What is the appropriate dosage and usage of Dextroamphetamine (amphetamine) for a patient with ADHD or narcolepsy?

Dextroamphetamine Dosing and Usage

For ADHD in adults, start dextroamphetamine at 10 mg once daily in the morning and titrate by 5 mg weekly increments based on response, with a maximum dose of 50 mg daily; for narcolepsy, start at 10 mg daily in patients 12 years and older, increasing by 10 mg weekly intervals up to 60 mg daily as needed. 1, 2

ADHD Treatment

Initial Dosing

• Begin with 10 mg once daily administered upon awakening to minimize sleep disturbances 1, 2
• Avoid starting at higher doses, as this increases unnecessary side effects and reduces medication adherence 1

Titration Protocol

• Increase by 5 mg increments at weekly intervals until optimal symptom control is achieved 1, 2
• Allow at least one week between dose increases to properly evaluate therapeutic response 1
• Maximum recommended daily dose is 50 mg for adults 1, 2
• Assess both therapeutic effects and side effects systematically before each dose increase using standardized ADHD rating scales 1

Monitoring Requirements

• Check blood pressure and pulse at baseline and with each dose increase, as cardiovascular effects are common 1, 3
• Schedule follow-up appointments at least monthly until symptoms are stabilized 1
• Monitor for common adverse effects including insomnia, decreased appetite, irritability, and palpitations 1, 2

Efficacy Evidence

• Dextroamphetamine demonstrates robust efficacy with effect sizes of 0.8 to 1.0 SD on behavioral measures in short-term trials 4
• Long-term studies show persistence of medication effects over 24 months without diminution of efficacy 4
• Response rates approach 70% when a single stimulant is tried, though fewer than half of patients achieve complete normalization 4

Narcolepsy Treatment

Dosing for Narcolepsy

• For patients 12 years and older, start with 10 mg daily and increase by 10 mg weekly intervals until optimal response is obtained 2
• For patients aged 6-12 years, start with 5 mg daily and increase by 5 mg weekly 2
• Typical effective doses range from 60 mg daily for dextroamphetamine 4, 2

Administration Schedule

• Give first dose upon awakening, with additional doses (1-2) at 4-6 hour intervals throughout the day 2
• This divided dosing maintains therapeutic effect while managing excessive daytime sleepiness 4

Alternative Considerations

• While dextroamphetamine has traditionally been used for narcolepsy, modafinil has gained favor as first-line treatment due to a more favorable side effect profile 4
• For elderly patients with narcolepsy, consider starting modafinil at 100 mg once daily instead, as older adults are more sensitive to stimulant effects 4

Special Populations

Older Adults

• Use more conservative titration schedules in older adults, such as increasing by 5 mg every 2 weeks instead of weekly 1
• Age-related pharmacokinetic changes increase sensitivity to both therapeutic and adverse effects 1
• Careful monitoring of vital signs is particularly important in this population 1

Medically Ill Patients

• Start at approximately half the usual ADHD starting dose and titrate slowly with careful monitoring 4
• Stimulants can be beneficial for apathy and depression in medically ill patients, but require cautious dosing 4

Treatment Optimization

When Current Dose is Inadequate

• Before increasing dose, confirm consistent medication use and rule out other contributing factors such as sleep issues or comorbid conditions 1
• Evaluate for potential drug interactions that may affect efficacy 1

Maximum Dose Considerations

• If reaching 50 mg without adequate symptom control or with intolerable side effects, consider switching to a different stimulant formulation or adding a non-stimulant medication like atomoxetine 1
• Reevaluate the diagnosis and assess for comorbid conditions affecting treatment response 1

Common Pitfalls to Avoid

• Never administer late evening doses due to resulting insomnia 2
• Avoid rapid titration without allowing adequate time to assess response at each dose level 1
• Do not overlook the importance of morning administration to minimize sleep disturbances 1, 3
• Failure to systematically assess both benefits and side effects during titration leads to suboptimal outcomes 1
• Starting at excessively high doses increases side effects and decreases adherence 1

Discontinuation

• Dextroamphetamine can be stopped abruptly without serious medical consequences, as it does not cause physical dependence or dangerous withdrawal syndromes 5
• Pharmacodynamic effects disappear within 4-6 hours after the last dose of immediate-release formulations 5
• Patients may experience temporary fatigue, return of ADHD symptoms, and mild mood changes, but these are self-limited 5
• A brief taper may be considered for comfort but has no proven medical benefit 5