Table 2.

Dosages and dosing schedules of common antimicrobials in IEI

AntimicrobialDosageComments
TMP/SMX 5 mg/kg/day TMP component, divided twice daily; max dose 160 mg TMP
5 mg/kg TMP component divided twice daily 3 days/wk 
Twice daily dosing for bacterial prophylaxis in CGD, HIES; consider for PADs
3 days/wk dosing for PJP prevention in SCID, athymia, CID at risk (e.g., Hyper IgM syndrome)
Monitor for cytopenias; Folinic acid can minimize risk
Consider atovaquone or pentamidine as alternatives for PJP prevention 
Azithromycin 5 mg/kg/day; max dose of 250 mg daily or 5 mg/kg/day or 500 mg 3 days/wk Check EKG for QTc interval and consider hearing screen
Monitor for resistance with long-term use 
Penicillin 125 mg twice daily <5 years old
250 mg twice daily 5 years and older 
Asplenia, terminal complement defects 
Amoxicillin 40 mg/kg/day divided twice daily; max dose 500 mg Mild hypogammaglobulinemia as an alternative to IgRT 
Fluconazole 5–6 mg/kg/day; max 200 mg daily Consider drug interactions
Monitor transaminases
Prophylaxis against yeast; no filamentous mold (e.g., Aspergillus) activity 
Itraconazole 5–10 mg/kg/day; max 100 mg (<50 kg) or 200 mg (>50 kg) Consider drug interactions and monitoring drug levels
Monitor transaminases 
Posaconazole 300 mg tablets daily for adults and children >40 kg
6 mg/kg/day of tablets for children <40 kg 
Tablet dosing differs from suspension dosing
Consider drug interactions
Check trough level and transaminases 1–2 wk after initiation
Check EKG for QTc 
Acyclovir 80 mg/kg/day divided twice daily or TID
400 mg twice daily adult dosing for HSV/Varicella/Zoster (VZV) suppression 
Encourage hydration and monitor renal function
Can use in patients with SCID if at risk for HSV
Do not use if on valganciclovir
Consider acyclovir or valacyclovir with JAK inhibition 
Valacyclovir 500–1,000 mg daily for adults
20 mg/kg/day divided twice daily to 500 mg twice daily max for pediatrics 
Do not use if on valganciclovir
Consider acyclovir or valacyclovir with JAK inhibition 
Valganciclovir 10–20 mg/kg daily, max 900 mg/day Monitor for cytopenias and elevated transaminases
For SCID with suspicion of CMV exposure or CMV disease 
AntimicrobialDosageComments
TMP/SMX 5 mg/kg/day TMP component, divided twice daily; max dose 160 mg TMP
5 mg/kg TMP component divided twice daily 3 days/wk 
Twice daily dosing for bacterial prophylaxis in CGD, HIES; consider for PADs
3 days/wk dosing for PJP prevention in SCID, athymia, CID at risk (e.g., Hyper IgM syndrome)
Monitor for cytopenias; Folinic acid can minimize risk
Consider atovaquone or pentamidine as alternatives for PJP prevention 
Azithromycin 5 mg/kg/day; max dose of 250 mg daily or 5 mg/kg/day or 500 mg 3 days/wk Check EKG for QTc interval and consider hearing screen
Monitor for resistance with long-term use 
Penicillin 125 mg twice daily <5 years old
250 mg twice daily 5 years and older 
Asplenia, terminal complement defects 
Amoxicillin 40 mg/kg/day divided twice daily; max dose 500 mg Mild hypogammaglobulinemia as an alternative to IgRT 
Fluconazole 5–6 mg/kg/day; max 200 mg daily Consider drug interactions
Monitor transaminases
Prophylaxis against yeast; no filamentous mold (e.g., Aspergillus) activity 
Itraconazole 5–10 mg/kg/day; max 100 mg (<50 kg) or 200 mg (>50 kg) Consider drug interactions and monitoring drug levels
Monitor transaminases 
Posaconazole 300 mg tablets daily for adults and children >40 kg
6 mg/kg/day of tablets for children <40 kg 
Tablet dosing differs from suspension dosing
Consider drug interactions
Check trough level and transaminases 1–2 wk after initiation
Check EKG for QTc 
Acyclovir 80 mg/kg/day divided twice daily or TID
400 mg twice daily adult dosing for HSV/Varicella/Zoster (VZV) suppression 
Encourage hydration and monitor renal function
Can use in patients with SCID if at risk for HSV
Do not use if on valganciclovir
Consider acyclovir or valacyclovir with JAK inhibition 
Valacyclovir 500–1,000 mg daily for adults
20 mg/kg/day divided twice daily to 500 mg twice daily max for pediatrics 
Do not use if on valganciclovir
Consider acyclovir or valacyclovir with JAK inhibition 
Valganciclovir 10–20 mg/kg daily, max 900 mg/day Monitor for cytopenias and elevated transaminases
For SCID with suspicion of CMV exposure or CMV disease 

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