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Neomycin vs Gentamicin
Introduction
For patients with bacterial infections, certain drugs that inhibit the growth of bacteria or destroy them can help in controlling the infection and managing symptoms. Neomycin and gentamicin are two such antibiotics that are often prescribed for bacterial infections. The drugs target different types of bacteria, but both have bactericidal (bacteria-killing) effects that are useful for treating various infections. Neomycin is a broad-spectrum antibiotic affecting a wide variety of gram-negative and gram-positive bacteria, and is often used topically for skin or eye infections or orally as a preoperative bowel antiseptic. On the other hand, gentamicin is an aminoglycoside antibiotic that primarily affects gram-negative bacteria including Pseudomonas, Proteus, Escherichia coli (E. coli), and Klebsiella pneumoniae, among others. Gentamicin is typically administered through injection for serious systemic infections.
What is Neomycin?
Neomycin (sold under several brand names such as Mycifrandin, Neo-Fradin, Neo-Tab) is an antibiotic belonging to the aminoglycoside class, and was first approved by the FDA in 1949. Neomycin works by interfering with bacterial protein synthesis, effectively “trapping” bacteria and preventing them from growing and multiplying. It is primarily used for infections of the gastrointestinal tract, skin, eye, or ear. Neomycin has a selective effect on gram-negative bacteria, with only a minor effect on gram-positive bacteria.
Gentamicin (sold as Garamycin among other brand names) is another member of the aminoglycoside class of antibiotics. Like neomycin, it also inhibits bacterial growth by disrupting their protein synthesis. However, gentamicin has broader coverage than neomycin, acting against both gram-negative and some gram-positive bacteria. This makes gentamicin more effective in treating systemic infections caused by these microorganisms.
Both medications carry the risk of side effects such as kidney damage and hearing loss if not monitored properly. However, gentamicin tends to be associated with fewer side effects due its better absorption as compared to neomycin.
What conditions is neomycin approved to treat?
Neomycin is approved for the treatment of various bacterial infections, including:
- Infections caused by gram-negative bacteria
- Hepatic encephalopathy
- It is also prescribed for pre-operative bowel antisepsis
How does neomycin help with these illnesses?
Neomycin and Gentamicin are both antibiotics falling under the aminoglycoside category. They work by inhibiting protein synthesis in bacteria, making the microorganisms unable to grow and reproduce. Neomycin primarily targets gram-negative bacteria, and is most often used topically due to its potential side effects when administered orally or intravenously, such as ototoxicity (damage to the ear) and nephrotoxicity (damage to the kidneys). On the other hand, gentamicin has broad-spectrum activity against many types of bacteria, including certain gram-positive strains. It can be administered through various routes, but must be monitored carefully due to similar risks of ototoxicity and nephrotoxicity (like with neomycin). Both drugs should therefore be employed prudently in consideration of their potential toxicities.
What is gentamicin?
Gentamicin is a type of antibiotic known as an aminoglycoside, which works by inhibiting protein synthesis in bacteria, effectively preventing the bacteria from growing and multiplying. It was first approved by the FDA in 1966. As gentamicin does not act on fungi or viruses, it cannot be used to treat infections caused by these microorganisms. Its lack of action against non-bacterial pathogens means that its use is typically reserved for severe bacterial infections such as sepsis. Its side effect profile is also different than that of other antibiotics like neomycin, particularly in that it has potential to cause kidney damage (nephrotoxicity) or the inner ear (ototoxicity), which are less common with neomycin. Gentamicin's effects can be beneficial for treating serious bacterial infections when other antibiotics might not be effective or appropriate.
What conditions is gentamicin approved to treat?
Gentamicin is a powerful antibiotic that's been approved by the FDA for combatting several severe bacterial infections, such as:
- Bacteremia (bacteria in the blood)
- Certain types of pneumonia
- Certain infections of skin, bone, joints, and soft tissue
- Intra-abdominal infections like peritonitis
- Severe or serious bacterial infections that other antibiotics cannot treat
Remember to always follow your healthcare provider's instructions when taking antibiotics to ensure their efficacy and prevent the development of antibiotic resistance, wherein the drug loses its effectiveness against the bacteria.
How does gentamicin help with these illnesses?
Gentamicin is an antibiotic that works by inhibiting protein synthesis in bacteria, thus impairing their ability to grow and multiply. It is effective against a wide variety of infections caused by gram-negative bacteria such as E. coli and Pseudomonas aeruginosa, as well as some types of gram-positive bacteria like Staphylococcus. Gentamicin has robust antimicrobial activity, but its use is typically reserved for severe or hospital-acquired infections due to potential side effects including kidney damage and hearing loss. Despite these potential risks, gentamicin may be the preferred choice over neomycin for certain patients or types of infections because of its broader spectrum of action and better systemic absorption when administered intravenously. Gentamicin's strong bactericidal activity can be essential in managing serious bacterial infections where other antibiotics might fall short.
How effective are neomycin and gentamicin?
Both neomycin and gentamicin are well-established aminoglycoside antibiotics, with neomycin first approved by the FDA in 1949, followed by gentamicin in 1966. Their mechanisms of action involve binding to bacterial ribosomes to inhibit protein synthesis, which ultimately results in bacterial cell death.
A comparative study published in 2015 demonstrated that both neomycin and gentamicin have comparable efficacy against two bacterial strains, namely Pseudomonas aeruginosa and Staphylococcus aureus. However, specific circumstances often dictate when one antibiotic might be preferred over the other. For instance, due to its high risk for nephrotoxicity (kidney damage) and ototoxicity (ear damage), neomycin is generally reserved for topical or oral administration to treat local infections such as skin or gastrointestinal infections.
Gentamicin has a broader spectrum of activity compared to neomycin. It's effective against many gram-negative bacteria including Pseudomonas species, which are common culprits in hospital-acquired infections. Gentamicin has also been shown to be effective against some types of Mycobacterium that cause tuberculosis.
In terms of their side effect profiles, comparisons conducted through several studies over the years suggest that systemic use (i.e., orally administered or injectable forms) of neomycin carries a higher risk of kidney damage than gentamincin, particularly if not monitored closely.
Current clinical practice guidelines recommend monitoring drug levels regularly while using either of these antibiotics, particularly during long-term therapy. This is because they may cause serious adverse effects, especially at higher doses, including kidney toxicity and inner-ear toxicity leading hearing loss.
Different factors play into the choice between these two drugs, including the type and location of the infection and the patient’s age and renal function status.
At what dose is neomycin typically prescribed?
Dosages of neomycin for adults range from 3–12 g per day, divided into 3 to 4 doses. For children, the dosage is usually about 30–50 mg/kg per day, also divided into multiple doses per day. However, studies have shown that a lower dose can be effective in treating bacterial infections in many people. Dosage may be increased (as directed by a healthcare practitioner) after a few days if there is no response. The maximum dosage should not exceed 12 g per day for adults, and it's always important to consider the individual patient's kidney function before administering or prescribing this antibiotic.
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At what dose is Gentamicin typically prescribed?
Gentamicin dosing can vary depending on factors such as weight and kidney function, but gentamicin treatment typically begins with a dosage of 3–5 mg/kg per day, divided into three equal doses administered every 8 hours. The dose can then be increased (under direction of a healthcare professional) to up to 7.5 mg/kg per day, still split into three equal doses spaced 8 hours apart, if the infection doesn't respond adequately to the initial dosage after a few days. The maximum daily dose is normally capped at around 400–480mg per day (or approximately 7.5mg/kg). This higher dosage may be tested if there is no response to lower dosages in severe infections or those caused by less sensitive organisms within an appropriate timeframe.
In both adults and childen, dosage can be adjusted based on therapeutic drug monitoring, especially considering gentamicin's narrow therapeutic index and potential for toxicity.
What are the most common side effects of neomycin?
Neomycin is a potent antibiotic, and it carries a risk of different side effects, which include:
- Nausea or vomiting
- Diarrhea
- Abdominal pain or bloating
- Loss of appetite (anorexia)
- Rash or itching
- Hearing loss
As always, patients should report any unusual symptoms to their healthcare provider immediately.
Are there any potential serious side effects for Neomycin?
Despite being regarded as generally safe, there are some rare but serious potential side effects associated with neomycin:
- Signs of an allergic reaction: Difficulty breathing or swallowing, swelling of the face or throat
- Kidney problems: Reduced urination, swelling in your legs or feet, feeling tired
- Neurotoxicity: Can manifest as numbness, skin tingling, muscle twitching, and seizures
- Ototoxicity (damage to the ear): Dizziness, spinning sensation (vertigo), hearing loss
- Muscular issues: Muscle weakness or paralysis, including breath-holding spells due to possible effect on neuromuscular function.
Antibiotics like neomycin can also cause changes in electrolyte levels, which might lead to symptoms such as:
- Muscle cramps or weakness
- Fast heart rate
- Twitching
If you experience any of these side effects while taking neomycin, seek medical attention as soon as possible.
What are the most common side effects for Gentamicin?
Gentamicin can cause a few side effects, some of which include:
- Nausea and vomiting
- Loss of appetite
- Increased urination or thirst (indication of kidney problem)
- Hearing problems, hearing loss, or ringing in the ears (tinnitus)
- Dizziness, vertigo, or a sense of imbalance
- Muscle twitching or seizures
- Kidney problems
- Pain where the medicine was injected
This is not an exhaustive list of all possible side effects. Monitoring of patients taking gentamicin is necessary as it also has the potential to cause kidney damage and nerve damage. Always consult with your healthcare provider if you experience any of these side effects.
Are there any potential serious side effects for Gentamicin?
Gentamicin, while effective in treating certain bacterial infections, can potentially cause serious side effects. These may include:
- Signs of an allergic reaction such as difficulty breathing; swelling of your face, lips, tongue or throat
- Changes in urination (passing more or less urine than usual)
- Hearing loss and ringing in the ears
- Dizziness or spinning sensation
- Unsteadiness and a lack of coordination
- Muscle twitching or seizures
- Rash on the skin with itching
If you notice any of these symptoms after taking gentamicin, seek immediate medical attention.
Contraindications for neomycin and gentamicin
Both neomycin and gentamicin, like all aminoglycoside antibiotics, carry a risk of certain side effects such as kidney problems or hearing loss. If you notice these symptoms (or others such as increased thirst/urination, dizziness, or decreased hearing), please seek immediate medical attention.
Neither neomycin nor gentamicin should be used if you are currently taking or have been taking potent diuretics (such as furosemide), since they can increase the risk of ototoxicity caused by aminoglycoside antibiotics. Always inform your doctor about all the medications you are currently using. Those taking diuretics in particular will require careful monitoring during therapy with either neomycin or gentamicin to prevent dangerous interactions.
How much do neomycin and gentamicin cost?
The following comparison applies to the generic versions of these antibiotics, and assumes they're being used for their most-common indications (topical treatment for minor cuts and scrapes with neomycin, or treatment of eye infections with gentamicin).
- The price of a 15 g tube of neomycin (as part of a triple antibiotic ointment including polymyxin B and bacitracin) is approximately $10. With typical use, this might last for around 30 days, working out to an approximate daily cost of $0.33.
- A carton containing ten single-use vials (each with 2 mL) of gentamicin solution (40 mg/mL strength), commonly used in eye infections, averages around $200. This works out to about $20 per day if one vial is used per day, as typically directed.
Thus, if you are using these drugs for their most common uses, then neomycin would be less expensive than gentamicin on a per-day treatment basis.
Please note that cost should not be your primary consideration when determining which of these drugs is right for you, as they treat different types of bacterial infections. Antibiotics such as neomycin and gentamicin should be prescribed according to the type and location of the infection.
Both neomycin and gentamicin are typically available only in generic form nowadays since they're older antibiotics. Therefore, their costs will generally be lower than newer antibiotics with brand-name versions.
Popularity of Neomycin and Gentamicin
Neomycin and gentamicin are both aminoglycoside antibiotics, and both are commonly used to treat infections caused by gram-negative bacteria.
In 2020, approximately 3.2 million prescriptions were filled for neomycin in the US, making it one of the most widely prescribed topical antibiotics. Neomycin is often found combined with other treatments in over-the-counter first aid creams and ointments due to its broad-spectrum antibacterial activity.
On the other hand, gentamicin was estimated to have been prescribed about 1.8 million times in that same year, accounting for just under 15% of aminoglycoside antibiotic prescriptions in the US. Gentamicin has traditionally been preferred in treating severe systemic bacterial infections since it provides excellent coverage against several types of bacteria, including Pseudomonas aeruginosa, a common cause of hospital-acquired infections.
While both drugs have remained popular choices among healthcare providers over time, they are typically used in different scenarios. Neomycin is frequently indicated for minor skin injuries or eye/ear infections, whereas gentamicin is primarily used when more potent systemic action is needed.
Conclusion
Both neomycin and gentamicin are aminoglycoside antibiotics used to treat various types of bacterial infections. They have been widely utilized in clinical practice for decades, and their effectiveness is backed by extensive research and data. Both drugs work by inhibiting protein synthesis in bacteria, leading to the death of the bacteria.
Neomycin is primarily used topically for skin, eye, and ear infections/injuries, or orally for bowel sterilization before surgery. Gentamicin is most commonly administered via injection and is primarily used systemically to treat more serious infections such as sepsis or pneumonia caused by gram-negative bacteria.
Both medications are available in generic form, and they are relatively inexpensive and accessible antibiotics. The onset of action for both drugs can be relatively quick, but as with most antibiotics, it may take several days before patients notice an improvement in symptoms.
The side effect profiles of the two drugs differ somewhat, with gentamicin carrying a higher risk due to its potential nephrotoxicity (causing kidney damage) and ototoxicity (causing damage to the ears). Neomycin also carries a risk of ototoxicity, but tends not to affect renal function when used topically or orally because it is poorly absorbed into systemic circulation when administered via these routes. For both drugs, patients should report any sudden changes such as hearing loss or balance issues to their physician or other healthcare professional immediately, as these symptoms could indicate ototoxicity.
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Refrences
- Reynolds, A. V., Hamilton-Miller, J. M. T., & Brumfitt, W. (1976, November 1). In Vitro Activity of Amikacin and Ten Other Aminoglycoside Antibiotics against Gentamicin-Resistant Bacterial Strains. Journal of Infectious Diseases. Oxford University Press (OUP).http://doi.org/10.1093/infdis/135.supplement_2.s291
- Chen, C., Chen, Y., Wu, P., & Chen, B. (2014, February). Update on new medicinal applications of gentamicin: Evidence-based review. Journal of the Formosan Medical Association. Elsevier BV.http://doi.org/10.1016/j.jfma.2013.10.002
- Chambers, W. B., & Pallagrosi, A. U. (1973, January). Gentamicin in the Treatment of Staphylococcal Infections. Journal of International Medical Research. SAGE Publications.http://doi.org/10.1177/030006057300100211
- APPEL, G. B. (1978, October 1). Gentamicin in 1978. Annals of Internal Medicine. American College of Physicians.http://doi.org/10.7326/0003-4819-89-4-528
- El-Sayed, Y. M., & Islam, S. I. (1990, August). Comparison of non-kinetic and kinetic approaches to individualization of gentamicin dosage. European Journal of Clinical Pharmacology. Springer Science and Business Media LLC.http://doi.org/10.1007/bf00280050