CLINICAL PHARMACOLOGY
Microbiology
Chlorhexidine gluconate is active
against a broad spectrum of microbes. The chlorhexidine molecule, due to its
positive charge, reacts with the microbial cell surface, destroys the integrity
of the cell membrane, penetrates into the cell, precipitates the cytoplasm, and
the cell dies. Studies with PerioChip showed reductions in the numbers of the
putative periodontopathic organisms Porphyromonas (Bacteroides) gingivalis,
Prevotella (Bacteroides) intermedia, Bacteroides forsythus, and Campylobacter
rectus (Wolinella recta) after placement of the chip. No overgrowth of
opportunistic organisms or the adverse changes in the oral microbial ecosystem
were noted. The relationship of the microbial findings to clinical outcome has
not been established.
Pharmacokinetics
PerioChip releases chlorhexidine in
vitro in a biphasic manner, initially releasing approximately 40% of the
chlorhexidine within the first 24 hours and then releasing the remaining
chlorhexidine in an almost linear fashion for 7-10 days. This enzymatic release
rate assay is an experimental collagenase assay that differs from the
Regulatory Specification's Agar Release Rate Assay. This release profile may be
explained as an initial burst effect, dependent on diffusion of chlorhexidine
from the chip, followed by a further release of chlorhexidine as a result of
enzymatic degradation.
In an in vivo study of 18
evaluable adult patients, there were no detectable plasma or urine levels of
chlorhexidine following the insertion of 4 PerioChips under clinical
conditions. The concentration of chlorhexidine released from the PerioChip was
determined in the gingival crevicular fluid (GCF) of these same subjects. In
these subjects, a highly variable biphasic release profile for chlorhexidine
was demonstrated, with GCF levels 4 hours after chip insertion (mean: 1444 ±
783 μg/mL), followed by a second peak at 72 hours (mean: 1902 ± 1073
μg/mL). In a second study involving the insertion of 1 PerioChip under
clinical conditions, the mean GCF level of chlorhexidine peaked at 1088 ± 678
μg/mL at 4 hours. The mean GCF levels then declined in a highly
erratic fashion to levels of 482 ± 447 μg/mL at 72 hours without producing
a true second peak.
The results of these studies
confirm a high degree of intersubject variability in chlorhexidine release from
the PerioChip matrix in vivo that was not seen in vitro. Due to the nature and
clinical use of the PerioChip dosage form, dose proportionality was not and
would not be expected to be demonstrated between the two studies.
Clinical Studies
In two double-blind, randomized, controlled clinical trials,
447 adult patients with periodontitis were entered who had at least 4 pockets
with probing depth of 5-8 mm that bled on probing. Patients studied were in
good general health. Diabetics were excluded from the studies. PerioChip was
not studied in acutely abscessed periodontal pockets. Patients were free of
supragingival calculus prior to baseline. In these two studies, the effects of
scaling and root planing (SRP) alone, and SRP followed by PerioChip treatment,
were compared. All patients received full mouth SRP at baseline. If the pocket
depth remained ≥ 5 mm at 3 and/or 6 months after initial treatment,
another chip was placed into the pocket. Teeth treated with PerioChip were
found to have significantly reduced probing pocket depth (PD) compared with
those treated with SRP alone at 9 months after initial treatment, as shown on
Table 1.
Table 1 : Probing pocket depth (PD) at baseline and
reduction in PD at 9 months from 2 five-center U.S. clinical trials (in mm,
mean ± SE)
Time |
Study # 94 – 002 |
Study # 94 - 003 |
SRP alone |
SRP + PerioChip |
SRP alone |
SRP + PerioChip |
PD at Baseline |
5.69 ± 0.58
(n = 107) |
5.79 ± 0.61
(n = 108) |
5.56 ± 0.54
(n = 115) |
5.67 ± 0.56
(n = 117) |
PD Reduction at 9 months |
0.78 ± 0.07
(n = 101) |
1.06 ± 0.07*
(n = 101) |
0.52 ± 0.07
(n = 107) |
0.84 ± 0.08**
(n = 110) |
SE = standard error; SRP = Scaling
and Root Planing Significantly different from SRP alone:
* (p = 0.006);
** (p =
0.001) |
PerioChip treatment resulted in a
greater percentage of pockets and patients that showed an improvement in PD of
2 mm or more compared with SRP alone at 9 months, as shown in Table 2. The
differences in improvement were statistically significant when analyzed on a
per patient basis (p < 0.005). PerioChip treatment maintained probing
attachment level (PAL) compared with baseline or with SRP alone at 9 months.
The effects of PerioChip on bleeding upon probing have not been established. In
the two studies, there were no significant changes in plaque development or
gingivitis. Smokers and non-smokers were enrolled in these studies; although
non-smokers using PerioChip demonstrated significant improvement in PD, smokers
demonstrated a trend towards improvement that did not reach statistical
significance. This finding is consistent with the consensus that smoking is a
risk factor in periodontal diseases.
Table 2 : Number (percentage) of pockets and
patients with an improvement in PD ≥ 2mm at 9 months from 2 five-center
U.S. clinical trials
|
Study #94-002 |
Study #94-003 |
SRP alone |
SRP + PerioChip |
SRP alone |
SRP + PerioChip |
Pockets |
21/202 (11%) |
44/202 (22%) |
12/214 (6%) |
36/220 (16%) |
Patients (one or both sites) |
17/101 (17%) |
36/101 (36%) |
11/107 (10%) |
28/110 (25%) |
In the two clinical studies above
and an additional study (619 patients), the adverse effects of tooth staining
or altered taste perception were not reported after the use of PerioChip.