Dilantin 125® (Phenytoin Oral Suspension, USP) 125mg/5ml

VIATRIS PRIVATE LIMITED

VIATRIS PRIVATE LIMITED

Therapeutic

Prescription Only

SUSPENSION

**4.2 Posology and method of administration** **General** Serum concentrations should be monitored and care should be taken when switching a patient from the sodium salt to the free acid form. Phenytoin capsules and solution for injection are formulated with the sodium salt of phenytoin. The free acid form of phenytoin is used in the phenytoin suspensions (30 mg/5 mL \[pediatric\] and 125 mg/5 mL) and in the phenytoin tablets. Because there is approximately an 8% increase in drug content with the free acid form over that of the sodium salt, dosage adjustments and serum level monitoring may be necessary when switching from a product formulated with the free acid to a product formulated with the sodium salt and _vice versa_. Dosage should be individualized to provide maximum benefit. In some cases, serum drug level determinations may be necessary for optimal dosage adjustments. Optimum control without clinical signs of toxicity occurs more often with serum levels between 10 mcg/mL and 20 mcg/mL, although some mild cases of tonic-clonic (grand mal) epilepsy may be controlled with lower serum levels of phenytoin. With recommended dosage, a period of 7 to 10 days may be required to achieve steady-state serum levels with phenytoin, and changes in dosage (increase or decrease) should not be carried out at intervals shorter than 7 to 10 days. Phenytoin oral suspension is not for parenteral use. **Adult Dosage** Patients who have received no previous treatment may be started on 4 mL (100 mg) of Dilantin-125® suspension three times daily, and the dosage then adjusted to suit individual requirements. For most adults, the satisfactory maintenance dosage will be 12 mL (300 mg) to 16 mL (400 mg) daily, to be taken in three to four equally divided doses respectively. An increase up to 24 mL (600 mg) daily may be made if necessary. Patients should use an accurately calibrated measuring device when using this medication to ensure accurate dosing. **Pediatric Dosage** Initially 5 mg/kg/day in two or three equally divided doses with subsequent dosage individualized to a maximum of 300 mg daily. A recommended daily maintenance dosage is usually 4 mg/kg to 8 mg/kg. Children over 6 years old and adolescents may require the minimum adult dose (300 mg/day). If the daily dosage cannot be divided equally, the larger dose should be given at bedtime. **Dosing in Special Populations** _Patients with Renal or Hepatic Disease:_ see Section **4.4 Special warnings and precautions for use** – _please refer to the Product Insert/Patient Information Leaflet published on HSA for the full drug information_. _Elderly Patients:_ Phenytoin clearance is decreased slightly in elderly patients and lower or less frequent dosing may be required (see Section **5.2 Pharmacokinetic properties** – **Special Populations – Age** – _please refer to the Product Insert/Patient Information Leaflet published on HSA for the full drug information_).