Canagliflozin

About Canagliflozin

Canagliflozin blocks SGLT2, the protein in the kidney tubules that returns most filtered sugar to the blood, so extra glucose leaves in the urine. The label covers three uses: lowering blood sugar, with diet and exercise, in type 2 diabetes in adults and children aged 10 and older; reducing major cardiovascular events in adults with type 2 diabetes and established heart or blood vessel disease; and reducing kidney failure, worsening kidney function, cardiovascular death and heart failure admissions in adults with type 2 diabetes and kidney disease with more than 300 mg of albumin in the urine a day. It is not recommended for type 1 diabetes. The dose is 100 mg once a day before the first meal, raised to 300 mg for blood sugar only when the eGFR is 60 or more; between 30 and 60 the limit is 100 mg, and below 30 it is not started, though adults with that much albumin may continue 100 mg.

There is no boxed warning: the FDA removed the one about leg and foot amputations in 2020, but the label still warns that amputations, mostly of toes and midfoot, were more common than with placebo in two large trials, especially after a past amputation or with poor leg circulation or nerve damage, so routine foot care matters. The only contraindication now listed is a serious allergic reaction; dialysis, listed on earlier labels, no longer is, though people on dialysis were not studied. Ketoacidosis can occur even when blood sugar is not very high, and the drug is stopped, where possible, at least 3 days before surgery or prolonged fasting. Fluid loss can cause low blood pressure and sudden kidney injury, especially in older people, with reduced kidney function and with loop diuretics. Genital yeast infections in women, urinary tract infections and passing more urine are the most common side effects; rarer risks include kidney or blood infections, Fournier’s gangrene (a serious infection around the genitals and anus), low blood sugar with insulin or a sulfonylurea, allergic reactions and bone fractures.

Invokamet (twice a day with meals) and Invokamet XR (two tablets once a day with the morning meal) pair 50 or 150 mg of canagliflozin with 500 or 1,000 mg of metformin; they carry metformin’s boxed warning for lactic acidosis, are not started below an eGFR of 45 and are not used below 30. With any form, urine glucose tests read positive and the 1,5-AG blood test is unreliable, and the label advises against use in the second and third trimesters of pregnancy, while breastfeeding and with severe liver impairment.

Taking Canagliflozin

How to take it

Invokana: once a day, before the first meal of the day. Invokamet: twice a day with meals; Invokamet XR: two tablets once a day with the morning meal, swallowed whole, never crushed, cut or chewed. Drink plenty of liquids while taking it.

If you miss a dose

Take it as soon as you remember, but skip the missed dose if it is almost time for the next one. Do not take two doses at once.

Storage

At room temperature, away from moisture and heat, out of reach of children.

Interactions to know about

Insulin and sulfonylureas such as glipizide add to the risk of low blood sugar, and loop diuretics such as furosemide to fluid loss. Rifampin, phenytoin, phenobarbital and ritonavir lower its levels, so the dose may be raised; it raises digoxin levels and can lower lithium levels. Heavy drinking raises the risk of ketoacidosis.

This summarizes the official prescribing information. Your prescriber’s and pharmacist’s instructions, and the leaflet that comes with your medicine, take priority.

Why the cash price for Canagliflozin differs from pharmacy to pharmacy

While only the brand is on sale, canagliflozin is priced as a brand from a single maker, so quotes differ mainly by each pharmacy’s cost and markup, and a less common strength may need to be ordered. Once a generic reaches pharmacies, a prescription that names Invokana and blocks substitution is still filled at the brand price.

Invokamet can be filled as one combination tablet with one dispensing fee, or as canagliflozin plus generic metformin, which costs pharmacies little, with two fees; which comes out lower depends on the pharmacy, and whether separate tablets suit you is the prescriber’s decision.

Ways to pay less for Canagliflozin without insurance

• Ask whether the pharmacy stocks generic canagliflozin yet, and make sure the prescription allows substitution.
• Ask for a ninety-day supply once your dose is stable.
• For Invokamet or Invokamet XR, ask the prescriber whether separate canagliflozin and generic metformin tablets would suit you, and ask the pharmacy to quote both ways.
• Ask the maker whether its savings or patient assistance program applies to someone paying cash; many savings offers require commercial insurance.
• Upload the prescription to Script Unlock so licensed pharmacies can quote their cash price. You pay the pharmacy directly.

Questions to ask your pharmacist about Canagliflozin

1. 1.Is a generic version of my canagliflozin in stock yet?
2. 2.Should I stop it before surgery, or on days I am sick and not eating?
3. 3.How should I check my feet, and which foot problems mean I should call?
4. 4.Does it interact with my insulin, sulfonylurea, digoxin, lithium or water pills?

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