Microbiology
Doxycycline is a broad-spectrum semisynthetic tetracycline.1 Doxycycline
is bacteriostatic, inhibiting bacterial protein synthesis due to disruption
of transfer RNA and messenger RNA at ribosomal sites.1 In vitro testing
has shown that Porphyromonas gingivalis, Prevotella intermedia, Campylobacter
rectus, and Fusobacterium nucleatum, which are associated with periodontal disease,
are susceptible to doxycycline at concentrations ≤ 6.0 μg/mL.2 A
single-center, single-blind, randomized, clinical study in 45 subjects with
periodontal disease demonstrated that a single treatment with ATRIDOX® resulted
in the reduction in the numbers of P. gingivalis, P. intermedia, C. rectus,
F. nucleatum, Bacteroides forsythus, and E. corrodens in subgingival plaque
samples. Levels of aerobic and anaerobic bacteria were also reduced after treatment
with ATRIDOX® . The clinical significance of these findings, however, is
not known. During these studies, no overgrowth of opportunistic organisms such
as Gram-negative bacilli and yeast were observed. However, as with other antibiotic
preparations, ATRIDOX® therapy may result in the overgrowth of nonsusceptible
organisms including fungi. (See PRECAUTIONS)
Pharmacokinetics
In a clinical pharmacokinetic study, subjects were randomized to receive either
ATRIDOX® covered with Coe-Pak™ periodontal dressing (n=13), ATRIDOX® covered
with Octyldent® periodontal adhesive (n=13), or oral doxycycline (n=5) (according
to package dosing instructions). The doxycycline release characteristics in
gingival crevicular fluid (GCF), saliva, and serum were evaluated.
Doxycycline levels in GCF peaked (-1,500 μg/mL and -2000 μg/mL for Coe-Pak™
and Octyldent® groups, respectively) 2 hours following treatment with ATRIDOX® .
These levels remained above 1000 μg/mL through 18 hours, at which time the
levels began to decline gradually. However, local levels of doxycycline remained
well above the minimum inhibitory concentration (MIC90) for periodontal pathogens
( 6.0 μg/mL)2 through Day 7. In contrast, subjects receiving oral
doxycycline had peak GCF levels of -2.5 μg/mL at 12 hours following the initial
oral dosing with levels declining to -0.2 μg/mL by Day 7. High variability
was observed for doxycycline levels in GCF for both oral and ATRIDOX® treatment
groups.
The ATRIDOX® doxycycline release profile in GCF is illustrated in the figure
below.
The maximum concentration of doxycycline in saliva was achieved at 2 hours
after both treatments with ATRIDOX® , with means of 4.05 μg/mL and 8.78
μg/mL and decreased to 0.36 μg/mL and 0.23 μg/mL at Day 7 for the Coe-Pak™
group and the Octyldent® group, respectively.
The concentration of doxycycline in serum following treatment of ATRIDOX® never
exceeded 0.1 μg/mL.
Clinical Studies
In 2 well-controlled, multicenter, parallel-design, 9-month clinical trials,
831 patients patients (Study 1=411; Study 2=420) with chronic adult periodontitis
characterized by a mean probing depth of 5.9 to 6.0 mm were enrolled. Subjects
received 1 of 4 treatments: 1) ATRIDOX® , 2) Scaling and Root Planing, 3)
Vehicle Control, or 4) Oral Hygiene. Treatment was administered to sites with
probing depths 5 mm or greater that bled on probing. Subjects with detectable
subgingival calculus on greater than 80% of all tooth surfaces were excluded
from enrollment. All subjects received a second administration of the initially
randomized treatment 4 months after their Baseline treatment. Changes in the
efficacy parameters, attachment level, pocket depth, and bleeding on probing,
between Baseline and Month 9 showed that: 1) ATRIDOX® was superior to Vehicle
Control and Oral Hygiene, and 2) ATRIDOX® met the decision rule of being
at least 75% as good as Scaling and Root Planing (SRP) (the standard of at least
75% as good as SRP is required for any product approved as a stand alone therapy
for periodontitis). Clinicians should note that the studies were of 9 months
duration. Additional research would be necessary to establish long-term comparability
to SRP. The results of Studies #1 and 2 for efficacy parameters of attachment
level gain and probing depth reduction are included in the following graphs.
* denotes statistically significant superiority of ATRIDOX® and Sc/RP vs.
Vehicle and Oral Hygiene
† denotes statistically significant superiority of ATRIDOX® vs. Vehicle
and Oral Hygiene
Data were not collected at months 3 and 7
* denotes statistically significant superiority of ATRIDOX® and Sc/RP vs.
Vehicle and Oral Hygiene
† denotes statistically significant superiority of ATRIDOX® vs. Vehicle
and Oral Hygiene
Data were not collected at months 3 and 7
A third clinical trial was conducted to determine whether the product can be
left in the pocket to bioabsorb or be expelled naturally and achieve comparable
clinical results. In this study, the product was retained with Octyldent® dental
adhesive rather than Coe-Pak™ periodontal dressing as in the previously
mentioned studies. This was a 3-arm, randomized, controlled, parallel group,
single-blind trial that enrolled 605 subjects. The patient population studied
and study design were comparable to that in Studies 1 and 2. Subjects received
1 of 3 treatments: 1) ATRIDOX® with Coe-Pak™ removed after 7 days as
in the pivotal trials, 2) ATRIDOX® retained with Octyldent® and left to
bioabsorb or be expelled naturally or 3) Vehicle Control with Octyldent® left
to bioabsorb or be expelled naturally. Changes in the efficacy parameters, attachment
level, pocket depth and bleeding on probing were equivalent to those observed
in Studies 1 and 2. The results of the third study support the use of ATRIDOX® retained
with Octyldent® and left to bioabsorb or be expelled naturally.
REFERENCES
1. Stratton CW, Lorian V. Mechanisms of action for antimicrobial
agents: general principals and mechanisms for selected classes of antibiotics.
Antibiotics in Laboratory Medicine. 4th ed. Baltimore, MD: Williams & Wilkings;1996.
2. Slots J, Rams TE. Antibiotics in periodontal therapy: advantages
and disadvantages. J Clin Periodontal. 1990;17:479-493.
Last updated on RxList: 5/2/2008