Sitagliptin Phosphate
Brand Name: Januvia
Common Dosage Forms:
Tablets: 25 mg, 50 mg, 100 mg
FDA Indications/Dosages:
As an adjunct to diet and exercise to improve glycemic control in patients with type 2 diabetes mellitus as monotherapy or as combination therapy with metformin or a peroxisome proliferator-activated receptor gamma agonist (e.g., thiazolidinediones) when single agent does not provide adequate glycemic control: The normal adult dose is 100 mg once daily.
Dosage adjustments for renal impairment: CrCl ≥30 to <50 mL/min, serum Cr ≤3 (men), ≤2.5 (women): 50 mg once daily. CrCl <30 mL/min, serum Cr >3 (men), >2.5 women), dialysis: 25 mg once daily.
Monitor: FBG, HbA1c
Pharmacology/Pharmacokinetics: Sitagliptin inhibits the dipeptidyl peptidase-4 (DDP-4) enzyme. DDP-4 is responsible for deactivating the incretin hormones glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP). These hormones are released by the intestine in response to food and are credited with increasing insulin synthesis and release from pancreatic beta cells. GLP-1 also decreases hepatic glucose production by lowering glucagon secretion from pancreatic alpha cells. By inhibiting DDP-4, sitagliptin increases insulin and decreases glucagon in response to elevated blood glucose. Inhibition of DDP-4 by sitagliptin lasts for 24 hours. Sitagliptin is rapidly and almost completely absorbed orally with peak plasma levels being reached in 1-4 hours. Approximately 79% is excreted in the urine as unchanged drug, primarily by active tubular secretion. Plasma protein binding is low at 38%. The terminal half-life after an oral dose is approximately 12.4 hours.
Drug Interactions: May increase the peak plasma drug concentration of digoxin.
Contraindications/Precautions: Contraindicated in patients who have shown hypersensitivity to any ingredient. Use with caution in patients with renal insufficiency (see dosage adjustments). The use of sitagliptin phosphate with drugs which may cause hypoglycemic reactions, including sulfonylureas or insulin, has not been adequately studied and these combinations should be avoided. Pregnancy Category B.
Adverse Effects: The most common adverse effect is nasopharyngitis (5%).
Patient Consultation:
May be taken without regard to meals.
Closely follow recommended dietary and exercise instructions.
Quarterly HbA1c testing should be performed.
Store in a cool, dry place away from sunlight and children.
If a dose is missed, take it as soon as possible but do not double doses.
Call physician if the above side effects are persistent or severe.
