CLINICAL PHARMACOLOGY
Mechanism Of Action
Roflumilast and its active metabolite (roflumilast
N-oxide) are selective inhibitors of phosphodiesterase 4 (PDE4). Roflumilast
and roflumilast N-oxide inhibition of PDE4 (a major
cyclic-3',5'-adenosine monophosphate (cyclic AMP)-metabolizing
enzyme in lung tissue) activity leads to accumulation of intracellular cyclic
AMP. While the specific mechanism(s) by which DALIRESP exerts its therapeutic
action in COPD patients is not well defined, it is thought to be related to the
effects of increased intracellular cyclic AMP in lung cells.
Pharmacodynamics
In COPD patients, 4-week treatment with DALIRESP 500 mcg
oral once daily reduced sputum neutrophils and eosinophils by 31%, and 42%,
respectively. In a pharmacodynamic study in healthy volunteers, DALIRESP 500 mcg
once daily reduced the number of total cells, neutrophils and eosinophils found
in bronchoalveolar lavage fluid following segmental pulmonary
lipopolysaccharide (LPS) challenge by 35%, 38% and 73%, respectively. The
clinical significance of these findings is unknown.
Pharmacokinetics
Absorption
The absolute bioavailability of roflumilast following a
500 mcg oral dose is approximately 80%. Maximum plasma concentrations (Cmax) of
roflumilast typically occur approximately one hour after dosing (ranging from 0.5
to 2 hours) in the fasted state while plateau-like maximum concentrations of
the N-oxide metabolite are reached in approximately eight hours (ranging from 4
to 13 hours). Food has no effect on total drug absorption, but delays time to
maximum concentration (Tmax) of roflumilast by one hour and reduces Cmax by
approximately 40%, however, Cmax and Tmax of roflumilast N-oxide are
unaffected. An in vitro study showed that roflumilast and roflumilast N-oxide
did not inhibit P-gp transporter.
Distribution
Plasma protein binding of roflumilast and its N-oxide
metabolite is approximately 99% and 97%, respectively. Volume of distribution
for single-dose 500 mcg roflumilast is about 2.9 L/kg. Studies in rats with
radiolabeled roflumilast indicate low penetration across the blood-brain
barrier.
Metabolism
Roflumilast is extensively metabolized via Phase I
(cytochrome P450) and Phase II (conjugation) reactions. The N-oxide metabolite
is the only major metabolite observed in the plasma of humans. Together,
roflumilast and roflumilast N-oxide account for the majority (87.5%) of total
dose administered in plasma. In urine, roflumilast was not detectable while
roflumilast N-oxide was only a trace metabolite (less than 1%). Other
conjugated metabolites such as roflumilast N-oxide glucuronide and
4-amino-3,5-dichloropyridine N-oxide were detected in urine.
While roflumilast is three times more potent than
roflumilast N-oxide at inhibition of the PDE4 enzyme in vitro, the plasma AUC
of roflumilast N-oxide on average is about 10-fold greater than the plasma AUC
of roflumilast.
In vitro studies and clinical drug-drug interaction
studies suggest that the biotransformation of roflumilast to its N-oxide
metabolite is mediated by CYP1A2 and 3A4. Based on further in vitro results in
human liver microsomes, therapeutic plasma concentrations of roflumilast and
roflumilast N-oxide do not inhibit CYP1A2, 2A6, 2B6, 2C8, 2C9, 2C19, 2D6, 2E1,
3A4/5, or 4A9/11. Therefore, there is a low probability of relevant interactions
with substances metabolized by these P450 enzymes. In addition, in vitro studies
demonstrated no induction of the CYP 1A2, 2A6, 2C9, 2C19, or 3A4/5 and only a
weak induction of CYP2B6 by roflumilast.
Elimination
The plasma clearance after short-term intravenous
infusion of roflumilast is on average about 9.6 L/h. Following an oral dose,
the median plasma effective half-life of roflumilast and its N-oxide metabolite
are approximately 17 and 30 hours, respectively. Steady state plasma
concentrations of roflumilast and its N-oxide metabolite are reached after
approximately 4 days for roflumilast and 6 days for roflumilast N-oxide
following once-daily dosing. Following intravenous or oral administration of
radiolabeled roflumilast, about 70% of the radioactivity was recovered in the
urine.
Special Populations
Hepatic Impairment
Roflumilast 250 mcg once daily for 14 days was studied in
subjects with mild-to-moderate hepatic impairment classified as Child-Pugh A
and B (8 subjects in each group). The AUC of roflumilast and roflumilast
N-oxide were increased by 51% and 24%, respectively in Child-Pugh A subjects
and by 92% and 41%, respectively, in Child-Pugh B subjects, as compared to
age-, weight-, and gender-matched healthy subjects. The Cmax of roflumilast and
roflumilast N-oxide were increased by 3% and 26%, respectively, in Child-Pugh A
subjects and by 26% and 40%, respectively in Child-Pugh B subjects, as compared
to healthy subjects. DALIRESP 500 mcg has not been studied in hepatically
impaired patients. Clinicians should consider the risk-benefit of administering
DALIRESP to patients who have mild liver impairment (Child-Pugh A). DALIRESP is
not recommended for use in patients with moderate or severe liver impairment
(Child-Pugh B or C) [see CONTRAINDICATIONS and Use In Specific
Populations].
Renal Impairment
In twelve subjects with severe renal impairment
administered a single dose of 500 mcg roflumilast, roflumilast and roflumilast
N-oxide AUCs were decreased by 21% and 7%, respectively and Cmax were reduced
by 16% and 12%, respectively. No dosage adjustment is necessary for patients
with renal impairment [see Use In Specific Populations].
Age
Roflumilast 500 mcg once daily for 15 days was studied in
young, middle aged, and elderly healthy subjects. The exposure in elderly
(>65 years of age) were 27% higher in AUC and 16% higher in Cmax for
roflumilast and 19% higher in AUC and 13% higher in Cmax for
roflumilast-N-oxide than that in young volunteers (18-45 years old). No dosage
adjustment is necessary for elderly patients [see Use In Specific
Populations].
Gender
In a Phase I study evaluating the effect of age and
gender on the pharmacokinetics of roflumilast and roflumilast N-oxide, a 39%
and 33% increase in roflumilast and roflumilast N-oxide AUC were noted in
healthy female subjects as compared to healthy male subjects. No dosage
adjustment is necessary based on gender.
Smoking
The pharmacokinetics of roflumilast and roflumilast
N-oxide were comparable in smokers as compared to nonsmokers. There was no
difference in Cmax between smokers and non-smokers when roflumilast 500 mcg was
administered as a single dose to 12 smokers and 12 non-smokers. The AUC of
roflumilast in smokers was 13% less than that in non-smokers while the AUC of
roflumilast N-oxide in smokers was 17% more than that in nonsmokers.
Race
As compared to Caucasians, African Americans, Hispanics,
and Japanese showed 16%, 41%, and 15% higher AUC, respectively, for roflumilast
and 43%, 27%, and 16% higher AUC, respectively, for roflumilast N-oxide. As
compared to Caucasians, African Americans, Hispanics, and Japanese showed 8%,
21%, and 5% higher Cmax, respectively, for roflumilast and 43%, 27%, and 17%
higher Cmax, respectively, for roflumilast N-oxide. No dosage adjustment is
necessary for race.
Drug Interactions
Drug interaction studies were performed with roflumilast
and other drugs likely to be coadministered or drugs commonly used as probes
for pharmacokinetic interaction [see DRUG INTERACTIONS]. No significant
drug interactions were observed when 500 mcg oral roflumilast was administered
with inhaled salbutamol, formoterol, budesonide and oral montelukast, digoxin,
theophylline, warfarin, sildenafil, midazolam, or antacids.
The effect of concomitant drugs on the exposure of
roflumilast and roflumilast N-oxide is shown in the Figure 1 below.
Figure 1
Figure 1. Effect of concomitant drugs on the exposure of
roflumilast and roflumilast N-oxide. Note that the dashed lines indicate the lower
and higher bounds (0.8-1.25) of the 90% confidence interval of the geometric
mean ratio of Cmax or AUC for roflumilast or roflumilast N-oxide for Treatment
(DALIRESP+Coadministered Drug) vs. Reference (DALIRESP). The dosing regimens of
coadministered drugs was: Midazolam: 2 mg po SD; Erythromycin: 500 mg po TID;
Ketoconazole: 200 mg po BID; Rifampicin: 600 mg po QD; Fluvoxamine: 50 mg po
QD; Digoxin: 250 mcg po SD; Maalox: 30 mL po SD; Salbutamol: 0.2 mg po TID;
Cimetidine: 400 mg po BID; Formoterol: 40 mcg po BID; Budesonide: 400 mcg po
BID; Theophylline: 375 mg po BID; Warfarin: 250 mg po SD; Enoxacin: 400 mg po
BID; Sildenafil: 100 mg SD; Minulet (combination oral contraceptive): 0.075 mg
gestodene/0.03 mg ethinylestradiol po QD; Montelukast: 10 mg po QD
Drug interactions considered to be significant are
described in more detail below [see WARNINGS AND PRECAUTIONS and DRUG
INTERACTIONS].
Inhibitors Of CYP3A4 And CYP1A2
Erythromycin: In an open-label crossover study in 16
healthy volunteers, the coadministration of CYP3A4 inhibitor erythromycin (500
mg three times daily for 13 days) with a single oral dose of 500 mcg DALIRESP resulted
in 40% and 70% increase in Cmax and AUC for roflumilast, respectively, and a
34% decrease and a 4% increase in Cmax and AUC for roflumilast N-oxide,
respectively.
Ketoconazole: In an open-label crossover study in 16
healthy volunteers, the coadministration of a strong CYP3A4 inhibitor
ketoconazole (200 mg twice daily for 13 days) with a single oral dose of 500 mcg
DALIRESP resulted in 23% and 99% increase in Cmax and AUC for roflumilast,
respectively, and a 38% reduction and 3% increase in Cmax and AUC for
roflumilast N-oxide, respectively.
Fluvoxamine: In an open-label crossover study in 16
healthy volunteers, the coadministration of dual CYP 3A4/1A2 inhibitor
fluvoxamine (50 mg daily for 14 days) with a single oral dose of 500 mcg
DALIRESP showed a 12% and 156% increase in roflumilast Cmax and AUC along with
a 210% decrease and 52% increase in roflumilast N-oxide Cmax and AUC,
respectively.
Enoxacin: In an open-label crossover study in 16 healthy
volunteers, the coadministration of dual CYP 3A4/1A2 inhibitor enoxacin (400 mg
twice daily for 12 days) with a single oral dose of 500 mcg DALIRESP resulted
in an increased Cmax and AUC of roflumilast by 20% and 56%, respectively.
Roflumilast N-oxide Cmax was decreased by 14% while roflumilast N-oxide AUC was
increased by 23%.
Cimetidine: In an open-label crossover study in 16
healthy volunteers, the coadministration of a dual CYP 3A4/1A2 inhibitor
cimetidine (400 mg twice daily for 7 days) with a single dose of 500 mcg oral
DALIRESP resulted in a 46% and 85% increase in roflumilast Cmax and AUC; and a
4% decrease in Cmax and 27% increase in AUC for roflumilast N-oxide,
respectively.
Oral Contraceptives Containing Gestodene And Ethinyl
Estradiol
In an open-label crossover study in 20 healthy adult
volunteers, coadministration of a single oral dose of 500 mcg DALIRESP with
repeated doses of a fixed combination oral contraceptive containing 0.075 mg
gestodene and 0.03 mg ethinyl estradiol to steady state caused a 38% increase
and 12 % decrease in Cmax of roflumilast and roflumilast N-oxide, respectively.
Roflumilast and roflumilast N-oxide AUCs were increased by 51% and 14%,
respectively.
Inducers Of CYP Enzymes
Rifampicin: In an open-label, three-period,
fixed-sequence study in 15 healthy volunteers, coadministration of the strong
CYP3A4 inducer rifampicin (600 mg once daily for 11 days) with a single oral
dose of 500 mcg DALIRESP resulted in reduction of roflumilast Cmax and AUC by
68% and 79%, respectively; and an increase of roflumilast N-oxide Cmax by 30%
and reduced roflumilast N-oxide AUC by 56%.
Clinical Studies
Chronic Obstructive Pulmonary Disease (COPD)
The efficacy and safety of DALIRESP (roflumilast) in COPD
was evaluated in 8 randomized, double-blind, controlled, parallel-group
clinical trials in 9394 adult patients (4425 receiving DALIRESP 500 mcg) 40
years of age and older with COPD. Of the 8 trials, two were placebo-controlled
dose selection trials (Trials 1 and 2) of 6 months' duration that evaluated the
efficacy of DALIRESP 250 mcg and 500 mcg once daily, four were placebo-controlled
1-year trials (Trials 3, 4, 5, and 6) primarily designed to evaluate the
efficacy of DALIRESP on COPD exacerbations, and two were 6-month efficacy
trials (Trials 7 and 8) which assessed the effect of DALIRESP as add-on therapy
to a long-acting beta agonist or long-acting anti-muscarinic. The 8 trials
enrolled patients with nonreversible obstructive lung disease (FEV1/FVC
≤ 70% and ≤ 12% or 200 mL improvement in FEV1 in response to 4 puffs
of albuterol/salbutamol) but the severity of airflow obstruction at baseline
was different among the trials. Patients enrolled in the dose selection trials
had the full range of COPD severity (FEV1 30-80% predicted); median age of 63
years, 73% male, and 99% Caucasian. Patients enrolled in the four exacerbation
trials had severe COPD (FEV1 ≤ 50% predicted); median age of 64 years, 74%
male, and 90% Caucasian.
Patients enrolled in the two 6-month efficacy trials had
moderate to severe COPD (FEV1 40-70% predicted); median age of 65 years, 68%
male, and 97% Caucasian. COPD exacerbations and lung function (FEV1) were co-primary
efficacy outcome measures in the four 1-year trials. In the two 6-month
supportive efficacy trials, lung function (FEV1) alone was the primary efficacy
outcome measure.
The two 6-month dose-selection efficacy trials (Trials 1
and 2) explored doses of 250 mcg and 500 mcg once daily in a total of 1929
patients (751 and 724 on DALIRESP 250 and 500 mcg, respectively). The selection
of the 500 mcg dose was primarily based on nominal improvements in lung
function (FEV1) over the 250 mcg dose. The once-daily dosing regimen was
primarily based on the determination of a plasma half-life of 17 hours for
roflumilast and 30 hours for its active metabolite roflumilast N-oxide [see CLINICAL
PHARMACOLOGY].
An additional placebo-controlled 1-year trial (Trial 9)
evaluated the effect of DALIRESP 500 mcg on COPD exacerbations when added to a
fixed-dose combination (FDC) product containing an inhaled corticosteroid and long-acting
beta agonist (ICS/LABA). At screening, patients were required to have two or
more exacerbations in the previous year. This trial randomized a total of 2354
patients (1178 randomized to DALIRESP, 1176 to placebo). Approximately 60% of
the patients enrolled had severe COPD (postbronchodilator FEV1 30%-50% of predicted)
associated with chronic bronchitis and 39% had very severe COPD
(postbronchodilator FEV1 ≤ 30% of predicted) associated with chronic
bronchitis; mean age of 64 years, 69% male, and 80% Caucasian. The use of
long-acting muscarinic antagonists was allowed.
Effect On Exacerbations
The effect of DALIRESP 500 mcg once daily on COPD
exacerbations was evaluated in five 1-year trials (Trials 3, 4, 5, 6 and 9).
Two of the trials (Trials 3 and 4) conducted initially
enrolled a population of patients with severe COPD (FEV1 ≤50% of
predicted) inclusive of those with chronic bronchitis and/or emphysema who had
a history of smoking of at least 10 pack years. Inhaled corticosteroids were
allowed as concomitant medications and used in 61% of both DALIRESP and
placebo-treated patients and short-acting beta agonists were allowed as rescue
therapy. The use of long-acting beta agonists, long-acting anti-muscarinics,
and theophylline were prohibited. The rate of moderate or severe COPD
exacerbations was a co-primary endpoint in both trials. There was not a symptomatic
definition of exacerbation in these 2 trials. Exacerbations were defined in
terms of severity requiring treatment with a moderate exacerbation defined as
treatment with systemic glucocorticosteroids in Trial 3 or systemic
glucocorticosteroids and/or antibiotics in Trial 4 and a severe exacerbation
defined as requiring hospitalizations and/or leading to death in Trial 3 or
requiring hospitalization in Trial 4. The trials randomized 1176 patients (567
on DALIRESP) in Trial 3 and 1514 patients (760 on DALIRESP) in Trial 4. Both
trials failed to demonstrate a significant reduction in the rate of COPD
exacerbations.
Exploratory analyses of the results of Trials 3 and 4
identified a subpopulation of patients with severe COPD associated with chronic
bronchitis and COPD exacerbations within the previous year that appeared to demonstrate
a better response in the reduction of the rate of COPD exacerbations compared
to the overall population. As a result, two subsequent trials (Trial 5 and
Trial 6) were conducted that enrolled patients with severe COPD but associated
with chronic bronchitis, at least one COPD exacerbation in the previous year,
and at least a 20 pack-year smoking history. In these trials, long-acting beta
agonists and short-acting antimuscarinics were allowed and were used by 44% and
35% of patients treated with DALIRESP and 45% and 37% of patients treated with
placebo, respectively. The use of inhaled corticosteroids was prohibited. As in
trials 3 and 4, the rate of moderate exacerbations (defined as requiring
intervention with systemic glucocorticosteroids) or severe exacerbations
(defined as leading to hospitalization and/or to death) was a coprimary endpoint.
Trial 5 randomized a total of 1525 patients (765 on
DALIRESP) and Trial 6 randomized a total of 1571 patients (772 on DALIRESP). In
both trials, DALIRESP 500 mcg once daily demonstrated a significant reduction
in the rate of moderate or severe exacerbations compared to placebo (Table 2).
These two trials provide the evidence to support the use of DALIRESP for the
reduction of COPD exacerbations.
Table 2: Effect of DALIRESP on Rate of Moderate or
Severe Exacerbations
Study |
Exacerbations Per Patient-Year |
RR2 |
95% CI |
Percent Reduction |
DALIRESP |
Placebo |
Absolute Reduction1 |
Trial 5 |
1.1 |
1.3 |
0.2 |
0.85 |
0.74, 0.98 |
15 |
Trial 6 |
1.2 |
1.5 |
0.3 |
0.82 |
0.71, 0.94 |
18 |
1. Absolute reduction measured as difference between
placebo and roflumilast-treated patients.
2. RR is Rate Ratio.
3. Percent reduction is defined as 100 (1-RR). |
For patients in Trials 5 and 6 who received concomitant
long-acting beta agonists or short-acting antimuscarinics, reduction of
moderate or severe exacerbations with DALIRESP was similar to that observed for
the overall populations of the two trials.
In Trial 9, when added to background therapy of FDC
ICS/LABA, the rate ratio for COPD exacerbations among patients administered
DALIRESP vs. placebo was 0.92 (95% CI 0.81, 1.04).
Effect On Lung Function
While DALIRESP is not a bronchodilator, all 1-year trials
(Trials 3, 4, 5, and 6) evaluated the effect of DALIRESP on lung function as
determined by the difference in FEV1 between DALIRESP and placebo-treated patients
(pre-bronchodilator FEV1 measured prior to study drug administration in three
of the trials and postbronchodilator FEV1 measured 30 minutes after
administration of 4 puffs of albuterol/salbutamol in one trial) as a co-primary
endpoint. In each of these trials DALIRESP 500 mcg once daily demonstrated a
statistically significant improvement in FEV1 which averaged approximately 50
mL across the four trials. Table 3 shows FEV1 results from Trials 5 and 6 which
had demonstrated a significant reduction in COPD exacerbations.
Table 3: Effect of DALIRESP on FEV1
Study |
Change in FEV1 from Baseline, mL |
DALIRESP |
Placebo |
Effect1 |
95% CI |
Trial 5 |
46 |
8 |
39 |
18, 60 |
Trial 6 |
33 |
-25 |
58 |
41, 75 |
1. Effect measured as difference between DALIRESP and
placebo treated patients. |
Lung function was also evaluated in two 6-month trials
(Trials 7 and 8) to assess the effect of DALIRESP when administered as add-on
therapy to treatment with a long-acting beta agonist or a long-acting
anti-muscarinic. These trials were conducted in a different population of COPD
patients [moderate to severe COPD (FEV1 40 to 70% of predicted) without a
requirement for chronic bronchitis or frequent history of exacerbations] from
that for which efficacy in reduction of exacerbations has been demonstrated and
provide safety support to the DALIRESP COPD program.
Starting Dose Titration Trial
The tolerability of DALIRESP was evaluated in a 12-week
randomized, double-blind, parallel group trial in patients with severe COPD
associated with chronic bronchitis (Trial 10). At screening, patients were
required to have had at least one exacerbation in the previous year. A total of
1323 patients were randomized to receive DALIRESP 500 mcg once a day for 12
weeks (n=443), DALIRESP 500 mcg every other day for 4 weeks followed by
DALIRESP 500 mcg once a day for 8 weeks (n=439), or DALIRESP 250 mcg once a day
for 4 weeks followed by DALIRESP 500 mcg once a day for 8 weeks (n=441).
Over the 12 week study period, the percentage of patients
discontinuing treatment was 6.2% lower in patients initially receiving DALIRESP
250 mcg daily for 4 weeks followed by DALIRESP 500 mcg daily for 8 weeks (18.4%)
compared to those receiving DALIRESP 500 mcg daily for 12 weeks (24.6%) (Odds
Ratio = 0.66; 95% CI: 0.47 to 0.93; p=0.017). Because this trial was limited to
12 weeks in duration, whether initiation of dosing with DALIRESP 250 mcg
improves the long term tolerability of DALIRESP 500 mcg has not been
determined.