Introduction
Focalin (dexmethylphenidate hydrochloride) is a central nervous system (CNS) stimulant prescription medication approved for the treatment of attention-deficit/hyperactivity disorder (ADHD). It is the pharmacologically active d-enantiomer of racemic methylphenidate, offering a more targeted therapeutic approach with potentially improved side effect profile compared to the racemic mixture.
Mechanism of Action
Focalin exerts its therapeutic effects through blockade of dopamine and norepinephrine reuptake transporters in the presynaptic neurons, primarily in the striatum and prefrontal cortex. This mechanism increases the availability of these neurotransmitters in the synaptic cleft, enhancing neurotransmission. The drug's action is particularly relevant to ADHD pathophysiology, as dopamine and norepinephrine play crucial roles in attention, executive function, and impulse control.
Indications
- Treatment of Attention-Deficit/Hyperactivity Disorder (ADHD) in patients 6 years and older
- Approved as part of a comprehensive treatment program that may include psychological, educational, and social interventions
Dosage and Administration
Initial Dose:- Children (6-17 years): 2.5 mg twice daily (approximately 4 hours apart)
- Adults: 5 mg twice daily
- May increase weekly in increments of 2.5-5 mg
- Maximum recommended dose: 20 mg daily (10 mg twice daily)
- Renal impairment: Use with caution
- Hepatic impairment: Use with caution
- Geriatric patients: Not recommended due to limited experience
- Administration: May be taken with or without food
Pharmacokinetics
Absorption: Rapid and extensive absorption with peak plasma concentrations achieved in 1-1.5 hours (immediate-release formulation) Distribution: Apparent volume of distribution approximately 2.65 L/kg; protein binding is low (10-33%) Metabolism: Primarily metabolized by de-esterification to d-ritalinic acid Elimination: Half-life approximately 2.2 hours; primarily excreted renally (78-97% of dose recovered in urine within 48 hours)Contraindications
- Known hypersensitivity to methylphenidate or other product components
- Patients with glaucoma
- Patients with motor tics or with a diagnosis of Tourette's syndrome or family history of Tourette's syndrome
- During or within 14 days following MAO inhibitor therapy
Warnings and Precautions
Boxed Warning: High potential for abuse and dependence- Cardiovascular effects: May increase blood pressure and heart rate; use caution in patients with hypertension, heart failure, recent MI, or structural cardiac abnormalities
- Psychiatric adverse reactions: May exacerbate psychotic symptoms; may induce manic episodes in patients with bipolar disorder
- Priapism: Rare but serious reports of prolonged and painful erections
- Growth suppression: Monitor height and weight in pediatric patients
- Peripheral vasculopathy: Including Raynaud's phenomenon
- Visual disturbances: Difficulties with accommodation and blurring of vision
Drug Interactions
- MAO inhibitors: Risk of hypertensive crisis (contraindicated)
- Antihypertensive drugs: May decrease efficacy
- Warfarin: May alter anticoagulant response
- Clonidine: Serious adverse events reported (not recommended)
- Serotonergic drugs: Potential for serotonin syndrome
Adverse Effects
Common (≥5%):- Headache (25%)
- Abdominal pain (15%)
- Decreased appetite (27%)
- Anxiety (7%)
- Xerostomia (7%)
- Nausea (9%)
- Insomnia (17%)
- Cardiovascular events (sudden death, stroke, MI)
- Psychiatric events (psychosis, mania)
- Priapism
- Peripheral vasculopathy
- Growth suppression
Monitoring Parameters
- Height and weight in pediatric patients (every 3-6 months)
- Blood pressure and heart rate at each dose adjustment and periodically during treatment
- CBC with differential in patients with pre-existing leukopenia or thrombocytopenia
- Psychiatric symptoms assessment
- Signs of drug misuse, abuse, or dependence
- Visual function if symptoms occur
Patient Education
- Take medication exactly as prescribed; do not adjust dose without medical supervision
- Be aware of potential for abuse and dependence
- Report any chest pain, palpitations, or unexplained syncope immediately
- Monitor for new or worsening psychiatric symptoms
- Inform all healthcare providers about Focalin use
- Do not abruptly discontinue medication without medical guidance
- Be cautious when operating machinery or driving until effects are known
- Store medication securely to prevent misuse
References
1. Focalin® (dexmethylphenidate hydrochloride) prescribing information. Novartis Pharmaceuticals Corporation. 2. Biederman J, et al. A comparison of once-daily and divided doses of dexmethylphenidate in children with attention-deficit/hyperactivity disorder. J Clin Psychiatry. 2003;64 Suppl 11:24-29. 3. Wigal SB, et al. Efficacy and safety of dexmethylphenidate extended-release capsules in children with attention-deficit/hyperactivity disorder. J Am Acad Child Adolesc Psychiatry. 2004;43(11):1356-1364. 4. Adler LA, et al. Dexmethylphenidate extended-release capsules in adults with attention-deficit/hyperactivity disorder. Biol Psychiatry. 2009;65(2):138-144. 5. American Psychiatric Association. Practice guideline for the treatment of patients with attention-deficit/hyperactivity disorder. Am J Psychiatry. 2020;177(Suppl 1):1-32. 6. Pliszka S; AACAP Work Group on Quality Issues. Practice parameter for the assessment and treatment of children and adolescents with attention-deficit/hyperactivity disorder. J Am Acad Child Adolesc Psychiatry. 2007;46(7):894-921.