How should dextroamphetamine (amphetamine) be taken in relation to food?

Dextroamphetamine and Food Interactions

Dextroamphetamine should be taken on an empty stomach, avoiding vitamin C or citrus consumption within 1 hour before and after taking the medication to ensure optimal absorption and efficacy. 1

Mechanism of Food-Drug Interaction

The absorption and efficacy of dextroamphetamine can be significantly affected by food and acidic substances:

• Vitamin C and Citrus Interactions: The American Academy of Child and Adolescent Psychiatry recognizes that vitamin C/citrus can decrease dextroamphetamine absorption and accelerate its elimination from the body 1
• Gastrointestinal pH Effects:
  • Acidifying agents increase urinary excretion of amphetamines, lowering blood levels and efficacy 2
  • Alkalinizing agents (like sodium bicarbonate) increase absorption of amphetamines 2

Evidence on Food Effects

Research has demonstrated that food can significantly impact amphetamine absorption:

• A comparative study (CAFE Study) showed that amphetamine concentrations were markedly lower when subjects had eaten breakfast, resulting in lower early drug exposure (p < 0.0001) 3
• This food effect can lead to day-to-day variations in medication effectiveness depending on eating patterns 3

Practical Administration Guidelines

To maximize dextroamphetamine effectiveness:

1. Timing with meals:

   • Take dextroamphetamine on an empty stomach
   • Allow at least 1 hour before or after meals, particularly breakfast
   • Avoid taking medication with high-fat meals which can significantly reduce absorption 3

2. Specific dietary considerations:

   • Avoid vitamin C-rich foods and beverages within 1 hour before and after taking dextroamphetamine 1
   • Avoid citrus fruits and juices within 1 hour before and after taking the medication 1
   • Be consistent with eating patterns to maintain steady medication levels

Clinical Implications and Monitoring

• Inconsistent food intake patterns may lead to variable medication effectiveness throughout the day 3
• Patients should be monitored for:
  • Changes in symptom control that might correlate with dietary patterns
  • Blood pressure and heart rate changes, as amphetamines increase systolic blood pressure by approximately 1.93 mmHg and diastolic blood pressure by 1.84 mmHg 4

Potential Risks of Improper Administration

• Taking dextroamphetamine on an empty stomach can lead to faster absorption, which may increase side effects in some patients 5
• Rapid absorption on an empty stomach combined with other medications (like trazodone or clonidine) may increase the risk of adverse effects 5

Special Considerations

• For patients who cannot tolerate taking dextroamphetamine on an empty stomach due to side effects, a small, non-acidic snack might be considered
• For those who struggle with oral administration, alternative formulations like the dextroamphetamine transdermal system (d-ATS) may be considered 6