You are a drug information pharmacist at your hospital. You received an enquiry from a respiratory physician regarding the use of vancomycin in an adult patient whose clinical signs and chest X-ray are suggestive of pneumonia and whose sputum shows heavy growth of methicillin resistant Staphylococcus aureus (“MRSA”).

a) He tells you that he has ordered serum concentration monitoring. The peak and trough levels are found to be 20 µg/mL and 4 µg/mL respectively. He wants to know if the levels are appropriate and asks for your advice. What further information should you also inquire before providing any recommendations? (4 marks)

On further questioning, the physician is uncertain if therapeutic drug monitoring (“TDM”) is indeed necessary for this patient.

b) Suggest THREE situations in which TDM of vancomycin is recommended. Please justify. (6 marks)

c) On closer examination of the microbiology report you found out that the minimum inhibitory concentration (MIC) for vancomycin is 2 µg/mL for this MRSA isolate. What would you like to inform the position? (2 marks)

d) A few days later the physician calls you again. He would like to have your comments regarding use of alternative agent, compared vancomycin in the treatment of nosocomial MRSA pneumonia. What are the therapeutic and Pharmacokinetics and Pharmacodynamics (“PK/PD”) issues you may wish to discuss with the doctor ? (3 marks)