Gentamicin

Question 1

Gentamicin Mechanism of Action

Answer 1

• Gentamicin is an aminoglycoside antibiotic with broad activity against gram-negative bacteria. It inhibits bacterial cell protein synthesis.

Question 2

Gentamicin Indications

Answer 2

Sepsis (in addition to amoxicillin/clavulanic acid), where the site of infection is the urinary tract, the abdomen, or is unknown and:

• The patient is aged greater than or equal to 12 years, and
• One or more high risk factors are present, and
• Time to hospital is greater than 30 minutes.

Question 3

Gentamicin Contraindications

Answer 3

Known severe allergy.

Pregnancy

Question 4

Gentamicin Cautions

Answer 4

None

Question 5

Gentamicin Use during pregnancy/breastfeeding

Answer 5

• May cause foetal harm during pregnancy and should not be administered.
• May be administered if the patient is breastfeeding. Advise the patient to stop breastfeeding and seek further advice from their lead maternity carer or GP.

Question 6

Gentamicin Dose

Answer 6

• 400 mg if weighs greater than 80 kg.
• 320 mg if weighs 60-80 kg.
• 240 mg if weighs less than 60 kg.

Question 7

Gentamicin Administration

Answer 7

• Dilute the dose to a total of 10-20 ml using 0.9% sodium chloride and
administer IV over 1-2 minutes, preferably into a running IV line.
• Do not administer IM if IV access cannot be obtained.

Question 8

Gentamicin Common adverse effects

Answer 8

• Although renal impairment is commonly listed, this is usually not of significant concern unless there is repeated and/or prolonged dosing.
• Ototoxicity (damage to the inner ear) has been reported, but this usually only happens with repeated and/or prolonged dosing.

Question 9

Gentamicin Onset of effect

Answer 9

30-60 minutes

Question 10

Gentamicin Duration of effect

Answer 10

24 Hours

Question 11

Gentamicin Preparation

Answer 11

Ampoule containing 80 mg in 2 ml.

Question 12

Gentamicin Pharmacokinetics

Answer 12

• Gentamicin is excreted in urine.
• Clearance is prolonged if the patient has significant kidney impairment, but this does not alter the initial (loading) dose.

Question 13

Gentamicin Interactions

Answer 13

• Gentamicin may potentiate the actions of neuromuscular blockers, resulting in
a longer duration of action from these drugs.
Gentamicin reduces acetylcholine release - enhanced NMB action

Question 14

Gentamicin Additional Information

Answer 14

Gentamicin is not contraindicated if the patient has renal failure.
• Seek clinical advice if the patient is aged less than 12 years.

Question 15

Gentamicin Protein synthesis mechanism

Answer 15

• Proteins are building blocks of cellular organisms and carry out the majority of cellular activities
• Creation of proteins requires sequences of amino acid chains, which form proteins
• Gentamicin inhibits this protein synthesis, causes the wrong sequencing of amino acids, creating an inactive protein and causing cellular death.
• Breakdown of the cell wall by amoxicillin allows greater penetration by gentamicin