Gentamicin 40mg/ml Inj, 20ml
WARNING: This drug may cause kidney, nerve, and hearing problems (like long-lasting hearing loss), even at normal doses. The risk may be higher if you already have kidney or hearing problems, you take higher doses, or you use this drug for a long time. The risk may be higher in older people, infants, or with dehydration. Hearing loss can happen even after this drug is stopped. If you already have kidney problems or hearing problems, tell your doctor. You may need to have hearing and kidney tests.Do not use this drug if you are taking or have recently taken any drugs that can cause nerve, kidney, or hearing problems. This may be drugs like amphotericin B, bacitracin, cephaloridine, cisplatin, colistin, cyclosporine, ethacrynic acid, furosemide, paromomycin, polymyxin B, vancomycin, viomycin, or other drugs like this one. There are many other drugs that can do this. Ask your doctor or pharmacist if you are not sure.Muscle problems (muscle weakness) and severe breathing problems have happened with drugs like this one. The risk is higher in people who already have nerve or muscle problems like myasthenia gravis. The risk is also higher in people who are getting other drugs like those that are used to put you to sleep or to relax muscles. If you have questions, talk with the doctor.This drug may cause harm to the unborn baby if you take it while you are pregnant. If you are pregnant or you get pregnant while taking this drug, call your doctor right away. @ COMMON USES: It is used to treat bacterial infections.
Drug Class
Antibiotic, Aminoglycoside
Pharmacologic Class
Bactericidal protein synthesis inhibitor
Pregnancy Category
Category D
FDA Approved
Jun 1966
DEA Schedule
Not Controlled
Overview
What is this medicine?
Gentamicin is an antibiotic used to treat serious bacterial infections, especially those caused by certain types of bacteria that are resistant to other drugs. It works by stopping the growth of these bacteria. It is given as an injection, usually into a vein or muscle.
How to Use This Medicine
Taking Your Medication
To use this medication correctly, follow your doctor's instructions and read all the information provided. It is essential to follow the dosage instructions carefully. This medication is administered either as an injection into a muscle or as an infusion into a vein over a specified period.
Staying Hydrated
Drink plenty of non-caffeinated fluids, unless your doctor advises you to limit your fluid intake.
Storing and Disposing of Your Medication
If you need to store this medication at home, consult with your doctor, nurse, or pharmacist for guidance on proper storage.
Missing a Dose
If you miss a dose, contact your doctor to determine the best course of action.
To use this medication correctly, follow your doctor's instructions and read all the information provided. It is essential to follow the dosage instructions carefully. This medication is administered either as an injection into a muscle or as an infusion into a vein over a specified period.
Staying Hydrated
Drink plenty of non-caffeinated fluids, unless your doctor advises you to limit your fluid intake.
Storing and Disposing of Your Medication
If you need to store this medication at home, consult with your doctor, nurse, or pharmacist for guidance on proper storage.
Missing a Dose
If you miss a dose, contact your doctor to determine the best course of action.
Lifestyle & Tips
- Report any changes in hearing (ringing in ears, dizziness, difficulty hearing) or balance immediately.
- Report any signs of kidney problems (decreased urination, swelling in legs/feet, unusual tiredness).
- Stay well-hydrated unless otherwise instructed by your doctor.
- Avoid taking other medications that can harm your kidneys or ears without consulting your doctor.
Available Forms & Alternatives
Available Strengths:
- Gentamicin 0.3% Ophth Soln 5ml
- Gentamicin 0.3% Ophth Solution
- Gentamicin 40mg/ml Inj, 2ml
- Gentamicin 0.1% Cream 15gm
- Gentamicin 40mg/ml Inj, 20ml
- Gentamicin 0.1% Cream 30gm
- Gentamicin Pf Ped 10mg/ml Inj, 2ml
- Gentamicin 0.1% Oint 15gm (topical)
- Gentamicin 0.1% Oint 30gm (topical)
- Gentamicin 80mg/ml Inj, 2ml
Dosing & Administration
Adult Dosing
Standard Dose:
Conventional Dosing: 3-5 mg/kg/day IV/IM divided into 3 doses (q8h). Extended-Interval Dosing: 5-7 mg/kg IV/IM once daily.
Dose Range:
3 - 7 mg
Condition-Specific Dosing:
severeInfections:
5 mg/kg/day divided q8h or 7 mg/kg once daily
urinaryTractInfections:
3 mg/kg/day divided q8h or 5 mg/kg once daily
endocarditisSynergy:
1 mg/kg IV/IM q8h (in combination with beta-lactam)
Pediatric Dosing
Neonatal:
Premature or full-term <1 week: 2.5 mg/kg/dose IV/IM q12-24h (adjust interval based on gestational/postnatal age).
Infant:
1 week to 1 month: 2.5 mg/kg/dose IV/IM q8-12h.
Child:
1 month to 12 years: 2-2.5 mg/kg/dose IV/IM q8h or 5-7.5 mg/kg IV/IM once daily.
Adolescent:
12 to 18 years: 2-2.5 mg/kg/dose IV/IM q8h or 5-7 mg/kg IV/IM once daily.
Dose Adjustments
Renal Impairment:
Mild:
CrCl 60-90 mL/min: Administer 60-90% of dose or extend interval to q12h.
Moderate:
CrCl 30-59 mL/min: Administer 30-50% of dose or extend interval to q24h.
Severe:
CrCl <30 mL/min: Administer 20-30% of dose or extend interval to q48h or longer.
Dialysis:
Hemodialysis: Administer 1-1.7 mg/kg post-dialysis. Peritoneal Dialysis: 0.5-1 mg/kg q24h or 4-8 mg/L in dialysate.
Hepatic Impairment:
Mild:
No specific adjustment needed.
Moderate:
No specific adjustment needed.
Severe:
No specific adjustment needed. Monitor renal function closely as hepatic impairment can indirectly affect renal perfusion.
Pharmacology
Mechanism of Action
Gentamicin is an aminoglycoside antibiotic that binds irreversibly to the 30S ribosomal subunit of susceptible bacteria, leading to misreading of mRNA and inhibition of bacterial protein synthesis. This results in the production of non-functional proteins and ultimately bacterial cell death (bactericidal effect).
Pharmacokinetics
Absorption:
Bioavailability:
Poor (<1%) orally; nearly 100% via IM/IV
Tmax:
IM: 30-90 minutes; IV: End of infusion
FoodEffect:
Not applicable (parenteral administration)
Distribution:
Vd:
0.2-0.3 L/kg (increases in ascites, edema, burns; decreases in dehydration)
ProteinBinding:
Low (0-30%)
CnssPenetration:
Limited (increases with meningeal inflammation)
Elimination:
HalfLife:
2-4 hours (normal renal function); significantly prolonged in renal impairment
Clearance:
Primarily renal glomerular filtration; directly proportional to creatinine clearance
ExcretionRoute:
Renal (unchanged drug)
Unchanged:
>90%
Pharmacodynamics
OnsetOfAction:
Rapid (within minutes of IV administration)
PeakEffect:
Within 30-90 minutes post-IM injection or immediately post-IV infusion
DurationOfAction:
Concentration-dependent killing with post-antibiotic effect (PAE) allowing for extended-interval dosing.
Safety & Warnings
BLACK BOX WARNING
NEPHROTOXICITY: Aminoglycosides can cause nephrotoxicity. The risk is greater in patients with impaired renal function, those receiving high doses or prolonged therapy, the elderly, and those receiving concomitant nephrotoxic drugs. OTOTOXICITY: Aminoglycosides can cause ototoxicity (vestibular and auditory). The risk is greater in patients with impaired renal function, those receiving high doses or prolonged therapy, the elderly, and those receiving concomitant ototoxic drugs. Ototoxicity is often irreversible. NEUROMUSCULAR BLOCKADE: Aminoglycosides can cause neuromuscular blockade and respiratory paralysis, especially when administered rapidly or to patients with neuromuscular disorders (e.g., myasthenia gravis).
Side Effects
Serious Side Effects: Seek Medical Help Immediately
Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If you notice any of the following symptoms, contact your doctor or seek medical attention right away:
Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin with or without fever
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Signs of kidney problems, including:
+ Inability to pass urine
+ Changes in urine output
+ Blood in the urine
+ Sudden weight gain
Signs of high or low blood pressure, such as:
+ Severe headache
+ Dizziness
+ Fainting
+ Changes in vision
Dizziness or fainting
Balance problems
Ringing in the ears, hearing loss, or other changes in hearing
Muscle weakness
New or worsening breathing difficulties
Abnormal burning, numbness, or tingling sensations
Twitching
Seizures
Confusion
Extreme fatigue or weakness
Depression
Changes in vision
Fever
Other Possible Side Effects
Like all medications, this drug can cause side effects. While many people may not experience any side effects or only minor ones, it's essential to discuss any concerns with your doctor. If you experience any of the following side effects or any other unusual symptoms, contact your doctor for advice:
Decreased appetite
Weight loss
Headache
Upset stomach or vomiting
Excessive saliva production
Mouth irritation or sores
Hair loss
Joint pain
This is not an exhaustive list of possible side effects. If you have questions or concerns, consult your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If you notice any of the following symptoms, contact your doctor or seek medical attention right away:
Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin with or without fever
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Signs of kidney problems, including:
+ Inability to pass urine
+ Changes in urine output
+ Blood in the urine
+ Sudden weight gain
Signs of high or low blood pressure, such as:
+ Severe headache
+ Dizziness
+ Fainting
+ Changes in vision
Dizziness or fainting
Balance problems
Ringing in the ears, hearing loss, or other changes in hearing
Muscle weakness
New or worsening breathing difficulties
Abnormal burning, numbness, or tingling sensations
Twitching
Seizures
Confusion
Extreme fatigue or weakness
Depression
Changes in vision
Fever
Other Possible Side Effects
Like all medications, this drug can cause side effects. While many people may not experience any side effects or only minor ones, it's essential to discuss any concerns with your doctor. If you experience any of the following side effects or any other unusual symptoms, contact your doctor for advice:
Decreased appetite
Weight loss
Headache
Upset stomach or vomiting
Excessive saliva production
Mouth irritation or sores
Hair loss
Joint pain
This is not an exhaustive list of possible side effects. If you have questions or concerns, consult your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Seek Immediate Medical Attention If You Experience:
- Ringing in the ears (tinnitus)
- Hearing loss or difficulty hearing
- Dizziness or vertigo
- Unsteadiness or difficulty with balance
- Decreased urine output
- Swelling in the ankles, feet, or hands
- Unusual tiredness or weakness
- Muscle weakness or difficulty breathing
- Rash, itching, or hives
Before Using This Medicine
Before Taking This Medication: Important Information to Share with Your Doctor
It is essential to inform your doctor about the following:
Any allergies you have, including allergies to this medication, its components, or other substances, such as foods or drugs. Be sure to describe the symptoms you experienced as a result of the allergy.
All medications you are currently taking, including prescription and over-the-counter (OTC) drugs, natural products, and vitamins. This information will help your doctor and pharmacist assess potential interactions between this medication and other substances you are taking.
* Any existing health problems, as this medication may interact with certain conditions.
To ensure your safety, it is crucial to verify that it is safe to take this medication with all your current medications and health conditions. Do not initiate, discontinue, or modify the dosage of any medication without first consulting your doctor.
It is essential to inform your doctor about the following:
Any allergies you have, including allergies to this medication, its components, or other substances, such as foods or drugs. Be sure to describe the symptoms you experienced as a result of the allergy.
All medications you are currently taking, including prescription and over-the-counter (OTC) drugs, natural products, and vitamins. This information will help your doctor and pharmacist assess potential interactions between this medication and other substances you are taking.
* Any existing health problems, as this medication may interact with certain conditions.
To ensure your safety, it is crucial to verify that it is safe to take this medication with all your current medications and health conditions. Do not initiate, discontinue, or modify the dosage of any medication without first consulting your doctor.
Precautions & Cautions
It is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are taking this medication. If you have a known allergy to sulfites, consult with your doctor, as some formulations of this drug may contain sulfites.
Regular monitoring of your blood work, hearing, and other laboratory tests is crucial, as directed by your doctor. Do not exceed the recommended duration of treatment, as this may increase the risk of developing a secondary infection.
If you are 65 years or older, exercise caution when using this medication, as you may be more susceptible to experiencing side effects. Additionally, if you are breastfeeding, consult with your doctor to discuss potential risks to your baby and determine the best course of action.
Regular monitoring of your blood work, hearing, and other laboratory tests is crucial, as directed by your doctor. Do not exceed the recommended duration of treatment, as this may increase the risk of developing a secondary infection.
If you are 65 years or older, exercise caution when using this medication, as you may be more susceptible to experiencing side effects. Additionally, if you are breastfeeding, consult with your doctor to discuss potential risks to your baby and determine the best course of action.
Overdose Information
Overdose Symptoms:
- Severe kidney damage (renal failure)
- Severe hearing loss or deafness
- Severe dizziness or vertigo
- Neuromuscular blockade (muscle weakness, respiratory depression, paralysis)
- Nausea, vomiting
What to Do:
Seek immediate medical attention. Treatment may involve hemodialysis to remove the drug from the body, supportive care for respiratory depression (e.g., mechanical ventilation), and management of electrolyte imbalances. Call 1-800-222-1222 (Poison Control).
Drug Interactions
Major Interactions
- Nephrotoxic drugs (e.g., amphotericin B, cisplatin, cyclosporine, NSAIDs, vancomycin, loop diuretics like furosemide, tacrolimus): Increased risk of nephrotoxicity.
- Ototoxic drugs (e.g., loop diuretics, cisplatin, vancomycin, erythromycin, ethacrynic acid): Increased risk of ototoxicity.
- Neuromuscular blocking agents (e.g., succinylcholine, rocuronium, vecuronium): Potentiation of neuromuscular blockade, leading to respiratory depression/paralysis.
Moderate Interactions
- Cephalosporins (e.g., cephalothin): May increase risk of nephrotoxicity (especially with high doses or pre-existing renal impairment).
- Polymyxins (e.g., colistin): Increased risk of nephrotoxicity and neuromuscular blockade.
- Oral anticoagulants (e.g., warfarin): May potentiate anticoagulant effect (rare, possibly due to gut flora alteration).
Minor Interactions
- Not available
Monitoring
Baseline Monitoring
Renal function (Serum Creatinine, BUN, CrCl)
Rationale: Gentamicin is renally eliminated and nephrotoxic; baseline function is crucial for dosing and monitoring for toxicity.
Timing: Prior to first dose
Audiometry/Vestibular function
Rationale: Baseline assessment for ototoxicity, especially in patients at higher risk (e.g., prolonged therapy, pre-existing hearing loss).
Timing: Prior to therapy for high-risk patients or prolonged courses
Electrolytes (Magnesium, Potassium, Calcium)
Rationale: Aminoglycosides can cause electrolyte disturbances, and pre-existing imbalances can worsen toxicity.
Timing: Prior to first dose
Weight
Rationale: Dosing is weight-based.
Timing: Prior to first dose
Routine Monitoring
Serum Gentamicin levels (Peak and Trough)
Frequency: Conventional: Trough before 3rd or 4th dose, Peak 30 min after end of infusion. Extended-interval: Random level 6-14 hours after dose.
Target: Conventional: Peak 4-10 mcg/mL, Trough <2 mcg/mL. Extended-interval: Nomogram-guided (e.g., Hartford nomogram).
Action Threshold: Trough >2 mcg/mL (conventional) or levels outside nomogram range (extended-interval) indicate need for dose adjustment or interval extension.
Renal function (Serum Creatinine, BUN)
Frequency: Daily or every 2-3 days, especially in patients with unstable renal function or concomitant nephrotoxic drugs.
Target: Stable or improving
Action Threshold: Increase in serum creatinine >0.5 mg/dL or >25% from baseline, or oliguria, indicates potential nephrotoxicity and requires dose adjustment or discontinuation.
Urine output
Frequency: Daily
Target: >0.5 mL/kg/hr
Action Threshold: Significant decrease in urine output.
Electrolytes (Magnesium, Potassium, Calcium)
Frequency: Weekly or as clinically indicated.
Target: Within normal limits
Action Threshold: Hypomagnesemia, hypokalemia, hypocalcemia requiring supplementation.
Symptom Monitoring
- Hearing loss (tinnitus, high-frequency hearing loss, difficulty understanding speech)
- Vestibular dysfunction (dizziness, vertigo, ataxia, nystagmus)
- Renal impairment (decreased urine output, edema, fatigue, nausea)
- Neuromuscular blockade (muscle weakness, respiratory depression)
- Hypersensitivity reactions (rash, itching, swelling, difficulty breathing)
Special Patient Groups
Pregnancy
Category D. Gentamicin crosses the placenta and can cause fetal harm, including irreversible congenital bilateral deafness and renal toxicity. Use only if the potential benefit justifies the potential risk to the fetus.
Trimester-Specific Risks:
First Trimester:
Potential for teratogenicity, though specific defects not well-defined beyond ototoxicity.
Second Trimester:
Risk of fetal ototoxicity (irreversible bilateral deafness) and nephrotoxicity.
Third Trimester:
Highest risk of fetal ototoxicity and nephrotoxicity due to increased fetal renal function and drug accumulation.
Lactation
L3 (Moderately Safe). Gentamicin is excreted into breast milk in small amounts. Oral absorption by the infant is poor, so systemic effects are unlikely. However, monitor breastfed infants for diarrhea, candidiasis, and potential effects on gut flora. Consider alternative if infant is premature or has impaired renal function.
Infant Risk:
Low risk of systemic effects due to poor oral absorption. Potential for alteration of gut flora, diarrhea, or candidiasis.
Pediatric Use
Dosing must be carefully calculated based on age, weight, and renal function. Neonates and infants have immature renal function, requiring longer dosing intervals. Close monitoring of serum levels and renal function is crucial due to increased susceptibility to nephrotoxicity and ototoxicity.
Geriatric Use
Elderly patients are at increased risk for nephrotoxicity and ototoxicity due to age-related decline in renal function and pre-existing hearing impairment. Dose adjustment based on creatinine clearance is essential. Close monitoring of renal function and serum drug levels is recommended.
Clinical Information
Clinical Pearls
- Always obtain baseline renal function and weight before initiating gentamicin.
- Therapeutic drug monitoring (TDM) with peak and trough levels (for conventional dosing) or random levels (for extended-interval dosing) is critical to optimize efficacy and minimize toxicity.
- Hydration is important to minimize nephrotoxicity.
- Extended-interval (once-daily) dosing is often preferred for most indications due to reduced nephrotoxicity and comparable efficacy, but is contraindicated in certain conditions (e.g., endocarditis, ascites, burns, pregnancy, severe renal impairment).
- Be vigilant for signs of ototoxicity (tinnitus, hearing loss, dizziness) and nephrotoxicity (rising creatinine, decreased urine output). These toxicities can be irreversible.
- Avoid concomitant use with other nephrotoxic or ototoxic drugs whenever possible.
Alternative Therapies
- Other aminoglycosides (e.g., tobramycin, amikacin, streptomycin)
- Fluoroquinolones (e.g., ciprofloxacin, levofloxacin)
- Third/Fourth-generation cephalosporins (e.g., ceftazidime, cefepime)
- Carbapenems (e.g., meropenem, imipenem)
- Polymyxins (e.g., colistin, polymyxin B) for multi-drug resistant Gram-negative infections
Cost & Coverage
Average Cost:
Varies widely, typically $10-$50 per 20ml vial (40mg/ml) per 20ml vial
Generic Available:
Yes
Insurance Coverage:
Tier 1 (Generic)
General Drug Facts
If your symptoms or health problems persist or worsen, it is essential to contact your doctor promptly. To ensure safe use, never share your medication with others, and do not take medication prescribed for someone else. Store all medications in a secure location, out of reach of children and pets, to prevent accidental ingestion. Dispose of unused or expired medications properly. Unless instructed otherwise, do not flush medications down the toilet or pour them down the drain. If you are unsure about the correct disposal method, consult your pharmacist, who can also inform you about potential drug take-back programs in your area. Some medications may come with an additional patient information leaflet, which your pharmacist can provide. If you have any questions or concerns about your medication, discuss them with your doctor, nurse, pharmacist, or other healthcare provider. In the event of a suspected overdose, immediately contact your local poison control center or seek emergency medical attention. Be prepared to provide information about the medication taken, the amount, and the time of ingestion.