GENTAMICIN INTERMITTENT DOSING

• If there are no contraindications to its use, once-daily dosing (7mg/kg) with gentamicin is safer, more convenient, and cheaper than multiple daily dose regimens

Cautions

• Unless advised in a guideline or by consultant in infectious diseases/microbiologist, do not prescribe gentamicin treatment for >3 days
• In all patients being treated with gentamicin, measure serum creatinine daily and serum gentamicin where recommended
• As gentamicin has a narrow therapeutic index, accurate dosing is essential to prevent toxicity
• Deafness and balance problems may occur at therapeutic levels. If they occur, stop gentamicin 

Contraindications

• DO NOT use this protocol for patients in the following categories:
• ascites
• pregnant women
• endocarditis. See Gentamicin for Infective Endocarditis
• cystic fibrosis (CF)
• major burns
• creatinine clearance (CrCl) ≤20 mL/min
• In these situations, use a speciality protocol

• Ideal body weight and actual (or estimated) weight are used in calculating the doses
• Measure Height
• Weigh patient
• if unfit to be weighed, estimate weight
• Measure creatinine

Administration

• Dilute gentamicin dose in 100 mL glucose 5% or sodium chloride 0.9%
• administer by IV infusion over 1 hr
• Record time infusion started on drug chart

Measure concentration

• Take blood samples for gentamicin (10 mL clotted blood) and creatinine 6–14 hr after start of infusion
• do not sample via cannula used for infusion
• Request measurement of gentamicin concentration and document in patient record
• Complete microbiology request form
• accurately document when infusion began and time when sample was taken on the microbiology request card; this will appear on the report

Gentamicin concentration known

• Use if serum gentamicin concentration taken between 6–14 hr from first/previous dose is available within 24 hr of first/previous dose
• Check blood results for gentamicin level
• Calculate time interval between start of gentamicin infusion and time level taken 

Dose interval

• If you are unsure how to interpret the result, seek advice

Dose

• Measure Height
• Weigh patient
• if unfit to be weighed, estimate weight
• Ideal body weight and actual (or estimated) weight are used in calculating the doses
• Measure creatinine

Administration

• Dilute gentamicin dose in 100 mL glucose 5% or sodium chloride 0.9%
• administer by IV infusion over 1 hr
• Record time infusion started on drug chart

Gentamicin concentration unknown

• Use if serum gentamicin concentration taken between 6–14 hr from first dose is not available within 24 hr of first dose
• Take a sample for serum gentamicin at 20-24 hr after first dose and wait for result
• if concentration is <1 mg/L, give next dose
• if concentration is > 1mg/L, withhold the dose and recheck in 12-24 hr

• Check serum creatinine daily
• Every 2-3 days, take a sample for gentamicin concentration
• if the concentration is unexpectedly high, or if renal function alters, daily sampling may be necessary
• If dose interval has to be changed, check gentamicin concentration 6–14 hr after start of last infusion (note time of start of infusion and time of sampling) and go to NEXT dose to choose dose and dose interval