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Invokana Insights: 10 Drug-Specific Facts You Should Know

Medically reviewed by L. Anderson, PharmD. Last updated on Apr 9, 2018.

1. Invokana Is Canagliflozin: How Does It Work?

If you or a family member have been diagnosed with prediabetes or type 2 diabetes, this slideshow is important for you.

Invokana, known generically as canagliflozin, is in a class of drugs called the sodium-glucose transporter-2 (SGLT2) inhibitors. Invokana comes as a tablet taken once daily by mouth.

These drugs are hypoglycemics (drugs used to lower blood sugar) in patients with type 2 diabetes. The SGLT2 inhibitors block the kidney from reabsorbing sugar (glucose). In turn, you eliminate more glucose in your urine which lowers your blood sugar levels. Invokana is also associated with reductions in blood pressure and weight loss, and was the first SGLT2 inhibitor FDA-approved in March 2013.

2. Invokana: When to Start?

When someone is first diagnosed with type 2 diabetes, they will not typically start with Invokana alone as an initial treatment.

Invokana is usually added on to other diabetes treatments, such as metformin, sulfonylureas, or insulin, as an "adjunct", when a patient no longer responds, or if the blood sugar level is too high at the outset. Invokana is commonly combined with metformin.

The SGLT-2 inhibitor drugs, which come as oral tablets, are sold as individual agents and in combination with other diabetes drugs. Examples include:

However, the combination agents like Invokamet or Invokamet XR that contain metformin may be appropriate to start as a first-line agent in certain patients who need greater blood sugar control.

3. How Effective Is Invokana?

Invokana is used with other diabetes meds to lower blood sugar. In studies it lowered A1C (a measure of blood sugar control over the past two to three months) up to 0.7 percent, so it's a weak blood sugar lowering agent. However, Invokana is usually used as an "adjunct" (added to) to metformin, which boosts blood sugar control.

There's now a combined pill that makes it easier. Invokamet contains both metformin and canagliflozin in one tablet, which may be more convenient.

When compared to Januvia (sitagliptin) plus metformin, Invokana plus metformin has been shown to be better at lowering blood sugar and also leads to weight loss. In fact, studies have shown metformin plus canagliflozin led to a 10-pound weight loss over one year in some patients, which is a big advantage in type 2 diabetes.

4. Who Should Not Use Invokana?

Invokana was developed to treat type 2 diabetes; it is not to be used to treat type 1 diabetes.

Invokana works in the kidneys, so you should not use Invokana if you have severe kidney problems or are on kidney dialysis. Your doctor will check your kidneys to see how well they work before you start Invokana or Invokamet, and periodically thereafter.

If you notice signs of kidney injury, like decreased urine or swelling in the legs or feet, be sure to contact a healthcare provider immediately. If you've had an allergic reaction in the past to canagliflozin - such as a rash, hives, or swelling - you should also not use Invokana.

Invokana should not be used to treat a condition called diabetic ketoacidosis, which is a potentially deadly complication of diabetes when you do not have enough insulin. In ketoacidosis, your blood becomes acidic (the pH is too low). In fact, on the next slide, you'll see some news the FDA released in May 2015 on SGLT2 Inhibitors causing ketoacidosis.

5. FDA: Other Warnings with Canagliflozin

Before you take Invokana or other medications containing canagliflozin, tell your doctor if you have a history of amputation, nerve damage, or peripheral vascular disease. Canagliflozin may increase your risk of lower limb amputations. Invokana, Invokamet, and Invokamet XR contain a boxed warning about the risk for amputations, the most prominent type of FDA warning. In studies, a roughly 2-fold increased risk of lower limb amputations was seen with canagliflozin. Amputations have mainly involved removal of the toe or part of the foot; however, amputations involving the leg, below and above the knee, have also occurred.

Ketoacidosis usually occurs in patients with type 1 diabetes. However, in May 2015, the FDA issued an important warning that the SGLT2 inhibitors like canagliflozin can infrequently cause ketoacidosis, usually in less than 1 out of every 100 patients. Major illness, reduced food and fluids, and reduced insulin doses can also cause ketoacidosis.

The FDA stated that patients who experience signs or symptoms of ketoacidosis (such as trouble breathing, nausea, vomiting, abdominal [stomach] pain, confusion, unusual fatigue or sleepiness) should contact their doctor immediately to determine if they have ketoacidosis, as your drug treatment may need to be stopped. Ask your health care provider about when and how to test for ketones.

Also, the FDA warned that patients taking canaglifozin should notify their doctor right away if they notice any new pain, tenderness, sores, ulcers, or infections in their legs or feet. Plus, patients should talk to their doctor about factors that may increase their risk for bone fracture.

6. Invokana Side Effects: What Do You Need to Know?

The most common Invokana side effects include:

  • Yeast infections in vagina or penis
  • Urinary tract infections or frequent urgent need to urinate
  • Thirst

More serious side effects may include:

  • Ketoacidosis (increased ketones in your blood or urine)
  • High blood potassium levels (hyperkalemia)
  • Kidney injury
  • Low blood sugar (especially when used with other diabetes drugs like insulin or sulfonylureas)
  • Serious allergies or angioedema
  • Broken bones (fractures)

Serious urinary tract infections (UTI) have occurred with this class of medications; contact your doctor if you have any symptoms of a UTI, such as:

  • Burning when urinating
  • Frequent need to urinate
  • Lower stomach or pelvis pain
  • Fever
  • Blood in the urine.

7. Invokana: Drug and Dose Specifics

Your doctor will review how well your kidney works before and during treatment with Invokana; you need good kidney function to take Invokana as that's where the drug works. You may need a dose reduction if you have kidney impairment, or for severe kidney disease, you may not be able to use Invokana at all.

Invokana is taken by mouth, and it comes in 100 milligram (mg) and 300 mg tablets. Usually, most patients will start at the 100 mg dose, but your dose may go up. You should take Invokana once a day before your first meal.

If your blood sugar control is not adequate, your doctor may decide a higher Invokana dose is needed (but only if your kidney function is good enough for the higher dose).

Learn More: Review Invokana Dosing

8. What Other Medicines Do You Take?

Drug interactions should always be assessed whenever you start -- or even stop -- a medication. Like most other medicines, Invokana has important drug interactions you should be aware of.

Tell your doctor if you take diuretics (water pills to help with fluid) or digoxin (used to treat heart problems).

UGT enzyme inducers speed up removal of Invokana from the body and make it less effective. In patients who take UGT enzyme inducers (such as rifampin, phenytoin, phenobarbital, or ritonavir), higher doses of Invokana may be needed to control blood sugar.

Learn More: Search for Drug Interactions with Invokana

9. I Missed My Dose of Invokana. What Should I Do?

Low blood sugar is not common with normal doses of Invokana. If you missed your dose of Invokana, take it as soon as you remember. But if it is almost time for next dose, skip the missed dose and take Invokana at your regularly scheduled time.

It is very important you do not take two doses of Invokana at the same time, unless your doctor instructs you to do this. Taking too much Invokana may excessively lower your blood sugar.

Signs of low blood sugar include:

  • headache
  • drowsiness
  • weakness
  • dizziness
  • confusion
  • hunger
  • fast heartbeat
  • sweating
  • a shaky feeling.

Always keep a source of sugar, like fruit juice, hard candy, or crackers with you in case you have low blood sugar.

10. Can I Afford To Buy Invokana?

Since Invokana is a relatively new medicine, lower cost generics for this drug will not be available for many more years. The retail cash price for this drug varies around the country, but in general may run from $500 to $600 per month.

Your insurance may cover all or some of the cost of this medication. Most medicare plans will also cover the cost of Invokana.

If you are not able to afford your medication, do not hesitate to speak to your doctor about this. It may be that another more affordable medication can be prescribed.

If needed, Janssen, the manufacturer of Invokana, may be able to offer cost assistance for Invokana if you qualify. You can call them at 1-877-468-6526 (8 AM to 8 PM ET Monday - Friday), or utiize their web-based patient savings programs.

Finished: Invokana Insights: 10 Drug-Specific Facts You Should Know

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