Core pharmacology

Class Group

ANTIBIOTIC:
PENICILLIN

Legacy Cicm Level

Level 1

Introduction

Narrow spectrum naturally occurring penicillin

Mechanism of action

β lactam antibiotic
Binds to penicillin binding protein (transpeptidase) and
prevents crosslinking of bacterial peptidoglycan
impairs cell wall synthesis

Antimicrobial Spectrum

Narrow-Spectrum
Natural Penicillin

Highly bactericidal, only
gram positives/anaerobes,
susceptible to betalactamases

Targets
GPC: Streptococci, Meningococcus
Listeria (GPB)
GNC: Neisseria, Clostridia
Treponemma (Spiral)

Synergistic effects with
aminoglycosides

Resistance Mechanism

Resistance
MRSA
Many Staph
-Betalactamase prod
Gram Negatives

Adverse Effects Toxicity

GIT– abdominal pain, N/V/D, pseudomembranous colitis, hepatitis
HAEM- agranulocytosis
CNS- confusion, seizure, encephalopathy
HYPERSENSITIVITY- rash, anaphylaxis

Absorption

Orally not absorbed (need penicillin V)

Distribution

CSF and bone penetration if inflammation present

Protein binding

60% PB

Volume of distribution

Vd <1L/kg

Metabolism

Inactive metabolite penicollic acid

Excretion

90% excreted in urine by tubular secretion
25% unchanged