PEBC: What You Need to Know: Penicillins

Penicillins describe a whole set of medications including penicillin V, amoxicillin, cloxacillin and amoxicillin/clavulanate.

Indications:

Penicillin V: strep throat [drug of choice]

Amoxicillin: pneumonia, strep throat, dental surgery, otitis media, asymptomatic bacteriuria in pregnancy

Cloxacillin: impetigo, skin infections, Staphylococcus aureus infections

Amoxicillin/clavulanate: broad spectrum antibiotic for severe infections; contains clavulanate to overcome beta-lactamase resistance

Adverse Effects:

Common to all: nausea, vomiting, diarrhea, may lower seizure threshold, potential for allergic reaction

Adverse effects are more common with broad spectrum amoxicillin/clavulanate due to the clavulanate portion.

All safe in pregnancy.

Dosing:

Penicillin: with or without food

Amoxicillin: with food generally better. High dose regimen recommended for otitis media and pneumonia. This overcomes Strep pnuemoniae resistance, but at the expense of more adverse effects.

Cloxacillin: on empty stomach (1 hour before or 2 hours after meals)

Amoxicillin/clavulanate: with food. Two formulations available: 7:1 and 4:1 ratios. Generally, 7:1 is dosed twice daily, whereas 4:1 is dosed three times daily.