Azithromycin in Acne
3
ment of lesions); 2=clear (no lesions). Variables
of the two groups such as sex, age, duration of
disease and the entry-level total scores were com-
pared. Discrete variables were analyzed by Fish-
ers Exact Test supplemented by categorical lin-
ear models. The studen’s t test was used to ana-
lyze the differences in means. Chi-square test
with or without Yates correction was applied. In-
tention to treat analysis was also used. Intention
to treat includes all randomized patients in the
groups to which they were randomly assigned,
regardless of the treatment they actually re-
ceived, and regardless of subsequent withdrawal
from the treatment on division from the proto-
col. There are two reasons why one might use
this approach first; intention to treat preserves
the effect of ramdomization. Second, intention
to treat often provides an assessment of the prac-
tical impact of a treatment.
tion in inflammatory as well as non-inflam-
matory lesion counts. Both treatment
groups showed reductions in lesions from
the baseline at each evaluation time. There
were no significant differences in the lesion
counts between the two treatment groups
on a pure protocol basis. The ITT showed a
highly statistically significant decrease in le-
sions in group B patients (Azithromycin)
(Fig. 2).
Efficacy results—severity grade:
The efficacy was also determined from
the global severity grade and is shown in
Table 2. There were no significant differ-
ences in the baseline severity grade. The
scores of both groups decreased from base-
line to week 12 with no statistically signifi-
cant differences. However, ITT showed a
highly statistically significant decrease in
severity score in the azithromycin group.
Efficacy results—global assessment of improve-
ment:
Results
Of 60 patients, 22 in group A and 28 in
group B could be evaluated (Table 1).
Three patients in group A discontinued
treatment because of intolerable side effects
of doxycycline and five patients discontin-
ued for non-medical reasons (protocol vio-
lation, loss to follow up etc.). Two patients
in group B discontinued because of reasons
unrelated to the study. All the patients en-
rolled in the study were retained for the in-
tention to treat analysis (ITT). There was no
significant difference at baseline in disease
severity parameters between the two groups.
Two patients in group A complained of se-
vere nausea and one developed photosensi-
tivity with doxycycline and withdrew from
the study. Two patients developed vaginitis
and five complained of mild to moderate
gastrointestinal discomfort. Monthly doses
of azithromycin were well tolerated except
for patients who complained of mild and
transient gastrointestinal discomfort. Three
patients in group A and four patients in
group B complained of mild irritation from
the topical tretinoin application.
Eighteen patients in group A and 23 pa-
tients in group B were rated as improved;
the Chi-square test and ITT indicated statis-
tically significant improvement in the
azithromycin group.
Discussion
The unique pharmacokinetics of azithro-
mycin makers it a highly suitable agent for
the treatment of acne. It appears that tissue
fibroblasts act as a natural reservoir for the
drug in vivo and that transfer of the drug to
phagocytes is easily accomplished. These
phagocytic cells could act as a vector for de-
livering azithromycin to the site of infection.
Azithromycin shows activity against many
anaerobic species, including Propionobacteri-
um acnes, which is inhibited in vitro at a min-
imum inhibitory concentration of 0.15
µg/ ml or even less for 90% of isolates.
Whether its action is medicated through an-
timicrobial activity or through some anti-in-
flammatory activities is not yet clear. A de-
crease in free fatty acid formation has been
reported with erythromycin. No pharmaco-
kinetic drug-drug interactions have been
observed in trials studying the concomitant
Efficacy results—lesion counts:
Figure 1 shows the efficacy results of both
the treatments in term of percentage reduc-