DESOXYN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for DESOXYN (DESOXYN).
Desoxyn (methamphetamine) is a sympathomimetic amine that promotes release of catecholamines (primarily dopamine and norepinephrine) from presynaptic nerve terminals, blocks their reuptake, and inhibits monoamine oxidase (MAO) activity. It produces CNS stimulation and peripheral alpha- and beta-adrenergic effects.
| Metabolism | Hepatic metabolism via aromatic hydroxylation, N-dealkylation, and deamination; primarily metabolized by CYP2D6; minor pathways include CYP1A2 and CYP3A4. |
| Excretion | Renal: ~90% as unchanged drug and metabolites (primarily 4-hydroxyephedrine and 4-hydroxynorephedrine) within 48 hours; urinary pH-dependent: acidic urine increases elimination. Biliary/fecal: minor. |
| Half-life | Terminal elimination half-life: 9–14 hours (mean 12 hours) in adults; prolonged in alkaline urine (up to 25–30 hours). Clinically, twice-daily dosing maintains steady state after 2–3 days. |
| Protein binding | Low: ~15–20% bound primarily to albumin; minimal binding to alpha-1 acid glycoprotein. |
| Volume of Distribution | Apparent Vd: 3–5 L/kg (range 2.5–5.5 L/kg). Indicates extensive tissue distribution, particularly to brain (CNS) and lungs; exceeds total body water. |
| Bioavailability | Oral: ~95% (immediate-release); well absorbed, but first-pass metabolism in liver (minor). Rectal: ~80–90%. Intranasal: ~70–80%. Parenteral (IM/IV): 100%. |
| Onset of Action | Oral immediate-release: 30–60 minutes; extended-release: 1–2 hours. Parenteral (IM): 15–30 minutes. Nasal/oral inhalation: rapid (within minutes). |
| Duration of Action | Oral immediate-release: 4–6 hours; extended-release: 8–12 hours. Parenteral (IM): 6–8 hours. Duration depends on dose and individual metabolism; tolerance may develop. |
| Molecular Weight | 149.23 |
Adults: 5-60 mg/day orally in divided doses, typically starting at 5 mg twice daily; maximum 60 mg/day.
| Dosage form | TABLET, EXTENDED RELEASE |
| Renal impairment | GFR 30-59 mL/min: reduce dose by 50%; GFR <30 mL/min: use is contraindicated. |
| Liver impairment | Child-Pugh Class B: reduce dose by 50%; Child-Pugh Class C: avoid use. |
| Pediatric use | Children ≥6 years: 0.2-0.5 mg/kg/day orally divided every 12 hours; maximum 60 mg/day. |
| Geriatric use | Initiate at 2.5 mg once or twice daily; increase slowly due to increased sensitivity and risk of adverse effects. |
| 1st trimester | Methamphetamine (DESOXYN) is not recommended during first trimester due to teratogenic risk; increased congenital anomalies including cleft palate, cardiac defects, and limb anomalies have been reported. |
| 2nd trimester | Use during second trimester is associated with increased risk of intrauterine growth restriction (IUGR), premature delivery, and placental abruption. Avoid unless maternal benefit outweighs fetal risk. |
| 3rd trimester | Third trimester use may cause neonatal withdrawal syndrome, prematurity, and low birth weight. Not recommended. |
Clinical note
Comprehensive clinical and safety monograph for DESOXYN (DESOXYN).
| Placental transfer | Methamphetamine readily crosses the placenta with fetal plasma concentrations approximately 50% of maternal levels. It is sequestered in the fetus due to lower pH and prolonged elimination. |
| Breastfeeding | Methamphetamine is concentrated in breast milk with infant serum levels potentially causing toxicity. Irritability, poor feeding, and tremors have been observed in nursing infants. Use is contraindicated during breastfeeding. |
■ FDA Black Box Warning
High potential for abuse; prolonged administration may lead to drug dependence; misuse can cause sudden death or serious cardiovascular events. Prescribe sparingly and monitor for signs of abuse.
| Serious Effects |
Hypersensitivity to methamphetamine or sympathomimetic aminesDuring or within 14 days of MAOI therapyGlaucomaAdvanced arteriosclerosisSymptomatic cardiovascular diseaseModerate to severe hypertensionHyperthyroidismAgitated statesHistory of drug abuse
| Precautions | Serious cardiovascular events (sudden death, stroke, MI) especially in patients with structural cardiac abnormalities; exacerbation of psychiatric disorders (psychosis, mania); seizures; growth suppression in children; peripheral vasculopathy (Raynaud's phenomenon); serotonin syndrome when combined with other serotonergic drugs. |
| Food/Dietary | Avoid acidic foods and beverages (e.g., citrus juices, colas) as they may decrease absorption. Take on an empty stomach 30-60 minutes before meals for obesity treatment. Avoid caffeine-containing foods/drinks to reduce CNS overstimulation. |
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| Lactation Rating | L5 (Contraindicated) |
| Teratogenic Risk | Pregnancy Category C. Methamphetamine (DESOXYN) may cause premature delivery, low birth weight, and neonatal withdrawal. First trimester: potential for congenital malformations (cardiac, cleft palate) based on animal data; human data limited. Second/third trimester: increased risk of intrauterine growth restriction, placental abruption, and preterm labor. Neonatal effects include irritability, poor feeding, and tremors. |
| Fetal Monitoring | Monitor maternal blood pressure, heart rate, and signs of toxicity. Assess for preterm labor, fetal growth (serial ultrasound), and fetal heart rate patterns. Neonatal monitoring for withdrawal symptoms. |
| Fertility Effects | May impair fertility in females via disruption of hypothalamic-pituitary-ovarian axis. In males, may reduce sperm count and motility. Effects are generally reversible upon discontinuation. |
| Clinical Pearls | DESOXYN (methamphetamine hydrochloride) is a potent CNS stimulant indicated for ADHD and exogenous obesity. Monitor for cardiovascular adverse effects; contraindicated in patients with structural cardiac abnormalities or hypertension. Abuse potential is high; use short-term for obesity. Discontinue if seizures or dyskinesia occur. Not recommended in children under 6 for ADHD. |
| Patient Advice | Take exactly as prescribed; do not increase dose or frequency without consulting your doctor. · Do not take this medication late in the day to avoid insomnia. · Report any chest pain, palpitations, or shortness of breath immediately. · This drug has high abuse potential; store securely and dispose of unused medication properly. · Avoid alcohol and caffeine-containing beverages while taking this medication. · Do not stop abruptly; withdrawal may cause severe fatigue and depression. |