JANUMET XR tablets contain two oral antidiabetic medications used in
the management of type 2 diabetes: sitagliptin and metformin hydrochloride
Sitagliptin is an orally-active inhibitor of the dipeptidyl peptidase-4
(DPP-4) enzyme. Sitagliptin phosphate monohydrate drug substance is used to
manufacture JANUMET XR. Sitagliptin phosphate monohydrate is described
chemically as 7-[(3R)-3-amino-1-oxo-4-(2,4,5-trifluorophenyl)butyl]-5,6,7,8tetrahydro-3-(trifluoromethyl)-1,2,4-triazolo[4,3-α]pyrazine
phosphate (1:1) monohydrate with an empirical formula of C16H15F6N5O•H3PO4•H2O
and a molecular weight of 523.32. The structural formula is:
Sitagliptin phosphate monohydrate is a white to off-white, crystalline,
non-hygroscopic powder. It is soluble in water and N,N-dimethyl formamide;
slightly soluble in methanol; very slightly soluble in ethanol, acetone, and
acetonitrile; and insoluble in isopropanol and isopropyl acetate.
Metformin hydrochloride (N,N-dimethylimidodicarbonimidic diamide
hydrochloride) is a white to off-white crystalline compound with a molecular
formula of C4H11N5•HCl and a molecular weight
of 165.63. Metformin hydrochloride is freely soluble in water and is
practically insoluble in acetone, ether, and chloroform. The pKa of metformin
is 12.4. The pH of a 1% aqueous solution of metformin hydrochloride is 6.68.
The structural formula is as shown:
JANUMET XR consists of an extended-release metformin core tablet coated
with an immediate-release layer of sitagliptin. The sitagliptin layer is coated
with a soluble polymeric film. JANUMET XR is available for oral administration
as tablets containing 64.25 mg sitagliptin phosphate monohydrate (equivalent to
50 mg sitagliptin as free base) and either 500 mg metformin hydrochloride
extended-release (50 mg/500 mg) or 1000 mg metformin hydrochloride
extended-release (50 mg/1000 mg). Additionally, JANUMET XR is available for
oral administration as tablets containing 128.5 mg sitagliptin phosphate
monohydrate (equivalent to 100 mg sitagliptin as free base) and 1000 mg
metformin hydrochloride extended-release (100 mg/1000 mg).
All doses of JANUMET XR contain the following inactive ingredients:
povidone, hypromellose, colloidal silicon dioxide, sodium stearyl fumarate,
propyl gallate, polyethylene glycol, and kaolin. The JANUMET XR 50 mg/500 mg
tablet contains the additional inactive ingredient microcrystalline cellulose.
In addition, the film coating for all doses contains the following inactive
ingredients: hypromellose, hydroxypropyl cellulose, titanium dioxide, FD&C
#2/Indigo Carmine Aluminum Lake and carnauba wax. The JANUMET XR 50 mg/1000 mg
tablet film coating also contains the inactive ingredient yellow iron oxide.
Last reviewed on RxList: 11/8/2012
This monograph has been modified to include the generic and brand name in many instances.