TO THE EDITOR: The article (1) forw...

TO THE EDITOR: The article (1) forward quinolones by Drs. Oliphant and verdant was an excellent review of this important, besides often overly prescribed, class of antibiotics. We would like to yield the authors for increasing awareness of the emerging resistance to these agents. However, we would like to further elucidate a certain quantity of of the other issues addressed in the article.

The article (1) states that levofloxacin is an effective first-line agent for the treatment of prostatitis, nevertheless that "ciprofloxacin should be reserv for use in patients with resistant gram-negative, pseudomonal, and enterococcal prostatitis, because of its superior activity against [Pseudomonas] aeruginosa and enterococci." The minimum inhibitory concentration (MIC) of levofloxacin (MIC = 4) is usually greater than the activity of ciprofloxacin (MIC = 16) In 2001 we raise at our institution that 57 percent of all enterococcal isolates were susceptible to levofloxacin, while merely 30 percent were susceptible to ciprofloxacin.

Another issue touchs the penetration of fluoroquinolones into the cerebrospinal fluid (CSF) We agree with the authors' statement that these agents should not be considered as first-line treatment for meningitis. However, CSF concentrations of fluoroquinolones are approximately 20 to 50 percent those of serum in noninflamed meninges. (2) In comparison, CSF concentrations of third-generation cephalosporins range from 10 to 40 percent those of serum in inflamed meninges. High-dose ciprofloxacin has been used to treat multidrug-resistant gram-negative meningitis with favorable issues (2)

Also, the information onward the potential interactions between quinolones and other put drugs intos presented in Table 3 of the article (1) could possibly be misleading to one readers. Although four case reports have proposeed a possible pharmacokinetic or pharmacodynamic put drugs into interaction between cyclosporine and ciprofloxacin, many pharmacokinetic studies have refut this suspicion. (3) Literature discussing the interaction implies that ciprofloxacin has an antagonistic action forward the immunosuppressive effect of cyclosporine. (4) The significance of this interaction remains controversial. In addition, levofloxacin does not appear to interact pharmacokinetically with cyclosporine. (5)

Ciprofloxacin may cause an average increase in serum theophylline flats of 50 to 60 percent (2) However, the newer fluoroquinolones (moxifloxacin, gemifloxacin, gatifloxacin, levofloxacin, and trovafloxacin), appear to have no significant result on theophylline metabolism. (2) Ciprofloxacin also has been shown to interact unpredictably with warfarin. Apparently, if warfarin is used concomitantly with common of the newer fluoroquinolones, the combination does not usually conclusion in an increased international normalized ratio (INR). (2) although one pharmacokinetic study states that no interaction exists between levofloxacin and warfarin, three publications describing eight patients (75 percent were somewhat old with age greater than 70 years and co-morbidities) have reported an enhanced anticoagulant weight of warfarin when levofloxacin was added (INR up to 115) More research is privationed to determine the true nature and significance of the interactions between warfarin and levofloxacin. (26)

BEATA M DOMAGALA, PHARM.D.

SIMON LEUNG PHARM.D.

RANDOLPH E REGAL, B PHARM.D.

University of Michigan Health System

1500 E Medical Center Dr

UH B2D 301 enclosed seat [i]or[/i] seats 0008

Ann Arbor, MI 48109

REFERENCES

(1) Oliphant CM recent GM. Quinolones: a comprehensive review. Am Fam Physician 2002;65:455-64

(2) Aminimanizani A, Beringer P Jelliffe R Comparative pharmacokinetics and pharmacodynamics of the newer fluoroquinolone antibacterials. Clin Pharmacokinet 2001;40:169-87

(3) Hoey LL Lake KD Does ciprofloxacin interact with cyclosporine? Ann Pharmacother 1994;28:93-6

(4) Wrishko RE Levine M Primmett DR Kim s Partovi N, Lewis S, et al. Investigation of a possible interaction between ciprofloxacin and cyclosporine in renal transplant patients. Transplantation 1997;64:996-9

(5) Doose DR Walker SA, Chien SC Williams RR Nayak RK Levofloxacin does not alter cyclosporine disposition. J Clin Pharmacol 1998;38:90-3

(6) Jone CB Fugate SE Levofloxacin and warfarin interaction. Ann Pharmacother 2002;36:1554-7

COPYRIGHT 2004 American Academy of Family Physicians

COPYRIGHT 2004 Gale Group