Merck Manual

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Dosages of Penicillins

Dosages of Penicillins


Dosage, Route, and Frequency

Sodium penicillin G

10,000–20,000 IU/kg, IV or IM, qid

Potassium penicillin G

25,000 IU/kg, PO, qid

Procaine penicillin G

10,000–30,000 IU/kg, IM or SC, once to twice daily

Benzathine penicillin G

10,000–40,000 IU/kg, IM (horses) or SC (cattle), every 48–72 hr

Penicillin V

15,000 IU/kg or 8–10 mg/kg, PO, tid-qid


10–25 mg/kg, IM or PO, qid


5–10 mg/kg, IV, IM, or SC, bid-tid; 10–25 mg/kg, PO, bid-qid


4–10 mg/kg, IM, once to twice daily; 10–20 mg/kg, PO, bid-qid (dogs)

Sodium carbenicillin

10–20 mg/kg, IV or IM, bid-qid

Potassium clavulanate:amoxicillin (1:4)

10–20 mg/kg (amoxicillin) and 2.5–5 mg/kg (clavulanate), PO, bid-qid

Probenecid (prolongs blood concentrations of penicillins that have short plasma half-lives or that are costly)

1–2 mg/1,000 IU penicillin G (dogs), PO, qid

Amoxicillin-clavulanic acid

10–20 mg/kg, PO, bid-qid


1–7 mg/kg, IV or IM, bid-tid


12–24 mg/kg, IV or SC, bid-tid

Ticarcillin (with or without clavulanic acid)

40–110 mg/kg, IM or IV, tid-qid