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

bactericidal

Binds to the bacterial 30S ribosomal subunit to inhibit protein synthesis and thus bacterial growth

BA 62%

BA no oral absorption, rapid and complete IM.
IV (poor lipid solubility)
doses 3-10mcg/kg depending on severity
onset / duration 30mins

penetration into CSF occurs with inflamed meninges only

lip sol low - reduces gut absorption
some CSF penetration with inflamed meninges (30%)

20% PB

<30% PB

Vd 0.2-0.3 L/kg

Some Hepatic Metabolism

not metabolised

Mostly unchanged in urine.
Rest is feces and bile

excretion urine as unchanged drug

half life 1.5-3 hrs, +++ in renal impairment (up to 70hrs)

ototoxicity
nephrotoxicity (worse with loop diuretics or pre-existing renal disease)
pre-jn Ach release   post-jn sensitivity to Ach NMBD activity can cause paralysis.

May cause C.Diff.

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

provide good gram negative coverage and some gram positive
most often used against enteric infections and in sepsis
usually used in combination with a beta lactam

ANTIBIOTIC:
PENICILLIN

ANTIBIOTIC:
AMINOGLYCOSIDE

aminoglycoside of choice because of its lower cost and reliable activity against GNB.
It is often used in combination
with a beta lactam antibiotic for serious but uncultured infections. They also have
limited gram positive coverage including staph and some strep

Betalactam

Aminoglycoside

Level 1

Level 1

clear solution for injection. Requires monitoring of levels especially
if there is any renal impairment, to prevent complications

Bacteria produce beta lactamases, which hydrolyse and inactivate the antibiotic

Resistance
MRSA
Many Staph
-Betalactamase prod

Alteration in access to target site – membrane impermeability / transport defect in the active transport.
Lack of O2-transport channels: Anaerobes
Multiple enzymes which block gentamicin (acetytransferases, adenyltransferases, phosphotransferases)