Reference no: EM133012817

Pharmacokinetic assignment

Please answer the following questions about antibiotic dosing. You may need to access multiple IDSA guidelines in order to successfully answer the questions. For adult vancomycin doses, please give your dose in a rounded, 250 mg increment. For pediatric patients, round your dose to the nearest 10 mg. Please give specific dosing recommendations, complete with the interval (i.e. 1250 mg IV Q12 hrs). Write or type your answers in the space provided. Please show all work for full credit.

1. You are asked to help dose vancomycin for a 48 year-old woman who was admitted to the medical ICU 5 days ago with a gastrointestinal bleed and altered mental status. She has been on the ventilator for 4 days now and is suspected to have ventilator associated pneumonia. She was treated for a MRSA pneumonia six months earlier in your facility (MIC = 0.5). Her pertinent labs/measurements are: height: 67", weight 72 kg, SCr 0.9 mg/dL (0.8 mg/dL on admission).
a- Based on her presumed infection, what should be the patient's goal vancomycin trough and goal AUC?
b- What is the estimated T1/2 for vancomycin in this patient?
c- What initial, empiric vancomycin dose do you recommend? Please include loading doses and maintenance doses as appropriate.
d- Please include a projected trough for your above recommended dose (assume a Vd of 0.8L/kg for critical illness; must get dose above correct to receive points).

2. You are on your pediatrics APPE when a two-year old child presents with likely meningitis symptoms. She is started on empiric ceftriaxone and vancomycin. Her weight is 32 lbs. No other labs are available at this time.
a. Based on her presumed infection, what should be the patient's goal vancomycin trough and goal AUC:MIC ratio (assume MIC=1)?
b. What initial, empiric vancomycin dose do you recommend? Please include loading doses and maintenance doses and intervals as appropriate.

3. You are on your cardiology APPE when a 46 year-old man presents with infective endocarditis of his native mitral valve. He has been exhibiting symptoms for 3-4 weeks and presented to your institution 4 days ago. Numerous blood cultures show that he is growing penicillin-susceptible enterococcus faecalis. Gentamicin susceptibility has also been confirmed. The ID consult service recommends that his broad antibiotics be changed to high-dose ampicillin and gentamicin synergy. You are asked to help dose his antibiotics. His pertinent labs/measurements are: height: 72", weight 121 kg, SCr 1.3 mg/dL.

a. What dosing weight is appropriate for this patient?
b. What synergy dosing regimen would you recommend? Round your answer to the nearest 10 mg.

c. What would be your goal peak and trough with this regimen?
d. According to IDSA guidelines, how long should each antibiotic be given?

4. You are on your critical care APPE when a 56 year-old man presents with a necrotizing fasciitis of the left upper extremity following a deep laceration that has appeared infected for 1 week. The patient immediately underwent surgical debridement, but may require additional surgery. The patient weighs 97 kg and he is 71 ins tall. His SCr is 3.0 mg/dL with minimal urine output (no baseline). Piperacillin-tazobactam 3.375 mg Q8h, clindamycin 600 mg q8h, and vancomycin 2000mg pulse dosing is empirically started on presentation. The vancomycin serum concentrations and doses for the last 48 hours are as follows:
10/13 0905: 2000mg x 1 dose
10/14 0305: 26 mcg/mL
10/14 No vancomycin doses given
10/15 0200: 21 mcg/mL
a. The creatinine on 10/15 remains at 3.3 mg/dL with 350 mL urine output for the 24-hour period. The team wants to re-dose the vancomycin when the serum concentration reaches 18 mcg/mL. Based on the information you have, when should this patient receive the next dose (round to the nearest hour, provide in date and time)?
b. What is the half-life of vancomycin in this patient currently?
c. Assuming that we are continuing to spot dose, please recommend an appropriate spot dose for vancomycin to be given at the above time (assume that we want the trough to be therapeutic again within the half-life timeframe).
d. Based on his calculated creatinine clearance, what dose of piperacillin/tazobactam should be recommended?

5. You are on your trauma APPE rotation when a 26 year-old patient presents from a rehab facility with likely vertebral osteomyelitis. He initially sustained an T12 spinal transverse process fracture, among other injuries following a motorcycle collision about 14 days previously. His pertinent labs/measurements are: height: 69", weight 78 kg, SCr 1.0mg/dL. Assume Vd = 0.8 L/kg for critical illness.
a. What initial, empiric vancomycin dose do you recommend (include dose and dosing interval)?
b. The new vancomycin guidelines recommend AUC:MIC monitoring for vancomycin and your facility utilizes this. What would the projected AUC:MIC be for the dose and interval ordered above on this patient?
c. When would you recommend checking serum concentrations to determine AUC:MIC and how would you do it? Be specific on the timing.