The goal of this clinical trial is to evaluate the protective effect of metformin on nephrotoxicity of cisplatin in patients with bladder cancer. The main questions it aims to answer are:

• To determine protective effect of metformin on structural and functional kidney injury caused by cisplatin in patients with bladder cancer.
• To evaluate the safety of combining cisplatin and metformin on patients with bladder cancer

Inclusion Criteria:

1. Non-diabetic adults of age between 18 to 65.
2. Chemotherapy naïve patients diagnosed with bladder cancer.
3. Patients with stable renal function: eGFR is above 60 ml/min/1.73 m2

Exclusion Criteria:

1. Patients with history of lactic acidosis.

2. Patients taking any nephrotoxic medication other than cisplatin (e.g., frusemide, NSAIDs, aminoglycoside or vancomycin).

3. Unstable renal function (defined as an increase in serum creatinine of 0.3 mg/dL or greater suddenly in 48 hours according to the acute kidney injury network (AKIN) classification

4. Patients with heart failure, acute myocardial infarction or cardiogenic collapse (shock).

5. Severe infection and sepsis.

   • Any infection requiring hospitalization.
   • Any infection leading to a need for oxygen, intubation, vasopressors or fluids to support blood pressure.

6. Alcohol intake.

7. Respiratory failure.

8. Severe hepatic impairment (Child-Pugh class C).

9. Patients with metastasis.