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

Contains a beta lactam ring structure. Betalactam antibiotics inhibit the growth of sensitive bacteria by inactivating transpeptidase enzymes located in the bacterial cell membrane, inhibiting crosslinkage of peptidoglycans and thus impairing cell wall synthesis

Orally not absorbed (need penicillin V)

BA 62%

CSF and bone penetration if inflammation present

penetration into CSF occurs with inflamed meninges only

60% PB

20% PB

Vd <1L/kg

Inactive metabolite penicollic acid

Some Hepatic Metabolism

90% excreted in urine by tubular secretion
25% unchanged

Mostly unchanged in urine.
Rest is feces and bile

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

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

Moderate spectrum
Semisynthetic
Can penetrate some gram
negative outer membranes,
but susceptible to betalactamases. Often given with clauvanic acid
Targets
Strep, Listeria, Enterococcus, Haemophilus

ANTIBIOTIC:
PENICILLIN

ANTIBIOTIC:
PENICILLIN

Narrow spectrum naturally occurring penicillin

Betalactam

Level 1

Level 1

Resistance
MRSA
Many Staph
-Betalactamase prod
Gram Negatives

Bacteria produce beta lactamases, which hydrolyse and inactivate the antibiotic

Resistance
MRSA
Many Staph
-Betalactamase prod