^Penicillins

 

Spectrum

Amoxicillin and ampicillin

Certain Gram-positives and Gram-negatives and anaerobes but not those that produce

beta-lactamases e.g. Staphylococcus aureus and Escherichia coli. Certain Gram-negatives

are often resistant e.g. Klebsiella spp. and Pseudomonas spp.⁵

 

Amoxicillin-clavulanic acid

Gram-positive and Gram-negative aerobes and many facultative and obligate anaerobes.

Effective against those that produce beta-lactamases but certain Gram-negatives are often

resistant e.g. Klebsiella spp. and Pseudomonas spp.⁵

 

Physicochemical properties

Acidic, hydrophilic.³

 

Distribution^3,4,7

Do not cross the blood-brain barrier (BBB) or enter the eye or the prostate.

Will reach joints, bile and milk.

Will cross the placenta.

 

Pharmacokinetics

Antimicrobial

C_max

Protein
binding

Volume of distribution

Metabolism & elimination

Terminal
half life

Absorption

T_max

Amoxicillin

 

 

18-20µg/ml.²⁴

AUC(0-24) 69-80µg.h/ml.²⁴

13%²⁵

0.312L/kg²⁴

 

 

Renal.²⁵

45-90 minutes in dogs and cats.²⁵

74-92% absorbed in monogastrics.²⁵

1.4-2 hours.²⁴

Amoxicillin-Clavulanic acid

 

 

In dogs:

8.5 µg/ml for amoxicillin, 0.9 µg/ml for clavulanic acid.⁶

In cats:

6.6 µg/ml for amoxicillin, 3.7 µg/ml for clavulanic acid.⁶

 13%²⁵

Clavulanic acid 0.32L/kg.²⁵

 

Hepatic metabolism and renal clearance.²⁵

In dogs:

1.5 hours for amoxicillin, 0.76 hours for clavulanic acid.²⁶

In cats:

1.2 hours for amoxicillin, 0.6 hours for clavulanic acid.²⁷

Absorption is fast⁶

In dogs:

1.4 hours for amoxicillin, 0.9 hours for clavulanic acid.⁶

In cats:

1.8 hours for amoxicillin, 0.75 hours for clavulanic acid.⁶

Ampicillin

Data not sourced

20%²⁵

In dogs:

0.3L/kg.²⁵

In cats:

0.167L/kg.²⁵

 

Renal.²⁵

45-80 minutes in dogs and cats.²⁵

Poor oral absorption: 30-55% absorbed in monogastrics, decreased with food.²⁵

Data not sourced