Dapagliflozin And Metformin

Introduction Overview

Generic Name

dapagliflozin and metformin

Brand Name

Xigduo XR

Dosage Form

oral extended-release tablet

Drug Class

Antidiabetic combinations

Pharmacokinetics

Absorption:
Xigduo XR comprises dapagliflozin and metformin, both of which are administered orally as extended-release tablets. Dapagliflozin exhibits high oral bioavailability (~78%) with peak plasma concentrations achieved approximately 2 hours post-administration in immediate-release forms; with extended-release formulations, absorption is slower but sufficient for once-daily dosing. Metformin extended-release tablets demonstrate a slower rate of absorption compared to immediate-release metformin, with peak plasma concentrations occurring between 4-8 hours post-dose. Food intake can influence absorption; specifically, taking Xigduo XR with food enhances gastrointestinal tolerability and does not significantly impair the absorption of either component.

Distribution:
Dapagliflozin is moderately bound to plasma proteins (~91%), predominantly albumin, which facilitates its systemic distribution. Metformin exhibits negligible plasma protein binding (<20%), thus it remains primarily unbound in the bloodstream. The volume of distribution for dapagliflozin is approximately 118 L, indicating extensive distribution into tissues. Metformin has a relatively large volume of distribution (approximately 654 L), distributing widely into body tissues, particularly the intestinal mucosa, liver, and kidneys, correlating with its sites of action.

Metabolism:
Dapagliflozin undergoes hepatic metabolism primarily via UGT1A9-mediated glucuronidation to inactive metabolites that have no significant pharmacological effects. It has minimal involvement with cytochrome P450 enzymes. Metformin is not metabolized by the liver and is excreted unchanged by the kidneys, which reduces the potential for hepatic drug interactions but necessitates renal function monitoring.

Elimination:
Dapagliflozin and its metabolites are excreted mainly via the urine (~75%) and feces (~21%). The plasma elimination half-life is approximately 12.9 hours, supporting once-daily dosing. Metformin is eliminated unchanged primarily by renal excretion through tubular secretion and glomerular filtration. Its half-life varies from 4 to 8.7 hours in plasma but is prolonged in cases of renal impairment. Because metformin is renally cleared, renal function significantly impacts its elimination, necessitating dosage adjustments and precautions to avoid toxicity, including lactic acidosis.

Dosage Forms

Available Dosage Forms:
Xigduo XR is available as oral extended-release tablets with the following dapagliflozin-metformin component combinations:
- 2.5 mg dapagliflozin / 1000 mg metformin
- 5 mg dapagliflozin / 500 mg metformin
- 5 mg dapagliflozin / 1000 mg metformin
- 10 mg dapagliflozin / 500 mg metformin
- 10 mg dapagliflozin / 1000 mg metformin

Dosages for Adults and Adolescents:
For adults and children aged 10 years and older with type 2 diabetes mellitus, the initial dose is typically 5 mg dapagliflozin once daily, with metformin dosage individualized between 500 mg and 2000 mg according to glycemic control and tolerability. If additional glycemic control is needed, the dapagliflozin dose may be increased to 10 mg once daily, maintaining the metformin dose accordingly. The maximum daily dose is 10 mg dapagliflozin with 2000 mg metformin. Xigduo XR tablets are administered once daily with food to improve gastrointestinal tolerability. Extended-release formulation supports once-daily dosing.

Specific Patient Populations:
In patients with renal impairment, Xigduo XR is contraindicated in those with severe kidney disease or on dialysis due to impaired clearance of metformin and increased risk for lactic acidosis. Dose adjustments or discontinuation may be required based on eGFR levels. Elderly patients (≥65 years) are at increased risk of dehydration and adverse effects; careful monitoring and hydration status assessment are recommended. Pediatric use is approved for children aged 10 years and above; however, safety and dosing should be individualized. Use during pregnancy is not recommended, particularly in the second and third trimesters due to potential fetal kidney effects. Breastfeeding is contraindicated due to metformin excretion in breast milk.

Mechanism Of Action

Xigduo XR combines the actions of dapagliflozin, a sodium-glucose co-transporter 2 (SGLT2) inhibitor, and metformin, an insulin sensitizer and hepatic gluconeogenesis suppressor, producing synergistic glycemic control in patients with type 2 diabetes mellitus.

Dapagliflozin acts primarily in the proximal renal tubules by selectively inhibiting SGLT2, which is responsible for approximately 90% of renal glucose reabsorption. By blocking this transporter, dapagliflozin reduces glucose reabsorption, promoting glucosuria and thereby lowering plasma glucose concentration. This mechanism is insulin-independent, providing an advantage in patients with insulin resistance. The resultant glucosuria also induces mild osmotic diuresis, contributing to reductions in blood pressure and body weight, which have additional cardiovascular and renal benefits.

Metformin reduces hepatic glucose production by inhibiting mitochondrial respiratory chain complex I, resulting in decreased gluconeogenesis and lower fasting plasma glucose levels. It also enhances peripheral glucose uptake and utilization, particularly in skeletal muscle, and decreases intestinal glucose absorption. Metformin’s actions improve overall insulin sensitivity, mitigate insulin resistance, and contribute to HbA1c lowering effects. Importantly, metformin does not cause significant hypoglycemia as it does not stimulate insulin secretion.

Clinically, the combined mechanism results in improved glycemic control through complementary pathways: dapagliflozin facilitating urinary glucose excretion and metformin suppressing endogenous glucose production. This dual action addresses multiple pathophysiological defects of type 2 diabetes. Furthermore, dapagliflozin has been shown in clinical trials to reduce hospitalization for heart failure and progression of kidney disease, adding cardioprotective and nephroprotective effects beyond glycemic management. The combination improves patient adherence by providing moderate dose reductions of each agent in one extended-release tablet formulation. Comparative mechanisms also show advantages over sulfonylureas and insulin, which increase hypoglycemia risk and weight gain; Xigduo XR tends to promote weight loss and has a low hypoglycemia risk profile when used appropriately.

Pharmacological Actions

Inhibits renal sodium-glucose co-transporter 2 (SGLT2) to increase urinary glucose excretion (dapagliflozin component)
Suppresses hepatic gluconeogenesis and decreases intestinal glucose absorption (metformin component)
Enhances peripheral insulin sensitivity and glucose uptake
Produces insulin-independent glycemic control
Promotes osmotic diuresis leading to blood pressure reduction
Contributes to weight loss through glucosuria-induced calorie loss
Reduces risk of hospitalization for heart failure in patients with type 2 diabetes and cardiovascular disease
Slows progression of chronic kidney disease and reduces renal endpoints
Does not stimulate insulin secretion, minimizing hypoglycemia risk
Extended-release formulation allows once-daily dosing with improved gastrointestinal tolerability
Low potential for drug-drug interactions due to distinct metabolic pathways
May improve endothelial function and reduce oxidative stress according to preclinical studies
Combination therapy addresses multiple defects of type 2 diabetes pathophysiology
May increase renal sodium delivery contributing to enhanced natriuresis
Long-term use may lead to vitamin B12 deficiency due to metformin component

Therapeutic Or Clinical Uses

Management of type 2 diabetes mellitus in adults and children aged 10 years and older to improve glycemic control
Adjunct to diet and exercise for blood glucose lowering
Reduction of risk for hospitalization due to heart failure in adults with type 2 diabetes and established cardiovascular disease
Delay in progression of chronic kidney disease and reduction in renal endpoints in patients with type 2 diabetes
Lowering risk of cardiovascular mortality in certain high-risk diabetic populations
Use in patients inadequately controlled on metformin or dapagliflozin monotherapy
Alternative oral antidiabetic combination therapy to reduce pill burden
Adjunct therapy in patients with insulin resistance where additional glucose lowering is needed
Potential use in weight management adjunct due to modest weight loss observed with therapy
Use in patients with hypertension and type 2 diabetes benefiting from blood pressure lowering effect
Treatment aimed at reducing hyperglycemia without significant hypoglycemia risk
Management option when sulfonylureas or insulin are contraindicated or not tolerated
Option for patients at risk for heart failure with type 2 diabetes requiring glycemic control
Use in combination with lifestyle modifications for overall cardiovascular risk reduction
Long-term therapy to maintain stable glycemic levels and prevent diabetic complications

Side Or Adverse Effects

Female genital infections including vulvovaginitis and candidiasis
Headache
Gastrointestinal disturbances such as nausea, vomiting, and diarrhea
Upper respiratory tract infections manifested as runny or stuffy nose and sore throat
Dehydration leading to dizziness, lightheadedness, or orthostatic hypotension
Increased risk of urinary tract infections and bladder infections with symptoms like pain, burning, or blood in urine
Potential for diabetic ketoacidosis presenting with nausea, vomiting, confusion, and abdominal pain
Lactic acidosis, a rare but serious metabolic complication associated with metformin
Vitamin B12 deficiency with long-term metformin use resulting in neuropathy or anemia
Allergic reactions such as rash, urticaria, or facial swelling
Electrolyte imbalances secondary to osmotic diuresis
Possible hypoglycemia when used in combination with insulin or insulin secretagogues
Fatigue and unusual muscle pain related to metabolic disturbances
Increased risk of renal impairment particularly in elderly or dehydrated patients
Rare but serious genital infections such as necrotizing fasciitis of the perineum (Fournier’s gangrene)

Precautions

Ensure patients are well hydrated before starting treatment to minimize risk of dehydration
Monitor renal function regularly, especially in elderly and those with pre-existing kidney disease
Avoid use in patients with severe kidney impairment or on dialysis
Avoid using Xigduo XR in patients with metabolic or diabetic ketoacidosis
Caution in patients on diuretics or low salt diet to prevent hypotension and electrolyte imbalances
Advise patients to report signs of genital infections promptly for early treatment
Assess vitamin B12 levels periodically during prolonged therapy
Adjust doses or increase monitoring when used concomitantly with insulin or insulin secretagogues to prevent hypoglycemia
Educate patients about recognizing symptoms of lactic acidosis and to seek immediate medical care if suspected
Counsel patients to avoid excessive alcohol intake to reduce risk of lactic acidosis
Advise against abrupt cessation of drug before major surgery or radiologic studies involving iodinated contrast media; withhold per guidelines
Monitor blood glucose closely when initiating therapy or changing dose
Use caution in patients with a history of bladder infections or urinary tract abnormalities
Evaluate cardiovascular status periodically given the osmotic diuretic effect and volume changes
Avoid use during pregnancy, especially second and third trimesters, due to potential fetal risks

Warnings

Contraindicated in patients with severe kidney disease or end-stage renal disease
Risk of lactic acidosis, a potentially fatal metabolic disorder, particularly in cases of renal impairment, dehydration, or acute illness
May precipitate diabetic ketoacidosis even with normal or mildly elevated blood glucose levels
Monitor for serious genital infections including necrotizing fasciitis of the perineum (Fournier’s gangrene)
Increased risk of dehydration leading to hypotension and renal impairment, especially in elderly patients
Temporary discontinuation required before iodinated contrast radiologic studies to prevent acute kidney injury
Potential for hypoglycemia when combined with insulin or insulin secretagogues
Contains metformin which may stimulate ovulation, potentially increasing risk of unintended pregnancy
Not recommended for use during the second and third trimesters of pregnancy
Avoid use in patients with metabolic acidosis including diabetic ketoacidosis
Use with caution in patients with hepatic impairment
Advise patients to avoid excessive alcohol consumption to minimize risk
Emergent treatment required if signs of allergic reaction or severe infection are noted
Caution regarding possible vitamin B12 deficiency with long-term use
Drug should be stopped before surgery or procedures with prolonged fasting to reduce metabolic risks

Contraindication

Known hypersensitivity or allergy to dapagliflozin, metformin, or any component of the formulation
Severe renal impairment (eGFR below threshold specified by guidelines) or patients on dialysis
Patients with metabolic acidosis including diabetic ketoacidosis (requires emergency treatment)
Acute or chronic metabolic acidosis, including lactic acidosis
Severe hepatic impairment which may predispose to lactic acidosis
Conditions that predispose to hypoxia such as acute heart failure or recent myocardial infarction
Patients undergoing radiologic studies involving iodinated contrast media without appropriate discontinuation
Pregnancy during second and third trimesters due to potential fetal harm
Breastfeeding women as metformin is excreted in human milk
Patients with known bladder cancer due to concerns from dapagliflozin preclinical studies
Severe gastrointestinal disease that may interfere with absorption
Type 1 diabetes mellitus as Xigduo XR is not effective in this population
History of serious hypersensitivity reactions to any SGLT2 inhibitors or biguanides
Use in pediatric patients under age 10 not established and thus contraindicated
Conditions of dehydration or volume depletion not corrected before therapy initiation

Drug Interactions

Digoxin – potential increase in serum digoxin levels due to altered renal clearance necessitating monitoring
Rifampin – may reduce the effectiveness of dapagliflozin via induction of metabolic pathways
Phenytoin – possible lowered efficacy of dapagliflozin due to enzyme induction
Diuretics (water pills) – additive risk of volume depletion, dehydration, and hypotension
Insulin and insulin secretagogues (e.g., sulfonylureas) – increased risk of hypoglycemia; dose adjustments may be necessary
Nonsteroidal anti-inflammatory drugs (NSAIDs) – increased risk of renal impairment and fluid retention
Iodinated contrast media (used in imaging) – risk of acute kidney injury; temporary discontinuation recommended
Cationic drugs eliminated by renal tubular secretion (e.g., cimetidine, vancomycin) – potential competition affecting metformin renal elimination
Agents that increase blood pressure-lowering effects (e.g., antihypertensives) – enhanced hypotensive effects especially with volume depletion
Alcohol – increased risk of lactic acidosis and hypoglycemia if consumed in excess
Corticosteroids and sympathomimetic agents – may antagonize blood glucose lowering effects
Other glucose-lowering agents – additive or synergistic hypoglycemic effects
Drugs affecting CYP enzymes have minimal interaction with dapagliflozin but caution advised with strong UGT inducers
Medications causing volume depletion or electrolyte imbalance may exacerbate adverse effects associated with dapagliflozin
Herbal supplements with hypoglycemic potential may increase risk of low blood sugar

Preparations Of The Drug

Xigduo XR 2.5 mg dapagliflozin / 1000 mg metformin extended-release oral tablets
Xigduo XR 5 mg dapagliflozin / 500 mg metformin extended-release oral tablets
Xigduo XR 5 mg dapagliflozin / 1000 mg metformin extended-release oral tablets
Xigduo XR 10 mg dapagliflozin / 500 mg metformin extended-release oral tablets
Xigduo XR 10 mg dapagliflozin / 1000 mg metformin extended-release oral tablets
Inactive ingredients include anhydrous lactose, carboxymethylcellulose sodium, crospovidone, hypromellose, magnesium stearate, microcrystalline cellulose, and silicon dioxide
Film coating composed of polyethylene glycol, polyvinyl alcohol, talc, titanium dioxide, and colorants such as FD&C Yellow No. 6 aluminum lake and iron oxides depending on the formulation
Extended-release tablets designed for once-daily administration to improve adherence and reduce gastrointestinal side effects
Provided in blister packs or bottles with instructions for storage at controlled room temperature away from moisture and heat
Manufactured and supplied by AstraZeneca Pharmaceuticals LP
Packaging includes detailed patient instructions emphasizing the importance of swallowing tablets whole without crushing or chewing
Available under prescription only status with professional healthcare provider supervision
Supplied with patient information leaflets detailing risks of adverse effects including genital infections and lactic acidosis
Produced under Good Manufacturing Practices to ensure consistency and quality
Available in multiple strengths to facilitate individualized dosing regimens according to clinical need