ADHD Medication Guide

Attention Deficit/Hyperactivity Disorder (ADHD) is common among children and adolescents in Hong Kong. Patients often present with inattention, hyperactivity, and impulsive behaviors. These symptoms not only affect academic performance but may also lead to strained relationships, low self-esteem, and an increased risk of anxiety or depression in adulthood. Pharmacological treatment is well established in Hong Kong and can effectively improve quality of life.

Methylphenidate (Ritalin, Ritalin LA, Concerta) and Lisdexamfetamine (Vyvanse) are both central nervous system stimulants and among the most frequently prescribed medications for ADHD. Methylphenidate works by inhibiting the reuptake of dopamine and norepinephrine, allowing these neurotransmitters to remain longer in the synaptic cleft and enhancing signal transmission. This improves attention, reduces impulsivity, and increases learning efficiency. Because of its rapid onset—usually within 30–60 minutes—it is widely used in Hong Kong. Methylphenidate is available in short-acting (Ritalin), long-acting (Ritalin LA), and extended-release (Concerta) formulations. Physicians select the appropriate version based on the patient’s lifestyle and needs.

Vyvanse, in contrast, is a prodrug of the amphetamine class. Once ingested, it is metabolized into dextroamphetamine (d-amphetamine), which also increases dopamine and norepinephrine levels. Its release is smoother, with effects lasting 12–14 hours, reducing the likelihood of sudden “wearing off” or rebound effects. Both medications effectively improve core ADHD symptoms, but psychiatrists choose between methylphenidate and lisdexamfetamine based on age, lifestyle, side effect tolerance, and therapeutic needs.

Atomoxetine (Strattera) is a non-stimulant. It selectively inhibits norepinephrine reuptake, enhancing neural transmission efficiency. Unlike methylphenidate, it does not directly stimulate the dopamine system, so side effects are relatively mild. Atomoxetine requires several weeks before therapeutic effects appear, making it a gradual medication suitable for long-term use.

Clonidine and Guanfacine are α-2 adrenergic receptor agonists. They regulate prefrontal cortical activity, reducing hyperactivity and impulsivity. Wellbutrin (Bupropion) is a norepinephrine–dopamine reuptake inhibitor (NDRI). Although primarily used for depression, it can improve ADHD symptoms in some patients.

Stimulant Medications: Methylphenidate and Lisdexamfetamine

1. Mechanism of Action
   Methylphenidate is one of the most commonly used ADHD medications in Hong Kong. It inhibits the reuptake of dopamine and norepinephrine, enhancing signal transmission. This improves prefrontal cortex function, attention, working memory, and impulse control. Because of its rapid onset, usually within 30–60 minutes, it is widely prescribed.
   Lisdexamfetamine (Vyvanse) is a prodrug of the amphetamine class. After ingestion, it is metabolized into dextroamphetamine, which also increases dopamine and norepinephrine levels. Its release is smoother, with effects lasting 12–14 hours, reducing the likelihood of sudden “wearing off” or rebound effects. It is particularly suitable for patients requiring stable concentration throughout the day.
2. Formulations and Usage Context

• • Methylphenidate:

• • • Short-acting Ritalin: lasts about 4 hours, requires multiple doses daily, suitable for short-term concentration needs such as exams or study sessions.

• • • Long-acting Ritalin LA: lasts about 8 hours, suitable for school days, reducing the inconvenience of mid-day dosing.

• • • Extended-release Concerta: lasts about 12 hours, convenient once-daily dosing, suitable for patients needing all-day stable effects.

• • Lisdexamfetamine (Vyvanse): once daily, with effects lasting more than half a day. As a prodrug, its risk of misuse is relatively low, with good clinical safety.

3. Clinical Effectiveness
   Studies show that about 70–80% of patients respond well to methylphenidate, with significant improvements in attention and learning efficiency. Vyvanse has similar effectiveness, but because of its smoother release, some patients show better emotional stability and sustained concentration, especially in contexts requiring prolonged focus.
4. Side Effects
   Stimulant medications share similar side effect profiles, commonly including:

• • Decreased appetite: may lead to weight loss, requiring growth monitoring.
  • Sleep difficulties: insomnia or delayed sleep onset, especially if taken late in the day.
  • Headache or abdominal pain: mild discomfort in some patients.
  • Emotional fluctuations: irritability or anxiety.
  • Tics: some patients may develop or worsen pre-existing tic symptoms.

Although side effects are common, most are mild and manageable. Doctors will adjust the dosage or switch medications according to the patient’s response.

5. Monitoring Process
   Stimulant medications require regular monitoring to ensure safety and effectiveness:

• • Height and weight: to prevent growth being affected by long-term appetite suppression.
  • Blood pressure and heart rate: stimulants may increase heart rate and blood pressure.
  • Emotional state: observe for anxiety, depression, or psychotic symptoms.
  • Tic symptoms: pay special attention to whether tics emerge or worsen.
  • School and family feedback: continuously track learning and behavioral performance.

6. Clinical Considerations
   Psychiatrists decide between methylphenidate or lisdexamfetamine based on the patient’s age, lifestyle, tolerance of side effects, risk of tics or psychotic symptoms, and therapeutic needs.

Atomoxetine 

1. Mechanism of Action
   Atomoxetine is a non-stimulant medication classified as a selective norepinephrine reuptake inhibitor (NRI). By increasing norepinephrine levels in the prefrontal cortex, it enhances signal transmission, improves attention, and reduces impulsivity. Unlike stimulants, atomoxetine does not act directly on the dopamine system, which makes its side effects relatively mild and lowers the risk of misuse or dependence.
2. Formulation and Usage Context
   Atomoxetine is usually taken once daily or in divided doses. Its therapeutic effects require several weeks of continuous use to become evident. It is particularly suitable for:

• • Patients who respond poorly to stimulants or experience intolerable side effects.
  • Patients with anxiety or tic symptoms.
  • Families or individuals who prefer to avoid stimulant medications.

3. Clinical Effectiveness
   Clinical studies show that approximately 60–70% of patients respond well to atomoxetine. It improves attention and reduces impulsive behaviors, with especially good outcomes in patients who also have anxiety or tics. Because of its slower onset, significant improvement typically appears after 4–6 weeks.
4. Side Effects
   Common side effects include:

• • Drowsiness or fatigue.
  • Gastrointestinal discomfort (such as nausea or abdominal pain).
  • Mild changes in blood pressure.
  • Liver function abnormalities in a small number of patients.
  • Rarely, emotional fluctuations or psychotic symptoms.

5. Monitoring Process

• • Liver function tests: regular monitoring to prevent liver damage.
  • Blood pressure and heart rate: observe for significant changes.
  • Emotional state: monitor for anxiety, depression, or psychotic symptoms.
  • School and family feedback: track improvements in learning and behavior.

6. Clinical Considerations
   Atomoxetine is recommended for patients who do not respond well to stimulants or cannot tolerate their side effects, particularly those with anxiety or tic symptoms. Although its onset is slower, it provides stable, sustained improvement and carries a low risk of misuse.

Clonidine and Guanfacine (Intuniv)

1. Mechanism of Action
   Clonidine and guanfacine are α-2 adrenergic receptor agonists. They stimulate α-2 receptors in the brain, reducing excessive sympathetic activity and stabilizing prefrontal cortical function. This helps decrease impulsivity, improve emotional regulation, and promote sleep. Guanfacine is more selective, acting primarily on α-2A receptors, which results in fewer sedative side effects and better tolerability.
2. Formulation and Usage Context

• • Clonidine: available in oral tablet form, often taken at night to improve sleep. Suitable for ADHD patients with hyperactivity, impulsivity, or insomnia.
  • Guanfacine (Intuniv): available in extended-release form, taken once daily with effects lasting throughout the day. Particularly suitable for children and adolescents, especially those with emotional dysregulation or aggressive behaviors.

3. Clinical Effectiveness
   Both medications improve hyperactivity, impulsivity, and emotional dysregulation, and can aid sleep. Clonidine is especially effective in patients with comorbid tics or insomnia, while guanfacine provides longer-lasting control and is better tolerated in children and adolescents.
4. Side Effects
   Common side effects include drowsiness, fatigue, lowered blood pressure, and dizziness. A small number of patients may experience bradycardia or emotional fluctuations. Guanfacine, due to its higher selectivity, generally causes less sedation.
5. Monitoring Process

• • Blood pressure and heart rate: regular monitoring to prevent hypotension or bradycardia.
  • Sleep quality: observe for improvement or excessive sedation.
  • Behavioral performance: track changes in impulsivity and emotional control.
  • Tic symptoms: monitor for improvement or worsening.

6. Clinical Considerations
   Clonidine and guanfacine are often used as adjuncts to stimulants or atomoxetine. Clonidine is suitable for patients with tics, insomnia, or emotional dysregulation, while guanfacine is preferred for children and adolescents requiring long-term stable control, especially those with emotional instability or aggressive behaviors.

Bupropion (Wellbutrin )

1. Mechanism of Action
   Bupropion is a norepinephrine–dopamine reuptake inhibitor (NDRI). It is primarily used in the treatment of depression and smoking cessation, but in some ADHD patients it can improve attention and impulse control.
2. Formulation and Usage Context
   Bupropion is available in immediate-release and extended-release forms, taken once daily or in divided doses. It is commonly prescribed for ADHD patients with comorbid depression or nicotine dependence, and its use in ADHD is considered “off-label.”
3. Clinical Effectiveness
   Bupropion can improve both mood and attention, making it particularly suitable for patients with coexisting depression. Although its effectiveness is not as pronounced as that of stimulants, it has clinical value in specific populations.
4. Side Effects
   Common side effects include insomnia, anxiety, dry mouth, and headache. A small number of patients may develop tics or psychotic symptoms. Seizure risk must be considered, and the medication should be avoided in patients with a history of seizures or at high doses.
5. Monitoring Process

• • Emotional state: observe improvements in depression or anxiety.
  • Sleep quality: monitor for insomnia or heightened anxiety.
  • Neurological status: watch for seizures or psychotic symptoms.

Principles of Medication Treatment

The principle of ADHD medication treatment is to adjust the balance of neurotransmitters, not to change the patient’s personality. The goal is to enable patients to better use their abilities, improving learning and overall quality of life. Medication treatment is usually combined with behavioral therapy, family support, and school collaboration to achieve the best outcomes.