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The patient has normal renal function and thus qualifies for once-daily dosing. Tobramycin could be administered as a single once-daily injection at a dose of 350–490 mg (5–7 mg/kg). A serum level between 1.5 and 6 mcg/mL mea-sured 8 hours after infusion correlates with an appropriate trough level. Alternatively, the same total daily dose could be divided and administered every 8 hours, as a conventional dosing strategy. With conventional dosing, peak and trough concentrations should be monitored with the target peak concentration of 5–10 mcg/mL and the target trough con-centration of <2 mcg/mL.
CHAPTER 46 Sulfonamides,
Trimethoprim, & Quinolones
Camille E. Beauduy, PharmD, & Lisa G. Winston, MD*
A 59-year-old woman presents to an urgent care clinic with a 4-day history of frequent and painful urination. She has had fevers, chills, and flank pain for the past 2 days. Her physician advised her to come immediately to the clinic for evaluation. In the clinic she is febrile (38.5°C [101.3°F]) but otherwise stable and states she is not experiencing any nausea or vomiting. Her urine dipstick test is positive for leukocyte esterase. Urinalysis and urine culture are ordered. Her past medical history is significant for three urinary tract infections in the past year. Each episode was uncom-plicated, treated with trimethoprim-sulfamethoxazole, and promptly resolved. She also has osteoporosis for which she takes a daily calcium supplement. The decision is made to treat her with oral antibiotics for a complicated urinary tract infection with close follow-up. Given her history, what would be a reasonable empiric antibiotic choice? Depending on the antibiotic choice are there potential drug interactions?