A 67 year old woman is admitted with hospital-acquired pneumonia. Sputum culture has grown Pseudomonas aeruginosa and she is commenced on intravenous tobramycin and piperacillin/tazobactam. PMH. Bronchiectasis, hypertension. DH. Tobramycin 60 mg IV every 8 hours, piperacillin/tazobactam 4.5 g IV every 8 hours, amlodipine 5 mg PO once daily. SH. Lives with her husband. Independent with activities of daily living.

On examination
Temperature 38.1°C, heart rate 94 beats/min, blood pressure 126/74 mmHg, respiratory rate 20 breaths/min, oxygen saturation 95% on room air. Weight 60 kg.

Investigations
Haemoglobin 131 g/L (115-165)
WCC 15.4 × 10⁹/L (3-10)
Platelets 292 × 10⁹/L (150-400)
Sodium 139 mmol/L (137-144)
Potassium 4.1 mmol/L (3.5-5.5)
Urea 6.8 mmol/L (2.5-7)
Creatinine 82 micromol/L (60-110)
eGFR 72 mL/min/1.73 m² (>60)
Tobramycin 1-hour (‘peak’) serum concentration 13 mg/L
Tobramycin pre-dose (‘trough’) serum concentration 1.1 mg/L

Select the most appropriate decision regarding her tobramycin prescription based on the data given.