What is Dexedrine? Composition and Mechanism of Action
Dexedrine is the brand name for dextroamphetamine sulfate, a powerful central nervous system (CNS) stimulant that affects the brain's neurochemical balance. Unlike other related medications, Dexedrine is composed solely of the dextroamphetamine isomer, the more potent of the two amphetamine enantiomers.
How does dextroamphetamine work in the brain?
The primary mechanism of action for Dexedrine involves boosting the levels of two key neurotransmitters in the brain: dopamine and norepinephrine. It accomplishes this through several pathways:
- Promotes Release: It triggers the release of these neurotransmitters from nerve terminals within the brain.
- Blocks Reuptake: It competitively inhibits the reuptake of dopamine and norepinephrine back into the presynaptic neuron, leaving more of them available in the synaptic space.
- Inhibits Breakdown: In some cases, it also inhibits monoamine oxidase, an enzyme that breaks down neurotransmitters.
For individuals with ADHD, this increase in neurotransmitter activity can improve attention, reduce impulsivity, and help regulate behavior. For those with narcolepsy, it enhances wakefulness and reduces excessive daytime sleepiness.
Therapeutic Uses and Indications
Dexedrine is an established treatment, but it is important to understand its specific FDA-approved uses and the patient populations for whom it is intended.
Attention-Deficit/Hyperactivity Disorder (ADHD)
As part of a comprehensive treatment program including behavioral, educational, and social interventions, Dexedrine is indicated for children and adolescents between 6 and 17 years of age with ADHD. A diagnosis of ADHD is based on a full evaluation and requires symptoms of inattention or hyperactivity-impulsivity that significantly impair functioning in multiple settings.
Narcolepsy
Dexedrine is also approved to treat narcolepsy, a sleep disorder that causes excessive daytime sleepiness and sudden sleep attacks. The stimulant effect of dextroamphetamine helps patients maintain wakefulness throughout the day.
Important Warnings and Contraindications
Due to its potent effects, Dexedrine comes with several critical warnings and is not suitable for everyone. Patients should be screened for risk factors and monitored throughout treatment.
Boxed Warnings
- High Potential for Abuse and Dependence: Dexedrine is a Schedule II controlled substance, indicating a high risk for abuse, misuse, and addiction. Misuse can lead to overdose and death, a risk that increases with higher doses or unapproved methods of administration.
- Serious Cardiovascular Events: Stimulants can cause a modest increase in blood pressure and heart rate. Sudden death, stroke, and heart attack have been reported in adults with heart defects or other serious heart problems.
Contraindications
Patients with the following conditions should generally not take Dexedrine:
- Advanced arteriosclerosis or other symptomatic cardiovascular disease.
- Moderate to severe hypertension.
- Hyperthyroidism.
- Glaucoma.
- Agitated states or severe anxiety/tension.
- History of drug abuse.
- Concurrent use of monoamine oxidase inhibitors (MAOIs) or within 14 days of stopping MAOIs, as this can lead to a hypertensive crisis.
Common Side Effects of Dexedrine
Like all medications, Dexedrine can cause a range of side effects. While many are mild, some can be serious:
- Psychological: Overstimulation, restlessness, nervousness, dizziness, mood changes, and insomnia.
- Gastrointestinal: Decreased appetite, dry mouth, upset stomach, constipation, or diarrhea.
- Cardiovascular: Fast heartbeat (tachycardia) and elevated blood pressure.
- Other: Headaches, tremors, and weight loss.
Dexedrine vs. Adderall: A Comparison
While both Dexedrine and Adderall are stimulant medications used for ADHD and narcolepsy, their composition leads to some key differences in effect and duration.
| Feature | Dexedrine | Adderall |
|---|---|---|
| Composition | Pure dextroamphetamine sulfate. | A mix of dextroamphetamine and levoamphetamine salts (3:1 ratio). |
| Potency | Considered more potent and fast-acting due to its pure d-isomer content. | Generally considered milder or more balanced due to the inclusion of the less potent l-amphetamine. |
| Effect Profile | A strong and concentrated effect. | A more balanced effect, with a potentially slower onset and longer duration for some individuals. |
| Onset/Duration | Immediate-release tablets act faster (around 30-60 min) but last 4-6 hours. Extended-release (Spansule) can last up to 12 hours. | Immediate-release tablets act in 30-60 min and last 4-6 hours. Extended-release (XR) capsules can last up to 12 hours. |
| Use in Adults | FDA labeling emphasizes ADHD treatment for ages 6-17; use in adults for ADHD may be off-label or for narcolepsy. | FDA-approved for adults with ADHD and narcolepsy. |
Proper Use, Dosage, and Storage
It is crucial to take Dexedrine exactly as prescribed by a healthcare provider. Never increase the dose or take it more frequently without medical guidance.
Dosage and Administration
- Formulations: Dexedrine is available in immediate-release tablets, extended-release capsules (Spansule), and a liquid solution.
- Dosage: Doses vary based on age, condition, and individual response, and are titrated slowly to find the optimal therapeutic effect.
- Timing: Late evening doses should be avoided to prevent insomnia.
Storage and Disposal
As a controlled substance, proper handling is essential:
- Store Dexedrine in a safe, secure, and preferably locked place to prevent misuse or theft.
- Keep it at room temperature and protect it from excess heat and moisture.
- Unused or expired medication should be disposed of properly through a drug take-back program or by mixing it with an undesirable substance before sealing it in a bag for trash disposal.
Conclusion
Dexedrine is a long-standing central nervous system stimulant with proven efficacy for treating attention-deficit/hyperactivity disorder and narcolepsy. Its ability to increase dopamine and norepinephrine levels helps improve focus, manage impulsivity, and promote wakefulness. However, as a Schedule II controlled substance, it carries a significant risk for misuse, dependence, and serious side effects, particularly cardiovascular and psychiatric events. It is vital for patients to be carefully assessed and medically supervised throughout the course of treatment. Understanding the distinction between Dexedrine and other stimulants like Adderall, as well as following all prescribed instructions for dosage and storage, is crucial for maximizing benefits and minimizing risks.
For more in-depth prescribing information, consult the official FDA drug label: DEXEDRINE® - accessdata.fda.gov.
