Quinolone Antibiotic Medications Have Some Nasty Side Effects

The fluoroquinolone antibiotics, which include drugs like Cipro, were first introduced in the 1980s. They inhibit DNA gyrase, an enzyme needed for bacterial DNA replication and therefore bacterial cell replication. Fluoroquinolones are used for lower respiratory tract infections, especially in the treatment of infections caused by methicillin-sensitive or resistant staphylococci, Pseudomonas and intracellular organisms.

Fluoroquinolones are widely overprescribed for problems like urinary tract infection, in spite of the fact that they cost over 10 times as much as drugs like Septra, and are not more effective. A recent study showed that 81% of patients prescribed fluoroquinolones were not prescribed these drugs appropriately.

The fluoroquinolones are the most commonly used antibiotics today and are potentially very toxic. For example, amongst women with a new onset bladder infection, only 37% were given the preferred treatment, which is Septra, while 32% were given Cipro. In addition, most women were treated for a week or more, while the preferred treatment is only three days. Cipro is the most complained about medication on the web site www.askthepatient.com, where patients log on their reactions to different medications. Cipro and all of the fluoroquinolones can cause damage to cartilage, leading to pain in the joints that could last for years, and even rupture of the tendons.

The most common side effects of fluoroquinolones are nausea, vomiting, and diarrhea, which occur in 3-6% of patients. Other side effects include headache, confusion, and dizziness, phototoxicity and cardiotoxicity. Most of them have interactions with warfarin (Coumadin), a medication used to decrease blood clotting. They also require dosage adjustment in patients with kidney disease. Animal studies show that quinolones can have effects on cartilage in young animals; these drugs are therefore not recommended for children. Related to this, quinolones have been associated with the development of joint pain and even tendon rupture.

Side Effects of Fluoroquinolones

Fluoroquinolones are antimicrobials, medications used to treat infections caused by microorganisms. Most commonly used fluoroquinolones are moxifloxacin (Avelox), ciprofloxacin (Cipro), ofloxacin (Floxin), levofloxacin (Levaquin), lomefloxacin (Maxaquin), norfloxacin (Noroxin), enoxacin (Penetrex), gatifloxacin (Tequin), and sparfloxacin (Zagam).

The fluoroquinolones as a class are generally well tolerated. Most side effects are mild in severity, self-limited, and rarely result in treatment discontinuation. However, some people have had severe and life-threatening reactions to fluoroquinolones. Some side effects are so strange, that people often don't associate them with the drug. It's unclear why some people react to medication while others do not.

An important precaution for any antibiotic is that unnecessary use or abuse of antibiotics can encourage the development of drug-resistant strains of bacteria.

Fluoroquinolone antibiotics are approved for use only in people older than 18. Research suggests that this class of medicines may cause bone development problems in children and teenagers. Infants, children, teenagers, pregnant women, and women who are breastfeeding should not take this medicine unless directed to do so by a physician.

• Gastrointestinal effects. The most common side effects with fluoroquinolones are nausea, vomiting, diarrhea, constipation, and abdominal pain, which occur in 1 to 5% of patients.
• Central Nervous System effects. These medicines make some people feel drowsy, dizzy, lightheaded, or less alert. Insomnia occurs in 3-7% of patients who take ofloxacin. These drugs can quickly concentrate in the brain and interfere with a receptor that normally prevents seizures. Although seizures are very rare, fluoroquinolones should be avoided in patients with a history of convulsion, cerebral trauma, or anoxia. No seizures have been reported with levofloxacin, moxifloxacin, gatifloxacin, and gemifloxacin.
• Phototoxicity. These antibiotics may increase sensitivity to sunlight. Even brief exposure to sun can cause severe sunburn or a rash. While being treated with fluoroquinolones, avoid being in direct sunlight, especially between 10 a.m. and 3 p.m.; wear a hat and tightly woven clothing that covers the arms and legs; use a sunscreen with a skin protection factor (SPF) of at least 15; protect the lips with a sun block lipstick; and do not use tanning beds, tanning booths, or sunlamps. The degree of phototoxic potential of fluoroquinolones is as follows: lomefloxacin > sparfloxacin > ciprofloxacin > norfloxacin = ofloxacin = levofloxacin = gatifloxacin = moxifloxacin.
• Tendon damage (tendonitis and tendon rupture). Some fluoroquinolones may weaken the tendons in the shoulder, hand, or heel, making the tendons more likely to tear. Anyone who notices pain or inflammation in these or other tendon areas should stop taking the medicine immediately and call a physician. Rest and avoid exercise until the physician determines whether the tendons are damaged. If the tendons are torn, surgery may be necessary to repair them. Potential risk factors for tendon damage include age >50 years, male gender, and concomitant use of corticosteroids.
• Cardiovascular effects. The newer quinolones have been found to produce additional toxicities to the heart that were not found with the older compounds. Evidence suggests that sparfloxacin and grepafloxacin may have the most cardiotoxic potential.
• Hypoglycemia/Hyperglycemia. Recently, rare cases of hypoglycemia have been reported with gatifloxacin and ciprofloxacin in patients also receiving oral diabetic medications, primarily sulfonylureas. Although hypoglycemia has been reported with other fluoroquinolones (levofloxacin and moxifloxacin), the effects have been mild.
• Hypersensitivity. Hypersensitivity reactions occur only occasionally during quinolone therapy and are generally mild to moderate in severity, and usually resolve after treatment is stopped.