Gentamicin parenteral
- Drugs List
- Therapeutic Indications
- Dosage
- Administration
- Contraindications
- Precautions and Warnings
- Pregnancy and Lactation
- Side Effects
- Monograph
Presentation
Solution for injection containing gentamicin.
Drugs List
Therapeutic Indications
Uses
Bacterial endocarditis
Pseudomonal lung infection in cystic fibrosis
Severe neonatal infections
Severe systemic infections
Urinary tract infection
Gentamicin is a broad spectrum bactericidal antibiotic and is usually effective against most strains of Escherichia coli, Klebsiella spp., Proteus spp., Salmonella, Serratia, Pseudomonas aeruginosa, Staphylococci, Enterobacter spp., Citrobacter spp. and Providencia spp.
It is indicated in the treatment of systemic infections when caused by susceptible organisms, such as the following:
Urinary tract infections, respiratory tract infections, bacteraemia, septicaemia, burns and wound infections, severe neonatal infections, bacterial endocarditis, surgical infections, biliary tract infections, acute pyelonephritis, meningitis and other CNS infections, intra-abdominal infections and other antibiotic sensitive serious systemic infections.
Unlicensed Uses
Prophylaxis against infection during surgical procedures
Treatment by nebulisation of lung infections caused by P. aeruginosa.
Dosage
A once-daily, high dose regimen of an aminoglycoside should be avoided in patients with endocarditis due to Gram-positive bacteria, HACEK endocarditis, burns of more than 20% of the total body surface area or creatinine clearance less than 20ml/minute.
Adults
Multiple daily dose regimen
Serious Infections
5mg/kg daily in divided doses at 6 or 8 hourly intervals. The subsequent dose should be adjusted as clinically indicated.
Endocarditis (in combination with other antibacterials)
The following alternative dosing schedule may be suitable
1mg/kg every 12 hours.
Systemic Infections
3mg/kg/day to 5mg/kg/day in divided doses according to severity of infection. Adjust dose according to clinical response and body weight.
Urinary Tract Infections
3mg/kg/day to 5mg/kg/day in divided doses according to severity of infection. Adjust dose according to clinical response and body weight. Or a dose of 160mg once per day may be used.
Once daily dose regimen
Serious Infections
3mg/kg to 6mg/kg per day.
The following alternative dosing schedule may be suitable.
Initial dose: 5mg/kg to 7mg/kg once daily by intravenous infusion. Then adjust according to serum gentamicin concentration.
Surgical prophylaxis (unlicensed)
The following alternative dosing schedule may be suitable:
1.5mg/kg up to 30 minutes before the procedure by slow intravenous injection (up to 3 further doses of 1.5mg/kg may be given every 8 hours for high risk procedures).
For joint replacement surgery, 5mg/kg as a single dose by intravenous infusion up to 30 minutes before the procedure.
Uncomplicated gonorrhoea (anogenital and pharyngeal infection-adjunctive treatment) (unlicensed)
240mg for 1 dose by intramuscular injection.
Elderly
(See Dosage; Adult)
Children
Serious Infections
Children aged 1 to 18 years
3mg/kg to 6mg/kg body weight per day as 1 dose (preferred) or up to 2 divided doses.
Children aged 1 month to 1 year
4.5mg/kg to 7.5mg/kg body weight per day as 1 dose (preferred) or up to 2 divided doses.
The following alternative dosing schedule may be suitable:
Children aged 1 month to 18 years
Initially 7mg/kg once daily by intravenous infusion, then adjusted according to serum-gentamicin concentration
Note: This once daily dose regimen is not for endocarditis or meningitis.
OR
Children aged 12 to 18 years
2 mg/kg every 8 hours by intramuscular or by slow intravenous injection.
Children aged 1 month to 12 years
2.5mg/kg every 8 hours by intramuscular or by slow intravenous injection.
Pseudomonal lung infection in cystic fibrosis
Children aged 1 month to 18 years
3mg/kg every 8 hours by slow intravenous injection or by intravenous infusion.
Acute pyelonephritis, Urinary tract infection (catheter-associated)
Children aged 16 to 18 years
5mg/kg to 7mg/kg once daily by intravenous infusion, then adjusted according to serum-gentamicin concentration.
Children aged 3 month to 16 years
7mg/kg once daily by intravenous infusion, then adjusted according to serum-gentamicin concentration.
Uncomplicated gonorrhoea (anogenital and pharyngeal infection-adjunctive treatment) (unlicensed)
Children aged 16 to 18 years
240mg for 1 dose by intramuscular injection.
Neonates
The daily dose in neonates and pre-term infants (aged 0 to 4 weeks old) is 4mg/kg to 7mg/kg body weight per day. Due to the longer half-life, newborns are given the required daily dose in 1 single dose.
Neonatal sepsis
The following alternative dosing schedule may be suitable:
Neonate less 7 days after birth: 5mg/kg every 36 hours by slow intravenous injection or intravenous infusion.
Neonate more than 7 days after birth: 5mg/kg every 24 hours by slow intravenous injection or intravenous infusion.
Patients with Renal Impairment
Nomograms are available for the calculation of dose, which depends on the patient's age, weight and renal function.
The following suggestions may be useful:
Creatinine clearance greater than 70ml/minute with blood urea less than 40mg/100 ml (6 to 7mmol/litre): 80mg every 8 hours.
Creatinine clearance 30 to 70ml/minute with blood urea 40 to 100mg/100ml (6 to 17mmol/litre): 80mg every 12 hours.
Creatinine clearance 10 to 30ml/minute with blood urea 100 to 200mg/100ml (17 to 34mmol/litre): 80mg daily.
Creatinine clearance 5 to 10ml/minute with blood urea greater than 200mg/100ml (greater than 34mmol/litre): 80mg every 48 hours.
Creatinine clearance less than 5ml/minute with twice weekly intermittent haemodialysis: 80mg after dialysis.
If the patient's body weight is below 60 kilograms the dose in the above suggestions should be reduced to 60mg (replacing 80mg). Frequency of dosage in hours may also be approximated as serum creatinine (mg%) x 8 or in SI units, as serum creatinine (micromole/litre) divided by 11. If these dosage suggestions are used, peak serum levels must be measured. One hour post-administration concentrations of gentamicin should not exceed 10micrograms/ml (but should reach 4micrograms/ml), while the pre-dose trough concentration should be less than 2micrograms/ml.
Administration
Gentamicin may be given by intramuscular injection or intravenous injection/infusion. It is normally given by intramuscular injection.
Once daily dosing should only be administered through the intravenous route.
When given intravenously, gentamicin should be administered slowly directly into a vein or into the drip set tubing over at least 3 minutes. For intravenous infusion, administer over no longer than 20 to 30 minutes, in a limited fluid volume (100ml).
Longer infusion times of up to 60 minutes may be used, in particular for a once daily dosing regimen.
Nebulisation (unlicensed)
For nebulisation, dilute preservative-free preparation of gentamicin in 3ml sodium chloride 0.9%. Administer after physiotherapy and bronchodilators.
Therapeutic Drug Monitoring
Toxicity can be minimised by monitoring serum - gentamicin concentrations regularly.
Multiple daily dose regimen
Peak levels (measured one hour post dose) should be 5mg/litre to 10mg/litre. Trough levels (measured just prior to a dose) should be below 2mg/litre.
Endocarditis
Peak levels (measured one hour post dose) should be 3mg/litre to 5mg/litre. Trough levels (measured just prior to a dose) should be below 1mg/litre.
Cystic fibrosis
Peak levels (measured one hour post dose) should be 8mg/litre to 12mg/litre. Trough levels (measured just prior to a dose) should be below 2mg/litre.
Once daily dose regimen
Trough levels (measured just prior to a dose) should be below 1mg/litre.
Extended interval dose regimen in neonates
Pre-dose (trough) concentration should be less than 2mg/litre (less than 1mg/litre if more than 3 doses administered). Consider monitoring one hour peak concentration in neonates with poor response to treatment, with oedema, with gram-negative infection, or with birth weight greater than 4.5kg (consider increasing dose if peak concentration less than 8mg/litre in severe sepsis).
Dosage should be adjusted in all patients according to these concentrations, but this is of particular importance where factors such as age, renal impairment, or high dosage may predispose to toxicity.
Contraindications
Myasthenia gravis
Precautions and Warnings
Bacteraemia
Children under 1 year
Elderly
Premature infants
Pyrexia
Significant obesity
Auditory impairment
Breastfeeding
Dehydration
Hepatic disorder
Hypotension
Hypovolaemia
Known or suspected mitochondrial disorder
Muscle weakness
Neuromuscular disorder
Parkinsonism
Pregnancy
Renal impairment
Vestibular impairment
Correct dehydration before commencing therapy
Reduce dose in patients with renal impairment
Advise ability to drive/operate machinery may be affected by side effects
Consult national/regional policy on the use of anti-infectives
Not all available brands are licensed for all routes of administration
Some brands contain metabisulfite, may cause bronchospasm/allergies
Evaluate renal function before and during treatment
Elderly: Monitor renal function and consider dose modification
Monitor auditory and vestibular function
Monitor hepatic function
Monitor peak and trough serum levels
Monitor toxicity - discontinue or modify dose if necessary
Monitor urine output
Advise patient to seek medical advice if severe skin reaction occurs
Potentially ototoxic and nephrotoxic
Discontinue if severe skin reaction occurs
Discontinue therapy if marked diarrhoea occurs
Dose varies with brand
In obese patients dosing should be based on ideal weight
Care should be taken when treatment duration exceeds 7 days
Maintain treatment for the shortest possible duration
Toxicity can be minimised by monitoring serum - gentamicin concentrations regularly. Serum gentamicin concentrations should be measured in all patients and must be determined in neonates, in the elderly, in obesity, and in cystic fibrosis, or if high doses are being given, or if there is renal impairment. Gentamicin should not be prescribed if serum concentrations cannot be monitored.
Since the risk of both ototoxicity and nephrotoxicity can be related to the level of total exposure, duration of therapy should be the shortest possible compatible with clinical recovery. In some patients with renal impairment a transient rise in blood urea nitrogen may occur, although this usually resolves during or after cessation of therapy. It is important to adjust the frequency of dosage according to renal function.
Ototoxicity has been observed with treatment with gentamicin. Important risk factors include renal impairment, high doses, prolonged duration of treatment and age (neonates/infants and potentially the elderly). Due to the possibility of ototoxicity and nephrotoxicity, monitoring of vestibule, cochlea and renal function is recommended before, during and shortly after treatment.
There have been observed cases of an increased risk of ototoxicity with aminoglycosides administered to patients with mitochondrial mutations, particularly the m.1555A G mutation, including cases where the patients aminoglycoside serum levels were within the recommended range. Some cases were associated with maternal history of deafness and or mitochondrial mutation. Mitochondrial mutations are rare, and the extent of this observed effect is unknown.
Pregnancy and Lactation
Pregnancy
Use gentamicin with caution during pregnancy.
Manufacturer advises do not use during pregnancy except in cases of life-threatening situations were expected benefit may outweigh possible risks.
Gentamicin rapidly crosses the human placenta. Animal studies have shown a risk of ototoxicity (vestibulocochlear nerve damage) and/or renal damage in the fetus.
When indicated, maternal serum levels should be carefully monitored and dose should be adjusted as necessary. Monitor renal function in the neonate and perform an auditory test if high doses are used.
Treatment with aminoglycosides during pregnancy is not an indication for termination of pregnancy or invasive diagnostic procedures (Schaefer 2015).
Lactation
Use gentamicin with caution during breastfeeding.
Gentamicin is poorly excreted into breast milk. Newborn infants absorb small amounts of gentamicin which are unlikely to produce systemic effects if the mother is given typical three times daily dosage. Older infants would be expected to absorb even less gentamicin. Due to little variability in the milk gentamicin levels during multiple daily dose regimens, timing of breastfeeding with respect to the dose is of little benefit in reducing exposure. There are insufficient data available on the use of single daily dose regimens.
Monitor the infant for possible effects indicative of disruption of the gastro-intestinal flora, especially those indicative of antibiotic-associated diarrhoea.
Manufacturer advises in the case of suspected severe mucosal erosion, if the infant is breast-fed during gentamicin treatment, monitor the infants serum concentration of gentamicin. Consider discontinuation of gentamicin treatment or breastfeeding if infants gentamicin serum concentration exceeds 1microgram per ml.
Side Effects
Acute renal failure
Alopecia
Aminoaciduria
Amyostasia
Anaemia
Anaphylactic reaction
Antibiotic-associated colitis
Blood dyscrasias
Blood urea increased
CNS effects
Confusion
Convulsions
Deafness
Decreased appetite
Depression
Dizziness
Drug fever
Encephalopathy
Eosinophilia
Epidermal necrolysis
Erythema multiforme
Exanthema
Fanconi's syndrome (reversible)
Granulocytopenia
Hallucinations
Headache
Hearing loss
Hearing loss (reversible)
Hepatic impairment
Hyperphosphaturia
Hypersensitivity reactions
Hypertension
Hypocalcaemia
Hypokalaemia
Hypomagnesaemia
Hypophosphataemia
Hypotension
Increase in alkaline phosphatase
Increase in aminotransferase level
Lethargy
Leukopenia
Local pain (injection site)
Loss of balance
Meniere's disease
Muscle weakness
Myalgia
Nausea
Nephrotoxicity
Neuromuscular block
Neurotoxicity
Ototoxicity
Paraesthesia
Peripheral neuropathy
Polyneuropathy
Pseudo Barrter's syndrome
Purpura
Rash
Reduction in reticulocytes
Renal impairment
Rise in body temperature
Salivation
Serum bilirubin increased
Skin reddening
Stevens-Johnson syndrome
Stomatitis
Superinfections
Thrombocytopenia
Tinnitus
Urticaria
Vertigo
Vestibular and auditory damage
Visual disturbances
Vomiting
Weight loss
Overdosage
It is strongly recommended that the UK National Poisons Information Service be consulted on cases of suspected or actual overdose where there is doubt over the degree of risk or about appropriate management.
The following number will direct the caller to the relevant local centre (0844) 892 0111
Information may be obtained if you have access to ToxBase the primary clinical toxicology database of the National Poisons Information Service. This is available via password on the internet ( www.toxbase.org ) or if this is unavailable at the backup site ( www.toxbasebackup.org ).
Further Information
Last Full Review Date: April 2022
Reference Sources
Drugs During Pregnancy and Lactation: Treatment Options and Risk Assessment, 3rd edition (2015) ed. Schaefer, C., Peters, P. and Miller, R. Elsevier, London.
Summary of Product Characteristics: Cidomycin 80mg/2ml Solution for Injection. Sanofi. Revised January 2022.
Summary of Product Characteristics: Gentamicin 10mg/1ml Solution for Injection or Infusion. Wockhardt Ltd. Revised April 2022.
Summary of Product Characteristics: Gentamicin Paediatric 20mg/2ml. Zentiva. Revised March 2021.
Summary of Product Characteristics: Gentamicin 1mg/1ml Solution for Infusion. B.Braun. Revised January 2021.
Summary of Product Characteristics: Gentamicin 3mg/1ml Solution for infusion. B. Braun. Revised January 2021.
NICE Evidence Services Available at: www.nice.org.uk Last accessed: 09 March 2022
US National Library of Medicine. Toxicology Data Network. Drugs and Lactation Database (LactMed).
Available at: https://www.ncbi.nlm.nih.gov/books/NBK501922/
Gentamicin Last revised: 16 August 2021
Last accessed: 28 March 2022
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