Primidone
Mechanism :
It is a precursor of phenobarbitone and is used as an antiepileptic agent. It is a GABAergic agent. It is used in the treatment of generalized and partial tonic clonic seizures.
Indication :
- Seizure disorder (generalized tonic clonic seizures, complex partial, simple partial seizures)
Contraindications :
Hypersensitivity to drug/class/component, Porphyria, Avoid abrupt withdrawal.
Dosing :
Neonates:
12-20 mg/kg/day PO divided bid-qid. Start with low dose and increase gradually.
<8 years:
10-25 mg/kg/day PO divided tid-qid. (Max: 2 g/day) Start with low dose and increase gradually.
>8 years:
250 mg PO tid-qid. (Max: 2 g/day) Start with low dose and increase gradually.
Adverse Effect :
Respiratory depression, hypotension, paradoxical excitement, hepatitis, mental confusion and impaired performance, hypersensitivity and severe hematological reaction. It is contraindicated in children with porphyria.
Interaction :
Ethosuximide, Valproic Acid, Griseofulvin: It may decrease levels serum concentrations.
phenytoin: May decrease primidone serum concentrations.
Renal Dose :
Dose in Renal Impairment GFR (mL/min)
| 20-50 | Dose as in normal renal function |
| 10-20 | Dose as in normal renal function, but avoid very large doses |
| <10 | Reduce dose by 25–50% initially, and avoid very large single doses |
Dose in Patients undergoing Renal Replacement Therapies
| CAPD | Unknown dialysability. Dose as in GFR<10 mL/min |
| HD | Dialysed. Dose as in GFR<10 mL/ min |
| HDF/High flux | Dialysed. Dose as in GFR<10 mL/ min |
| CAV/VVHD | Dialysed. Dose as in GFR=10– 20 mL/min |
Hepatic Dose :
Dose adjustment guidelines are not available. Dose adjustment may be required. In severe impairment use drug with caution, monitor closely, side effect risk is increased.