General:
SUBOXONE and SUBUTEX should be administered with caution in
elderly or debilitated patients and those with severe impairment of hepatic,
pulmonary, or renal function; myxedema or hypothyroidism, adrenal cortical
insufficiency (e.g., Addison's disease); CNS depression or coma; toxic
psychoses; prostatic hypertrophy or urethral stricture; acute alcoholism;
delirium tremens; or kyphoscoliosis.
The effect of hepatic impairment on the pharmacokinetics of buprenorphine and
naloxone is unknown. Since both drugs are extensively metabolized, the plasma
levels will be expected to be higher in patients with moderate and severe
hepatic impairment. However, it is not known whether both drugs are affected to
the same degree. Therefore, dosage should be adjusted and patients should be
watched for symptoms of precipitated opioid withdrawal.
Buprenorphine has been shown to increase intracholedochal pressure, as do
other opioids, and thus should be administered with caution to patients with
dysfunction of the biliary tract.
As with other mu-opioid receptor agonists, the administration of SUBOXONE or
SUBUTEX may obscure the diagnosis or clinical course of patients with acute
abdominal conditions.
Drug Interactions:
Buprenorphine is metabolized to norbuprenorphine by cytochrome
CYP 3A4. Because CYP 3A4 inhibitors may increase plasma concentrations of
buprenorphine, patients already on CYP 3A4 inhibitors such as azole antifungals
(e.g. ketoconazole), macrolide antibiotics (e.g. erythromycin), and HIV protease
inhibitors (e.g. ritonavir, indinavir and saquinavir) should have their dose of
SUBUTEX or SUBOXONE adjusted.
Based on anecdotal reports, there may be an interaction between buprenorphine
and benzodiazepines. There have been a number of reports in the post-marketing
experience of coma and death associated with the concomitant intravenous misuse
of buprenorphine and benzodiazepines by addicts. In many of these cases,
buprenorphine was misused by self-injection of crushed SUBUTEX tablets. SUBUTEX
and SUBOXONE should be prescribed with caution to patients on benzodiazepines or
other drugs that act on the central nervous system, regardless of whether these
drugs are taken on the advice of a physician or are taken as drugs of abuse.
Patients should be warned of the potential danger of the intravenous
self-administration of benzodiazepines while under treatment with SUBOXONE or
SUBUTEX.
Information for Patients:
Patients should inform their family members that, in the event of
emergency, the treating physician or emergency room staff should be informed
that the patient is physically dependent on narcotics and that the patient is
being treated with SUBOXONE or SUBUTEX.
Patients should be cautioned that a serious overdose and death may occur if
benzodiazepines, sedatives, tranquilizers, antidepressants, or alcohol are taken
at the same time as SUBOXONE or SUBUTEX.
SUBOXONE and SUBUTEX may impair the mental or physical abilities required for
the performance of potentially dangerous tasks such as driving a car or
operating machinery, especially during drug induction and dose adjustment.
Patients should be cautioned about operating hazardous machinery, including
automobiles, until they are reasonably certain that buprenorphine therapy does
not adversely affect their ability to engage in such activities. Like other
opioids, SUBOXONE and SUBUTEX may produce orthostatic hypotension in ambulatory
patients.
Patients should consult their physician if other prescription medications are
currently being used or are prescribed for future use.
Carcinogenesis, Mutagenesis and Impairment of
Fertility:
Carcinogenicity: Carcinogenicity data
on SUBOXONE are not available. Carcinogenicity studies of buprenorphine were
conducted in Sprague-Dawley rats and CD-1 mice. Buprenorphine was administered
in the diet to rats at doses of 0.6, 5.5, and 56 mg/kg/day (estimated exposure
was approximately 0.4, 3 and 35 times the recommended human daily sublingual
dose of 16 mg on a mg/m2 basis) for 27 months.
Statistically significant dose-related increases in testicular interstitial
(Leydig's) cell tumors occurred, according to the trend test adjusted for
survival. Pair-wise comparison of the high dose against control failed to show
statistical significance. In an 86-week study in CD-1 mice, buprenorphine was
not carcinogenic at dietary doses up to 100 mg/kg/day (estimated exposure was
approximately 30 times the recommended human daily sublingual dose of 16 mg on a
mg/m2 basis).
Mutagenicity:
SUBOXONE: The 4:1 combination of buprenorphine and naloxone was
not mutagenic in a bacterial mutation assay (Ames test) using four strains of
S. typhimurium and two strains of E coli. The combination was not clastogenic in an in vitro cytogenetic assay in human lymphocytes, or in an
intravenous micronucleus test in the rat.
SUBUTEX: Buprenorphine was studied in a series of tests utilizing
gene, chromosome, and DNA interactions in both prokaryotic and eukaryotic
systems. Results were negative in yeast (Saccharomyces
cerevisiae) for recombinant, gene convertant, or forward mutations;
negative in Bacillus subtilis "rec"assay, negative
for clastogenicity in CHO cells, Chinese hamster bone marrow and spermatogonia
cells, and negative in the mouse lymphoma L5178Y assay. Results were equivocal
in the Ames test: negative in studies in two laboratories, but positive for
frame shift mutation at a high dose (5mg/plate) in a third study. Results were
positive in the Green-Tweets (E. coli) survival test,
positive in a DNA synthesis inhibition (DSI) test with testicular tissue from
mice, for both in vivo and in
vitro incorporation of [3H]thymidine, and positive
in unscheduled DNA synthesis (UDS) test using testicular cells from mice.
Impairment of Fertility:
SUBOXONE: Dietary administration of SUBOXONE in the rat at dose
levels of 500 ppm or greater (equivalent to approximately 4/mg/kg/day or
greater; estimated exposure was approximately 28 times the recommended human
daily sublingual dose of 16 mg on a mg/m2 basis) produced
a reduction in fertility demonstrated by reduced female conception rates. A
dietary dose of 100 ppm (equivalent to approximately 10 mg/kg/day; estimated
exposure was approximately 6 times the recommended human daily sublingual dose
of 16 mg on a mg/m2 basis) had no adverse effect on
fertility.
SUBUTEX: Reproduction studies of buprenorphine in rats
demonstrated no evidence of impaired fertility at daily oral doses up to
80mg/kg/day (estimated exposure was approximately 50 times the recommended human
daily sublingual dose of 16 mg on a mg/m2 basis) or up to
5mg/kg/day im or sc
(estimated exposure was approximately 3 times the recommended human daily
sublingual dose of 16 mg on a mg/m2 basis).
Pregnancy;Pregnancy Category C:Teratogenic effects:
SUBOXONE: Effects on embryo-fetal development were studied in
Sprague-Dawley rats and Russian white rabbits following oral (1:1) and
intramuscular (3:2) administration of mixtures of buprenorphine and naloxone.
Following oral administration to rats and rabbits, no teratogenic effects were
observed at doses up to 250 mg/kg/day and 40 mg/kg/day, respectively (estimated
exposure was approximately 150 times and 50 times, respectively, the recommended
human daily sublingual dose of 16 mg on a mg/m2 basis).
No definitive drug-related teratogenic effects were observed in rats and rabbits
at intramuscular doses up to 30 mg/kg/day (estimated exposure was approximately
20 times and 35 times, respectively, the recommended human daily dose of 16 mg
on a mg/m2 basis). Acephalus was observed in one rabbit
fetus from the low-dose group and omphacele was observed in two rabbit fetuses
from the same litter in the mid-dose group; no findings were observed in fetuses
from the high-dose group. Following oral administration to the rat, dose-related
post-implantation losses, evidenced by increases in the numbers of early
resorptions with consequent reductions in the numbers of fetuses, were observed
at doses of 10 mg/kg/day or greater (estimated exposure was approximately 6
times the recommended human daily sublingual dose of 16 mg on a mg/m2 basis). In the rabbit, increased post-implantation losses
occurred at an oral dose of 40 mg/kg/day. Following intramuscular administration
in the rat and the rabbit, post-implantation losses, as evidenced by decreases
in live fetuses and increases in resorptions, occurred at 30 mg/kg/day.
SUBUTEX: Buprenorphine was not teratogenic in rats or rabbits after im or sc doses up to 5 mg/kg/day
(estimated exposure was approximately 3 and 6 times, respectively, the
recommended human daily sublingual dose of 16 mg on a mg/m2 basis), after iv doses up to 0.8
mg/kg/day (estimated exposure was approximately 0.5 times and equal to,
respectively, the recommended human daily sublingual dose of 16 mg on a
mg/m2 basis), or after oral doses up to 160 mg/kg/day in
rats (estimated exposure was approximately 95 times the recommended human daily
sublingual dose of 16 mg on a mg/m2 basis) and 25
mg/kg/day in rabbits (estimated exposure was approximately 30 times the
recommended human daily sublingual dose of 16 mg on a mg/m2 basis). Significant increases in skeletal abnormalities
(e.g., extra thoracic vertebra or thoraco-lumbar ribs) were noted in rats after
sc administration of 1 mg/kg/day and up (estimated
exposure was approximately 0.6 times the recommended human daily sublingual dose
of 16 mg on a mg/m2 basis), but were not observed at oral
doses up to 160 mg/kg/day. Increases in skeletal abnormalities in rabbits after
im administration of 5 mg/kg/day (estimated exposure
was approximately 6 times the recommended human daily sublingual dose of 16 mg
on a mg/m2 basis) or oral administration of 1 mg/kg/day
or greater (estimated exposure was approximately equal to the recommended human
daily sublingual dose of 16 mg on a mg/m2 basis) were not
statistically significant.
In rabbits, buprenorphine produced statistically significant pre-implantation
losses at oral doses of 1 mg/kg/day or greater and post-implantation losses that
were statistically significant at iv doses of 0.2
mg/kg/day or greater (estimated exposure was approximately 0.3 times the
recommended human daily sublingual dose of 16 mg on a mg/m2 basis).
There are no adequate and well-controlled studies of SUBOXONE or SUBUTEX in
pregnant women. SUBOXONE or SUBUTEX should only be used during pregnancy if the
potential benefit justifies the potential risk to the fetus.
Non-teratogenic effects.
Dystocia was noted in pregnant rats treated im with buprenorphine 5 mg/kg/day (approximately 3 times
the recommended human daily sublingual dose of 16 mg on a mg/m2 basis). Both fertility and peri- and postnatal development
studies with buprenorphine in rats indicated increases in neonatal mortality
after oral doses of 0.8 mg/kg/day and up (approximately 0.5 times the
recommended human daily sublingual dose of 16 mg on a mg/m2 basis), after im doses of 0.5
mg/kg/day and up (approximately 0.3 times the recommended human daily sublingual
dose of 16 mg on a mg/m2 basis), and after sc doses of 0.1 mg/kg/day and up (approximately 0.06 times
the recommended human daily sublingual dose of 16 mg on a mg/m2 basis). Delays in the occurrence of righting reflex and
startle response were noted in rat pups at an oral dose of 80 mg/kg/day
(approximately 50 times the recommended human daily sublingual dose of 16 mg on
a mg/m2 basis).
Neonatal Withdrawal:
Neonatal withdrawal has been reported in the infants of women
treated with SUBUTEX during pregnancy. From post-marketing reports, the time to
onset of neonatal withdrawal symptoms ranged from Day 1 to Day 8 of life with
most occurring on Day 1. Adverse events associated with neonatal withdrawal
syndrome included hypertonia, neonatal tremor, neonatal agitation, and
myoclonus. There have been rare reports of convulsions and in one case, apnea
and bradycardia were also reported.
Nursing Mothers:
An apparent lack of milk production during general reproduction
studies with buprenorphine in rats caused decreased viability and lactation
indices. Use of high doses of sublingual buprenorphine in pregnant women showed
that buprenorphine passes into the mother's milk. Breast-feeding is therefore
not advised in mothers treated with SUBUTEX or SUBOXONE.
Pediatric Use:
SUBOXONE and SUBUTEX are not recommended for use in pediatric
patients. The safety and effectiveness of SUBOXONE and SUBUTEX in patients below
the age of 16 have not been established.