An elderly patient with fever, confusion, costovertebral angle tenderness arrives, was initially diagnosed with pyelonephritis and I started him on Levofloxacin. The professor changed the medication to SMX/TMP 2gm then 1 gm bid, pt returned with fever and crackles in the lung fields and a secondary diagnosis of pneumonia was made. I then started the patient back on Levofloxacin. Now the patient has a GFR of 40, Cr of 3.0. How do adjust the med based on this lab finding, how do you monitor efficacy and toxicity of this patient with a summary of where the patient should stand in his medical treatment?