Standard regimen for acute appendicitis
For empirical therapy of acute appendicitis in adults and children without sepsis or septic shock, as a 3-drug regimen, use:
1gentamicin intravenously; see Principles of aminoglycoside use for prescribing considerations and subsequent dosing. See Modification and duration of therapy for acute appendicitis gentamicin gentamicin gentamicin
adult: see Gentamicin initial dose calculator for adults for initial dose
child younger than 18 years: 7 mg/kg up to 560 mg for initial dose1 2
OR
1tobramycin intravenously; see Principles of aminoglycoside use for prescribing considerations and subsequent dosing. See Modification and duration of therapy for acute appendicitis tobramycin tobramycin tobramycin
adult: see Tobramycin initial dose calculator for adults for initial dose
child younger than 18 years: 7 mg/kg up to 560 mg for initial dose12
PLUS WITH EITHER OF THE ABOVE DRUGS
metronidazole 500 mg (child: 12.5 mg/kg up to 500 mg) intravenously, 12-hourly. See Modification and duration of therapy for acute appendicitis metronidazole metronidazole metronidazole
PLUS EITHER
1amoxicillin 2 g (child: 50 mg/kg up to 2 g) intravenously, 6-hourly. For dosage adjustment in adults with kidney impairment, see amoxicillin dosage adjustment. See Modification and duration of therapy for acute appendicitis amoxicillin amoxicillin amoxicillin
OR
1ampicillin 2 g (child: 50 mg/kg up to 2 g) intravenously, 6-hourly. For dosage adjustment in adults with kidney impairment, see ampicillin dosage adjustment. See Modification and duration of therapy for acute appendicitis. ampicillin ampicillin ampicillin
To avoid the need to switch between intravenous antibiotics at 72 hours, a non-aminoglycoside–containing regimen may be used if it is suspected that intravenous therapy will continue for at least 72 hours. If the likely duration of intravenous therapy is not known, start with the aminoglycoside-containing regimen; do not delay antibiotic administration to make this determination. Non-aminoglycoside–containing regimens are also used if gentamicin or tobramycin is contraindicated. For empirical therapy of acute appendicitis in adults and children without sepsis or septic shock, use:
1ceftriaxone 2 g (child 1 month or older: 50 mg/kg up to 2 g) intravenously, daily. See Modification and duration of therapy for acute appendicitis ceftriaxone ceftriaxone ceftriaxone
OR
1cefotaxime 2 g (child: 50 mg/kg up to 2 g) intravenously, 8-hourly. For dosage adjustment in adults with kidney impairment, see cefotaxime dosage adjustment. See Modification and duration of therapy for acute appendicitis cefotaxime cefotaxime cefotaxime
PLUS with either of the above drugs
metronidazole 500 mg (child: 12.5 mg/kg up to 500 mg) intravenously, 12-hourly. See Modification and duration of therapy for acute appendicitis metronidazole metronidazole metronidazole
OR as a single drug
2+0.2 g formulation
adult, or child 40 kg or more: 2+0.2 g 8-hourly. For dosage adjustment in adults with kidney impairment, see amoxicillin+clavulanate intravenous dosage adjustment
OR
1+0.2 g formulation
adult, or child 40 kg or more: 1+0.2 g 6-hourly. For dosage adjustment in adults with kidney impairment, see amoxicillin+clavulanate intravenous dosage adjustment
child 1 month to younger than 3 months and less than 4 kg: 25+5 mg/kg 12-hourly
child 1 month to younger than 3 months and 4 kg or more: 25+5 mg/kg 8-hourly
child 3 months or older and less than 40 kg: 25+5 mg/kg up to 1+0.2 g 6-hourly.