Pharmacokinetics, drug elimination, acute kidney injury

A 58-year-old woman with type 2 diabetes mellitus and hypertension is prescribed metformin (oral bioavailability 50–60%, renal clearance 90% of total body clearance) and amlodipine (hepatic metabolism >90%, oral bioavailability 6–29% due to first-pass effect). She develops acute kidney injury (serum creatinine rises from 0.9 to 2.8 mg/dL over 48 hours). Which of the following pharmacokinetic parameters will be MOST significantly altered in this patient, and what is the primary mechanism?