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Gentamicin 40 mg/ml Injection

Gentamicin 40 mg/ml Injection

This is an extract from the Summary of Product Characteristics (SPC) to assist in the administration of Gentamicin 40 mg/ml Injection. You should however be familiar with the full SPC.

Gentamicin is normally given by the intramuscular route, but can be given intravenously when intramuscular administration is not feasible.


Gentamicin Injection should not be mixed with other drugs before injection and where co-administration of penicillins, cephalosporins, erythromycin, lipiphysan, sulphadiazine, furosemide, betalactam antibiotics and heparin is necessary, the drugs should be administered separately, either as bolus injections into the tubing of the giving set or at separate sites. Addition of gentamicin to solutions containing bicarbonate may lead to the release of carbon dioxide.

Preparation Instructions

The prescribed dose may be dissolved in up to 100 ml of normal saline or 5% glucose in water, but not solutions containing bicarbonate, and the solution infused over a period of 20 to 30 minutes.

Dosage and Administration

Gentamicin is normally given by the intramuscular route, but can be given intravenously when intramuscular administration is not feasible, e.g. in shocked or severely burned patients. The same dosage schedule is recommended for intramuscular and intravenous dosing. Dosage is related to the severity of infection, the age of the patient and the patient’s renal function.

When given intravenously, the prescribed dose should be administered slowly over 2 to 3 minutes directly into a vein or into the rubber tubing of a giving set.

Dosage in Patients with Normal Renal Function:

Adult Dosage:

Type of infection Dosage Time interval between doses Duration of therapy
Systemic and urinary tract infections 3 mg/kg/day up to 80 mg 8 hours 7-10 days


5 mg/kg/day initially then 3 mg/kg/day as soon as improvement is indicated 6-8 hours 7-10 days (Longer therapy may be required. If so, auditory renal and vestibular functions should be monitored).

Paediatric Dosage

Infection Age Dose/Route Frequency
Systemic 0-7 days1 week – 1 year

1 year – 12 years

5  mg/kg/day IM6  mg/kg/day IM 4.5 mg/kg/day IM 12 hours 12 hours 8 hours
Urinarytract infections 3 mg/kg/day IM 8 hours -12 hours


0-7 days1 week – 1 year

1 year – 12 years

5  mg/kg/day 7.5 mg/kg/day6  mg/kg/day 12 hours 8 hours 8 hours

Doses in Patients with Impaired Renal Function

Dosage is adjusted for patients with renal impairment to minimise the risk of toxicity. The first dose should be as normal – after this, doses should be given less frequently, the interval being determined by results of renal function tests as below:

Renal Function Tests:

Dose Creatinine Clearance (ml/min) Serumcreatinine


BUN mmol/l Intervalbetween


80 mg over 7035-70





less than 0.120.12-0.17





less than 6.56.5-10





8 hours 12 hours 18 hours 24 hours 36 hours 48 hours


Patients being treated with gentamicin should be under close clinical observation because of its potential toxicity.

Rapid, direct intravenous administration may give rise, initially, to potentially neurotoxic concentrations and it is essential that the prescribed dose is administered over the recommended period of time.

Gentamicin 40 mg/ml Injection

The active substance is gentamicin sulphate

The other ingredients are sodium metabisulphite (E223), disodium edetate, methyl hydroxybenzoate, propyl hydroxybenzoate, sulphuric acid, sodium hydroxide and Water for Injections.

What Gentamicin Injection is and what it is used  for

Gentamicin Injection is an aminoglycoside   antibiotic medicine, in the form of a solution for injection (a solution which can be given as an injection).

The medicine is presented in glass containers called vials. Each millilitre (ml) of Gentamicin Injection contains 40 milligrams (mg) of gentamicin (as sulphate). The 2 ml vial contains 80 mg of gentamicin (as sulphate). It is available in packs containing 5 vials.

Gentamicin Injection is used to treat a wide variety of infections such as chest, wound and blood infections.

Gentamicin Injection should not be used:

  • if you have shown signs of hypersensitivity (severe allergy) to gentamicin on previous occasions.

Gentamicin Injection will not normally be used:

  • if you are pregnant or breastfeeding

Special care will be taken:

  1. if treating premature babies
  2. if you are an elderly patient
  3. if your kidneys are not working properly
  4. if you have diabetes
  5. if you have an ear, hearing or balance disorder, a history of ear infections or if you have been treated with medicines that affect hearing in the past
  6. if you are taking certain other   medicines, such as:
    1. antibiotics that also affect your kidneys or hearing such as other aminoglycosides, cephalothin and methicillin
    2. medicines used to thin the blood, such as warfarin and phenindione
    3. amphotericin (medicine used to treat fungal infections)
    4. neostigmine and pyridostigmine (medicines used in the treatment of muscle weakness)
    5. cyclosporin (a medicine that reduces the activity of the body’s immune system)
    6. cisplatin (anti-cancer medicine)
    7. some diuretics (water tablets), such as ethacrynic acid and furosemide
    8. muscle relaxants used during general anaesthesia (such as tubocurarine and succinylcholine)

Please tell your doctor if you are taking, or have recently taken, any other medicines, including ones that are not prescribed for you.

Do not drive or use machines

if you experience any effect which may impair your ability to drive or use machines.

How Gentamicin Injection  is used

The dose of medicine given to you will depend on how serious the infection is, your age, body weight and how well your kidneys are working.

The medicine is usually injected into a muscle but may also be injected into a vein in some patients. If it is given into a vein, it can either be given as an injection or dissolved with, e.g. saline or 5% glucose in water and given as a slow injection via a drip (infusion). It will be given daily, with your dose usually divided into two or three separate doses.

As this medicine will be given to you whilst you are in hospital it is unlikely that you will be given too little or too much, however tell you doctor or pharmacist if you have any concerns.

The amount of gentamicin in your blood will be measured regularly to check that the correct blood levels have been achieved. Treatment with gentamicin may cause damage to hearing and also to kidney function. In some cases, your doctor may carry out blood tests to check your kidney function before and during treatment with gentamicin. Occasionally you may also be asked to take a hearing test to check the drug is not affecting your hearing.

Possible side-effects

Like all medicines gentamicin sulphate can have side-effects.

If any of the following happen, tell your doctor immediately:

severe allergic reaction – you may experience a sudden itchy rash (hives), swelling of the hands, feet, ankles, face, lips, mouth or throat (which may cause difficulty in swallowing or breathing), and you may feel you are going to faint.

This is a very serious side-effect. You may need urgent medical attention. This very serious side-effect is rare.

If you experience any of the following tell your doctor as soon as possible:

  • hearing problems (if you have this side-effect your doctor may need to change your dose or give you other treatments)
  • feeling or being sick
  • skin rash or development of raised coloured blotches which may be itchy
  • fever
  • sore throat
  • muscle weakness

Your doctor may also carry out blood tests to check for changes in your kidney function.

If you notice any side-effects not mentioned in this leaflet, please tell your doctor or pharmacist.

Storing Gentamicin Injection

Keep out of the reach of children.

The vials should not be stored above 25°C.

This medicine should not be used after the expiry date printed on the vial.

Serum levels should be monitored .  daily.

As with other aminoglycosides toxicity is related to serum concentration.

At serum levels more than 10 micrograms/ml the vestibular mechanism may be affected. Toxicity can be minimised by monitoring serum concentrations and it is advisable to check serum levels to confirm that peak levels (one hour) do not exceed 10 micrograms/ml and that trough levels (one hour before next injection) do not exceed 2 micrograms/ml. Evidence of toxicity requires adjustment of dosage or withdrawal of the drug.

Concurrent use of other neurotoxic and/or nephrotoxic drugs can increase the possibility of gentamicin toxicity.


As in the case of other aminoglycosides, toxicity is associated with serum levels above a critical value. In patients with normal renal function it is unlikely that toxic serum levels (in excess of 10 micrograms/ml) will be reached after administration of recommended doses. Where higher levels occur because of renal impairment, dosage should be reduced. In the event of an overdose or toxic reaction, peritoneal dialysis or haemodialysis will lower serum gentamicin levels.


Do not store above 25°C.

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