Canagliflozin

Introduction Overview

Generic Name

canagliflozin

Brand Name

Invokana

Dosage Form

oral tablet

Drug Class

SGLT-2 inhibitors (Sodium-glucose co-transporter 2 inhibitors)

Pharmacokinetics

Absorption:
Canagliflozin is rapidly absorbed following oral administration, with peak plasma concentrations (Cmax) typically reached within 1 to 2 hours post-dose. The drug demonstrates dose-proportional pharmacokinetics over the therapeutic dose range. Oral bioavailability is estimated to be approximately 65%, though this can be influenced by factors such as food intake and gastrointestinal motility. Food does not significantly affect the extent of absorption, but can delay Tmax slightly.

Distribution:
Canagliflozin exhibits moderate volume of distribution, approximately 119 liters, indicating distribution beyond the vascular compartment into tissues. It is highly bound to plasma proteins (>99%), primarily albumin, limiting the free fraction of the drug available for activity or clearance. This high protein binding suggests that displacement interactions with other highly protein-bound drugs could potentially alter pharmacodynamics.

Metabolism:
Metabolism of canagliflozin occurs mainly via O-glucuronidation mediated by UDP-glucuronosyltransferase (UGT) enzymes, predominantly UGT1A9 and UGT2B4 isoforms. This phase II metabolism transforms canagliflozin into pharmacologically inactive O-glucuronide metabolites. Minor metabolism occurs through oxidation involving cytochrome P450 enzymes but is clinically insignificant. The metabolic pathway minimizes potential cytochrome P450-mediated drug interactions.

Elimination:
Elimination occurs primarily via feces (approximately 41.9%) and urine (approximately 33.3%) mainly as unchanged drug and glucuronide metabolites. The renal clearance of canagliflozin is relatively low due to its high protein binding, but the drug’s mechanism involves renal glucose transport inhibition. The terminal elimination half-life ranges from 10.6 to 13.1 hours, supporting once-daily dosing. Factors affecting renal function, including estimated glomerular filtration rate (eGFR), significantly influence drug efficacy and exposure, with reduced effectiveness in patients with moderate to severe renal impairment.

Dosage Forms

Available Dosage Forms:
- Oral tablet: 100 mg
- Oral tablet: 300 mg

Dosages for Adults and Adolescents:
- Initial dose: 100 mg orally once daily before the first meal of the day.
- Dose may be increased to 300 mg once daily for additional glycemic control in patients who tolerate the lower dose and have eGFR ≥ 60 mL/min/1.73 m2.
- Maximum recommended dose: 300 mg per day.
- Not recommended to initiate therapy in patients with eGFR less than 45 mL/min/1.73 m2 due to reduced efficacy.

Specific Patient Populations:
- Renal impairment: Use caution and do not start treatment if eGFR < 45 mL/min/1.73 m2. Dose adjustment not recommended but therapy should be discontinued when eGFR persistently falls below 45.
- Hepatic impairment: No dose adjustment required; metabolized mainly via glucuronidation.
- Elderly: Increased risk of adverse effects such as dehydration and fractures; start at lowest effective dose with close monitoring.
- Pediatric: Safety and efficacy not established; not approved for use under 18 years.
- Pregnancy: Should not be used during second and third trimesters; risk-benefit must be assessed in first trimester.
- Breastfeeding: Contraindicated; excreted in breast milk potentially causing harm.

Clinical guidelines recommend administration prior to first meal to maximize patient adherence and relevant pharmacodynamic effect on renal glucose reabsorption.

Mechanism Of Action

Canagliflozin exerts its primary therapeutic effect by selectively inhibiting sodium-glucose co-transporter 2 (SGLT-2), which is predominantly expressed in the proximal renal tubules of the kidneys. SGLT-2 is responsible for approximately 90% of glucose reabsorption from the glomerular filtrate back into the bloodstream. By blocking this transporter, invokana reduces glucose reabsorption leading to increased urinary glucose excretion (glucosuria) and consequently lowers plasma glucose levels.

At the molecular level, canagliflozin binds to the SGLT-2 protein's glucose-binding site, preventing glucose molecules from being transported across the brush-border membrane of proximal tubular cells. This effect leads to decreased renal threshold for glucose, enabling removal of excess circulating glucose independent of insulin secretion or insulin action, making it effective even in insulin-resistant states typical of type 2 diabetes.

Moreover, the glucosuric effect produces osmotic diuresis, promoting natriuresis and mild volume contraction. This mechanism contributes to reductions in blood pressure and has the potential to alleviate cardiovascular and renal strain, which aligns with observed clinical benefits in reducing cardiovascular events and progression of diabetic nephropathy among treated patients.

Comparatively, unlike other antihyperglycemic agents such as sulfonylureas or insulin which increase insulin secretion or sensitize insulin receptors, canagliflozin’s insulin-independent pathway provides an adjunctive approach, decreasing hypoglycemia risk. Clinical studies have demonstrated improvements in glycemic control, reductions in HbA1c, weight loss, and favorable cardiovascular and renal outcomes, affirming its mechanism’s physiological and clinical relevance.

Pharmacological Actions

Selective inhibition of sodium-glucose co-transporter 2 (SGLT-2) in renal proximal tubules.
Reduction of glucose reabsorption leading to increased urinary glucose excretion (glucosuria).
Improvement of glycemic control by lowering plasma glucose levels in type 2 diabetes mellitus.
Promotion of mild osmotic diuresis and natriuresis resulting in reduced blood pressure.
Reduction in body weight due to loss of calories through urinary glucose excretion.
Delayed progression of diabetic nephropathy by reducing hyperfiltration and renal glucose burden.
Reduction of cardiovascular risk including lower incidence of heart failure hospitalization and major adverse cardiovascular events.
Insulin-independent mechanism lowering risk of hypoglycemia compared to secretagogues.
Improvement in metabolic parameters when used adjunctively with other antidiabetics including metformin and insulin.
Modulation of renal sodium and volume homeostasis contributing to beneficial hemodynamic effects.
Potential to decrease albuminuria in patients with diabetic kidney disease.
Provides an option for patients inadequately controlled with diet, exercise, and other pharmacotherapy.
Demonstrates sustained efficacy over long-term administration with consistent safety profile.
May exert anti-inflammatory and antifibrotic effects contributing to organ protection.

Therapeutic Or Clinical Uses

Adjunctive treatment to diet and exercise to improve glycemic control in adults with type 2 diabetes mellitus.
Reduction of risk of major adverse cardiovascular events (including heart attack and stroke) in adults with type 2 diabetes and established cardiovascular disease.
Lowering the risk of hospitalization for heart failure in patients with type 2 diabetes.
Slowing the progression of diabetic kidney disease and reducing risk of end-stage kidney disease in adults with type 2 diabetes and diabetic nephropathy.
Potential weight loss aid due to glucosuric calorie loss.
Use in combination with other antihyperglycemic agents such as metformin, insulin, or sulfonylureas for enhanced glycemic control.
Therapeutic option for patients at high cardiovascular risk requiring integrated management of type 2 diabetes and cardiovascular comorbidities.
Management of hypertension adjunctively due to natriuretic effect contributing to blood pressure control.
Improved quality of life through control of hyperglycemia and associated metabolic consequences.
Reduction of hyperglycemia-related complications through sustained HbA1c lowering.
Provides benefit in patients intolerant to or contraindicated for other antidiabetic agents.
May reduce albuminuria independent of glucose lowering in diabetic nephropathy.
Facilitates glycemic control without dependence on pancreatic beta-cell function.

Side Or Adverse Effects

Increased risk of genital mycotic infections (fungal infections of penis or vagina), presenting with burning, itching, odor, discharge, redness, swelling, or pain.
Urinary tract infections, sometimes leading to pyelonephritis or urosepsis.
Dehydration symptoms including dizziness, weakness, and hypotension, particularly in elderly or volume-depleted patients.
Hypotension, especially in patients with underlying renal impairment or concomitant diuretic use.
Risk of ketoacidosis presenting with nausea, vomiting, abdominal pain, confusion, or difficulty breathing even with normal or mildly elevated blood glucose.
Increased risk of lower limb amputations, particularly in patients with a prior history of amputation, foot ulcers, peripheral vascular disease, or neuropathy.
Increased incidence of bone fractures possibly due to decreased bone mineral density or volume depletion.
Hyperkalemia manifesting as nausea, irregular heartbeats, and muscle weakness.
Potential acute kidney injury related to volume depletion or renal hypoperfusion.
Hypoglycemia when used concomitantly with insulin or insulin secretagogues.
Allergic reactions ranging from rash to severe hypersensitivity including angioedema.
Increased LDL cholesterol levels observed in some patients.
Gastrointestinal symptoms such as constipation or diarrhea.
Possible increase in urinary frequency and urgency due to osmotic diuresis.
Fatigue and weakness especially related to volume status changes.

Precautions

Avoid use in patients with severe renal impairment (eGFR less than 45 mL/min/1.73 m2) due to mitigated efficacy and increased adverse effects.
Close monitoring for signs of genital and urinary tract infections; treat promptly if infections occur.
Assess risk factors for lower limb amputation prior to initiation, including peripheral artery disease, diabetic foot ulcers, and neuropathy.
Use with caution in elderly patients who may be more sensitive to volume depletion and fractures.
Monitor blood pressure regularly to detect hypotension, especially in combination with diuretics or antihypertensive agents.
Evaluate serum electrolytes including potassium concentrations due to risk of hyperkalemia.
Educate patients regarding symptoms of ketoacidosis and advise immediate medical attention if suspected.
Avoid in type 1 diabetes mellitus or for diabetic ketoacidosis treatment due to insufficient evidence and risk profile.
Ensure adequate hydration to reduce risk of volume depletion and associated complications.
Adjust doses of insulin or insulin secretagogues when used concomitantly to minimize hypoglycemia risk.
Consider risk-benefit before use during pregnancy and breastfeeding; contraindicated in second and third trimester and during lactation.
Caution in hepatic impairment although specific dose adjustments are not required.
Monitor renal function periodically during therapy especially in patients at risk for renal impairment.
Advise patients to avoid rapid position changes to prevent orthostatic hypotension.
Use cautiously in patients with bladder infections or other urinary tract abnormalities.

Warnings

Not for use in patients with severe kidney disease or those on dialysis.
Black box warning regarding increased risk of lower limb amputations, particularly toes and feet; surveillance required during therapy.
Serious genital infections including necrotizing fasciitis of the perineum (Fournier's gangrene) reported; emergent medical evaluation warranted if symptoms develop.
Potential for ketoacidosis even in the absence of significant hyperglycemia; instruct patients on recognizing symptoms.
Risk of dehydration and hypotension leading to dizziness, syncope, or falls, especially in elderly or volume-depleted patients.
Use associated with increased risk of bone fractures; monitor and counsel patients to prevent fractures.
Hypoglycemia risk increased when combined with insulin or sulfonylureas; dose adjustments necessary.
Not approved for treatment of type 1 diabetes; off-label use contraindicated due to unfavorable risk profile.
Pregnancy contraindications during the second and third trimesters due to potential fetal harm.
Discontinue promptly if serious hypersensitivity reactions occur.
Potential interference with certain laboratory tests; inform healthcare providers regarding use.
Monitor for signs of urinary tract infections progressing to sepsis or pyelonephritis.
Warn patients about warning signs of elevated potassium and encourage periodic monitoring.
Avoid use in patients with volume depletion until condition is corrected.
Consider risk of interactions with other medications affecting renal clearance or volume status.

Contraindication

Known hypersensitivity to canagliflozin or any component of the formulation.
Severe renal impairment defined as eGFR less than 30 mL/min/1.73 m2.
End-stage renal disease or patients on dialysis.
Type 1 diabetes mellitus due to insufficient efficacy and high risk of ketoacidosis.
Pregnancy during second and third trimester.
Breastfeeding women due to potential drug excretion in milk and risk to infant.
Patients with a history of serious hypersensitivity reaction to canagliflozin.
Concurrent use with other SGLT-2 inhibitors to avoid additive adverse effects.
Off-label use in conditions not approved by regulatory authorities.
Active bladder infections or severe urinary tract infections at therapy initiation.
Volume depletion states without correction prior to starting therapy.
Known severe hepatic impairment with caution due to limited data.
Use in pediatric patients less than 18 years of age is contraindicated due to unknown safety and efficacy.
Patients with history of frequent urinary tract infections requiring multiple courses of antibiotics.
Co-administration with medications causing increased risk of hypotension without close monitoring.

Drug Interactions

Insulin and insulin secretagogues (e.g., sulfonylureas): increased risk of hypoglycemia; dose adjustment recommended.
Diuretics (especially loop or thiazide diuretics): additive risk of volume depletion and hypotension.
Digoxin: potential altered plasma concentrations; monitoring advised due to narrow therapeutic index.
Rifampin: induces UGT enzymes potentially decreasing canagliflozin exposure; clinical monitoring required.
Ritonavir and other strong CYP3A4 inhibitors or inducers: potential interactions affecting metabolism and efficacy.
Phenobarbital and phenytoin (antiepileptic drugs): may reduce canagliflozin plasma levels through enzyme induction.
Other antihypertensive agents: increased risk of hypotension and syncope when used concomitantly.
Lithium: risk of lithium toxicity due to altered renal clearance; monitoring lithium levels recommended.
NSAIDs: potential additive risk of renal impairment especially in volume-depleted patients.
Agents affecting potassium levels (e.g., ACE inhibitors, potassium supplements): enhanced risk of hyperkalemia.
Medications that alter renal function or hemodynamics may impact canagliflozin efficacy and safety.
Concomitant use with SGLT-2 inhibitors or SGLT-1 inhibitors is not recommended due to overlapping adverse effect profiles.
Live vaccines: no direct interaction but use with caution due to immunocompromised state in diabetes.
Alcohol: may increase risk of hypoglycemia and dehydration.
Oral contraceptives or hormone therapy: no significant known interactions but monitor glucose parameters.

Preparations Of The Drug

Invokana 100 mg oral tablets.
Invokana 300 mg oral tablets.
Film-coated tablets for oral administration designed for once-daily dosing.
Packaging available in blister packs and bottles to maintain drug stability.
Available in standard strengths for titration based on glycemic response and tolerability.
Supplied with medication guides that include patient counseling information on warnings and administration.
Storage instructions specify keeping tablets at room temperature away from excessive heat and moisture.
Manufactured to comply with regulatory quality standards ensuring consistent potency and purity.
Prescription-only medication requiring healthcare provider oversight.
Tablets designed for ease of swallowing and compatibility with routine medication schedules.
Formulation includes inactive ingredients to optimize absorption and stability.
No extended-release or injectable forms currently available for canagliflozin.
No non-oral formulations (such as intravenous or subcutaneous) approved for canagliflozin usage.
Commercial supply includes product information for healthcare professionals outlining clinical use.