Clarithromycin is an orally active, advanced-generation
macrolide that has been reformulated as an extended-release
tablet (
Biaxin) XL Filmtab allowing convenient once-daily administration. The reformulation is intended to improve patient compliance and the tolerability of the
drug. Although maximum plasma
clarithromycin concentrations are lower and reached later with the extended-release
tablets than with the immediate-release
tablets, the two formulations are bioequivalent with respect to the area under the plasma concentration-time curve. Bioequivalence is also achieved between the formulations for the microbiologically active metabolite, 14-hydroxy-clarithromycin. Two randomized trials in patients with acute exacerbations of
chronic bronchitis (AECB) showed that a 7-day course of
clarithromycin extended-release 1000 mg once daily produced clinical cure rates of 83% and 85% and bacteriologic cure rates of 86% and 92% at the test-of-cure study visit. Similar rates of cure were achieved with a 7-day course of twice-daily
clarithromycin immediate-release and with a 10-day course of twice-daily
amoxicillin/clavulanic acid.A 7-day course of
clarithromycin extended-release 1000 mg once daily produced clinical and bacteriologic cure rates of 88% and 86%, respectively, in patients with community-acquired
pneumonia (CAP). Similar cure rates were achieved in recipients of once-daily
levofloxacin in the same trial. In patients with acute
maxillary sinusitis, a 14-day course of either once-daily
clarithromycin extended-release or twice-daily
clarithromycin immediate-release produced statistically equivalent clinical cure rates of 85% and 79%, respectively. Both treatment groups achieved similar rates of radiographic success and resolution of
sinusitis. Recent results indicate that
clarithromycin extended-release 500 mg once daily for 5 days is also effective in the treatment of patients with streptococcal
pharyngitis/
tonsillitis and in the treatment of AECB. The most frequently reported
drug-related events with
clarithromycin extended-release were abnormal taste (7% incidence),
diarrhea (6%) and
nausea (3%). Most
adverse drug reactions were of a mild and transient nature. In comparative clinical trials,
clarithromycin extended-release had an improved gastrointestinal tolerability profile compared with the immediate-release formulation. In addition,
clarithromycin extended-release was better tolerated than
amoxicillin/clavulanic acid and as well tolerated as
levofloxacin. Further studies are required to assess the cost-effectiveness ratio of
clarithromycin relative to comparator
antibacterial agents.
CONCLUSION: