
- Peak concentration (Tmax): ~1–1.5 h for IR, ~4 h for extended‑release (XR).
- Duration: 4–6 h (IR); 12–14 h (XR).
- Half‑life: 3–6 h (IR), 12–14 h (XR).
- Metabolism: Oxidative demethylation predominantly via CYP2D6; minor glucuronidation.
- Elimination: Primarily renal; ∼90 % excreted unchanged or as metabolites.
- Drug interactions: Strong CYP2D6 inhibitors (e.g., fluoxetine) can raise steady‑state levels; caution with MAO inhibitors & antihypertensives.
Indications
- ADHD
- Children (≥6 yr) & adolescents (≥13 yr) – IR or XR.
- Adults with ADHD – IR or XR, particularly when motor hyperactivity or impaired executive function is prominent.
- Premedication for certain procedures – Rarely used as a short‑acting CNS stimulant to mitigate procedural anxiety (off‑label).
Contraindications
- Absolute contraindications
- Severe cardiovascular disease (congestive heart failure, arrhythmia, ischemic heart disease).
- Narrow‑angle glaucoma.
- Known hypersensitivity to dexmethylphenidate, methylphenidate, or any component.
- Warnings
- Cardiovascular monitoring: Hypertension, tachycardia, orthostatic changes.
- Growth suppression: Documented reduction in mean height velocity in pediatric patients.
- Psychiatric effects: Potential for agitation, anxiety, mood swings, and, in susceptible individuals, psychosis or suicidal ideation.
- Risk of abuse: Consider abuse‑potential monitoring, especially in patients with substance‑use disorders.
Dosing
- Children (6–12 yr)
- IR: Start 2.5 mg once daily. Titrate 2.5–5 mg weekly based on response and tolerability, maximum 20 mg/day (up to 30 mg/day if tolerated).
- XR: Start 10 mg once daily. Increment 5 mg weekly; max 60 mg/day.
- Adolescents (13–17 yr)
- IR: 5 mg once daily, up‑titrate 5–10 mg weekly; max 40 mg/day.
- XR: 15 mg once daily; titrate 5 mg weekly; max 60 mg/day.
- Adults
- IR: 10 mg once daily, titrate 10 mg weekly; max 60 mg/day.
- XR: 20 mg once daily; titrate 10 mg weekly; max 60 mg/day.
- Timing: Administer in the morning to reduce insomnia risk; XR dose should be taken at the first bite of the day, allowing a 30‑minute window before physical activity.
- Missed dose: Take within 1 h of scheduled time; skip if >12 h have passed.
Adverse Effects
- Common
- Decreased appetite, weight loss.
- Insomnia, fatigue in the late afternoon.
- Irritability, anxiety, headaches.
- GI upset (dyspepsia, abdominal pain).
- Orthostatic hypotension (rare).
- Serious
- Hypertension, tachycardia, palpitations.
- Psychiatric: mania, psychosis, suicidal ideation—especially in those with pre‑existing mood disorders.
- Cerebrovascular events: rare but serious.
- Growth suppression: measurable decline in percentile growth curves.
Monitoring
| Parameter | Frequency | Rationale |
| Blood pressure & heart rate | Baseline, 2 weeks, 4 weeks, and every 3 months thereafter | Detect stimulant‑induced hypertension/tachycardia |
| Weight & height (pediatrics) | Every clinic visit (≥3 months) | Monitor growth suppression |
| Growth velocity | Annually (pediatric patients) | Compliance with appropriate pediatric dosing |
| Neuropsychiatric status | Baseline and every visit | Identify emergent mood or psychotic symptoms |
| Laboratory tests | Baseline, then annually | CBC, CMP not routinely required but may be indicated if symptoms present |
| Adverse effect diary | Patient/parent report | Ensure timely dose adjustments |
Clinical Pearls
- Better selectivity, less abuse: Dexmethylphenidate’s d‑enantiomer confers a 2–3 × increase in potency per mg and a lower abuse‑potential profile compared with racemic methylphenidate – useful in patients with a history of substance abuse.
- Start low, go slow: Pediatric patients often require lower initial doses because their drug range is narrower; pediatric patients also have higher sensitivity to growth‑suppression.
- Extended‑release advantages: XR formulations reduce peak–trough fluctuations, decreasing insomnia and evening‑time jitter. XR dosing in the morning supports activity throughout the day while minimizing mid‑day crashes.
- Combination therapies: Non‑stimulant ADHD agents (e.g., atomoxetine) can be added for augmentation; be mindful that combined stimulants may intensify cardiovascular side effects.
- Special populations: In patients with hepatic impairment, the drug’s short half‑life makes dose adjustments less critical; however, renal impairment can extend clearance, so monitor dosing and pulse‑oximetry.
- Trial period: Consider a 4‑week evaluation period before commending long‑term therapy; this timeframe allows adequate assessment of efficacy and tolerability.
- Patient education: Emphasize adherence to morning dosing and avoiding late‑day dosing of XR to prevent insomnia.
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• References
• F. P. Edag, *Pharmacotherapy of ADHD in Children and Adolescents*, 2019.
• U.S. Food and Drug Administration. *Dexamethylphenidate prescribing information*, 2022.
• A. W. Nielsen et al., "Growth Suppression with Stimulants in Pediatric ADHD," *Pediatrics*, 2021.
• D. E. Himes, *Cardio‑pulse monitoring in stimulant therapy*, *Journal of Clinical Pharmacology*, 2020.