CELONTIN vs PHENYTOIN SODIUM

Independent side-by-side comparison.

Rated against independent regulatory sources·Last updated June 7, 2026·How we rate

Possible drug interaction. CELONTIN and PHENYTOIN SODIUM are different prescription medicines. Combining or switching between them can cause interactions — talk to a pharmacist or prescriber before making changes. This page is not medical advice.

Attribute	CELONTIN	PHENYTOIN SODIUM
Rating	New	New
Pharmacy pays	—	$0.18 /mL
Type	RX	RX
Active ingredient	METHSUXIMIDE	PHENYTOIN SODIUM
Manufacturer	Parke Davis	Marsam Pharms LLC
Dosage forms	Capsule	Capsule, Injectable
Drug class	Anti-Epileptic Agent	Anti-Epileptic Agent
Boxed warning	None	None
Half-life	—	About 22 hours on average, ranging from 7 to 42 hours — but phenytoin does NOT have a single fixed half-life. It follows nonlinear, saturable (Michaelis-Menten) kinetics, so the half-life lengthens as the dose and blood level rise; the label warns that "small incremental doses may increase the half-life and produce very substantial increases in serum levels" once levels are in the upper range.
Treats	Absence Epilepsy	Tonic-Clonic Epilepsy, Temporal Lobe Epilepsy, Status Epilepticus

celontin phenytoin sodium

Rating

New

Pharmacy pays

—

$0.18 /mL

Type

Active ingredient

METHSUXIMIDE

PHENYTOIN SODIUM

Manufacturer

Parke Davis

Marsam Pharms LLC

Dosage forms

Capsule

Capsule, Injectable

Drug class

Anti-Epileptic Agent

Boxed warning

None

Half-life

—

About 22 hours on average, ranging from 7 to 42 hours — but phenytoin does NOT have a single fixed half-life. It follows nonlinear, saturable (Michaelis-Menten) kinetics, so the half-life lengthens as the dose and blood level rise; the label warns that "small incremental doses may increase the half-life and produce very substantial increases in serum levels" once levels are in the upper range.

Treats

Absence Epilepsy

Tonic-Clonic Epilepsy, Temporal Lobe Epilepsy, Status Epilepticus

Frequently asked questions

What is the difference between Celontin and Phenytoin Sodium?

Celontin contains Methsuximide, while Phenytoin Sodium contains Phenytoin Sodium — they have different active ingredients.

Ratings are based on FDA regulatory (recall-safety) data. This comparison is for general reference only — not medical advice. Always consult a licensed professional before choosing or switching a medication.