Dosing Trimethoprim-Sulfamethoxazole for Urinary Tract Infection, Acute Otitis and Other Infections in Children

 

Infections for which TMP-SMX may be considered:

(1) urinary tract infections

(2) acute otitis media

(3) shigellosis

(4) acute sinusitis

 

Oral formulations for TMP-SMX (in fixed dose ratio of 1 to 5):

(1) single strength tablet (80 mg TMP, 400 mg SMX)

(2) double strength tablet (DS, 160 mg TMP, 800 mg SMX)

(3) suspension (8 mg TMP per mL, 40 mg SMX per mL)

 

TMP-SMX is contraindicated in infants < 2 months old because of the risk for kernicterus.

 

For acute bacterial infections dosing is 8 mg/kg TMP and 40 mg/kg SMX per day.

 

The daily dose is divided for q12h po administration. This means that 4 mg/kg TMP and 20 mg/kg SMX are given twice a day.

 

Duration of therapy is usually for 10 days.

 

If tablets are given the following table can be used for the high end of the dosage range:

Body Weight in Kg	Single Strength Tablet po q12h	Double Strength Tablet po q12h
10	0.5
20	1.0	0.5
30	1.5
40	2.0	1

 

If renal function is impaired, then the dose should be reduced.

 

Creatinine Clearance	Dosing Adjustment
> 30 mL per min	normal
15 - 30 mL per min	reduce by 50%
< 15 mL per min	use alternative therapy

 

For the creatinine clearance of 15 - 30 mL this works out to the following:

 

Body Weight in Kg	Single Strength Tablet po q12h
10
20	0.5
30
40	1.0