MYDAYIS
Clinical safety rating: caution
Comprehensive clinical and safety monograph for MYDAYIS (MYDAYIS).
MYDAYIS is a fixed-dose combination of amphetamine and dextroamphetamine, which are non-catecholamine sympathomimetic amines with CNS stimulant activity. The mechanism of action in ADHD is not fully elucidated, but they block the reuptake of norepinephrine and dopamine into the presynaptic neuron and increase their release into the extraneuronal space.
| Metabolism | Amphetamine and dextroamphetamine are extensively metabolized by the liver via oxidative deamination, aromatic hydroxylation, and oxidative N-dealkylation, primarily by CYP2D6 and to a lesser extent by other CYP enzymes. The major metabolites include 4-hydroxyamphetamine, norephedrine, and 4-hydroxynorephedrine. |
| Excretion | Renal (approx. 90% as unchanged drug and 10% as inactive metabolites); fecal <5% |
| Half-life | 12 hours for d-methylphenidate; 3-4 hours for l-methylphenidate; clinical context: d-isomer provides extended coverage; l-isomer contributes minimal activity |
| Protein binding | d-methylphenidate: ~58% bound to albumin; l-methylphenidate: ~46% bound to albumin |
| Volume of Distribution | d-methylphenidate: 1.8 L/kg; l-methylphenidate: 1.6 L/kg; clinical meaning: high tissue distribution |
| Bioavailability | Oral: 22-25% due to first-pass metabolism (d-methylphenidate); l-methylphenidate: lower due to extensive presystemic metabolism |
| Onset of Action | Oral: 1-2 hours (peak effect at 4-5 hours for d-methylphenidate); immediate-release component: 30-60 minutes |
| Duration of Action | 12-14 hours; clinical notes: biphasic release profile with immediate-release and extended-release components; suitable for once-daily dosing |
Oral, 12.5 mg or 25 mg once daily in the morning.
| Dosage form | CAPSULE, EXTENDED RELEASE |
| Renal impairment | GFR 30-89 mL/min: No adjustment. GFR 15-29 mL/min: Maximum 25 mg once daily. GFR <15 mL/min or dialysis: Not recommended. |
| Liver impairment | Child-Pugh A: No adjustment. Child-Pugh B: Maximum 12.5 mg once daily. Child-Pugh C: Not recommended. |
| Pediatric use | Ages 13-17: Same as adult. Not approved for children <13 years. |
| Geriatric use | No specific adjustment; monitor for insomnia, agitation, and cardiovascular effects. Start at lowest dose (12.5 mg) due to potential increased sensitivity. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for MYDAYIS (MYDAYIS).
| Breastfeeding | Contraindicated in breastfeeding due to potential for amphetamine excretion into breast milk causing agitation, poor feeding, and reduced weight gain in infants. M/P ratio: not established; amphetamines are known to concentrate in breast milk (approximately 2- to 3-fold higher than maternal plasma). |
| Teratogenic Risk | MYDAYIS (dextroamphetamine/amphetamine) is FDA Pregnancy Category C. First trimester: increased risk of major congenital malformations, particularly gastroschisis, oral clefts, and cardiac anomalies based on epidemiological data. Second and third trimesters: risk of premature delivery, low birth weight, and neonatal withdrawal symptoms including dysphoria, agitation, and feeding difficulties. Use only if potential benefit justifies risk. |
■ FDA Black Box Warning
WARNING: ABUSE AND DEPENDENCE. CNS stimulants, including MYDAYIS, have a high potential for abuse and dependence. Assess the risk of abuse prior to prescribing and monitor for signs of abuse and dependence while on therapy.
| Serious Effects |
["Known hypersensitivity to amphetamine or other components of the product","Concomitant use of monoamine oxidase inhibitors (MAOIs) or within 14 days of discontinuing MAOIs","Advanced arteriosclerosis","Symptomatic cardiovascular disease","Moderate to severe hypertension","Hyperthyroidism","Glaucoma","Agitated states","History of drug abuse","During or within 14 days following the administration of MAOIs"]
| Precautions | ["Serious cardiovascular events: sudden death, stroke, myocardial infarction in patients with pre-existing cardiac abnormalities","Blood pressure and heart rate increase","Psychiatric adverse events: exacerbation of pre-existing psychosis, mania, aggressive behavior","Long-term suppression of growth in children","Seizures: may lower seizure threshold","Peripheral vasculopathy, including Raynaud's phenomenon","Serotonin syndrome, particularly with concomitant serotonergic drugs","Visual disturbance: difficulty with accommodation","Potential for abuse and dependence"] |
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| Fetal Monitoring | Monitor maternal blood pressure, heart rate, and weight gain. Assess for signs of abuse or dependency. Fetal monitoring: ultrasound for growth and anatomy; consider fetal echocardiogram if first-trimester exposure. Neonatal monitoring: observe for withdrawal symptoms (irritability, jitteriness, poor feeding) for 48-72 hours after delivery. |
| Fertility Effects | No well-controlled studies on fertility. Amphetamines may suppress spermatogenesis and reduce sperm motility in males based on animal studies. In females, may cause menstrual irregularities and anovulation due to appetite suppression and weight loss. Limited human data suggest possible reversible impairment of fertility. |