How levofloxacin works
The antibiotic levofloxacin blocks two enzymes that are vital for bacteria: DNA gyrase and topoisomerase IV.
The genetic material of bacteria, DNA, is in the form of a knitting ladder-shaped molecule that is normally tightly coiled. This changes when genetic information stored for the formation of proteins is to be read or the entire genome is to be duplicated in preparation for cell division. The DNA must then be “unwound”. This requires the two enzymes mentioned above.
However, if these are inhibited by levofloxacin, the bacterium cannot survive and dies. The antibiotic therefore has a bactericidal (bactericidal) effect. The immune system then only has to take care of excreting the killed pathogens. The symptoms of the disease (e.g. pneumonia or conjunctivitis) then improve very quickly.
Absorption, breakdown and excretion
When administered by mouth, the active ingredient is almost completely absorbed from the intestine into the blood. It is distributed throughout the body and is then excreted largely unchanged via the kidneys.
When is levofloxacin used?
The areas of application (indications) for levofloxacin include
- pneumonia
- Complicated urinary tract infections (involving the renal pelvis)
- Chronic lung infections caused by the bacterium Pseudomonas aeruginosa in adult patients with cystic fibrosis (cystic fibrosis)
As a rule, doctors only prescribe levofloxacin for severe bacterial infections if no other treatment options are available.
How levofloxacin is used
Levofloxacin is used in the form of tablets or eye drops, and in the case of very severe infections also by infusion (administration directly into the bloodstream). A new application is inhalation, whereby the active substance is selectively effective in the lungs.
When taken orally (by mouth in the form of tablets), the dosage is usually between 250 and 500 milligrams per day. The duration of treatment is between seven and 28 days, depending on the severity of the infection.
Eye drops containing levofloxacin are dripped into the affected eye four to eight times a day. The duration of treatment also depends on the severity of the disease.
The amount of active ingredient administered directly into the bloodstream (infusion) is usually determined individually for each patient.
For inhalation, doctors prescribe 240 milligrams of levofloxacin twice a day, preferably at intervals of twelve hours. It is administered in cycles of 28 days each, followed by a 28-day break. Treatment is continued for as long as the patient continues to benefit from it.
What are the side effects of levofloxacin?
The adverse effects that levofloxacin can cause depend largely on how the active substance is administered.
Levofloxacin tablets and infusions: Side effects
Levofloxacin frequently causes gastrointestinal complaints as side effects, i.e. in one to ten percent of those treated. The antibiotic not only kills pathogenic bacteria, but also beneficial bacteria in the intestine. The intestinal flora is thrown out of balance. As a result, patients feel nauseous and suffer from diarrhea or vomiting.
The natural vaginal flora is also thrown out of balance by levofloxacin. This favors fungal infections in the genital area.
Occasionally (in less than one percent of those treated), weight loss occurs after taking levofloxacin. Some patients are nervous, have headaches, muscle or joint pain or have difficulty sleeping. Some develop a numb feeling or tingling on the skin. Such sensory disturbances can also be side effects of levofloxacin.
Ideally, sports that put a lot of strain on tendons such as soccer and jogging should be avoided during levofloxacin therapy.
If you notice any signs of muscle weakness, tendon, joint or muscle pain, do not take another dose of levofloxacin and talk to your doctor. The symptoms may occur both at the start of treatment and several months after the end of treatment.
Levofloxacin may change the patient’s blood count. In addition, the kidney and liver values in the blood count occasionally deviate. These usually normalize on their own after the end of therapy.
In individual cases, levofloxacin disrupts conduction in the heart muscle (prolongation of the QT time). Doctors also speak of a long QT syndrome.
In rare cases, the aorta may dilate (aortic aneurysm) or the aortic wall may tear (aortic dissection). Both can be life-threatening.
If you suddenly experience severe pain in the chest, abdomen or back, you should go to the emergency room immediately. You should also seek medical help immediately if you suddenly experience shortness of breath or new palpitations or cardiac arrhythmia, or if swelling (oedema) develops in your abdomen or legs.
In rare cases, patients react very hypersensitively to levofloxacin to the point of allergic (anaphylactic) shock. Symptoms of such a severe allergic shock include skin rashes, palpitations, shortness of breath and circulatory problems, depending on the severity.
If you experience possible symptoms of severe allergic shock, you should not take any further doses of levofloxacin and contact a doctor immediately.
Tablets and infusions containing levofloxacin can impair your ability to react. Patients often feel drowsy and sleepy, especially if they have also consumed alcohol. For this reason, patients should not actively participate in road traffic or operate heavy machinery during antibiotic treatment.
Eye drops with levofloxacin: side effects
If the active ingredient is used in the form of eye drops, very little of it enters the body’s circulation. The side effects are therefore generally limited to the application site in the eye:
The eye often burns or itches or vision is blurred for a short time (in the latter case, you should wait until your vision is clear again before driving a motor vehicle or operating machinery).
Inhalation of levofloxacin: side effects
The most frequently reported side effects with inhalation of the active substance are cough with and without sputum, taste disturbances, fatigue and a feeling of weakness.
The same applies to inhalations as to tablets and infusions with levofloxacin: Reactivity and therefore the ability to drive and operate machinery may be impaired. This is particularly true in combination with alcohol.
Further information on undesirable side effects can be found in the package leaflet for your levofloxacin medication. Talk to your doctor or pharmacist if you notice or suspect any other side effects.
When should Levofloxacin not be used?
Levofloxacin in the form of tablets, infusions or inhalations must not be used in the following cases:
- Hypersensitivity to the active substance or any of the other ingredients of the medicine
- Convulsive disorders (epilepsy)
- Pregnancy and breastfeeding
- Age under 18 years (exception: eye drops containing levofloxacin are also available for children in Germany and Austria)
- Tendon complaints following previous use of a fluoroquinolone antibiotic
The same applies to patients who have an increased risk of so-called long QT syndrome (a disorder of cardiac conduction). The risk increases due to heart diseases such as heart failure or a heart attack.
Levofloxacin eye drops should not be used if you are hypersensitive to the active substance or any of the other ingredients of the drops.
These interactions are possible with levofloxacin
Levofloxacin may interfere with conduction in the heart muscle and prolong the QT time (a time interval in the ECG). If patients take medication at the same time that is also known to prolong the QT time, the risk of cardiac arrhythmia increases. Doctors therefore only prescribe levofloxacin in such cases if the benefits outweigh the risks and there are no other treatment options. Drugs with known QT prolongation include, among others:
- Antidepressants such as haloperidol
- Active substances against cardiac arrhythmia such as amiodarone
- other antibiotics such as erythromycin
If patients take glucocorticoids (“cortisone”) at the same time, the risk of tendon inflammation and tendon ruptures increases.
Quinolones such as levofloxacin in combination with theophylline (reserve medication for COPD) and non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen, naproxen and diclofenac can reduce the seizure threshold.
The effect of the “blood thinners” warfarin and phenprocoumon increases when levofloxacin is taken at the same time.
Tell your doctor and pharmacist about all other medicines and food supplements you are taking. This also includes herbal medicines or medicines that you buy from a pharmacy without a prescription. Further information on interactions can be found in the package leaflet for your levofloxacin medication.
Pregnancy and breastfeeding
Due to a lack of data, experts advise against the use of levofloxacin during pregnancy. Better alternatives for the treatment of bacterial infections in pregnant women are penicillins, cephalosporins and macrolides. However, local application of levofloxacin (eye drops) may be acceptable.
Levofloxacin passes into breast milk. In rare cases, breastfed children then suffer from diarrhea. Where possible, doctors therefore prescribe better-studied antibiotics such as penicillins or cephalosporins to breastfeeding mothers.
How to obtain medication with levofloxacin
How long has Levofloxacin been known?
Levofloxacin is a relatively new active ingredient. Researchers developed it from another drug against bacterial diseases by slightly modifying its chemical structure. As a second-generation quinolone, levofloxacin is better tolerated than older representatives of this drug class – and with comparable efficacy.
