When dispensing Septra Suspension, which has now been genericized and contains sulfamethoxazole (SMX) 40 mg/mL and trimethoprim (TMP) 8 mg/mL, be careful when calculating volume based on a prescription written in mg of trimethoprim (TMP). This will help you avoid the error recently brought to ACP’s attention.
A prescription was written for Septra Suspension 145 mg of TMP component po bid. Two different pharmacies filled the suspension, calculating the volume based on the sulfamethoxazole (SMX) component rather than TMP component. This resulted in a five times underdose. This is significant for a child who is being treated for osteomyelitis.
Originally published in the November 17, 2009, issue of The Link