Monograph: |
Roxithromycin
A white crystalline powder. It exhibits polymorphism. Very
slightly soluble in water, freely soluble in alcohol, in acetone.
and in dichloromethane; slightly soluble in dilute hydrochlo-
ric acid. Store in airtight containers .
Adverse Effects and Precautions
As for Erythromycin . Gastro-intestinal disturbances
are the most frequent adverse effect, but are less frequent than
with erythromycin. Increases in liver enzyme values and hep-
atitis have been reported. Rashes and other hypersensitivity
reactions, headache, dizziness, weakness, and changes in
blood cell counts have also occurred.
Effects on the pancreas. Acute pancreatitis, with duodenal
inflammation, pain, pancreatic enlargement and raised serum-
amylase developed within 24 hours of substitution of roxi-
thromycin for erythromycin ethyl succinate in a patient being
treated for respiratory-tract infection. Symptoms resolved
rapidly once roxithromycin was withdrawn.
Eosinophilia. For a report of an eosinophilic syndrome in a
patient following treatment with azithromycin or roxithromy-
cin. see Azithromycin.
Interactions
For a discussion of drug interactions with macrolide antibac-
terials, see Erythromycin.
Antimicrobial Action
As for Erythromycin. It is reported to be as active or
slightly less active than erythromycin.
Pharmacokinetics
Following oral administration roxithromycin is absorbed.
with a bioavailability of about 50%. Peak plasma concentra-
tions of about 6 to 8 ng per mL occur around 2 hours after a
single dose of 150 mg. The mean peak plasma concentration
at steady state after a dose of 150 mg twice daily is 9,3 ng per
mL. Absorption is reduced when taken after, but not before, a
meal. It is widely distributed in tissues and body fluids. It is
reported to be about 96% bound to plasma protein (mainly a)-
acid glycoprotein) at trough concentrations, but binding is
saturable. and only about 86% is bound at usual peak concen-
trations. Small amounts of roxithromycin are metabolised in
the liver, and the majority of a dose is excreted in the faeces
as unchanged drug and metabolites; about 7 to 12% is excret-
ed in urine, and up to 15% via the lungs. The elimination half-
life is reported to range between about 8 and 13 hours, but
may be more prolonged in patients with impaired hepatic or
renal function and in children.
Uses and Administration
Roxithromycin is a macrolide antibiotic with actions and uses
similar to those of erythromycin . It is given by mouth
in a dose of 150 mg twice daily or sometimes 300 mg once
daily, before meals, in the treatment of susceptible infections.
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