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Tobramycin vs Azithromycin
Introduction
For patients combatting bacterial infections, certain antibiotics that target and inhibit the growth of specific bacteria can be vital in overcoming the infection. Tobramycin and Azithromycin are two such drugs that are often prescribed for a variety of bacterial infections. Each drug works differently by targeting different types of bacteria, but both aim to prevent further bacterial growth or kill existing bacteria outright. Tobramycin belongs to a class of medications known as aminoglycoside antibiotics which primarily fight against gram-negative bacteria like E.coli or Klebsiella species. On the other hand, Azithromycin is classified as a macrolide antibiotic and targets a broader spectrum of gram-positive and gram-negative bacteria including Streptococcus pneumoniae or Haemophilus influenzae.
Tobramycin vs Azithromycin Side By Side
| Attribute | Tobrex | Zithromax |
|---|---|---|
| Brand Name | Tobrex | Zithromax |
| Contraindications | Patients with kidney problems should use caution due to potential nephrotoxicity. Should not be taken with certain types of diuretics. | Patients with liver disease need to be careful due to metabolism in the liver. Should not be taken with certain types of diuretics. |
| Cost | As low as $4 to about $8 per bottle for the generic version | About $15 for six tablets (250 mg) for the generic version |
| Generic Name | Tobramycin | Azithromycin |
| Most Serious Side Effect | Hearing problems or loss, kidney issues | Severe stomach pain with diarrhea that is watery or bloody, fast/irregular heartbeats |
| Severe Drug Interactions | Certain diuretics | Drugs that prolong QT interval |
| Typical Dose | 1–2.5 mg/kg every 8 hours; not to exceed a total daily dose of 5mg/kg/day | 500mg on day 1, then 250mg/day for four additional days |
What is Tobramycin?
Tobramycin (often sold as Tobrex among other names) is a type of antibiotic in the aminoglycoside category, which was first approved by the FDA in 1975. As an antibiotic, it prevents bacterial growth by inhibiting protein synthesis within bacteria, thus effectively halting their ability to replicate and spread. It is primarily used to treat different forms of serious bacterial infections such as urinary tract infections, respiratory infections, skin and bone infections that are resistant to other antibiotics.
On the other hand, Azithromycin (commonly known under its brand name Zithromax) belongs to the macrolide class of antibiotics which were introduced later than aminoglycosides. Approved by the FDA in 1991, Azithromycin works by interfering with microbial protein synthesis and thus preventing bacteria from multiplying. While both Tobramycin and Azithromycin work towards hindering bacterial growth through disruption of protein synthesis, they do so at different stages leading them to be effective against various types of bacteria.
Azithromycin has been found effective for treating many types of mild-to-moderate bacterial infection such as those affecting skin tissue or causing ear or sinus problems – areas where Tobramycin may not always be as potent due its narrower spectrum activity compared with Azithromycin's broader range.
What conditions is Tobramycin approved to treat?
Tobramycin is approved for the treatment of various bacterial infections, including:
- Pseudomonas aeruginosa in cystic fibrosis patients
- Bacterial eye infections (in ophthalmic form)
- Serious bacterial infections caused by susceptible bacteria, such as sepsis
Conversely, Azithromycin is used to treat different types of bacterial conditions:
- Respiratory infections including bronchitis and pneumonia
- Skin Infections
- Ear Infections
- Sexually transmitted diseases like chlamydia and gonorrhea.
How does Tobramycin help with these illnesses?
Tobramycin is an antibiotic that fights bacteria in the body by inhibiting the production of bacterial proteins, which are necessary for the bacteria's growth and multiplication. It works by binding to part of the bacterial cell machinery used to synthesise these proteins, thus disrupting this process and leading to death of the bacterial cells.
Azithromycin also acts against harmful bacteria, but it does so slightly differently. Like Tobramycin, Azithromycin interferes with protein synthesis in bacteria; however it binds at a different site on the bacterial ribosome (the structure within cells where proteins are made), thereby affecting another step within this complex process.
Both antibiotics can be very effective against certain types of infections; your healthcare provider will choose between them based on various factors such as type and location of infection, potential side effects or interactions with other medications you may be taking.
What is Azithromycin?
Azithromycin, often marketed under the brand name Zithromax, is a type of antibiotic known as a macrolide. It operates by inhibiting bacterial protein synthesis, effectively stopping bacteria from growing and multiplying. This makes it effective against a wide variety of bacterial infections. Azithromycin was first approved by the FDA in 1991.
As Azithromycin is not an aminoglycoside antibiotic like Tobramycin, it does not inhibit protein synthesis in the same way. Its distinct mechanism means that its side-effect profile is also different to that of antibiotics such as Tobramycin; for example, it doesn't have significant nephrotoxic or ototoxic effects which are common with Aminoglycosides. The actions on protein synthesis can be beneficial for treating various types of infections including respiratory tract and skin infections, particularly in patients who do not respond well to other "typical" antibiotics such as Tobramycin.
What conditions is Azithromycin approved to treat?
Azithromycin is a widely used antibiotic that has been approved for the treatment of various bacterial infections, including:
- Bacterial infections of the skin and soft tissues
- Respiratory tract infections such as bronchitis and pneumonia
- Sinusitis and throat infections caused by streptococcus
- Certain sexually transmitted diseases like chlamydia and gonorrhea.
How does Azithromycin help with these illnesses?
Azithromycin is an antibiotic, part of the macrolide category, and works by inhibiting bacterial protein synthesis. It does this by binding to the 50S subunit of the bacterial ribosome, which prevents translation of mRNA. Azithromycin is noted for its broad-spectrum activity against a wide variety of bacteria including Staphylococcus species, Streptococcus species, Moraxella catarrhalis, Bacteroides fragilis and Haemophilus influenzae. Its long half-life allows it to be administered once daily or even less frequently in some cases. This characteristic differentiates azithromycin from other antibiotics such as Tobramycin which require multiple doses per day and primarily target gram-negative bacteria like Pseudomonas aeruginosa.
How effective are both Tobramycin and Azithromycin?
Both Tobramycin and Azithromycin have established histories of efficacy in treating bacterial infections, albeit against different types of bacteria. They were both approved by the FDA in the 1980s, with Tobramycin receiving approval in 1981 and Azithromycin following seven years later. As they belong to different classes of antibiotics (Tobramycin is an aminoglycoside while Azithromycin is a macrolide), their mechanism of action differs which makes them more effective against certain strains of bacteria.
The effectiveness of these two drugs was studied in several clinical trials over the years; for instance, one study on cystic fibrosis patients reported that nebulized Tobramycin effectively decreased Pseudomonas aeruginosa density and improved pulmonary function.[1]
Azithromycin on the other hand has been extensively studied for its effects on various respiratory tract infections such as pneumonia and bronchitis where it showed promising results[2]. Importantly, due to its longer half-life compared to other antibiotics, it allows once-daily dosing which can improve patient compliance.
A 2015 systematic review indicated that Azithromycin seems to be beneficial when used as an add-on therapy for patients suffering from persistent asthma.[3] Similar studies have shown that Tobramycin can be useful as an adjunct treatment along with other antibiotics particularly in hospital-acquired infections caused by gram-negative organisms resistant to multiple drugs[4].
Despite being potent antimicrobials, both drugs are generally well tolerated but may occasionally cause side-effects including gastrointestinal issues or potential ototoxicity (Tobramyin) or QT interval prolongation (Azithromyicn).
References:
[1] https://pubmed.ncbi.nlm.nih.gov/14769731/
[2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4284115/
[3] https://pubmed.ncbi.nlm.nih.gov/26184304/
[4] https://www.sciencedirect.com/science/article/pii/S2213716513000367
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At what dose is Tobramycin typically prescribed?
The dosages for Tobramycin can range from 1–2.5 mg/kg every 8 hours, depending on the severity of the infection and the patient's body weight. Children may be started at a lower dosage of around 0.3 mg/kg per day in divided doses every 12 hours. The dose can be increased after a few weeks if there is no response to initial treatment or based on your doctor's discretion. However, it should not exceed a total daily dose of 5mg/kg/day as Tobramycin has potential nephrotoxicity and ototoxicity with higher doses.
On the other hand, Azithromycin typically has an oral dosage that ranges from 250-500 mg/day once daily for adults over three days to one week depending upon type and severity of infection while children are usually given between 10–20 mg/kg once daily for three to five days depending on their age and health condition. The maximum dosage that should not be exceeded in any case is dependent upon individual tolerance levels but generally does not exceed more than two grams (2000mg) in adults per single administration.
At what dose is Azithromycin typically prescribed?
Azithromycin treatment usually commences with a dosage of 500mg per day. After the initial dose, subsequent doses can be reduced to 250mg/day for four additional days, amounting to a five-day treatment course in total. In cases of sexually transmitted diseases, a single larger dose may be prescribed instead. For chronic conditions like lung disease or cystic fibrosis, Azithromycin might be taken three times per week in an ongoing fashion. Always ensure you follow your healthcare provider's instructions when taking this medication and do not exceed the recommended dosage unless advised by your physician.
What are the most common side effects for Tobramycin?
Common side effects of Tobramycin can include:
- Nausea
- Vomiting
- Diarrhea
- Rash, itching or hives
- Headache
- Muscle weakness and pain
- Difficulty breathing
On the other hand, Azithromycin may cause side effects like:
-Nausea, vomiting, stomach pain, diarrhea
-Dizziness
-Palpitations or chest pain
-Skin rash and itching
-Fatigue and headaches
-Hearing disturbances
Always consult your healthcare provider if any of these symptoms persist.
Are there any potential serious side effects for Tobramycin?
Though Tobramycin is generally well-tolerated, it can occasionally cause serious side effects which may include:
- Hearing problems or loss
- Kidney issues: significant decrease in the amount of urine, blood in the urine, change in the frequency of urination
- Signs of allergic reaction such as difficulty breathing; swelling of your face, lips, tongue or throat
- Muscle weakness or twitching
- Nausea and vomiting that doesn't stop
- Severe headaches with vision changes
On the other hand Azithromycin has its own set of potentially severe side effects. These could include:
- Severe stomach pain accompanied by diarrhea that is watery or bloody
- Fast heart rate, fluttering in your chest feeling like you might pass out
- Liver problems - nausea, upper stomach pain, itching tiredness; dark urine and jaundice (yellowing skin and eyes) -An older adult may experience a severe skin reaction - fever sore throat burning eyes skin pain red/purple rash with blistering/peeling
In case any symptoms occur while taking either Tobramycin or Azithromycin immediately seek medical attention.
What are the most common side effects for Azithromycin?
Azithromycin, another antibiotic alternative to Tobramycin, has its own unique set of side effects. These can include:
- Stomach upset or abdominal pain
- Nausea and vomiting
- Diarrhea
- Headaches
- Dizziness
- Feeling nervous or anxious
- Mild skin rash or itching These symptoms are typically mild and often resolve on their own. However, if they persist or become severe, you should seek medical attention immediately. In rare cases, azithromycin can cause a faster than normal heartbeat that may feel irregular. If this occurs, immediate medical attention is necessary.
Are there any potential serious side effects for Azithromycin?
While Azithromycin is generally well-tolerated, it can occasionally cause some severe side effects. These may include:
- Signs of an allergic reaction such as hives, difficulty breathing or swallowing, swelling in the face or throat.
- Symptoms of liver problems like yellowing eyes/skin, persistent nausea/vomiting, severe stomach/abdominal pain or dark urine.
- Severe dizziness and fainting; fast/irregular heartbeats (symptoms related to QT prolongation).
- Diarrhea that doesn't stop and may even be bloody (this could indicate a potential intestinal condition due to a type of resistant bacteria).
- Serious skin reactions: fever, sore throat, swelling in the face or tongue, burning in your eyes leading to skin pain followed by a red/purple skin rash causing blistering and peeling.
Should you experience any of these symptoms while taking Azithromycin do not ignore them. Stop taking this medication immediately and seek urgent medical attention.
Contraindications for Tobramycin and Azithromycin?
Both Tobramycin and Azithromycin, like many other antibiotic medications, may cause side effects in some individuals. If you experience severe reactions such as difficulty breathing or swallowing, swelling of the face or throat, sudden dizziness or fainting after taking these antibiotics, seek immediate medical attention.
Neither Tobramycin nor Azithromycin should be taken if you are using certain types of diuretics (water pills) that could interact harmfully with them. Always inform your physician about all medications and supplements you are currently taking; certain drugs will require a period to clear from your system to prevent dangerous interactions with Tobramycin and Azithromycin.
Moreover, patients with kidney problems should use caution when considering Tobramycin due to its potential nephrotoxicity (kidney damage). On the other hand, those suffering from liver disease need to be careful when using Azithromycin because it is metabolized in the liver which could potentially worsen their condition.
How much do Tobramycin and Azithromycin cost?
For the brand name versions of these drugs:
- The price of 5 mL bottle of Tobramycin eye drops (0.3%) averages around $9, which works out to approximately $1–2/day, depending on your dose.
- The price of a pack containing six tablets (250 mg each) of Zithromax, the brand-name version of Azithromycin, is about $50 and typically covers a five-day course treatment regimen. This equates to approximately $10/day.
As such, if you are in need for an extended use period with the Tobramycin eye drops or higher dosage range, then branded Zithromax will be less expensive on a per-day treatment basis. However, remember that cost should not be the primary factor determining which medication would best suit your needs.
When considering generic versions:
- Generic Tobramycin (0.3% solution) is available in 5 mL bottles and above with costs ranging from as low as $4 to about $8 per bottle - spanning roughly between $.80-$1.60 per day based on typical dosages.
- On the other hand, generic Azithromycin runs at about $15 for six tablets (250 mg), translating into a daily expense starting from as low as ~$3/day during a typical five-day course treatment regimen.
Popularity of Tobramycin and Azithromycin
Tobramycin and Azithromycin are both antibiotics used to treat bacterial infections, but they belong to different classes and have distinct uses.
In 2020, Tobramycin was prescribed around 1 million times in the United States. It belongs to a class of antibiotics known as aminoglycosides which are commonly used for severe infections that are resistant to other antibiotics. Its usage has remained relatively stable over the last decade with slight fluctuations.
On the other hand, Azithromycin is one of the most frequently prescribed antibiotics in America with an estimated 38 million prescriptions filled in 2020 alone. Belonging to the macrolide class of antibiotics, it's often utilized for more common conditions such as ear infections or strep throat due its broad-spectrum effectiveness and convenient dosing schedule (usually once daily). The use of azithromycin has been steadily increasing since its introduction in the late '90s because it offers a good balance between efficacy and side effect profile.
Conclusion
Both Tobramycin and Azithromycin have long-standing records of usage in patients with bacterial infections, supported by numerous clinical studies indicating their effectiveness over placebo treatments. They are occasionally combined for treating certain types of infections, but this requires careful consideration by a physician due to potential drug interactions. Their different mechanisms of action - with Tobramycin inhibiting protein synthesis in bacteria and Azithromycin interfering with bacterial protein production - mean they tend to be prescribed under varying circumstances.
Tobramycin is often used as a first-line treatment for severe hospital-acquired infections such as Pseudomonas aeruginosa, whereas Azithromycin is commonly administered for community-acquired infections like strep throat or ear and sinus infections. Both drugs are available in generic form, which can lead to significant cost savings especially for patients who must pay out-of-pocket.
While both antibiotics may require some time before effects become noticeable, the side effect profiles differ between the two medications. Tobramycin can potentially cause kidney toxicity and hearing loss while Azithromycin might lead to gastrointestinal upset or irregular heart rhythms. Therefore, it's crucial that patients closely monitor any adverse reactions when starting these treatments and should seek medical help immediately if they notice any worsening symptoms or unexpected side effects.
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Refrences
- Parnham, M. J., Haber, V. E., Giamarellos-Bourboulis, E. J., Perletti, G., Verleden, G. M., & Vos, R. (2014, August). Azithromycin: Mechanisms of action and their relevance for clinical applications. Pharmacology & Therapeutics. Elsevier BV.http://doi.org/10.1016/j.pharmthera.2014.03.003
- Nichols, D. P., Happoldt, C. L., Bratcher, P. E., Caceres, S. M., Chmiel, J. F., Malcolm, K. C., … Nick, J. A. (2017, May). Impact of azithromycin on the clinical and antimicrobial effectiveness of tobramycin in the treatment of cystic fibrosis. Journal of Cystic Fibrosis. Elsevier BV.http://doi.org/10.1016/j.jcf.2016.12.003
- Wilms, E. B., Touw, D. J., Heijerman, H. G. M., & van der Ent, C. K. (2012, January 3). Azithromycin maintenance therapy in patients with cystic fibrosis: A dose advice based on a review of pharmacokinetics, efficacy, and side effects. Pediatric Pulmonology. Wiley.http://doi.org/10.1002/ppul.21620
- Lockwood, A. M., Cole, S., & Rabinovich, M. (2010, May 15). Azithromycin-induced liver injury. American Journal of Health-System Pharmacy. Oxford University Press (OUP).http://doi.org/10.2146/ajhp080687
- Ren, H., Zhang, J., Zhou, J., Xu, C., Fan, Z., Pan, X., … Wu, W. (2021, May 28). Synergistic bactericidal activities of tobramycin with ciprofloxacin and azithromycin against Klebsiella pneumoniae. The Journal of Antibiotics. Springer Science and Business Media LLC.http://doi.org/10.1038/s41429-021-00427-0
- Ballow, C. H., & Amsden, G. W. (1992, October). Azithromycin: The First Azalide Antibiotic. Annals of Pharmacotherapy. SAGE Publications.http://doi.org/10.1177/106002809202601014
- Altucci, P., Abbate, G. F., Alagia, I., & Leonessa, V. (1976, August 1). Clinical Evaluation of Tobramycin in Respiratory and Systemic Infections in Immunodepressed and Normal Patients. Journal of Infectious Diseases. Oxford University Press (OUP).http://doi.org/10.1093/infdis/134.supplement_1.s182
- VandenBussche, H. L., & Homnick, D. N. (2012, August 1). Evaluation of Serum Concentrations Achieved With an Empiric Once-Daily Tobramycin Dosage Regimen in Children and Adults With Cystic Fibrosis. The Journal of Pediatric Pharmacology and Therapeutics. Pediatric Pharmacy Advocacy Group.http://doi.org/10.5863/1551-6776-17.1.67