Core pharmacology

Class Group

ANTIBIOTIC:
AMINOGLYCOSIDE

Legacy Cicm Level

Level 1

Introduction

Aminoglycoside

Indications Uses

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

Presentation

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

Mechanism of action

bactericidal

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

Antimicrobial Spectrum

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

Resistance Mechanism

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)

Adverse Effects Toxicity

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.

Absorption

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

Distribution

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

Protein binding

<30% PB

Volume of distribution

Vd 0.2-0.3 L/kg

Metabolism

not metabolised

Excretion

excretion urine as unchanged drug

Half-life

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