ONEXTON
Clinical safety rating: caution
Comprehensive clinical and safety monograph for ONEXTON (ONEXTON).
Selective α2A-adrenergic receptor agonist in the prefrontal cortex; modulates glutamate and GABA neurotransmission to improve cognitive function.
| Metabolism | Primarily hepatic via CYP3A4; also involves glucuronidation and sulfation. |
| Excretion | Renal: 70% unchanged; biliary/fecal: 20% as metabolites |
| Half-life | Terminal t1/2 12-15 hours in healthy adults; prolonged to 24-30 hours in moderate renal impairment (CrCl <30 mL/min) |
| Protein binding | 95% bound to albumin |
| Volume of Distribution | Vd 3-5 L/kg; extensive tissue distribution |
| Bioavailability | Oral: 60% (first-pass metabolism); intramuscular: 90% |
| Onset of Action | Oral: 30-45 minutes; intravenous: 2-5 minutes |
| Duration of Action | 4-6 hours after single oral dose; sustained-release formulation: 12-24 hours |
1 tablet (amoxicillin 875 mg / clavulanate 125 mg) orally every 12 hours for 5-10 days.
| Dosage form | GEL |
| Renal impairment | CrCl 10-30 mL/min: 1 tablet (amoxicillin 875 mg / clavulanate 125 mg) every 24 hours; CrCl <10 mL/min: 1 tablet every 24 hours, avoid if possible; hemodialysis: dose after dialysis. |
| Liver impairment | Child-Pugh A: no adjustment; Child-Pugh B: use with caution, consider alternative; Child-Pugh C: contraindicated. |
| Pediatric use | Based on amoxicillin component: 45 mg/kg/day divided every 12 hours (using 875 mg tablet not suitable; use 250 mg or 500 mg amoxicillin/clavulanate oral suspension or chewable tablets). |
| Geriatric use | Monitor renal function; adjust dose based on CrCl as per renal adjustment guidelines; consider lower dose if renal impairment present. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for ONEXTON (ONEXTON).
| Breastfeeding | Excreted in human breast milk; milk-to-plasma ratio not established. Use caution; may cause adverse effects in nursing infant. Decision to breastfeed should consider importance of drug to mother. |
| Teratogenic Risk | Pregnancy Category C. First trimester: potential teratogenic effects based on animal studies, including cardiovascular and neural tube defects; second and third trimesters: risk of fetal hypotension, renal impairment, and oligohydramnios. Use only if benefit outweighs risk. |
| Fetal Monitoring |
■ FDA Black Box Warning
None.
| Serious Effects |
Hypersensitivity to guanfacine or any component; concomitant use with strong CYP3A4 inhibitors (e.g., ketoconazole); severe cardiovascular disease.
| Precautions | Risk of hypotension and bradycardia; syncope; QT interval prolongation; sedation; hepatic impairment; renal impairment; avoid abrupt discontinuation. |
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| Monitor maternal blood pressure, renal function, and electrolytes. Fetal monitoring includes serial ultrasound for growth, amniotic fluid index, and fetal heart rate monitoring. Assess fetal renal function postpartum. |
| Fertility Effects | No known adverse effects on fertility in human studies; animal studies show no impairment of fertility at therapeutic doses. |