Pharmacotherapeutic Group: Drugs used in diabetes, other blood glucose lowering drugs, excluding insulins. ATC Code: A10BX11.
Pharmacology: Pharmacodynamics: Mechanism of Action: The SGLT2 transporter, expressed in the proximal renal tubules, is responsible for the majority of the reabsorption of filtered glucose from the tubular lumen. Patients with diabetes have been shown to have elevated renal glucose reabsorption which may contribute to persistent elevated blood glucose concentrations. Canagliflozin is an orally-active inhibitor of SGLT2. By inhibiting SGLT2, canagliflozin reduces reabsorption of filtered glucose and lowers the renal threshold for glucose (RTG), and thereby increases UGE, lowering elevated plasma glucose concentrations by this insulin-independent mechanism in patients with type 2 diabetes. The increased UGE with SGLT2 inhibition also translates to an osmotic diuresis, with the diuretic effect leading to a reduction in systolic blood pressure; the increase in UGE results in a loss of calories and therefore a reduction in body weight, as has been demonstrated in studies of patients with type 2 diabetes.
Canagliflozin's action to increase UGE directly lowering plasma glucose is independent of insulin. Improvement in homeostasis model assessment for beta-cell function (HOMA beta-cell) and improved beta-cell insulin secretion response to a mixed-meal challenge has been observed in clinical studies with canagliflozin.
In phase 3 studies, pre-meal administration of canagliflozin 300 mg provided a greater reduction in postprandial glucose excursion than observed with the 100 mg dose. This effect at the 300 mg dose of canagliflozin may, in part, be due to local inhibition of intestinal SGLT1 (an important intestinal glucose transporter) related to transient high concentrations of canagliflozin in the intestinal lumen prior to medicinal product absorption (canagliflozin is a low potency inhibitor of the SGLT1 transporter). Studies have shown no glucose malabsorption with canagliflozin.
Pharmacodynamic Effects: Following single and multiple oral doses of canagliflozin to patients with type 2 diabetes, dose-dependent decreases in RTG and increases in UGE were observed. From a starting value of RTG of approximately 13 mmol/L, maximal suppression of 24-hour mean RTG was seen with the 300 mg daily dose to approximately 4 mmol/L to 5 mmol/L in patients with type 2 diabetes in phase 1 studies, suggesting a low risk for treatment-induced hypoglycaemia. The reductions in RTG led to increased UGE in subjects with type 2 diabetes treated with either 100 mg or 300 mg of canagliflozin ranging from 77 g/day to 119 g/day across the phase 1 studies; the UGE observed translates to a loss of 308 kcal/day to 476 kcal/day. The reductions in RTG and increases in UGE were sustained over a 26-week dosing period in patients with type 2 diabetes. Moderate increases (generally <400 mL to 500 mL) in daily urine volume were seen that attenuated over several days of dosing. Urinary uric acid excretion was transiently increased by canagliflozin (increased by 19% compared to baseline on day 1 and then attenuating to 6% on day 2 and 1% on day 13). This was accompanied by a sustained reduction in serum uric acid concentration of approximately 20%.
In a single-dose study in patients with type 2 diabetes, treatment with 300 mg before a mixed meal delayed intestinal glucose absorption and reduced postprandial glucose through both a renal and a non-renal mechanism.
Clinical Efficacy and Safety: A total of 10,285 patients with type 2 diabetes participated in nine double-blind, controlled clinical efficacy and safety studies conducted to evaluate the effects of Invokana on glycaemic control. The racial distribution was 72% White, 16% Asian, 4% Black, and 8% other groups. 16% of patients were Hispanic. Approximately 58% of patients were male. Patients had an overall mean age of 59.6 years (range 21 years to 96 years), with 3,082 patients ≥65 years of age and 510 patients ≥75 years of age. 58% of patients had a body mass index (BMI) ≥30 kg/m2. In the clinical development programme, 1,085 patients with a baseline eGFR 30 mL/min/1.73 m2 to <60 mL/min/1.73 m2 were evaluated.
Placebo-Controlled Studies: Canagliflozin was studied as monotherapy, dual therapy with metformin, dual therapy with a sulphonylurea, triple therapy with metformin and a sulphonylurea, triple therapy with metformin and pioglitazone, and as an add-on therapy with insulin (see Table 1). In general, canagliflozin produced clinically and statistically significant (p<0.001) results relative to placebo in glycaemic control, including HbA1c, the percentage of patients achieving HbA1c <7%, change from baseline fasting plasma glucose (FPG), and 2-hour postprandial glucose (PPG). In addition, reductions in body weight and systolic blood pressure relative to placebo were observed. (See Table 1).
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In addition to the studies presented above, glycaemic efficacy results observed in an 18-week dual therapy sub-study with a sulphonylurea and a 26-week triple therapy study with metformin and pioglitazone were generally comparable with those observed in other studies.
Active-Controlled Studies: Canagliflozin was compared to glimepiride as dual therapy with metformin and compared to sitagliptin as triple therapy with metformin and a sulphonylurea (see Table 2). Canagliflozin 100 mg as dual therapy with metformin produced similar reductions in HbA1c from baseline and 300 mg produced superior (p<0.05) reductions in HbA1c compared to glimepiride, thus demonstrating non-inferiority. A lower proportion of patients treated with canagliflozin 100 mg (5.6%) and canagliflozin 300 mg (4.9%) experienced at least one episode/event of hypoglycaemia over 52 weeks of treatment compared to the group treated with glimepiride (34.2%). In a study comparing canagliflozin 300 mg to sitagliptin 100 mg in triple therapy with metformin and a sulphonylurea, canagliflozin demonstrated non-inferior (p<0.05) and superior (p<0.05) reduction in HbA1c relative to sitagliptin. The incidence of hypoglycaemia episodes/events with canagliflozin 300 mg and sitagliptin 100 mg was 40.7% and 43.2%, respectively. Significant improvements in body weight and reductions in systolic blood pressure compared to both glimepiride and sitagliptin were also observed. (See Table 2).
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Special Populations: In three studies conducted in special populations (older patients, patients with an eGFR of 30 mL/min/1.73 m2 to <50 mL/min/1.73 m2 and patients with or at high risk for cardiovascular disease), canagliflozin was added to patients' current stable diabetes treatments (diet, monotherapy, or combination therapy).
Older Patients: A total of 714 patients ≥55 years of age to ≤80 years of age (227 patients 65 years of age to <75 years of age and 46 patients 75 years of age to ≤80 years of age) with inadequate glycaemic control on current diabetes treatment (glucose-lowering medicinal products and/or diet and exercise) participated in a double-blind, placebo-controlled study over 26 weeks. Statistically significant (p<0.001) changes from baseline HbA1c relative to placebo of -0.57% and -0.70% were observed for 100 mg and 300 mg, respectively (see Dosage & Administration and Adverse Reactions).
Patients with eGFR 45 mL/min/1.73 m2 to <60 mL/min/1.73 m2: In a pooled analysis of patients (N=721) with a baseline eGFR 45 mL/min/1.73 m2 to <60 mL/min/1.73 m2, canagliflozin provided clinically meaningful reduction in HbA1c compared to placebo, with -0.47% for canagliflozin 100 mg and -0.52% for canagliflozin 300 mg. Patients with a baseline eGFR 45 mL/min/1.73 m2 to < 60 mL/min/1.73 m2 treated with canagliflozin 100 mg and 300 mg exhibited mean improvements in percent change in body weight relative to placebo of -1.8% and -2.0%, respectively.
The majority of patients with a baseline eGFR 45 mL/min/1.73 m2 to <60 mL/min/1.73 m2 were on insulin and/or a sulphonylurea [85% (614/721)]. Consistent with the expected increase of hypoglycaemia when a medicinal product not associated with hypoglycaemia is added to insulin and/or sulphonylurea, an increase in hypoglycaemia episodes/events was seen when canagliflozin was added to insulin and/or a sulphonylurea (see Adverse Reactions).
Fasting Plasma Glucose: In four placebo-controlled studies, treatment with canagliflozin as monotherapy or add-on therapy with one or two oral glucose-lowering medicinal products resulted in mean changes from baseline relative to placebo in FPG of -1.2 mmol/L to -1.9 mmol/L for canagliflozin 100 mg and -1.9 mmol/L to -2.4 mmol/L for canagliflozin 300 mg, respectively. These reductions were sustained over the treatment period and near maximal after the first day of treatment.
Postprandial Glucose: Using a mixed-meal challenge, canagliflozin as monotherapy or add-on therapy with one or two oral glucose-lowering medicinal products reduced postprandial glucose (PPG) from baseline relative to placebo by -1.5 mmol/L to -2.7 mmol/L for canagliflozin 100 mg and -2.1 mmol/L to -3.5 mmol/L for 300 mg, respectively, due to reductions in the pre-meal glucose concentration and reduced postprandial glucose excursions.
Body Weight: Canagliflozin 100 mg and 300 mg as monotherapy and as dual or triple add-on therapy resulted in statistically significant reductions in the percentage of body weight at 26 weeks relative to placebo. In two 52-week active-controlled studies comparing canagliflozin to glimepiride and sitagliptin, sustained and statistically significant mean reductions in the percentage of body weight for canagliflozin as add-on therapy to metformin were -4.2% and -4.7% for canagliflozin 100 mg and 300 mg, respectively, compared to the combination of glimepiride and metformin (1.0%) and -2.5% for canagliflozin 300 mg in combination with metformin and a sulphonylurea compared to sitagliptin in combination with metformin and a sulphonylurea (0.3%).
A subset of patients (N=208) from the active-controlled dual therapy study with metformin who underwent dual energy X-ray densitometry (DXA) and abdominal computed tomography (CT) scans for evaluation of body composition demonstrated that approximately two-thirds of the weight loss with canagliflozin was due to loss of fat mass with similar amounts of visceral and abdominal subcutaneous fat being lost. Two hundred eleven (211) patients from the clinical study in older patients participated in a body composition substudy using DXA body composition analysis. This demonstrated that approximately two-thirds of the weight loss associated with canagliflozin was due to loss of fat mass relative to placebo. There were no meaningful changes in bone density in trabecular and cortical regions.
Cardiovascular Safety: A pre-specified interim meta-analysis was conducted of adjudicated major cardiovascular events in the phase 2 and 3 clinical studies in 9,632 patients with type 2 diabetes, including 4,327 patients (44.9%) with cardiovascular disease or at high risk for cardiovascular disease who are participating in an ongoing cardiovascular study. The hazard ratio for the composite primary endpoint (time to event of cardiovascular death, non-fatal stroke, non-fatal myocardial infarction, and unstable angina requiring hospitalisation) for canagliflozin (both doses pooled) versus combined active and placebo comparators was 0.91 (95% CI: 0.68; 1.22); therefore, there was no evidence of an increase in cardiovascular risk with canagliflozin relative to comparators. The hazard ratios for the 100 mg and 300 mg doses were similar.
Blood Pressure: In placebo-controlled studies, treatment with canagliflozin 100 mg and 300 mg resulted in mean reductions in systolic blood pressure of -3.9 mmHg and -5.3 mmHg, respectively, compared to placebo (-0.1 mmHg) and a smaller effect on diastolic blood pressure with mean changes for canagliflozin 100 mg and 300 mg of -2.1 mmHg and -2.5 mmHg, respectively, compared to placebo (-0.3 mmHg). There was no notable change in heart rate.
Patients with Baseline HbA1c >10% to ≤12%: A substudy of patients with baseline HbA1c >10% to ≤12% with canagliflozin as monotherapy resulted in reductions from baseline in HbA1c (not placebo-adjusted) of -2.13% and -2.56% for canagliflozin 100 mg and 300 mg, respectively.
Pharmacokinetics: The pharmacokinetics of canagliflozin are essentially similar in healthy subjects and patients with type 2 diabetes. After single-dose oral administration of 100 mg and 300 mg in healthy subjects, canagliflozin was rapidly absorbed, with peak plasma concentrations (median Tmax) occurring 1 hour to 2 hours post-dose. Plasma Cmax and AUC of canagliflozin increased in a dose-proportional manner from 50 mg to 300 mg. The apparent terminal half-life (t½) (expressed as mean ± standard deviation) was 10.6 ± 2.13 hours and 13.1 ± 3.28 hours for the 100 mg and 300 mg doses, respectively. Steady-state was reached after 4 days to 5 days of once-daily dosing with canagliflozin 100 mg to 300 mg. Canagliflozin does not exhibit time-dependent pharmacokinetics, and accumulated in plasma up to 36% following multiple doses of 100 mg and 300 mg.
Absorption: The mean absolute oral bioavailability of canagliflozin is approximately 65%. Co-administration of a high-fat meal with canagliflozin had no effect on the pharmacokinetics of canagliflozin; therefore, Invokana may be taken with or without food. However, based on the potential to reduce postprandial plasma glucose excursions due to delayed intestinal glucose absorption, it is recommended that Invokana be taken before the first meal of the day (see Pharmacology: Pharmacodynamics under Actions and Dosage & Administration).
Distribution: The mean steady-state volume of distribution of canagliflozin following a single intravenous infusion in healthy subjects was 119 litres, suggesting extensive tissue distribution. Canagliflozin is extensively bound to proteins in plasma (99%), mainly to albumin. Protein binding is independent of canagliflozin plasma concentrations. Plasma protein binding is not meaningfully altered in patients with renal or hepatic impairment.
Biotransformation: O-glucuronidation is the major metabolic elimination pathway for canagliflozin, which is mainly glucuronidated by UGT1A9 and UGT2B4 to two inactive O-glucuronide metabolites. CYP3A4-mediated (oxidative) metabolism of canagliflozin is minimal (approximately 7%) in humans.
In in vitro studies, canagliflozin neither inhibited cytochrome P450 CYP1A2,CYP2A6, CYP2C19, CYP2D6, or CYP2E1, CYP2B6, CYP2C8, CYP2C9, nor induced CYP1A2, CYP2C19, CYP2B6, CYP3A4 at higher than therapeutic concentrations. No clinically relevant effect on CYP3A4 was observed in vivo (see Interactions).
Elimination: Following administration of a single oral [14C]canagliflozin dose to healthy subjects, 41.5%, 7.0%, and 3.2% of the administered radioactive dose was recovered in faeces as canagliflozin, a hydroxylated metabolite, and an O-glucuronide metabolite, respectively. Enterohepatic circulation of canagliflozin was negligible.
Approximately 33% of the administered radioactive dose was excreted in urine, mainly as O-glucuronide metabolites (30.5%). Less than 1% of the dose was excreted as unchanged canagliflozin in urine. Renal clearance of canagliflozin 100 mg and 300 mg doses ranged from 1.30 mL/min to 1.55 mL/min.
Canagliflozin is a low-clearance substance, with a mean systemic clearance of approximately 192 mL/min in healthy subjects following intravenous administration.
Special Populations: Patients with Renal Impairment: A single-dose, open-label study evaluated the pharmacokinetics of canagliflozin 200 mg in subjects with varying degrees of renal impairment (classified using CrCl based on the Cockroft-Gault equation) compared to healthy subjects. The study included 8 subjects with normal renal function (CrCl ≥80 mL/min), 8 subjects with mild renal impairment (CrCl 50 mL/min to <80 mL/min), 8 subjects with moderate renal impairment (CrCl 30 mL/min to <50 mL/min), and 8 subjects with severe renal impairment (CrCl <30 mL/min) as well as 8 subjects with ESRD on haemodialysis.
The Cmax of canagliflozin was moderately increased by 13%, 29%, and 29% in subjects with mild, moderate, and severe renal failure, respectively, but not in subjects on haemodialysis. Compared to healthy subjects, plasma AUC of canagliflozin was increased by approximately 17%, 63%, and 50% in subjects with mild, moderate, and severe renal impairment, respectively, but was similar for ESRD subjects and healthy subjects.
Canagliflozin was negligibly removed from haemodialysis.
Patients with Hepatic Impairment: Relative to subjects with normal hepatic function, the geometric mean ratios for Cmax and AUC∞ of canagliflozin were 107% and 110%, respectively, in subjects with Child-Pugh class A (mild hepatic impairment) and 96% and 111%, respectively, in subjects with Child-Pugh class B (moderate) hepatic impairment following administration of a single 300 mg dose of canagliflozin.
These differences are not considered to be clinically meaningful. There is no clinical experience in patients with Child-Pugh class C (severe) hepatic impairment.
Elderly (≥65 Years Old): Age had no clinically meaningful effect on the pharmacokinetics of canagliflozin based on a population pharmacokinetic analysis (see Dosage & Administration, Precautions and Adverse Reactions).
Paediatric Population: Studies characterising the pharmacokinetics of canagliflozin in paediatric patients have not been conducted.
Other Special Populations: Pharmacogenetics: Both UGT1A9 and UGT2B4 are subject to genetic polymorphism. In a pooled analysis of clinical data, increases in canagliflozin AUC of 26% were observed in UGT1A9*1/*3 carriers and 18% in UGT2B4*2/*2 carriers. These increases in canagliflozin exposure are not expected to be clinically relevant. The effect of being homozygote (UGT1A9*3/*3, frequency < 0.1%) is probably more marked, but has not been investigated.
Gender, race/ethnicity, or body mass index had no clinically meaningful effect on the pharmacokinetics of canagliflozin based on a population pharmacokinetic analysis.
Toxicology: Preclinical Safety Data: Non-clinical data reveal no special hazard for humans based on conventional studies of safety pharmacology, repeated dose toxicity, and genotoxicity.
Canagliflozin showed no effects on fertility and early embryonic development in the rat at exposures up to 19 times the human exposure at the maximum recommended human dose (MRHD).
In an embryo-foetal development study in rats, ossification delays of metatarsal bones were observed at systemic exposures 73 times and 19 times higher than the clinical exposures at the 100 mg and 300 mg doses. It is unknown whether ossification delays can be attributed to effects of canagliflozin on calcium homeostasis observed in adult rats. Ossification delays were also observed for the combination of canagliflozin and metformin, which were more prominent than for metformin alone at canagliflozin exposures 43 times and 12 times higher than clinical exposures at 100 mg and 300 mg doses.
In a pre- and postnatal development study, canagliflozin administered to female rats from gestation day 6 to lactation day 20 resulted in decreased body weights in male and female offspring at maternally toxic doses >30 mg/kg/day (exposures ≥5.9 times the human exposure to canagliflozin at the MHRD). Maternal toxicity was limited to decreased body weight gain.
A study in juvenile rats administered canagliflozin from day 1 through day 90 postnatal did not show increased sensitivity compared to effects observed in adults rats. However, dilatation of the renal pelvis was noticed with a No Observed Effect Level (NOEL) at exposures 2.4 times and 0.6 times the clinical exposures at 100 mg and 300 mg doses, respectively, and did not fully reverse within the approximately 1-month recovery period. Persistent renal findings in juvenile rats can most likely be attributed to reduced ability of the developing rat kidney to handle canagliflozin-increased urine volumes, as functional maturation of the rat kidney continues through 6 weeks of age.
Canagliflozin did not increase the incidence of tumours in male and female mice in a 2-year study at doses of 10, 30, and 100 mg/kg. The highest dose of 100 mg/kg provided up to 14 times the clinical dose of 300 mg based on AUC exposure. Canagliflozin increased the incidence of testicular Leydig cell tumours in male rats at all doses tested (10, 30, and 100 mg/kg); the lowest dose of 10 mg/kg is approximately 1.5 times the clinical dose of 300 mg based on AUC exposure. The higher doses of canagliflozin (100 mg/kg) in male and female rats increased the incidence of pheochromocytomas and renal tubular tumours. Based on AUC exposure, the NOEL of 30 mg/kg/day for pheochromocytomas and renal tubular tumours is approximately 4.5 times the exposure at the daily clinical dose of 300 mg. Based on preclinical and clinical mechanistic studies, Leydig cell tumours, renal tubule tumours, and pheochromocytomas are considered to be rat-specific. Canagliflozin-induced renal tubule tumours and pheochromocytomas in rats appear to be caused by carbohydrate malabsorption as a consequence of intestinal SGLT1 inhibitory activity of canagliflozin in the gut of rats; mechanistic clinical studies have not demonstrated carbohydrate malabsorption in humans at canagliflozin doses of up to 2-times the maximum recommended clinical dose. The Leydig cell tumours are associated with an increase in luteinizing hormone (LH), which is a known mechanism of Leydig cell tumour formation in rats. In a 12-week clinical study, unstimulated LH did not increase in male patients treated with canagliflozin.