From the FDA Drug Label
CLINICAL PHARMACOLOGY ... Pharmacokinetics ... The average plasma T1/2 was similar for both the tablet and sustained-release capsule and was approximately 12 hours. The duration of action of dexamphetamine (Dextroamphetamine) sulfate is related to its half-life (T1/2).
- The half-life (T1/2) of dexamphetamine is approximately 12 hours.
- However, the provided information does not specifically address the duration of action of a 2.5mg dose.
- Given the available data, it is not possible to determine the exact duration of action for this specific dose. 1
From the Research
Dexamphetamine sulfate 2.5mg typically lasts about 4-6 hours in the body. This is a relatively low dose of the medication, which is commonly prescribed for conditions like ADHD or narcolepsy. The duration can vary between individuals based on factors such as metabolism, body weight, liver function, and whether the medication is taken with food. Some people may experience effects for a shorter period (3 hours) while others might feel the effects for up to 8 hours. The medication works by increasing levels of dopamine and norepinephrine in the brain, which improves focus and reduces hyperactivity.
Key factors to consider when evaluating the duration of action of dexamphetamine sulfate include:
- Metabolism: individual variations in metabolic rate can affect how quickly the drug is broken down and eliminated from the body 2.
- Body weight: the dose of the medication is often calculated based on body weight, and individuals with a higher body mass index (BMI) may experience a longer duration of action 2.
- Liver function: the liver plays a crucial role in metabolizing dexamphetamine sulfate, and individuals with impaired liver function may experience a longer duration of action 3.
- Food intake: taking the medication with food can affect its absorption and duration of action, although the exact impact is not well established 4.
It's essential to take this medication exactly as prescribed, as the timing between doses is calculated based on this duration of action. If you're finding that the effects wear off too quickly or last too long, consult with your healthcare provider, as dosage adjustments may be needed. Side effects like decreased appetite or difficulty sleeping may persist beyond the main therapeutic effects. According to a systematic review and economic model of the effectiveness and cost-effectiveness of methylphenidate, dexamfetamine, and atomoxetine for the treatment of attention deficit hyperactivity disorder in children and adolescents, dexamphetamine sulfate is an effective treatment option, although the reporting of studies was poor, and the results should be interpreted with caution 2.