What to Know About Januvia (Sitagliptin)

Januvia (sitagliptin phosphate) is a medication used to lower blood glucose levels in people with type 2 diabetes. It does this by blocking an enzyme called dipeptidyl peptidase IV, or DPP-4. In 2006, it became the first DPP-4 inhibitor approved by the Food and Drug Administration (FDA) in the United States. Other gliptins now available include Onglyza (saxagliptin) and Tradjenta (linagliptin). Januvia is also available combined with metformin in a medication called Janumet.

Uses

Type 2 diabetes, once known as adult-onset or non-insulin-dependent diabetes, is a chronic condition that affects the way your body metabolizes sugar (glucose), your body's most important source of fuel.

With type 2 diabetes, your body either resists the effects of insulin—a hormone that regulates the movement of sugar into your cells—or it doesn't produce enough insulin to maintain a normal glucose level.

Januvia has been successful in clinical trials at helping to lower glucose in people with type 2 diabetes when standard methods, such as diet, exercise, and first-line medications, aren't enough. Januvia has shown good results in trials, both in combination with other drugs, such as metformin, as well as by itself. It is only prescribed to treat type 2 diabetes.

DPP-4 is responsible for breaking down the proteins that stimulate insulin production after a meal. If DPP-4 is inhibited, then these proteins can activate the release of insulin for a longer period of time, thereby lowering the glucose level in the blood.

Before Taking

Januvia is approved only for type 2 diabetes. If your doctor has suggested you take it, it's likely you've already tried diet, exercise, and first-line medications, such as metformin or a sulfonylurea.

Your doctor may prescribe Januvia instead of other, less expensive second-line diabetes medications because it is unlikely to cause hypoglycemia or weight gain. Januvia only works when it's needed, generally at mealtimes, so if there is no glucose in the blood, then there is no action from Januvia. If glucose levels rise, such as after a meal, then Januvia will work to lower that level.

Several trials have examined Januvia's use in people with type 1 diabetes, with mixed results. The long-term safety profile of Januvia for people with type 1 diabetes is unknown. It is not currently recommended for this condition.

Precautions and Contraindications

If you have or have had pancreatitis, tell your doctor about it before taking Januvia. Some people taking Januvia have experienced pancreatitis, though it's currently not known whether the medication is the cause. There have also been rare reports of kidney and heart failure in people taking Januvia or other DPP-4 inhibitors.

Januvia should not be used by people who are experiencing diabetic ketoacidosis. Women who are pregnant or nursing also should not take Januvia, since little is known about its effects in pregnancy or when nursing.

Dosage

Januvia comes in a 100-milligram tablet for once-daily dosing. For people with moderate kidney function, a 50-milligram tablet is available for once-daily dosing. For those with severe kidney disease, a 25-mg tablet is available.

How to Take and Store

Januvia does not need to be taken with food. It should be stored at room temperature.

Side Effects

The most commonly reported side effects of Januvia include upper respiratory infection, sore throat, and headache.

Severe

Rarely, some people experience severe allergic or skin reactions to Januvia, including anaphylaxis. If you develop hives, swelling in your throat or difficulty breathing, blisters, a skin rash, or other severe reactions, stop taking Januvia and get emergency medical assistance.

There have also been reports of pancreatitis and pancreatic cancer in a small number of people taking Januvia. A recent meta-analysis found a slightly increased risk of pancreatitis, but no risk of pancreatic cancer when taking Januvia or other DPP-4 inhibitors. Your doctor will evaluate your pancreas function soon after you start Januvia and at regular intervals thereafter.

Warnings and Interactions

Since Januvia is processed through the kidneys, your doctor will assess your renal (kidney) function before you take Januvia. People who have impaired renal function may need to take lower doses of Januvia lowered, since there have been rare reports of kidney failure when taking Januvia.

A risk of heart failure has also been reported with DPP-4 inhibitors that may be increased by impaired liver or kidney function. If you have any of these conditions, ask your doctor whether the benefits of Januvia outweigh the risks for you, and be sure to keep up with regular testing.

While Januvia is unlikely to lower blood sugar on its own, if you're combining Januvia with medications that do lower blood sugar, such as a sulfonylurea or insulin, you'll also need to watch for hypoglycemia.

Januvia and other DPP-4 inhibitors can cause severe joint pain in some people who take them. In 2015, the FDA added a warning regarding this side effect to gliptin drug labels. The symptoms can start immediately or begin years after taking a gliptin drug. In cases reported to the FDA, people who stopped taking DPP-4s stopped experiencing joint pain within a month. If you experience joint pain, contact your doctor so they can adjust your medications if necessary.

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