Aminoglycosides are derived from bacteria of the Streptomyces genus. They have several antibiotic mechanisms, which are thought to be related to the inhibition of bacterial protein synthesis. Aminoglycosides are not absorbed well from the gut so medication must be given by injection to help systemic infections. The main problem with aminoglycosides is that patients can easily suffer from toxic side effects due to inappropriate dosing. Consequently the monitoring of serum concentration is crucial, while treatment time does not exceed seven days.
Dosage regimen
(NB *Refer to SPC for children’s doses, specific infections and or local guidelines).
Drug name
Use
Dosage
Gentamicin
·Septicaemia
·Neonatal sepsis
·Meningitis and other CNS infections
·Biliary tract infection
·Acute pyelonephritis or prostatis
·Endocarditis
·Pneumonia in hospital patients
Multiple daily dose regimen, by IM or slow IV injection over at least three minutes or by IV infusion, 3-5mg/ kg daily (in divided doses every eight hours).
Once daily dose regimen by IV infusion, initially 5-7mg/kg, then adjust according to serum gentamicin concentration.*
Amikacin
·Serious Gram- negative infections resistant to gentamicin
By IM or slow IV injection, or by infusion:
15mg/kg daily in two divided doses, increased to 22.5mg/kg in three divided doses in severe infections (maximum 1.5g daily for up to 10 days, maximum cumulative dose 15g).*
Neomycin sulphate
·Bowel sterilisation before surgery
·Hepatic coma
By mouth:
Pre-operative bowel sterilisation, 1g every hour for four hours, then 1g every four hours for two to three days.
Hepatic coma, up to 4g daily in divided doses, usually for five to seven days.*
Tobramycin
·See gentamicin
·Urinary tract infection
·Chronic pulmonary Pseudomonas aeruginosa infection with cystic fibrosis
By IM or slow IV injection or IV infusion, 3mg/kg daily in divided doses every eight hours. In severe infections up to 5mg/kg daily in divided doses every six to eight hours (reduced to 3mg/kg as soon as clinically indicated).
UTI, by IM injection, 2-3mg/kg daily as single dose.
Chronic pulmonary Pseudomonas aeruginosa infection with cystic fibrosis, by inhalation of nebulised solution, adult and child over six years, 300mg every 12 hours for 28 days. Subsequent courses repeated after 28 day interval without tobramycin nebuliser solution.*
Patient knowledge Patient should be aware of treatment and/or prophylaxis procedure.
Is the medicine working? This will mainly be decided by doctors as the dosing is dependent on serum concentration and level of side effects.
Side effects Aminoglycoside side effects are dose related so it is important that serum concentration is monitored closely. The main side effects are vestibular and auditory damage and nephrotoxicity.
Monitoring • Serum concentration to prevent toxicity and encourage efficacy of medication. • Renal function. • For tobramycin, bronchospasm should be monitored before and after treatment by measuring peak flow.
Lifestyle • Patients should be aware of all possible symptoms in case infection relapses. • Where applicable, encourage compliance to minimise risk of antibiotic resistance.
Anita Bagga is a Boots community pharmacist from Leicester.
