Ofloxacin vs. erythromycin: What's the difference?

What is ofloxacin? What is erythromycin?

Ofloxacin is a fluoroquinolone antibiotic used to treat bacterial infections such as pneumonia, bronchitis, staph infections, STDs (gonorrhea, chlamydia), urinary tract infections (UTIs), and prostate infections caused by E. coli. Other fluoroquinolone antibiotics include levofloxacin (Levaquin), ciprofloxacin (Cipro), gatifloxacin (Tequin), norfloxacin (Noroxin), moxifloxacin (Avelox), and trovafloxacin (Trovan). Ofloxacin stops the multiplication of bacteria by inhibiting the reproduction and repair of their genetic material (DNA).

Erythromycin is a macrolide antibiotic used to treat bacterial infections such as streptococcal infections of the throat ("strep throat") and skin, lung infections such as pneumonia, pelvic inflammatory disease, erythrasma, whooping cough, listeriosis, intestinal amebiasis, and STDs (syphilis, gonorrhea, and chlamydia). Erythromycin is used in patients who are allergic to penicillin for the prevention of recurrent rheumatic fever and infections of the hearts' valves (endocarditis) in patients with valvular abnormalities of the heart before they undergo dental treatments. Other macrolide antibiotics include azithromycin (Zithromax, Zmax) and clarithromycin (Biaxin). Erythromycin works by preventing bacterial cells from growing and multiplying by interfering with their ability to make proteins while not affecting human cells. Bacteria such as Haemophilus influenzae are resistant to erythromycin alone and must be treated with a combination of erythromycin and adequate doses of sulfonamides

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What are the side effects of ofloxacin vs. erythromycin?

Ofloxacin

The most common side effects of ofloxacin include:

Allergic reactions have been described, such as hives and anaphylaxis (shock).

Other important side effects include symptoms of nervous system stimulation, such as:

Ofloxacin may cause low or high blood sugar levels especially in people with diabetes who are taking insulin or oral hypoglycemic drugs.

Patients taking ofloxacin can develop skin sensitivity (photsensitivity) to direct sunlight and should avoid exposure to sunlight or use sun protection and sunscreens.

Ofloxacin as well as other antibiotics in the fluoroquinolone class of antibiotics, has been associated with tendinitis and even rupture of tendons, particularly the Achilles tendon. Some physicians recommend that patients discontinue vigorous exercise while they are taking fluoroquinolone antibiotics.

Ofloxacin should be used with caution in patients with central nervous system diseases such as seizures because rare seizures have been reported in patients receiving this medication.

Ofloxacin should be avoided in children and adolescents under 18 years of age, as safe use in these patients have not been established.

Many antibiotics, including ofloxacin, can alter the normal bacteria in the colon and encourage overgrowth of a bacterium responsible for the development of inflammation of the colon (Clostridium difficile, pseudomembranous colitis). Pseudomembranous colitis can cause fever, abdominal pain, diarrhea, and sometimes even shock.

Ofloxacin should not be used in patients with myasthenia gravis because it can increase muscle weakness.

Erythromycin

The most frequent side effects of erythromycin are

These gastrointestinal side effects are usually dose-related, i.e., more pronounced with higher doses.

Allergic reactions such as hives, rash, or anaphylaxis (a severe allergic reaction which can lead to shock and death) have been reported rarely.

What is the dosage of ofloxacin vs. erythromycin?

Ofloxacin

  • The usual dose for patients with normal renal function is 200 to 400 mg every 12 hours.
  • Dosages require adjustment in patients with severely abnormal liver or kidney function.
  • Oflaxacin is availabile as tablets: 200, 300, and 400mg.
  • Ofloxacin should be stored in a closed container at 15 C - 30 C (59 F - 86 F).

Erythromycin

  • The usual dosage for adults is 250 mg every 6 hours, 333 mg every 8 hours or 500 mg every 12 hours. Doses may be increased up to 4 g/day according to the severity of the infection.
  • In children, the usual dosage is 30 to 50 mg/kg/day with age, weight, and severity of the infection being taken into consideration to determine the appropriate dosage.
  • Erythromycin may be taken with or without food; however optimal blood levels of erythromycin are obtained when taken on an empty stomach (at least 30 minutes and preferably 2 hours before or after meals).

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What drugs interact with ofloxacin and erythromycin?

Ofloxacin

Ofloxacin reduces the elimination of theophylline, elevating blood levels of theophylline. (Theophylline is used to open airways in the treatment of asthma.) If concurrent use of ofloxacin and theophylline cannot be avoided, frequent blood tests to monitor theophylline blood levels should be performed. Ofloxacin can enhance the action of the anticoagulant (blood thinner) warfarin (Coumadin), and increase the risk of bleeding. Both high and low blood sugar levels have been reported, especially in patients with diabetes who were also receiving insulin or other medications used to lower the blood sugar. Careful monitoring of blood sugar levels is recommended. Sucralfate (Carafate), iron, multivitamins containing zinc, didanosine (Videx), as well as antacids containing calcium, magnesium, or aluminum should not be taken within two hours before or after taking ofloxacin.

Erythromycin

Erythromycin when used with antiarrhythmic drugs such as, amiodarone (Cordarone), bretylium (Bretylol), disopyramide (Norpace), dofetilide (Tikosyn), procainamide (Pronestyl), quinidine (Quinaglute, Quinidex, Quinora) and sotalol (Betapace) exaggerates the effect of the antiarrhythmic drugs which may give rise to abnormal heart rhythms such as torsades de pointes.

Theophyllines such as theophylline (Theo-Dur), oxtriphylline (Choledyl SA), and aminophylline (Phyllocontin) reduce erythromycin blood levels by increasing elimination of erythromycin by the kidneys, which may reduce the effectiveness of erythromycin. Conversely, erythromycin inhibits the metabolism (breakdown) of theophyllines by the liver and causes an increase in blood levels of theophylline. High theophylline levels may give rise to side effects such as seizures and disturbances in heart rhythm. Therefore, the dose of theophyllines should be reduced or theophylline levels in the blood should be measured in patients taking erythromycin.

Combining erythromycin with ergotamine or ydroergotamine has been associated with acute ergot toxicity. This combination should be avoided.

Erythromycin prevents digoxin (Lanoxin) from being eliminated by the kidneys; this in turn causes increased levels of digoxin in the blood. Increased levels of digoxin can cause disturbances in heart rhythm. Therefore, it is important to monitor and adjust digoxin doses when treating with erythromycin.

Erythromycin prevents the elimination of warfarin (Coumadin) from the body which can raise the levels of warfarin in the blood. Warfarin is an anticoagulant or blood thinner, and an increase in its level in blood can increase the risk of bleeding. It is important to monitor the effects of warfarin and adjust warfarin doses when treating with erythromycin.

Erythromycin inhibits the breakdown of HMG-CoA reductase inhibitors (statins) such as atorvastatin (Lipitor), lovastatin (Mevacor) and simvastatin (Zocor) by the liver leading to increased levels of statins in the blood. High levels of statins could result in severe myopathy (muscle damage) with rhabdomyolysis (rapid breakdown of skeletal muscle) that may damage the kidneys or even lead to death. Erythromycin also can elevate blood levels of some anti-seizure drugs such as carbamazepine (Tegretol) by preventing the breakdown of the anti-seizure drug by the liver. Therefore, doses of the anti-seizure drugs may need to be reduced during treatment with erythromycin. Erythromycin also increases blood levels of sildenafil (Viagra). The dose of sildenafil should be reduced when treating with erythromycin.

Grapefruit juice may prevent the breakdown of erythromycin, resulting in elevated levels of erythromycin in the blood. Therefore, it is important to avoid eating grapefruit or drinking grapefruit juice during treatment with erythromycin.

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Are ofloxacin and erythromycin safe to use while pregnant or breastfeeding?

Ofloxacin

  • Ofloxacin should be avoided during pregnancy because it is secreted in breast milk and can cause adverse events in the infant.
  • Ofloxacin should be avoided in nursing mothers, as safe use has not been established.

Erythromycin

  • Erythromycin crosses the placenta, but its level in the blood of the fetus is low. There are no adequate studies in pregnant women, hence pregnant women should only use erythromycin if it is felt that the benefits of treatment outweigh the potential but unknown risks.
  • Erythromycin is excreted in breast milk; however, erythromycin is considered by the American Academy of Pediatrics to be compatible with breastfeeding. Caution should be exercised, however, when erythromycin is prescribed to women who are breastfeeding.

Summary

Ofloxacin and erythromycin are different types of antibiotics used to treat bacterial infections such as pneumonia, bronchitis, staph infections, and STDs (gonorrhea, chlamydia). Erythromycin is also used in patients who are allergic to penicillin for the prevention of recurrent rheumatic fever and infections of the hearts' valves (endocarditis) in patients with valvular abnormalities of the heart before they undergo dental treatments.

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Medically Reviewed on 10/24/2019
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