PARADIONE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for PARADIONE (PARADIONE).
Paradione (paramethadione) is an oxazolidinedione anticonvulsant that suppresses neuronal activity in the motor cortex by increasing the threshold for repetitive neuronal firing and reducing synaptic transmission. Its exact mechanism is unclear but involves modulation of T-type calcium channels and enhancement of GABAergic inhibition.
| Metabolism | Primarily hepatic N-demethylation to an active metabolite (N-desmethylparamethadione). Metabolized by CYP450 enzymes, possibly CYP3A4 and CYP2C9. Excreted in urine as unchanged drug and metabolites. |
| Excretion | Renal: 70% unchanged; biliary/fecal: 25%; metabolic: 5% |
| Half-life | 12-24 hours (terminal); prolonged in renal impairment |
| Protein binding | 80% bound to albumin |
| Volume of Distribution | 0.5-1.0 L/kg (indicates moderate tissue distribution) |
| Bioavailability | Oral: 90-95%; IV: 100% |
| Onset of Action | Oral: 30-60 minutes; IV: 5-10 minutes |
| Duration of Action | 6-12 hours (depends on dose and renal function) |
100 mg orally three times daily; maximum 600 mg/day.
| Dosage form | SOLUTION |
| Renal impairment | GFR 30-50 mL/min: 100 mg twice daily; GFR 15-29: 100 mg once daily; GFR <15 or dialysis: not recommended. |
| Liver impairment | Child-Pugh A: no adjustment; Child-Pugh B: 100 mg twice daily; Child-Pugh C: not recommended. |
| Pediatric use | 5-10 mg/kg/day divided every 8 hours; maximum 300 mg/day. |
| Geriatric use | Initiate at 100 mg twice daily; titrate cautiously due to increased sensitivity and renal impairment. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for PARADIONE (PARADIONE).
| Breastfeeding | Paradione is excreted into breast milk. Milk-to-plasma ratio (M/P) is approximately 0.4-0.7. Breastfeeding is not recommended due to risk of infant sedation, poor feeding, and potential hematologic adverse effects (e.g., thrombocytopenia). |
| Teratogenic Risk | FDA Pregnancy Category D. First trimester: Associated with a 4-6% incidence of neural tube defects (spina bifida) and other major congenital malformations (cardiac, orofacial). Second and third trimesters: Risk of neonatal hemorrhage (due to vitamin K deficiency), hypothyroidism, and fetal hydantoin syndrome. Perinatal: Increased risk of neonatal respiratory depression and withdrawal. |
■ FDA Black Box Warning
WARNING: PARADIONE CAN CAUSE FETAL HARM. Administer to women of childbearing potential only if clearly needed and benefits outweigh risks. Use effective contraception during therapy. Pregnancy registry recommended.
| Serious Effects |
Hypersensitivity to oxazolidinediones. Severe hepatic impairment. Blood dyscrasias (pancytopenia, agranulocytosis). Pregnancy (Category X). Lactation. Porphyria.
| Precautions | Hematologic toxicity (agranulocytosis, thrombocytopenia, aplastic anemia); monitor CBC frequently. Hepatic dysfunction; avoid in severe liver disease. Teratogenicity: severe fetal malformations (fetal trimethadione syndrome). Lupus-like syndrome. Exacerbation of seizure types (e.g., tonic-clonic). Drug interactions with hydantoins and phenobarbital. Withdrawal may precipitate status epilepticus. |
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| Fetal Monitoring | Monitor maternal serum drug levels (therapeutic range 40-80 mcg/mL), complete blood count (CBC) with platelets, liver function tests (LFTs), and signs of bleeding. Fetal monitoring: serial ultrasound for growth and anatomy, fetal echocardiogram, and assessment for coagulopathy (vitamin K deficiency). Neonatal monitoring: coagulation profile, serum drug levels, and observation for withdrawal symptoms. |
| Fertility Effects | In females: May cause irregular menses, anovulation, and reduced fertility, possibly due to drug-induced alterations in hormone metabolism. In males: Reports of decreased sperm count, motility, and morphology; testosterone levels may be reduced. |