DEXAMPEX
Clinical safety rating: caution
Comprehensive clinical and safety monograph for DEXAMPEX (DEXAMPEX).
Dextroamphetamine is a central nervous system stimulant that increases extracellular dopamine and norepinephrine levels by blocking their reuptake and promoting release from presynaptic terminals.
| Metabolism | Hepatic metabolism via cytochrome P450 enzymes, primarily CYP2D6, to inactive metabolites including 4-hydroxydextroamphetamine and alpha-hydroxydextroamphetamine. |
| Excretion | Renal: ~90% as unchanged drug and metabolites (primarily deaminated metabolites); fecal/biliary <2%. |
| Half-life | Terminal elimination half-life 10–13 hours in adults (7–8 hours in children). Longer in alkaline urine (up to 20 hours) due to reduced renal tubular reabsorption. |
| Protein binding | 15–25%, primarily albumin. |
| Volume of Distribution | 3.5–4.6 L/kg; indicates extensive tissue distribution, brain penetration (CNS: 10–20 x plasma concentrations). |
| Bioavailability | Oral immediate-release: 75–85% (fasting). Oral extended-release: ~80% relative to immediate-release. Intravenous: 100%. |
| Onset of Action | Oral immediate-release: 30–60 min. Oral extended-release: 1.5–2.5 hours. Intravenous: 2–5 min. |
| Duration of Action | Oral immediate-release: 4–6 hours. Oral extended-release: 8–12 hours. Intravenous: 4–6 hours. |
| Molecular Weight | 135.21 |
5-10 mg orally once daily in the morning, maximum 20 mg/day.
| Dosage form | TABLET |
| Renal impairment | GFR 30-89 mL/min: no adjustment needed. GFR 15-29 mL/min: reduce dose by 50%. GFR <15 mL/min: contraindicated. |
| Liver impairment | Child-Pugh A: no adjustment. Child-Pugh B: reduce dose by 50%. Child-Pugh C: contraindicated. |
| Pediatric use | 6-17 years: 5 mg once daily; may increase to 10 mg after 1 week if needed. Maximum 20 mg/day. |
| Geriatric use | Initiate at 2.5 mg once daily; titrate cautiously. Maximum 10 mg/day. |
| 1st trimester | Potential fetal harm based on amphetamine class; use only if benefit outweighs risk. Associated with increased risk of congenital malformations, particularly cardiac defects, when used in first trimester. |
| 2nd trimester | May cause fetal growth restriction, prematurity, and withdrawal symptoms; use only if clearly needed. |
| 3rd trimester | Risk of neonatal withdrawal syndrome, prematurity, low birth weight, and long-term neurodevelopmental effects; avoid use in third trimester if possible. |
Clinical note
Comprehensive clinical and safety monograph for DEXAMPEX (DEXAMPEX).
| Placental transfer | Amphetamines readily cross the placenta via passive diffusion and active transport; fetal concentrations can approach maternal levels. |
| Breastfeeding | Excreted into breast milk; may cause irritability, poor feeding, and growth restriction in nursing infants. Contraindicated in breastfeeding due to potential for adverse effects. |
■ FDA Black Box Warning
WARNING: ABUSE AND DEPENDENCE. Dextroamphetamine has a high potential for abuse and dependence. Prolonged administration may lead to drug dependence and must be avoided. Particular attention should be paid to the possibility of patients obtaining dextroamphetamine for non-therapeutic use or distribution to others, and the drug should be prescribed or dispensed sparingly.
| Serious Effects |
Hypersensitivity to amphetamines or any component of the formulationConcomitant use of MAOIs or within 14 days of MAOI therapyAdvanced arteriosclerosisSymptomatic cardiovascular diseaseModerate to severe hypertensionHyperthyroidismGlaucomaAgitated statesHistory of drug abuseLactation
| Precautions | Serious cardiovascular events including sudden death in patients with pre-existing structural cardiac abnormalities, Blood pressure and heart rate increases, Psychiatric adverse events including exacerbation of pre-existing psychosis, mania, and aggression, Long-term suppression of growth in children, Seizures in patients with prior seizure history, Peripheral vasculopathy including Raynaud's phenomenon, Serotonin syndrome if used with serotonergic drugs |
| Food/Dietary |
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| Lactation Rating | L5 (Contraindicated) |
| Teratogenic Risk | First trimester: Increased risk of major congenital malformations, particularly neural tube defects (e.g., spina bifida), congenital heart defects, and oral clefts. Second/third trimester: Associated with increased risk of spontaneous abortion, fetal growth restriction, and neurodevelopmental effects. Exposure at any trimester may cause permanent cognitive and behavioral deficits. No safe dose established. |
| Fetal Monitoring | Maternal: Monitor for seizures, hepatic injury, and hypersensitivity reactions. Fetal: Serial growth ultrasounds and echocardiography. Consider amniocentesis for alpha-fetoprotein levels. Postnatal: Evaluate for malformations and neurodevelopmental assessment. |
| Fertility Effects | Reversible impairments: females may experience anovulatory cycles and infertility; males may have reduced sperm motility, count, and abnormal morphology. Discontinuation restores fertility. |
| Avoid high-fat meals with immediate-release forms; can delay absorption. Acidic foods/juices (e.g., grapefruit) may affect absorption; maintain consistent intake. Separate dosing from acidic beverages by at least 1 hour. |
| Clinical Pearls | Monitor for signs of excessive CNS stimulation (insomnia, agitation, tremor) and cardiovascular effects (hypertension, tachycardia). Avoid evening doses due to insomnia risk. Use with caution in patients with history of substance abuse due to high abuse potential. Contraindicated with MAOIs within 14 days. |
| Patient Advice | Take exactly as prescribed; do not increase dose or duration. · Do not crush or chew extended-release tablets. · Avoid alcohol and caffeine; they may worsen side effects. · Report chest pain, palpitations, or severe anxiety/hallucinations immediately. · May cause dependence; do not stop abruptly without medical guidance. |