Indeed, when we speak of gentamicin we are referring more properly to a set of homologs of gentamicin (gentamicin C1, C1a and C2) that are structurally very similar.
Gentamicin is a compound of natural origin, obtained from Micromonospora purpurea and other soil microorganisms similar to the latter.
This active ingredient was one of the first antibiotics to be active against infections from Pseudomonas aeruginosa, a pathogenic, opportunistic and highly virulent bacterium that can cause lung, skin (often found in burns), ear, eye and urinary tract infections.
Gentamicin has a rather broad spectrum of action and is commercially available in medicinal products suitable for parenteral, cutaneous and ocular administration.
Medicines containing gentamicin for cutaneous and ocular use are usually sold upon presentation of a specific repeatable medical prescription and their cost is fully borne by the citizen (class C drugs). As for parenteral medicines based on gentamicin, on the other hand, some of them can be purchased on presentation of a medical prescription, while others are for hospital use (OSP).
The active ingredient is also used in the veterinary field in specific medicines dedicated to this type of use.
Note: There are many medicines on the market in the form of skin creams containing gentamicin in combination with betamethasone (a corticosteroid drug).For more information on this, we recommend reading the dedicated article: Gentamicin and Betamethasone.
Examples of Medicines containing Gentamicin
- Betacream®
- Ciclozinil®
- Citrizan Antibiotico Gel® (in association with catalase)
- Fidagenbeta® (in combination with betamethasone)
- Gentalyn®
- Gentalyn Beta® (in association with Betamethasone)
- Gentamicin B. Braun®
- Gentamicin Hexal®
- Genatmicin Mylan Generics®
- Genticol®
- Ribomicin®
- Sterozinil® (in combination with betamethasone)
Additionally, gentamicin can also be used in polymer matrices for orthopedic surgery to prevent joint infections.
. If this occurs, treatment with the antibiotic should be discontinued and appropriate therapy for superinfection initiated.
When gentamicin is administered parenterally over a long period or in high doses, it would be good to regularly monitor kidney and liver function and serum electrolytes.
Gentamicin is nephrotoxic (toxic to the kidneys). The risk of developing renal toxicity increases in patients with pre-existing renal disease and in patients receiving high doses of the drug for long periods.
Caution should be exercised when administering gentamicin to patients with myasthenia gravis, Parkinson's disease or infantile botulism, as the antibiotic can aggravate the muscle weakness caused by these drugs.
Cases of diarrhea and pseudomembranous colitis have been reported following treatment with gentamicin combined with other antibiotics. If severe diarrhea and / or bloody diarrhea occurs, treatment with gentamicin should be stopped immediately.
Please note
- Parenteral administration of gentamicin may cause side effects that affect the ability to drive and / or use machines, therefore great caution should be exercised.
- For more information on warnings and precautions for the use of gentamicin, carefully read the package leaflet of the medicine to be taken.
Concomitant or subsequent administration of gentamicin - especially for ocular and parenteral use - and other nephrotoxic or ototoxic drugs should be avoided. Among these drugs we mention:
- Cisplatin, methotrexate and ifosfamide, anticancer drugs;
- Colistin, an antibiotic;
- Streptomycin, kanamycin, tobramycin, paromomycin, neomycin and amikacin, other aminoglycosides;
- Aciclovir, ganciclovir, tenovir and other antiviral drugs;
- Amphotericin B, an antifungal;
- Immunosuppressive drugs such as cyclosporine;
- Iodized contrast media;
- Powerful diuretics, such as ethacrynic acid or furosemide;
- Some cephalosporins.
Incompatibilities with some beta-lactam antibiotics (such as some types of penicillins or cephalosporins) have been shown. In fact, if these drugs are administered concomitantly with gentamicin, there is an inactivation of both antibiotics. Therefore - if combination therapy is required - the two drugs should not be mixed in the same solution and should be administered in two different tissue compartments (for example, if gentamicin is injected into an arm, beta-lactam should be injected into the "other arm).
Please note
The above are just some of the possible drug interactions of gentamicin.
Also in this case, therefore, to know all the interactions between a given medicinal product containing gentamicin and other drugs, it is necessary to read the package leaflet carefully. It should also be remembered that when gentamicin is combined with betamethasone, the possible interactions given by this last active ingredient must also be taken into consideration when using the medicine.
If in doubt, consult your doctor.
, acute kidney failure and can lead to high levels of phosphates and amino acids in the urine.
Allergic reactions
Gentamicin can cause drug fever and hypersensitivity reactions, sometimes even severe ones.
Pathologies of metabolism and nutrition
Gentamicin treatment can cause:
- Decrease in blood levels of calcium, magnesium and potassium;
- Loss of appetite
- Weight loss;
- Decrease in blood levels of phosphate.
Nervous system disorders
Gentamicin therapy can cause:
- Damage to peripheral nerves
- Loss of sensation
- Organic brain syndrome;
- Headache;
- Dizziness
- Balance disorders;
- Convulsions.
Psychiatric disorders
Gentamicin treatment can cause mental depression, confusion and hallucinations.
Ear and labyrinth disorders
Gentamicin therapy can cause:
- Impairment of the acoustic nerve;
- Loss of hearing;
- Tinnitus;
- Dizziness;
- Ménière's syndrome.
Gastrointestinal disorders
Gentamicin treatment can cause nausea, vomiting, increased salivation and inflammation of the oral cavity.
Hepatobiliary disorders
Gentamicin therapy can cause an increase in blood levels of liver enzymes and bilirubin.
Skin and subcutaneous tissue disorders
Gentamicin treatment can result in:
- Allergic skin rash;
- Itching;
- Redness of the skin;
- Hair loss
- Erythema multiforme;
- Stevens-Johnson Syndrome;
- Toxic epidermal necrolysis.
Other side effects
Other adverse effects that may occur during gentamicin therapy are:
- Superinfections with resistant bacteria or fungi;
- Eosinophilia, ie the increase in the number of eosinophils in the bloodstream;
- Hypotension or hypertension;
- Myalgia;
- Tremors
- Fever;
- Pain at the injection site.
Gentamicin overdose
Cases of gentamicin overdose have only been reported during parenteral administration of the drug. In this case, hemodialysis can be useful to quickly remove excess gentamicin from the plasma.
However, no cases of overdose have been reported during topical or ocular administration of gentamicin.
The synthesis of proteins inside bacterial cells occurs thanks to organelles called ribosomes. These organelles are made up of ribosomal RNA and proteins associated with each other to form two subunits: the 30S subunit and the 50S subunit.
The task of the ribosome is to translate the messenger RNA coming from the cell nucleus and to synthesize the proteins for which it encodes.
Gentamicin - like all aminoglycosides - is capable of binding to the 30S ribosomal subunit and of:
- Preventing messenger RNA from binding to the ribosome;
- By inducing a "misread" of the "messenger RNA" by doing so, the ribosome synthesizes "wrong" proteins called nonsense proteins.
Some of these nonsense proteins "insert themselves into the bacterial cell membrane altering its permeability. The alteration of the permeability of the membrane allows the entry of additional antibiotic into the same cell, thus causing a total block of protein synthesis."
All this causes severe damage to the bacterial cell which eventually dies.
The dosage of gentamicin must be established by the physician according to the type and severity of the infection to be treated and according to the weight, age and health conditions of each individual patient.
Below are some indications on the doses of gentamicin usually administered. In any case, it is always good to follow the instructions provided by the doctor and reported on the package leaflet of the medicine to be used.
Intramuscular or intravenous administration
In adults, adolescents and children, the dose of gentamicin usually administered is 3-6 mg / kg of body weight, to be administered as a single dose or in two divided doses.
In infants, the daily dose of gentamicin is 4-7 mg / kg of body weight, to be administered as a single dose.
In obese patients, the calculation of the amount of gentamicin to be administered should be done based on their theoretical body weight and not based on actual body weight.
Usually, the treatment lasts from seven to ten days, but the doctor may decide to extend it.
In patients with impaired renal function and in adult patients with renal insufficiency and undergoing hemodialysis, lower doses of gentamicin will be administered than those usually used.
Topical administration
It is recommended to apply the gentamicin-based cream or ointment at least 3-4 times a day, until improvement is achieved. Thereafter, the frequency of applications can be reduced to 1-2 times over a 24 hour period.
Ocular administration
It is recommended to instill one or two drops of eye drops into the conjunctival fornix 3-4 times a day or as prescribed by the doctor. In the case of very serious infections, the doctor may decide to increase the frequency of administration.
The ophthalmic ointment should be applied 3-4 times a day.
If eye drops were also prescribed in conjunction with the ointment, then the ointment can be used in a single evening application.
Cases of irreversible bilateral congenital deafness have occurred in some infants whose mothers injected gentamicin during pregnancy. Therefore, parenteral use of gentamicin is not indicated during pregnancy.
Gentamicin is excreted in breast milk, therefore breastfeeding mothers, before taking the drug, should seek advice from the doctor who will decide whether to stop breastfeeding.
In any case, pregnant women and mothers who are breastfeeding, before taking gentamicin in any pharmaceutical form (including through the eye and skin) should ask their doctor or gynecologist for advice.
