Gentamicin
Brand names Cidomycin, Garamycin, Genticin, Minims gentamicin.
Used in the following combined preparations None
General Information
Gentamicin is one of the aminoglycoside antibiotics. The injectable form is usually reserved for treatment, in hospital, of serious or complicated infections.
These include infections of the lung, urinary tract, bone, joint, and wound, as well as peritonitis, septicaemia, and meningitis.
This form is also used together with a penicillin for prevention and treatment of heart valve infections (endocarditis).
Also available as drops and ointment, gentamicin is commonly used to treat eye and ear infections. The ointment
may in some cases be prescribed for infected burns or ulcers. Resistance is a common problem following treatment with skin preparations.
Gentamicin given by injection can have serious adverse effects on the ears, which may lead to damage to the balance mechanism and deafness, and on the kidneys.
Courses of treatment are therefore limited to seven days when possible.
Treatment is monitored with particular care when high doses are needed or kidney function is poor.
Interactions
General note
A wide range of drugs increase the risk of hearing loss and/or kidney failure with gentamicin. Such drugs include frusemide and vancomycin.
Quick Reference
Drug group Aminoglycoside antibiotic
Overdose danger rating Low
Dependence rating Low
Prescription needed Yes
Available as generic Yes
Information for Users
Your drug prescription is tailored for you. Do not alter dosage without checking with your doctor.
How taken
Injection, cream, ointment, eye ointment, eye and ear drops.
Frequency and timing of doses
1 -3 x daily (injection); 3-4 x daily or as directed (skin preparations, eye and ear drops, eye ointments).
Adult dosage range
According to condition and response (injection); according to your doctor’s instructions (eye, ear, and skin preparations).
Onset of effect
Within 1-2 hours.
Duration of action
8-12 hours.
Diet advice
None.
Storage
Keep in closed container in a cool, dry place out of the reach of children.
Missed dose
Apply skin, eye, and ear preparations as soon as you remember.
Stopping the drug
Complete the full course. Even if you feel better, the original infection may still be present and may recur if treatment is stopped too soon.
Exceeding the dose
Although overdose by injection is dangerous, it is unlikely because treatment is carefully monitored.
For other preparations of the drug, an occasional unintentional extra dose is unlikely to be a cause for concern.
But if you notice any unusual symptoms, notify your doctor.
Special Precautions
Be sure to tell your doctor if:
You have a long-term kidney problem.
You have a hearing disorder.
You have myasthenia gravis.
You have Parkinson’s disease.
You have previously had an allergic reaction to aminoglycosides.
You are taking other medications.
Pregnancy
No evidence of risk with topical preparations. Injections are not prescribed, as they may cause hearing defects in the baby. Discuss with your doctor.
Breast-feeding
No evidence of risk with topical preparations. Given by injection, the drug may pass into the breast milk. Discuss with your doctor.
Infants and children
Reduced dose necessary for injections.
Over 60
Increased likelihood of adverse effects. Reduced dose may therefore be necessary.
Driving and hazardous work
No known problems from preparations for the skin, eye, or ear.
Alcohol
No known problems.
Possible Adverse Effects
Adverse effects are rare but those that occur with the injectable form of gentamicin may be serious.
Dizziness, loss of balance (vertigo), impaired hearing, and changes in the urine should be reported promptly.
The drug may be absorbed if the ointment or cream is applied to large areas, and could cause hearing loss.
Allergic reactions, including rash and itching, may occur with all preparations that contain gentamicin.
Prolonged Use
Not usually given for longer than 10 days. When given by injection, there is a risk of adverse effects on hearing and balance.
Monitoring Blood levels of the drug are usually checked if it is given by injection.
