A Randomized controlled trial aiming to investigate whether ascorbic acid has a role in preventing vancomycin induced nephrotoxicity or not in critically ill patients.

Critically ill patients who have gram positive infection (MRSA) and need vancomycin will be assigned randomly into two groups. The first group will be given vancomycin intravenous only (15-20 mg/kg) every 8-12 hours , while the second group will take vancomycin intravenous (15-20 mg/kg) every 8-12 hours plus ascorbic acid 1 gram twice daily orally just before the vancomycin administration by half an hour. Patients will be monitored for one week where serum creatinine, BUN, urine output, trough level will be measured. Acute kidney injury will be determined according to RIFLE criteria.

Inclusion Criteria:

• Adults who are critically ill and with MRSA infection suspection.

Exclusion Criteria:

1. Pregnancy or breast feeding.
2. Known allergy to either vancomycin or ascorbic acid.
3. Base line serum creatinine ≥2mg/dl.
4. Patients receiving other nephrotoxic drug (e.g., aminoglycosides, amphotericin B, cisplatin or calcinurine inhibitors).
5. Anticepated administration of contrast medium within 7 days.
6. Patients suffering from some underlying diseases (e.g., cancer, HIV infection, systemic lupus erythematoses,or urinary tract stones).
7. Unlikelyhood of receiving the study medications for at least 72 hours