Gatifloxacin

Gatifloxacin is a prescription drug used for the treatment of various bacterial infections. It is an antibiotic in the category called fluoroquinolones. Other members of this family include ciprofloxacin (Cipro)and levofloxacin (Levaquin).

Gatifloxacin was introduced into the U.S. market in December 1999, under the name Tequin, for infections of the respiratory tract. However, seven years later it was removed from the U.S. and Canadian markets because of safety concerns. In these countries, gatifloxacin is available in an eye drop, called Zymar, for the treatment of bacterial conjunctivitis. Other forms of gatifloxacin, such as tablets and intravenously-administered solutions, are still available in other countries.

Structure of gatifloxacin. Source: Wikimedia Commons

Other Names

Gatifloxacin is sold as Tequin in several countries. The eye drop formulation is sold as Zymar.

Uses

Gatifloxacin, in Tequin, is used to treat numerous bacterial infections:

• worsening of chronic bronchitis
• sinusitis
• community-acquired pneumonia
• uncomplicated skin infections
• urinary tract infections
• pyelonephritis
• uncomplicated urethral, cervical and rectal gonorrhea

Gatifloxacin, in Zymar, is used to treat conjunctivitis, which is inflammation in the covering of the eyeball and is sometimes called pink eye.

How Gatifloxacin is Taken

Tequin is sold as 200-mg and 400-mg tablets or in an intravenous solution at a concentration of 2 mg gatifloxacin/ml. The recommended daily dose is 400 mg. The duration of treatment depends on the specific infection.

Zymar is provided as a 0.3% solution of gatifloxacin. The typical dosage regimen is as follows: on days one and two of infection, instill one drop into the affected eye every two hours while awake (but not to exceed eight drops a day), and for the next five days instill one drop up to four times daily.

How Gatifloxacin Works

Gatifloxacin is a fluoroquinolone antibiotic. Like all fluoroquinolones, gatifloxacin inhibits two bacterial enzymes, DNA gyrase and topoisomerase IV. DNA gyrase helps replicate and repair DNA, and topoisomerase IV helps bacterial cells replicate. Thus, gatifloxacin prevents bacteria from replicating. This allows the body’s immune system to remove the infection.

Gatifloxacin is effective in treating infections that are resistant to drugs in other antibiotic families. Similarly, other families of antibiotics are effective against infections that are resistant to treatment with gatifloxacin.

How the Body Affects Gatifloxacin

The oral form of gatifloxacin, Tequin, is well absorbed from the gastrointestinal tract and reaches a peak in the circulation one to two hours after dosing. Intravenously-administered Tequin is not absorbed in the intestines because it enters the bloodstream directly. Zymar, the eye drop form, does not appreciably enter the blood. It remains at the site of action, the eye.

Gatifloxacin is mainly excreted as unchanged drug via the kidney. More than 70% of the original dose is excreted as unchanged drug in the urine and 5% of the original dose is excreted in the feces.

Side Effects

Side effects of Tequin that occur in 3% or more of people include the following:

• nausea
• vaginitis
• diarrhea
• headache
• dizziness

Some of the most common side effects of Zymar include eye irritation, increased tear production, and inflammation.

Risks and Precautions

A major risk associated with Tequin is the development of severe diabetes. A study of approximately 1.4 million Canadians 66 years of age or older found that gatifloxacin increased the risk of low blood sugar over 400% and increased the risk of high blood sugar over 1,600%.^[1] Tequin was removed from the U.S. and Canadian markets because of this risk.

Premature discontinuation of any antibiotic increases the risk of bacteria growing resistant to treatment.

Drug Interactions

Because Tequin is primarily eliminated in the urine, drugs that affect kidney function could increase blood concentrations of the antibiotic. Some drugs that affect kidney function include digoxin and non-steroidal anti-inflammatory drugs (aspirin, ibuprofen).

History

Bristol-Myers Squibb began marketing Tequin in 1999. In March of 2006, a study was published in the New England Journal of Medicine that suggested Tequin negatively influences blood sugar control.^[1] The study showed that Tequin caused low blood sugar in some people and high blood sugar in others. Uncontrolled sugar levels increase the risk of diabetes. Bristol-Myers Squibb removed Tequin from the U.S. and Canadian markets two months later and returned rights to the drug back to Tequin’s developer, the Japanese pharmaceutical company Kyorin. Tequin is still available in some countries. The eye drop form of gatifloxacin, Zymar, entered the market in March 2003 and is marketed by Allergan. This form is available in the United States and Canada because the safety profile of Zymar is much better than that of Tequin and side effects are limited to the eye.

Research

Several studies have demonstrated Tequin's effectiveness in treating community-acquired respiratory infections. In one of the largest, TeqCES, , gatifloxacin had cure rates of over 90%.^[2] For sinusitis, gatifloxacin was found to be more effective thanamoxicillin/clavulanate in a 2002 multicenter study.^[3] Reviews have summarized the effectiveness of gatifloxacin in skin infections ^[4] and urinary tract infections.^[5]

In a study of 104 patients with bacterial conjunctivitis, cure rates of gatifloxacin eye drops were over 70%.^[6]

References

1. ↑ ^{1.0 1.1} Park-Wyllie LY, Juurlink DN, Kopp A, et al. Outpatient gatifloxacin therapy and dysglycemia in older adults. N Engl J Med. 2006 Mar 30;354(13):1352-61. Abstract | Full Text | PDF
2. ↑ Gotfried M, Quinn TC, Gothelf S, Wikler MA, Webb CD, Nicholson SC. Oral gatifloxacin in outpatient community-acquired pneumonia: results from TeqCES, a community-based, open-label, multicenter study. Diagn Microbiol Infect Dis. 2002 Sep;44(1):85-91. Abstract
3. ↑ Sher LD, McAdoo MA, Bettis RB, Turner MA, Li NF, Pierce PF. A multicenter, randomized, investigator-blinded study of 5- and 10-day gatifloxacin versus 10-day amoxicillin/clavulanate in patients with acute bacterial sinusitis. Clin Ther. 2002 Feb;24(2):269-81. Abstract
4. ↑ Giordano P, Weber K, Gesin G, Kubert J. Skin and skin structure infections: treatment with newer generation fluoroquinolones. Ther Clin Risk Manag. 2007 Jun;3(2):309-17. Abstract | Full Text | PDF
5. ↑ Mehnert-Kay SA. Diagnosis and management of uncomplicated urinary tract infections. Am Fam Physician. 2005 Aug 1;72(3):451-6. Abstract | Full Text
6. ↑ Yee RW, Tepedino M, Bernstein P, Jensen H, Schiffman R, Whitcup SM; Gatifloxacin BID/QID Study Group. A randomized, investigator- masked clinical trial comparing the efficacy and safety of gatifloxacin 0.3% administered BID versus QID for the treatment BID versus QID for the treatment of acute bacterial conjunctivitis of acute bacterial conjunctivitis. Curr Med Res Opin. 2005 Mar;21(3):425-31. Abstract

External Links

CNN News Report: Antibiotic gatifloxacin (Tequin) pulled from market

FDA: Patient Information Sheet