NUVIGIL (armodafinil) is a wakefulness-promoting agent.
Mechanism of action:
The mechanism(s) through which armodafinil promotes wakefulness is unknown. Armodafinil [(R)-modafinil)] has pharmacological properties similar to those of modafinil [a mixture of (R)- and (S)-modafinil] to the extent tested in animal and in vitro
studies. The (R)
- and (S)
-enantiomers have similar pharmacological actions in animals.
Armodafinil and modafinil have wake-promoting actions similar to sympathomimetic agents including amphetamine and methylphenidate, although their pharmacologic profile is not identical to that of the sympathomimetic amines.
Modafinil-induced wakefulness can be attenuated by the α1-adrenergic receptor antagonist, prazosin; however, modafinil is inactive in other in vitro
assay systems known to be responsive to α-adrenergic agonists such as the rat vas deferens preparation.
Armodafinil is an indirect dopamine receptor agonist; both armodafinil and modafinil bind in vitro
to the dopamine transporter and inhibit dopamine reuptake. For modafinil, this activity has been associated in vivo
with increased extracellular dopamine levels in some brain regions of animals. In genetically engineered mice lacking the dopamine transporter (DAT), modafinil lacked wake-promoting activity, suggesting that this activity was DAT-dependent. However, the wake-promoting effects of modafinil, unlike those of amphetamine, were not antagonized by the dopamine receptor antagonist haloperidol in rats. In addition, alpha-methyl-p-tyrosine, a dopamine synthesis inhibitor, blocks the action of amphetamine, but does not block locomotor activity induced by modafinil.
In addition to its wake-promoting effects and ability to increase locomotor activity in animals, modafinil produces psychoactive and euphoric effects, alterations in mood, perception, thinking, and feelings typical of other CNS stimulants in humans. Modafinil has reinforcing properties, as evidenced by its self-administration in monkeys previously trained to self-administer cocaine; modafinil was also partially discriminated as stimulant-like (see Abuse and Dependence Potential under PRECAUTIONS).
Based on nonclinical studies, two major metabolites, acid and sulfone, of modafinil or armodafinil, do not appear to contribute to the CNS-activating properties of the parent compounds.
The effectiveness of NUVIGIL in improving wakefulness has been established in the following sleep disorders: obstructive sleep apnoea/hypopnoea (OSAHS), narcolepsy and shift work sleep disorder (SWSD).
For each clinical trial, a p-value of ≤0.05 was required for statistical significance.
Obstructive Sleep Apnoea/hypopnoea (OSAHS): The effectiveness of NUVIGIL in improving wakefulness in patients with excessive sleepiness associated with OSAHS was established in two 12-week, multi-centre, placebo-controlled, parallel-group, double-blind studies of outpatients who met the International Classification of Sleep Disorders (ICSD) criteria for OSAHS (which are also consistent with the American Psychiatric Association DSM-IV-TR criteria). These criteria include either: excessive sleepiness or insomnia, plus frequent episodes of impaired breathing during sleep, and associated features such as loud snoring, morning headaches or dry mouth upon awakening; or excessive sleepiness or insomnia; and polysomnography demonstrating one of the following: more than five obstructive apnoeas, each greater than 10 seconds in duration, per hour of sleep; and one or more of the following: frequent arousals from sleep associated with the apnoeas, bradytachycardia, or arterial oxygen desaturation in association with the apnoeas.
In addition, for entry into these studies, all patients were required to have excessive sleepiness as demonstrated by a score ≥10 on the Epworth Sleepiness Scale, despite treatment with continuous positive airway pressure (CPAP). Evidence that CPAP was effective in reducing episodes of apnoea/hypopnoea was required along with documentation of CPAP use.
Patients were required to be compliant with CPAP, defined as CPAP use ≥4 hours/night on ≥70% of nights. CPAP use continued throughout the study. In both studies, the primary measures of effectiveness were 1) sleep latency, as assessed by the Maintenance of Wakefulness Test (MWT) and 2) the change in the patient's overall disease status, as measured by the Clinical Global Impression of Change (CGI-C) at the final visit. For a successful trial both measures had to show statistically significant improvement.
The MWT measures latency (in minutes) to sleep onset. An extended MWT was performed with test sessions at 2 hour intervals between 9AM and 7PM. The primary analysis was the average of the sleep latencies from the first four test sessions (9AM to 3PM). For each test session, the subject was asked to attempt to remain awake without using extraordinary measures. Each test session was terminated after 30 minutes if no sleep occurred or immediately after sleep onset. The CGI-C is a 7-point scale, centered at No Change, and ranging from Very Much Worse to Very Much Improved. Evaluators were not given any specific guidance about the criteria they were to apply when rating patients.
In the first study 3021, a total of 395 patients with OSAHS were randomized to receive NUVIGIL 150 mg/day, NUVIGIL 250 mg/day or matching placebo. Patients treated with NUVIGIL showed a statistically significant improvement in the ability to remain awake compared to placebo-treated patients as measured by the MWT at final visit. A statistically significant greater number of patients treated with NUVIGIL showed improvement in overall clinical condition as rated by the CGI-C scale at final visit. The average sleep latencies (in minutes) in the MWT at baseline for the trials are shown in Table 1 as follows, along with the average change from baseline on the MWT at final visit. The percentages of patients who showed any degree of improvement on the CGI-C in the clinical trials are shown in Table 2 as follows. The two doses of NUVIGIL produced statistically significant effects of similar magnitudes on the MWT, and also on the CGI-C.
In the second study 3025, 263 patients with OSAHS were randomized to either NUVIGIL 150 mg/day or placebo. Patients treated with NUVIGIL showed a statistically significant improvement in the ability to remain awake compared to placebo-treated patients as measured by the MWT (Table 1). A statistically significant greater number of patients treated with NUVIGIL showed improvement in overall clinical condition as rated by the CGI-C scale (Table 2).
Night time sleep measured with polysomnography was not affected by the use of NUVIGIL in either study.
Narcolepsy: The effectiveness of NUVIGIL in improving wakefulness in patients with excessive sleepiness (ES) associated with narcolepsy was established in one 12-week, multi-centre, placebo-controlled, parallel-group, double-blind study of outpatients who met the ICSD criteria for narcolepsy. A total of 196 patients were randomized to receive NUVIGIL 150 or 250 mg/day, or matching placebo. The ICSD criteria for narcolepsy include either: recurrent daytime naps or lapses into sleep that occur almost daily for at least three months, plus sudden bilateral loss of postural muscle tone in association with intense emotion (cataplexy), or a complaint of excessive sleepiness or sudden muscle weakness with associated features: sleep paralysis, hypnagogic hallucinations, automatic behaviours, disrupted major sleep episode; and polysomnography demonstrating one of the following: sleep latency less than 10 minutes or rapid eye movement (REM) sleep latency less than 20 minutes and a Multiple Sleep Latency Test (MSLT) that demonstrates a mean sleep latency of less than 5 minutes and two or more sleep onset REM periods and no medical or mental disorder accounts for the symptoms.
For entry into the study, all patients were required to have objectively documented excessive daytime sleepiness, via MSLT with a sleep latency of 6 minutes or less and the absence of any other clinically significant active medical or psychiatric disorder. The MSLT, an objective polysomnographic assessment of the patient's ability to fall asleep in an unstimulating environment, measured latency (in minutes) to sleep onset averaged over 4 test sessions at 2-hour intervals. For each test session, the subject was told to lie quietly and attempt to sleep. Each test session was terminated after 20 minutes if no sleep occurred or immediately after sleep onset.
The primary measures of effectiveness were: 1) sleep latency as assessed by the Maintenance of Wakefulness Test (MWT) and 2) the change in the patient's overall disease status, as measured by the CGI-C at the final visit. Each MWT test session was terminated after 20 minutes if no sleep occurred or immediately after onset in this study.
Patients treated with NUVIGIL showed a statistically significantly enhanced ability to remain awake on the MWT at each dose compared to placebo at final visit (See Table 1). A statistically significant greater number of patients treated with NUVIGIL at each dose showed improvement in overall clinical condition as rated by the CGI-C scale at final visit (Table 2).
The two doses of NUVIGIL produced statistically significant effects of similar magnitudes on the CGI-C. Although a statistically significant effect on the MWT was observed for each dose, the magnitude of effect was observed to be greater for the higher dose.
Night time sleep measured with polysomnography was not affected by the use of NUVIGIL.
Shift Work Sleep Disorder (SWSD): The effectiveness of NUVIGIL in improving wakefulness in patients with excessive sleepiness associated with SWSD was demonstrated in a 12-week, multi-centre, double-blind, placebo-controlled, parallel-group, clinical trial. A total of 254 patients with chronic SWSD were randomized to receive NUVIGIL 150 mg/day or placebo. All patients met the ICSD criteria for chronic SWSD (which are consistent with the American Psychiatric Association DSM-IV-TR criteria for Circadian Rhythm Sleep Disorder: Shift Work Type). These criteria include: 1) either, a) a primary complaint of excessive sleepiness or insomnia which is temporally associated with a work period (usually night work) that occurs during the habitual sleep phase, or b) polysomnography and the MSLT demonstrate loss of a normal sleep-wake pattern (i.e., disturbed chronobiological rhythmicity); and 2) no other medical or mental disorder accounts for the symptoms; and 3) the symptoms do not meet criteria for any other sleep disorder producing insomnia or excessive sleepiness (e.g., time zone change [jet lag] syndrome).
It should be noted that not all patients with a complaint of sleepiness who are also engaged in shift work meet the criteria for the diagnosis of SWSD. In the clinical trial, only patients who were symptomatic for at least 3 months were enrolled.
Enrolled patients were also required to work a minimum of 5 night shifts per month, have excessive sleepiness at the time of their night shifts (MSLT score ≤6 minutes), and have daytime insomnia documented by a daytime polysomnogram (PSG).
The primary measures of effectiveness were 1) sleep latency, as assessed by the Multiple Sleep Latency Test (MSLT) performed during a simulated night shift at the final visit, and 2) the change in the patient's overall disease status, as measured by the CGI-C at the final visit.
Patients treated with NUVIGIL showed a statistically significant prolongation in the time to sleep onset compared to placebo-treated patients, as measured by the night time MSLT at final visit (See Table 1). A statistically significant greater number of patients treated with NUVIGIL showed improvement in overall clinical condition as rated by the CGI-C scale at final visit (See Table 2).
Daytime sleep measured with polysomnography was not affected by the use of NUVIGIL. (See Tables 1 and 2.)
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Armodafinil exhibits linear time-independent kinetics following single and multiple oral dose administration. Increase in systemic exposure is proportional over the dose range of 50 to 400 mg. No time-dependent change in kinetics was observed through 12 weeks of dosing. Apparent steady state for armodafinil was reached within 7 days of dosing. At steady state, the systemic exposure for armodafinil is 1.8 times the exposure observed after a single dose. The concentration-time profiles of the (R)-enantiomer following administration of a single-dose of 50 mg NUVIGIL or 100 mg MODAVIGIL [modafinil, a 1:1 mixture of (R)- and (S)-enantiomers] are nearly superimposable. However, the Cmax and AUC0-∞, of armodafinil at steady-state were approximately 37% and 70% higher, respectively, following administration of 200 mg NUVIGIL than the corresponding values of modafinil following administration of 200 mg modafinil due to the more rapid clearance of the (S)-enantiomer (elimination half-life approximately 4 hours) as compared to the (R)-enantiomer.
NUVIGIL is readily absorbed after oral administration. The absolute oral bioavailability was not determined due to the aqueous insolubility of armodafinil, which precluded intravenous administration.
Effect of Food: Food effect on oral bioavailability of NUVIGIL is considered minimal; however, time to reach peak concentration (Tmax) may be delayed by approximately 2-4 hours in the fed state. Since the delay in Tmax is also associated with elevated plasma concentrations later in time, food can potentially effect the onset and time course of pharmacologic action for NUVIGIL.
NUVIGIL has an apparent volume of distribution of approximately 42 L. Data specific to armodafinil protein binding are not available. However, modafinil is moderately bound to plasma protein (approximately 60%), mainly to albumin. The potential for interactions of NUVIGIL with highly protein-bound drugs is considered to be minimal.
Metabolism: In vitro
and in vivo
data show that armodafinil undergoes hydrolytic deamidation, S-oxidation, and aromatic ring hydroxylation, with subsequent glucuronide conjugation of the hydroxylated products. Amide hydrolysis is the single most prominent metabolic pathway, with sulfone formation by cytochrome P450 (CYP) 3A4/5 being next in importance. The other oxidative products are formed too slowly in vitro
to enable identification of the enzyme(s) responsible. Only two metabolites reach appreciable concentrations in plasma [i.e., (R)-modafinil acid and modafinil sulfone].
Data specific to NUVIGIL disposition are not available. However, modafinil is mainly eliminated via metabolism, predominantly in the liver, with less than 10% of the parent compound excreted in the urine. A total of 81% of the administered radioactivity was recovered in 11 days post-dose, predominantly in the urine (80% vs. 1.0% in the faeces).
After oral administration of NUVIGIL, armodafinil exhibits an apparent monoexponential decline from the peak plasma concentration. The apparent terminal t½ is approximately 15 hours. The oral clearance of NUVIGIL is approximately 33 mL/min.
Children: The pharmacokinetics of armodafinil have not been studied in children.
Age: In a clinical study, systemic exposure of armodafinil was approximately 15% higher in elderly subjects (≥65 years of age, N=24), corresponding to approximately 12% lower oral clearance (CL/F), as compared to young subjects (18-45 years of age, N=25). Systemic exposure of armodafinil acid (metabolite) was approximately 61% and 73% greater for Cmax and AUC0-τ, respectively, compared to young subjects. Systemic exposure of the sulfone metabolite was approximately 20% lower for elderly subjects compared with young subjects. A subgroup analysis of elderly subjects demonstrated elderly subjects ≥75 and 65-74 years of age had approximately 21% and 9% lower oral clearance, respectively, compared to young subjects. Systemic exposure was approximately 10% greater in subjects 65-74 years of age (N=17) and 27% greater in subjects ≥75 years of age (N=7), respectively, when compared to young subjects. The change is considered not likely to be clinically significant for elderly patients, however, because some elderly patients have greater exposure to armodafinil, consideration should be given to the use of lower doses.
Gender: Population pharmacokinetic analysis suggests no gender effect on the pharmacokinetics of armodafinil.
Race: The influence of race on the pharmacokinetics of armodafinil has not been studied.
Renal impairment: In a single dose 200 mg modafinil study, severe chronic renal failure (creatinine clearance ≤20 mL/min) did not significantly influence the pharmacokinetics of modafinil, but exposure to modafinil acid (metabolite) was increased 9 fold. There is inadequate information to determine safety and efficacy of NUVIGIL (armodafinil) dosing in patients with renal impairment, mild, moderate or severe.
Hepatic impairment: The oral clearance of modafinil was decreased by about 60% in patients with cirrhosis of the liver (Child-Pugh Class B or C) and the steady state concentration was doubled compared to normal patients. Therefore, the dose of NUVIGIL should be reduced in patients with severe hepatic impairment (See DOSAGE & ADMINISTRATION and PRECAUTIONS). There is a lack of data on dosing information for NUVIGIL (armodafinil) specific to the degree of liver impairment.
Toxicology: Preclinical Safety Data:
Genotoxicity: Armodafinil was negative in an in vitro
bacterial reverse mutation assay and in an in vitro
chromosomal aberration assay in human lymphocytes. Modafinil was negative in a series of in vitro
(i.e., bacterial reverse mutation, mouse lymphoma tk, chromosomal aberration in human lymphocytes, cell transformation in BALB/3T3 mouse embryo cells) and in vivo
(mouse bone marrow micronucleus) assays. These studies indicate that armodafinil has a low genotoxic potential.
Carcinogenicity: An oral carcinogenicity study conducted for 94-101 weeks in mice found no evidence of tumour development or neoplastic change in mice that received up to 300 mg/kg/day armodafinil in males, or up to 100 mg/kg/day in females. At the highest dose in mice the plasma armodafinil exposure (AUC) was similar in males (1.3x) and less in females (0.5x) than that in humans at the maximum recommended human dose (MRHD) of NUVIGIL. Similarly, a carcinogenicity study which administered modafinil a mixture of (R)- and (S)- modafinil) to rats by the dietary route for 104 weeks at oral doses of 6, 30 and 60 mg/kg/day found no evidence of tumorigenesis associated with modafinil administration. However, minimal toxicity was observed in the high dose group. These results indicate that the exposure of armodafinil or modafinil was insufficient to adequately assess carcinogenic potential.