Pilot data suggest that inadequate antibiotic volumes are often dispensed. Study goals were to determine the frequency of inadequate antibiotic volumes dispensed by local pharmacies, develop prescription-writing guidelines to ensure that adequate antibiotic suspension volumes are dispensed, and document the adequacy of verbal/written counseling pharmacists provide.


Sixty-one local pharmacies filled prescriptions for penicillin potassium (PCN; 250 mg/5 mL [5 mL orally 3 times daily for 10 days]) and Bactrim (trimethoprim-sulfamethoxazole [TMP-SMX] 5 mL orally twice daily for 10 days). The prescriptions noted only to “dispense a 10-day supply.” Volumes were measured first as total amount dispensed and then into total doses dispensed. Written/verbal instructions were documented.


The volume of PCN dispensed was 195 ± 25 mL (range: 105–222 mL) for an average of 29.4 doses, where 30 doses were needed. TMP-SMX dispensed had a volume of 107 ± 5 mL (range: 98–120 mL) resulting in an average of 16.5 doses, where 20 doses were needed. Twenty pharmacies (33%) did not dispense a measuring device. Verbal counseling by the pharmacist and written instructions were not uniformly given.


We suggest calculating the actual volume needed plus an additional 10% to 30% of volume (depending on the viscosity). The prescription should also request a medication-measuring/administering device. Patient counseling and instruction should be expanded.

You do not currently have access to this content.