DrugLib.com — Drug Information Portal

Rx drug information, pharmaceutical research, clinical trials, news, and more

Phenytek (Phenytoin Sodium Extended Release) - Indications and Dosage

 
 



INDICATIONS AND USAGE

PHENYTEK® CAPSULES (extended phenytoin sodium capsules, USP) are indicated for the control of generalized tonic-clonic (grand mal) and complex partial (psychomotor, temporal lobe) seizures and prevention and treatment of seizures occurring during or following neurosurgery.

Phenytoin serum level determinations may be necessary for optimal dosage adjustments (see DOSAGE AND ADMINISTRATION and CLINICAL PHARMACOLOGY).

DOSAGE AND ADMINISTRATION

Serum concentrations should be monitored in changing from extended phenytoin sodium capsules, USP, to prompt phenytoin sodium capsules, USP, and from the sodium salt to the free acid form.

PHENYTEK® CAPSULES (extended phenytoin sodium capsules, USP) are formulated with the sodium salt of phenytoin. 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.

General

Dosage should be individualized to provide maximum benefit. In some cases, serum blood level determinations may be necessary for optimal dosage adjustments - the clinically effective serum level is usually 10 to 20 mcg/mL. With recommended dosage, a period of 7 to 10 days may be required to achieve steady-state blood levels with phenytoin and changes in dosage (increase or decrease) should not be carried out at intervals shorter than 7 to 10 days.

Adult Dosage

Divided Daily Dosage

Patients who have received no previous treatment may be started on one 100 mg extended phenytoin sodium capsule three times daily and the dosage then adjusted to suit individual requirements. For most adults, the satisfactory maintenance dosage will be one 100 mg capsule three to four times a day. An increase up to one 200 mg PHENYTEK® three times a day may be made, if necessary.

Once-A-Day Dosage

In adults, if seizure control is established with divided doses of three 100 mg extended phenytoin sodium capsules daily, once-a-day dosage with 300 mg PHENYTEK® may be considered. Studies comparing divided doses of 300 mg with a single daily dose of this quantity indicated absorption, peak plasma levels, biologic half-life, difference between peak and minimum values, and urinary recovery were equivalent. Once-a-day dosage offers a convenience to the individual patient or to nursing personnel for institutionalized patients and is intended to be used only for patients requiring this amount of drug daily. A major problem in motivating noncompliant patients may also be lessened when the patient can take this drug once a day. However, patients should be cautioned not to miss a dose, inadvertently.

Only extended phenytoin sodium capsules are recommended for once-a-day dosing. Inherent differences in dissolution characteristics and resultant absorption rates of phenytoin due to different manufacturing procedures and/or dosage forms preclude such recommendation for other phenytoin products. When a change in the dosage form or brand is prescribed, careful monitoring of phenytoin serum levels should be carried out.

Loading Dose

Some authorities have advocated use of an oral loading dose of phenytoin in adults who require rapid steady-state serum levels and where intravenous administration is not desirable. This dosing regimen should be reserved for patients in a clinic or hospital setting where phenytoin serum levels can be closely monitored. Patients with a history of renal or liver disease should not receive the oral loading regimen.

Initially, one gram of extended phenytoin sodium capsules is divided into three doses (400 mg, 300 mg, 300 mg) and administered at 2 hour intervals. Normal maintenance dosage is then instituted 24 hours after the loading dose, with frequent serum level determinations.

Dosing in Special Populations

Patients with Renal or Hepatic Disease

Due to an increased fraction of unbound phenytoin in patients with renal or hepatic disease, or in those with hypoalbuminemia, the interpretation of total phenytoin plasma concentrations should be made with caution. Unbound phenytoin concentrations may be more useful in these patient populations.

Elderly Patients

Phenytoin clearance is decreased slightly in elderly patients and lower or less frequent dosing may be required.

Pediatric

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 to 8 mg/kg. Children over 6 years old and adolescents may require the minimum adult dose (300 mg/day).

HOW SUPPLIED

PHENYTEK® CAPSULES (extended phenytoin sodium capsules, USP) are available containing 200 mg or 300 mg of phenytoin sodium, USP.

The 200 mg capsule has a dark blue opaque cap and a blue opaque body. The hard-shell gelatin capsule is filled with two white to off-white round tablets. The capsule is rectified radial printed with BERTEK over 670 in black ink on both the cap and the body. They are available as follows:

NDC 0378-2670-93
bottles of 30 capsules

NDC 0378-2670-01
bottles of 100 capsules

The 300 mg capsule has a blue opaque cap and a blue opaque body. The hard-shell gelatin capsule is filled with three white to off-white round tablets. The capsule is rectified radial printed with BERTEK over 750 in black ink on both the cap and the body. They are available as follows:

NDC 0378-3750-93
bottles of 30 capsules

NDC 0378-3750-01
bottles of 100 capsules

Store at 20° to 25°C (68° to 77°F). [See USP Controlled Room Temperature.]

Protect from light and moisture.

Dispense in a tight, light-resistant container as defined in the USP using a child-resistant closure.

PHARMACIST: Dispense a Medication Guide with each prescription.

-- advertisement -- The American Red Cross
 
Home | About Us | Contact Us | Site usage policy | Privacy policy

All Rights reserved - Copyright DrugLib.com, 2006-2017