JANUMET XR vs MYSOLINE

Independent side-by-side comparison.

Rated against independent regulatory sources·Last updated October 9, 2026·How we rate

Possible drug interaction. JANUMET XR and MYSOLINE 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	JANUMET XR	MYSOLINE
Rating	New	74/100
Pharmacy pays	~$0.74 /30	~$2.89 /30
Type	RX	RX
Active ingredient	METFORMIN HYDROCHLORIDE AND SITAGLIPTIN PHOSPHATE	PRIMIDONE
Manufacturer	Msd Sub Merck	Valeant Pharm Intl
Dosage forms	Tablet, extended release	Tablet
Drug class	—	Anti-Epileptic Agent
Boxed warning	Boxed warning	None
Half-life	about 12.4 hours (apparent terminal half-life after a single 100 mg oral dose in healthy volunteers)	—
Treats	—	Partial Epilepsies, Tonic-Clonic Epilepsy, Tremor

janumet xr mysoline

Rating

New

74/100

Pharmacy pays

~$0.74 /30

~$2.89 /30

Type

Active ingredient

METFORMIN HYDROCHLORIDE AND SITAGLIPTIN PHOSPHATE

PRIMIDONE

Manufacturer

Msd Sub Merck

Valeant Pharm Intl

Dosage forms

Tablet, extended release

Tablet

Drug class

—

Anti-Epileptic Agent

Boxed warning

None

Half-life

about 12.4 hours (apparent terminal half-life after a single 100 mg oral dose in healthy volunteers)

—

Treats

—

Partial Epilepsies, Tonic-Clonic Epilepsy, Tremor

Frequently asked questions

Which is cheaper, Janumet XR or Mysoline?

Janumet XR costs pharmacies less to acquire — about $0.74 vs $2.89 for a 30-count supply, per the CMS NADAC survey. That gap is in the pharmacy's cost of goods, not necessarily in what you pay: your price is set afterwards by your insurer and the pharmacy.

What is the difference between Janumet XR and Mysoline?

Janumet XR contains Metformin Hydrochloride and Sitagliptin Phosphate, while Mysoline contains Primidone — 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.