Pronunciation:

jen-ta-MYE-sin

Brand Names:

• Garamycin
• Genoptic
• Genoptic S.O.P.
• Gentacidin
• Gentafair
• Gentak
• Gentasol
• Ocu-Mycin

Dosage Forms:

• Solution
• Ointment

Warnings:

Patients treated with aminoglycosides should be under close clinical observation because of the potential toxicity associated with their use.

As with other aminoglycosides, gentamicin sulfate injection is potentially nephrotoxic. The risk of nephrotoxicity is greater in patients with impaired renal function and in those who receive high dosage or prolonged therapy.

Neurotoxicity manifested by ototoxicity, both vestibular and auditory, can occur in patients treated with gentamicin sulfate injection primarily in those with pre-existing renal damage and in patients with normal renal function treated with higher doses and/or for longer periods than recommended. Aminoglycoside-induced ototoxicity is usually irreversible. Other manifestations of neurotoxicity may include numbness, skin tingling, muscle twitching and convulsions.

Renal and eighth cranial nerve function should be closely monitored, especially in patients with known or suspected reduced renal function at onset of therapy and also in those whose renal function is initially normal but who develop signs of renal dysfunction during therapy. Urine should be examined for decreased specific gravity, increased excretion of protein, and the presence of cells or casts. Blood urea nitrogen, serum creatinine, or creatinine clearance should be determined periodically. When feasible, it is recommended that serial audiograms be obtained in patients old enough to be tested, particularly high-risk patients. Evidence of ototoxicity (dizziness, vertigo, tinnitus, roaring in the ears or hearing loss) or nephrotoxicity requires dosage adjustment or discontinuance of the drug. As with the other aminoglycosides, on rare occasions changes in renal and eighth cranial nerve function may not become manifest until soon after completion of therapy.

Serum concentrations of aminoglycosides should be monitored when feasible to assure adequate levels and to avoid potentially toxic levels. When monitoring gentamicin peak concentrations, dosage should be adjusted so that prolonged levels above 12 mcg/mL are avoided. When monitoring gentamicin trough concentrations, dosage should be adjusted so that levels above 2 mcg/mL are avoided. Excessive peak and/or trough serum concentrations of aminoglycosides may increase the risk of renal and eighth cranial nerve toxicity. In the event of overdose or toxic reactions, hemodialysis may aid in the removal of gentamicin from the blood, especially if renal function is, or becomes, compromised. The rate of removal of gentamicin is considerably lower by peritoneal dialysis than it is by hemodialysis.

Concurrent and/or sequential systemic or topical use of other potentially neurotoxic and/or nephrotoxic drugs, such as cisplatin, cephaloridine, kanamycin, amikacin, neomycin, polymyxin B, colistin, paromomycin, streptomycin, tobramycin, vancomycin, and viomycin, should be avoided.

Other factors which may increase patient risk to toxicity are advanced age and dehydration.

The concurrent use of gentamicin with potent diuretics, such as ethacrynic acid or furosemide, should be avoided, since certain diuretics by themselves may cause ototoxicity. In addition, when administered intravenously, diuretics may enhance aminoglycoside toxicity by altering the antibiotic concentration in serum and tissue.

Aminoglycosides can cause fetal harm when administered to a pregnant woman .

Therapy has been associated with potential neurotoxicity, ototoxicity, and nephrotoxicity. Patients with impaired renal function, advanced age, dehydration, and those who receive high dosage or prolonged therapy are at an increased risk of toxicity. Monitor renal and auditory function during therapy and discontinue therapy or adjust dose if there is evidence of ototoxicity or nephrotoxicity. Aminoglycoside-induced ototoxicity is usually irreversible. Serum concentrations of aminoglycosides should be monitored when feasible to assure adequate levels and to avoid potentially toxic levels. Concurrent use of other potentially neurotoxic or nephrotoxic agents, or potent diuretics should be avoided. Aminoglycosides can cause fetal harm when administered to a pregnant woman .

Classifications:

Therapeutic—

Antibiotic

Chemical—

Aminoglycoside

Uses of This Medicine:

Gentamicin belongs to the family of medicines called antibiotics. Gentamicin ophthalmic preparations are used to treat infections of the eye.

Gentamicin is available only with your doctor's prescription.

Before Using This Medicine:

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For this medicine, the following should be considered:

Allergies—

Tell your doctor if you have ever had any unusual or allergic reaction to this medicine or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.

Children—

There is no specific information comparing use of this medicine in babies up to one month of age with use in other age groups.

Older adults—

Many medicines have not been studied specifically in older people. Therefore, it may not be known whether they work exactly the same way they do in younger adults or if they cause different side effects or problems in older people. There is no specific information comparing use of this medicine in the elderly with use in other age groups.

Pregnancy—

	Pregnancy Category	Explanation
All Trimesters	D	Studies in pregnant women have demonstrated a risk to the fetus. However, the benefits of therapy in a life threatening situation or a serious disease, may outweigh the potential risk.

Breast-feeding—

Studies in women suggest that this medication poses minimal risk to the infant when used during breastfeeding.

Other medicines—

Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

• Alcuronium
• Atracurium
• Cidofovir
• Cisatracurium
• Decamethonium
• Doxacurium
• Fazadinium
• Gallamine
• Hexafluorenium
• Lysine
• Metocurine
• Mivacurium
• Pancuronium
• Pipecuronium
• Rapacuronium
• Rocuronium
• Succinylcholine
• Tacrolimus
• Tubocurarine
• Vancomycin
• Vecuronium

Other interactions—

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.

Proper Use of This Medicine:

For patients using the eye drop form of this medicine:

• The bottle is only partially full to provide proper drop control.
• To use:
  • First, wash your hands. Tilt the head back and with the index finger of one hand, press gently on the skin just beneath the lower eyelid and pull the lower eyelid away from the eye to make a space. Drop the medicine into this space. Let go of the eyelid and gently close the eyes. Do not blink. Keep the eyes closed for 1 or 2 minutes, to allow the medicine to come into contact with the infection.
• If you think you did not get the drop of medicine into your eye properly, use another drop.
• Avoid wearing contact lenses during treatment
• To keep the medicine as germ-free as possible, do not touch the applicator tip to any surface (including the eye). Also, keep the container tightly closed.

For patients using the eye ointment form of this medicine:

• First, wash your hands. Tilt the head back and with the index finger of one hand, press gently on the skin just beneath the lower eyelid and pull the lower eyelid away from the eye to make a space. Squeeze a thin strip of ointment into this space. A 1-cm (approximately ?-inch) strip of ointment is usually enough unless otherwise directed by your doctor. Let go of the eyelid and gently close the eyes and keep them closed for 1 or 2 minutes, to allow the medicine to come into contact with the infection.
• To keep the medicine as germ-free as possible, do not touch the applicator tip to any surface (including the eye). After using gentamicin eye ointment, wipe the tip of the ointment tube with a clean tissue and keep the tube tightly closed.

To help clear up your infection completely, keep using this medicine for the full time of treatment, even if your symptoms have disappeared. Do not miss any doses.

Dosing—

The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

• For ophthalmic ointment dosage form:
  • For eye infections:
    • Adults and children—Use every eight to twelve hours.
• For ophthalmic solution (eye drops) dosage form:
  • For mild to moderate eye infections:
    • Adults and children—One to two drops every four hours.
  • For severe eye infections:
    • Adults and children—One to two drops as often as once every hour as directed by your doctor.

Missed dose—

If you miss a dose of this medicine, apply it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule.

Storage—

Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.

Keep out of the reach of children.

Do not keep outdated medicine or medicine no longer needed.

Precautions While Using This Medicine:

If your symptoms do not improve within a few days, or if they become worse, check with your doctor.

Side Effects of This Medicine:

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur:

Less common

Itching, redness, swelling, or other sign of irritation not present before use of this medicine

redness of eye, eyelid, or inner lining of eyelid

Rare

Black, tarry stools; blood in urine or stools; or unusual bleeding or swelling

blurred vision, eye pain, sensitivity to light, and/or tearing

seeing, hearing, or feeling things that are not there

hallucinations

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

Less common

Burning or stinging

After application, eye ointments usually cause your vision to blur for a few minutes.

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.