2.1 Dosage in Narcolepsy and Obstructive Sleep Apnea (OSA)

The recommended dosage of modafinil tablets for patients with narcolepsy or OSA is 200 mg taken orally once a day as a single dose in the morning.

Doses up to 400 mg/day, given as a single dose, have been well tolerated, but there is no consistent evidence that this dose confers additional benefit beyond that of the 200 mg/day dose [see Clinical Pharmacology (12.3) and Clinical Studies (14.1, 14.2)].

2.2 Dosage in Shift Work Disorder (SWD)

The recommended dosage of modafinil tablets for patients with SWD is 200 mg taken orally once a day as a single dose approximately 1 hour prior to the start of their work shift.

2.3 Dosage Modifications in Patients with Severe Hepatic Impairment

In patients with severe hepatic impairment, the dosage of modafinil tablets should be reduced to one-half of that recommended for patients with normal hepatic function [see Use in Specific Populations (8.6) and Clinical Pharmacology (12.3)].

2.4 Use in Geriatric Patients

Consideration should be given to the use of lower doses and close monitoring in geriatric patients [see Use in Specific Populations (8.5)].

5.1 Serious Rash, including Stevens - Johnson Syndrome

Serious rash requiring hospitalization and discontinuation of treatment has been reported in association with the use of modafinil.

In clinical trials of modafinil, the incidence of rash resulting in discontinuation was approximately 0.8% (13 per 1,585) in pediatric patients (age <17 years); these rashes included 1 case of possible Stevens - Johnson Syndrome (SJS) and 1 case of apparent multi-organ hypersensitivity reaction. Several of the cases were associated with fever and other abnormalities (e.g., vomiting, leukopenia). The median time to rash that resulted in discontinuation was 13 days. No such cases were observed among 380 pediatric patients who received placebo. Modafinil tablets are not approved for use in pediatric patients for any indication [see Use in Specific Populations (8.4)].

Rare cases of serious or life-threatening rash, including SJS, Toxic Epidermal Necrolysis (TEN), and Drug Rash with Eosinophilia and Systemic Symptoms (DRESS) have been reported in adults and children in worldwide postmarketing experience. The reporting rate of TEN and SJS associated with modafinil use, which is generally accepted to be an underestimate due to underreporting, exceeds the background incidence rate. Estimates of the background incidence rate for these serious skin reactions in the general population range between 1 to 2 cases per million-person years.

There are no factors that are known to predict the risk of occurrence or the severity of rash associated with modafinil tablets. Nearly all cases of serious rash associated with modafinil occurred within 1 to 5 weeks after treatment initiation. However, isolated cases have been reported after prolonged treatment (e.g., 3 months). Accordingly, duration of therapy cannot be relied upon as a means to predict the potential risk heralded by the first appearance of a rash.

Although benign rashes also occur with modafinil tablets, it is not possible to reliably predict which rashes will prove to be serious. Accordingly, modafinil tablets should be discontinued at the first sign of rash, unless the rash is clearly not drug-related. Discontinuation of treatment may not prevent a rash from becoming life-threatening or permanently disabling or disfiguring.

5.2 Angioedema and Anaphylaxis Reactions

Angioedema and hypersensitivity (with rash, dysphagia, and bronchospasm), were observed in patients treated with armodafinil, the R enantiomer of modafinil (which is the racemic mixture). No such cases were observed in modafinil clinical trials. However, angioedema has been reported in postmarketing experience with modafinil. Patients should be advised to discontinue therapy and immediately report to their physician any signs or symptoms suggesting angioedema or anaphylaxis (e.g., swelling of face, eyes, lips, tongue or larynx; difficulty in swallowing or breathing; hoarseness).

5.3 Multi-organ Hypersensitivity Reactions

Multi-organ hypersensitivity reactions, including at least one fatality in postmarketing experience, have occurred in close temporal association (median time to detection 13 days: range 4-33) to the initiation of modafinil.

Although there have been a limited number of reports, multi-organ hypersensitivity reactions may result in hospitalization or be life-threatening. There are no factors that are known to predict the risk of occurrence or the severity of multi-organ hypersensitivity reactions. Signs and symptoms of this disorder were diverse; however, patients typically, although not exclusively, presented with fever and rash associated with other organ system involvement. Other associated manifestations included myocarditis, hepatitis, liver function test abnormalities, hematological abnormalities (e.g., eosinophilia, leukopenia, thrombocytopenia), pruritus, and asthenia. Because multi-organ hypersensitivity is variable in its expression, other organ system symptoms and signs, not noted here, may occur.

If a multi-organ hypersensitivity reaction is suspected, modafinil tablets should be discontinued. Although there are no case reports to indicate cross-sensitivity with other drugs that produce this syndrome, the experience with drugs associated with multi-organ hypersensitivity would indicate this to be a possibility.

5.4 Persistent Sleepiness

Patients with abnormal levels of sleepiness who take modafinil tablets should be advised that their level of wakefulness may not return to normal. Patients with excessive sleepiness, including those taking modafinil tablets, should be frequently reassessed for their degree of sleepiness and, if appropriate, advised to avoid driving or any other potentially dangerous activity. Prescribers should also be aware that patients may not acknowledge sleepiness or drowsiness until directly questioned about drowsiness or sleepiness during specific activities.

5.5 Psychiatric Symptoms

Psychiatric adverse reactions have been reported in patients treated with modafinil.

In the adult modafinil tablets controlled trials, psychiatric symptoms resulting in treatment discontinuation (at a frequency ≥0.3%) and reported more often in patients treated with modafinil tablets compared to those treated with placebo were anxiety (1%), nervousness (1%), insomnia (<1%), confusion (<1%), agitation (<1%), and depression (<1%).

Postmarketing adverse reactions associated with the use of modafinil have included mania, delusions, hallucinations, suicidal ideation, and aggression, some resulting in hospitalization. Many, but not all, patients had a prior psychiatric history. One healthy male volunteer developed ideas of reference, paranoid delusions, and auditory hallucinations in association with multiple daily 600 mg doses of modafinil tablets (three times the recommended dose) and sleep deprivation. There was no evidence of psychosis 36 hours after drug discontinuation.

Caution should be exercised when modafinil tablets are given to patients with a history of psychosis, depression, or mania. Consideration should be given to the possible emergence or exacerbation of psychiatric symptoms in patients treated with modafinil tablets. If psychiatric symptoms develop in association with modafinil tablets administration, consider discontinuing modafinil tablets.

5.6 Effects on Ability to Drive and Use Machinery

Although modafinil tablets has not been shown to produce functional impairment, any drug affecting the CNS may alter judgment, thinking or motor skills. Patients should be cautioned about operating an automobile or other hazardous machinery until it is reasonably certain that modafinil tablets therapy will not adversely affect their ability to engage in such activities.

5.7 Cardiovascular Events

In modafinil clinical studies, cardiovascular adverse reactions, including chest pain, palpitations, dyspnea, and transient ischemic T-wave changes on ECG occurred in three subjects in association with mitral valve prolapse or left ventricular hypertrophy. In a Canadian clinical trial, a 35 year old obese narcoleptic male with a prior history of syncopal episodes experienced a 9-second episode of asystole after 27 days of modafinil treatment (300 mg/day in divided doses). Modafinil tablets are not recommended in patients with a history of left ventricular hypertrophy or in patients with mitral valve prolapse who have experienced the mitral valve prolapse syndrome when previously receiving CNS stimulants. Findings suggestive of mitral valve prolapse syndrome include but are not limited to ischemic ECG changes, chest pain, or arrhythmia. If new onset of any of these findings occurs, consider cardiac evaluation. Consider increased monitoring in patients with a recent history of myocardial infarction or unstable angina.

Blood pressure monitoring in short term (≤3 months) controlled trials showed no clinically significant changes in mean systolic and diastolic blood pressure in patients receiving modafinil tablets as compared to placebo. However, a retrospective analysis of the use of antihypertensive medication in these studies showed that a greater proportion of patients on modafinil tablets required new or increased use of antihypertensive medications (2.4%) compared to patients on placebo (0.7%). The differential use was slightly larger when only studies in OSA were included, with 3.4% of patients on modafinil tablets and 1.1% of patients on placebo requiring such alterations in the use of antihypertensive medication. Increased monitoring of heart rate and blood pressure may be appropriate in patients on modafinil tablets. Caution should be exercised when prescribing modafinil tablets to patients with known cardiovascular disease.

6.1 Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.

Modafinil tablets has been evaluated for safety in over 3,500 patients, of whom more than 2,000 patients with excessive sleepiness associated with OSA, SWD, and narcolepsy.

Most Common Adverse Reactions

In placebo-controlled clinical trials, the most common adverse reactions (≥5%) associated with the use of modafinil tablets more frequently than placebo-treated patients were headache, nausea, nervousness, rhinitis, diarrhea, back pain, anxiety, insomnia, dizziness, and dyspepsia. The adverse reaction profile was similar across these studies.

Table 1 presents the adverse reactions that occurred at a rate of 1% or more and were more frequent in modafinil tablets-treated patients than in placebo-treated patients in the placebo-controlled clinical trials.

Dose-Dependent Adverse Reactions

In the placebo-controlled clinical trials which compared doses of 200, 300, and 400 mg/day of modafinil tablets and placebo, the following adverse reactions were dose related: headache and anxiety.

Adverse Reactions Resulting in Discontinuation of Treatment

In placebo-controlled clinical trials, 74 of the 934 patients (8%) who received modafinil tablets discontinued due to an adverse reaction compared to 3% of patients that received placebo. The most frequent reasons for discontinuation that occurred at a higher rate for modafinil tablets than placebo patients were headache (2%), nausea, anxiety, dizziness, insomnia, chest pain, and nervousness (each <1%).

Laboratory Abnormalities

Clinical chemistry, hematology, and urinalysis parameters were monitored in the studies. Mean plasma levels of gamma glutamyltransferase (GGT) and alkaline phosphatase (AP) were found to be higher following administration of modafinil tablets, but not placebo. Few patients, however, had GGT or AP elevations outside of the normal range. Shifts to higher, but not clinically significantly abnormal, GGT and AP values appeared to increase with time in the population treated with modafinil tablets in the placebo-controlled clinical trials. No differences were apparent in alanine aminotransferase (ALT), aspartate aminotransferase (AST), total protein, albumin, or total bilirubin.

6.2 Postmarketing Experience

The following adverse reactions have been identified during post approval use of modafinil tablets. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.

Hematologic: agranulocytosis

Psychiatric disorders: psychomotor hyperactivity

8.1 Pregnancy

Pregnancy Category C

There are no adequate and well-controlled studies of modafinil in pregnant women. Intrauterine growth restriction and spontaneous abortion have been reported in association with modafinil (a mixture of R-and S-modafinil) and armodafinil (the R-enantiomer of modafinil). Although the pharmacology of modafinil is not identical to that of the sympathomimetic amines, it does share some pharmacologic properties with this class. Certain of these drugs have been associated with intrauterine growth restriction and spontaneous abortions. Whether the cases reported with modafinil are drug-related is unknown. In studies of modafinil and armodafinil conducted in rats (modafinil, armodafinil) and rabbits (modafinil), developmental toxicity was observed at clinically relevant plasma exposures. Modafinil tablets should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

Modafinil (50, 100, or 200 mg/kg/day) administered orally to pregnant rats throughout organogenesis caused, in the absence of maternal toxicity, an increase in resorptions and an increased incidence of visceral and skeletal variations in the offspring at the highest dose tested. The higher no-effect dose for embryofetal developmental toxicity in rats (100 mg/kg/day) was associated with a plasma modafinil AUC less than that in humans at the recommended human dose (RHD) of modafinil tablets (200 mg/day). However, in a subsequent study of up to 480 mg/kg/day of modafinil, no adverse effects on embryofetal development were observed. Oral administration of armodafinil (60, 200, or 600 mg/kg/day) to pregnant rats throughout organogenesis resulted in increased incidences of fetal visceral and skeletal variations and decreased fetal body weight at the highest dose tested. The highest no-effect dose for embryofetal developmental toxicity in rats (200 mg/kg/day) was associated with a plasma armodafinil AUC less than that in humans at the RHD of modafinil tablets.

Modafinil administered orally to pregnant rabbits throughout organogenesis at doses of up to 100 mg/kg/day had no effect on embryofetal development; however, the doses used were too low to adequately assess the effects of modafinil on embryofetal development. In a subsequent developmental toxicity study evaluating doses of 45, 90, and 180 mg/kg/day in pregnant rabbits, the incidences of fetal structural alterations and embryofetal death were increased at the highest dose. The highest no-effect dose for developmental toxicity (100 mg/kg/day) was associated with a plasma modafinil AUC similar to that in humans at the RHD of modafinil tablets.

Modafinil administration to rats throughout gestation and lactation at oral doses of up to 200 mg/kg/day resulted in decreased viability in the offspring at doses greater than 20 mg/kg/day, a dose resulting in a plasma modafinil AUC less than that in humans at the RHD of modafinil tablets. No effects on postnatal developmental and neurobehavioral parameters were observed in surviving offspring.

8.3 Nursing Mothers

It is not known whether modafinil or its metabolites are excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when modafinil tablets are administered to a nursing woman.

8.4 Pediatric Use

Safety and effectiveness in pediatric patients have not been established. Modafinil tablets are not approved in this population for any indication.
Serious skin rashes, including erythema multiforme major (EMM) and Stevens - Johnson Syndrome (SJS) have been associated with modafinil use in pediatric patients [see Warnings and Precautions (5.1)].

In a controlled 6-week study, 165 pediatric patients (aged 5-17 years) with narcolepsy were treated with modafinil (n=123), or placebo (n=42). There were no statistically significant differences favoring modafinil over placebo in prolonging sleep latency as measured by MSLT, or in perceptions of sleepiness as determined by the clinical global impression-clinician scale (CGI-C).

In the controlled and open-label clinical studies, treatment emergent adverse reactions of the psychiatric and nervous system included Tourette’s syndrome, insomnia, hostility, increased cataplexy, increased hypnagogic hallucinations, and suicidal ideation. Transient leukopenia, which resolved without medical intervention, was also observed. In the controlled clinical study, 3 of 38 girls, ages 12 or older, treated with modafinil experienced dysmenorrhea compared to 0 of 10 girls who received placebo.

There were three 7 to 9 week, double-blind, placebo-controlled, parallel group studies in children and adolescents (aged 6-17 years) with Attention-Deficit Hyperactivity Disorder (ADHD). Two of the studies were flexible-dose studies (up to 425 mg/day), and the third was a fixed-dose study (340 mg/day for patients <30 kg and 425 mg/day for patients ≥30 kg). Although these studies showed statistically significant differences favoring modafinil over placebo in reducing ADHD symptoms as measured by the ADHD-RS (school version), there were 3 cases of serious rash including one case of possible SJS among 933 patients exposed to modafinil in this program. Modafinil is not approved for use in treating ADHD.

8.5 Geriatric Use

In clinical trials, experience in a limited number of modafinil-treated patients who were greater than 65 years of age showed an incidence of adverse reactions similar to other age groups. In elderly patients, elimination of modafinil and its metabolites may be reduced as a consequence of aging. Therefore, consideration should be given to the use of lower doses and close monitoring in this population [see Dosage and Administration (2.4)and Clinical Pharmacology (12.3)].

8.6 Hepatic Impairment

In patients with severe hepatic impairment, the dose of modafinil tablets should be reduced to one-half of that recommended for patients with normal hepatic function [see Dosage and Administration (2.3) and Clinical Pharmacology (12.3)].

9.1 Controlled Substance

Modafinil tablets contains modafinil, a Schedule IV controlled substance.

9.2 Abuse

In humans, modafinil produces psychoactive and euphoric effects, alterations in mood, perception, thinking, and feelings typical of other CNS stimulants. In in vitro binding studies, modafinil binds to the dopamine reuptake site and causes an increase in extracellular dopamine, but no increase in dopamine release. Modafinil is reinforcing, as evidenced by its self-administration in monkeys previously trained to self-administer cocaine. In some studies, modafinil was also partially discriminated as stimulant-like. Physicians should follow patients closely, especially those with a history of drug and/or stimulant (e.g., methylphenidate, amphetamine, or cocaine) abuse. Patients should be observed for signs of misuse or abuse (e.g., incrementation of doses or drug-seeking behavior).

The abuse potential of modafinil (200, 400, and 800 mg) was assessed relative to methylphenidate (45 and 90 mg) in an inpatient study in individuals experienced with drugs of abuse. Results from this clinical study demonstrated that modafinil produced psychoactive and euphoric effects and feelings consistent with other scheduled CNS stimulants (methylphenidate).

9.3 Dependence

In one placebo-controlled clinical trial, the effects of modafinil withdrawal were monitored following 9 weeks of modafinil use. There were no reported withdrawal symptoms with modafinil during 14 days of observation, although sleepiness returned in narcoleptic patients.

12.1 Mechanism of Action

The mechanism(s) through which modafinil promotes wakefulness is unknown. Modafinil has wake-promoting actions similar to sympathomimetic agents including amphetamine and methylphenidate, although the 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.

Modafinil is not a direct-or indirect-acting dopamine receptor agonist. However, in vitro, modafinil binds to the dopamine transporter and inhibits dopamine reuptake. 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 the cat, equal wakefulness-promoting doses of methylphenidate and amphetamine increased neuronal activation throughout the brain. Modafinil at an equivalent wakefulness-promoting dose selectively and prominently increased neuronal activation in more discrete regions of the brain. The relationship of this finding in cats to the effects of modafinil in humans is unknown.

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.

The optical enantiomers of modafinil have similar pharmacological actions in animals. Two major metabolites of modafinil, modafinil acid and modafinil sulfone, do not appear to contribute to the CNS-activating properties of modafinil.

12.3 Pharmacokinetics

Modafinil is a 1:1 racemic compound, whose enantiomers have different pharmacokinetics (e.g., the half-life of R-modafinil is approximately three times that of S-modafinil in adult humans). The enantiomers do not interconvert. At steady state, total exposure to R-modafinil is approximately three times that for S-modafinil. The trough concentration (Cmin,ss) of circulating modafinil after once daily dosing consists of 90% of R-modafinil and 10% of S-modafinil. The effective elimination half-life of modafinil after multiple doses is about 15 hours. The enantiomers of modafinil exhibit linear kinetics upon multiple dosing of 200-600 mg/day once daily in healthy volunteers. Apparent steady states of total modafinil and R-modafinil are reached after 2-4 days of dosing.

Absorption

Modafinil tablet is readily absorbed after oral administration, with peak plasma concentrations occurring at 2-4 hours. The bioavailability of modafinil tablets is approximately equal to that of an aqueous suspension. The absolute oral bioavailability was not determined due to the aqueous insolubility (<1 mg/mL) of modafinil, which precluded intravenous administration. Food has no effect on overall modafinil tablets bioavailability; however, time to reach peak concentration (tmax) may be delayed by approximately one hour if taken with food.

Distribution

Modafinil tablets has an apparent volume of distribution of approximately 0.9 L/kg. In human plasma, in vitro, modafinil is moderately bound to plasma protein (approximately 60%), mainly to albumin. The potential for interactions of modafinil tablets with highly protein-bound drugs is considered to be minimal.

Metabolism and Elimination

The major route of elimination is metabolism (approximately 90%), primarily by the liver, with subsequent renal elimination of the metabolites. Urine alkalinization has no effect on the elimination of modafinil.

Metabolism occurs through hydrolytic deamidation, S-oxidation, aromatic ring hydroxylation, and glucuronide conjugation. Less than 10% of an administered dose is excreted as the parent compound. In a clinical study using radiolabeled modafinil, 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 feces). The largest fraction of the drug in urine was modafinil acid, but at least six other metabolites were present in lower concentrations. Only two metabolites reach appreciable concentrations in plasma, i.e., modafinil acid and modafinil sulfone. In preclinical models, modafinil acid, modafinil sulfone, 2-[(diphenylmethyl) sulfonyl] acetic acid and 4-hydroxy modafinil, were inactive or did not appear to mediate the arousal effects of modafinil.

In adults, decreases in trough levels of modafinil have sometimes been observed after multiple weeks of dosing, suggesting auto-induction, but the magnitude of the decreases and the inconsistency of their occurrence suggest that their clinical significance is minimal. Significant accumulation of modafinil sulfone has been observed after multiple doses due to its long elimination half-life of 40 hours. Auto-induction of metabolizing enzymes, most importantly cytochrome P-450 CYP3A4, has also been observed in vitro after incubation of primary cultures of human hepatocytes with modafinil and in vivo after extended administration of modafinil at 400 mg/day.

Specific Populations

Age
A slight decrease (approximately 20%) in the oral clearance (CL/F) of modafinil was observed in a single dose study at 200 mg in 12 subjects with a mean age of 63 years (range 53 – 72 years), but the change was considered not likely to be clinically significant. In a multiple dose study (300 mg/day) in 12 patients with a mean age of 82 years (range 67 – 87 years), the mean levels of modafinil in plasma were approximately two times those historically obtained in matched younger subjects. Due to potential effects from the multiple concomitant medications with which most of the patients were being treated, the apparent difference in modafinil pharmacokinetics may not be attributable solely to the effects of aging. However, the results suggest that the clearance of modafinil may be reduced in the elderly [see Dosage and Administration (2.4) andUse in Specific Populations (8.5)].

Gender
The pharmacokinetics of modafinil are not affected by gender.

Race
The influence of race on the pharmacokinetics of modafinil 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 (an inactive metabolite) was increased 9-fold.

Hepatic Impairment
The pharmacokinetics and metabolism of modafinil were examined in patients with cirrhosis of the liver (6 men and 3 women). Three patients had stage B or B+ cirrhosis and 6 patients had stage C or C+ cirrhosis (per the Child-Pugh score criteria). Clinically 8 of 9 patients were icteric and all had ascites. In these patients, the oral clearance of modafinil was decreased by about 60% and the steady state concentration was doubled compared to normal patients[see Dosage and Administration (2.3) andUse in Specific Populations (8.6)].

Drug Interactions
In vitro data demonstrated that modafinil weakly induces CYP1A2, CYP2B6, and possibly CYP3A activities in a concentration-related manner and that CYP2C19 activity is reversibly inhibited by modafinil. In vitro data also demonstrated that modafinil produced an apparent concentration-related suppression of expression of CYP2C9 activity. Other CYP activities did not appear to be affected by modafinil.

Potential Interactions with Drugs That Inhibit, Induce, or Are Metabolized by Cytochrome P450 Isoenzymes and Other Hepatic Enzymes

The existence of multiple pathways for modafinil metabolism, as well as the fact that a non-CYP-related pathway is the most rapid in metabolizing modafinil, suggest that there is a low probability of substantive effects on the overall pharmacokinetic profile of modafinil tablets due to CYP inhibition by concomitant medications. However, due to the partial involvement of CYP3A enzymes in the metabolic elimination of modafinil, coadministration of potent inducers of CYP3A4/5 (e.g., carbamazepine, phenobarbital, rifampin) or inhibitors of CYP3A4/5 (e.g., ketoconazole, erythromycin) could alter the plasma concentrations of modafinil.

The Potential of Modafinil Tablets to Alter the Metabolism of Other Drugs by Enzyme Induction or Inhibition

• Drugs Metabolized by CYP3A4/5
  • In vitro data demonstrated that modafinil is a weak inducer of CYP3A activity in a concentration-related manner. Therefore, the blood levels and effectiveness of drugs that are substrates for CYP3A enzymes (e.g., steroidal contraceptives, cyclosporine, midazolam, and triazolam) may be reduced after initiation of concomitant treatment with modafinil tablets[see Drug Interactions (7)].
  • Ethinyl Estradiol -Administration of modafinil to female volunteers once daily at 200 mg/day for 7 days followed by 400 mg/day for 21 days resulted in a mean 11% decrease in mean Cmax and 18% decrease in mean AUC0-24 of ethinyl estradiol (EE2; 0.035 mg; administered orally with norgestimate). There was no apparent change in the elimination rate of ethinyl estradiol.
  • Triazolam -In the drug interaction study between modafinil tablets and ethinyl estradiol (EE2), on the same days as those for the plasma sampling for EE2 pharmacokinetics, a single dose of triazolam (0.125 mg) was also administered. Mean Cmax and AUC0-∞ of triazolam were decreased by 42% and 59%, respectively, and its elimination half-life was decreased by approximately an hour after the modafinil treatment.
  • Cyclosporine -One case of an interaction between modafinil and cyclosporine, a substrate of CYP3A4, has been reported in a 41 year old woman who had undergone an organ transplant. After one month of administration of 200 mg/day of modafinil, cyclosporine blood levels were decreased by 50%. The interaction was postulated to be due to the increased metabolism of cyclosporine, since no other factor expected to affect the disposition of the drug had changed.
  • Midazolam -In a clinical study, concomitant administration of armodafinil 250 mg resulted in a reduction in systemic exposure to midazolam by 32% after a single oral dose (5 mg) and 17% after a single intravenous dose (2 mg).
  • Quetiapine -In a separate clinical study, concomitant administration of armodafinil 250 mg with quetiapine (300 mg to 600 mg daily doses) resulted in a reduction in the mean systemic exposure of quetiapine by approximately 29%.
• Drugs Metabolized by CYP1A2
  • In vitro data demonstrated that modafinil is a weak inducer of CYP1A2 in a concentration-related manner. However, in a clinical study with armodafinil using caffeine as a probe substrate, no significant effect on CYP1A2 activity was observed.
• Drugs Metabolized by CYP2B6
  • In vitro data demonstrated that modafinil is a weak inducer of CYP2B6 activity in a concentration-related manner.
• Drugs Metabolized by CYP2C9
  • In vitro data demonstrated that modafinil produced an apparent concentration-related suppression of expression of CYP2C9 activity suggesting that there is a potential for a metabolic interaction between modafinil and the substrates of this enzyme (e.g., S-warfarin and phenytoin)[see Drug Interactions (7)].
  • Warfarin: Concomitant administration of modafinil with warfarin did not produce significant changes in the pharmacokinetic profiles of R-and S-warfarin. However, since only a single dose of warfarin was tested in this study, an interaction cannot be ruled out[see Drug Interactions (7)].
• Drugs Metabolized by CYP2C19
  • In vitro data demonstrated that modafinil is a reversible inhibitor of CYP2C19 activity. CYP2C19 is also reversibly inhibited, with similar potency, by a circulating metabolite, modafinil sulfone. Although the maximum plasma concentrations of modafinil sulfone are much lower than those of parent modafinil, the combined effect of both compounds could produce sustained partial inhibition of the enzyme. Therefore, exposure to some drugs that are substrates for CYP2C19 (e.g., phenytoin, diazepam, propranolol, omeprazole, and clomipramine) may be increased when used concomitantly with modafinil tablets [see Drug Interactions (7)].
  • In a clinical study, concomitant administration of armodafinil 400 mg resulted in a 40% increase in exposure to omeprazole after a single oral dose (40 mg), as a result of moderate inhibition of CYP2C19 activity.
• Interactions with CNS Active Drugs
  • Concomitant administration of modafinil with methylphenidate or dextroamphetamine produced no significant alterations on the pharmacokinetic profile of modafinil or either stimulant, even though the absorption of modafinil was delayed for approximately one hour.
  • Concomitant modafinil or clomipramine did not alter the pharmacokinetic profile of either drug; however, one incident of increased levels of clomipramine and its active metabolite desmethylclomipramine was reported in a patient with narcolepsy during treatment with modafinil.
  • CYP2C19 also provides an ancillary pathway for the metabolism of certain tricyclic antidepressants (e.g., clomipramine and desipramine) and selective serotonin reuptake inhibitors that are primarily metabolized by CYP2D6. In tricyclic-treated patients deficient in CYP2D6 (i.e., those who are poor metabolizers of debrisoquine; 7-10% of the Caucasian population; similar or lower in other populations), the amount of metabolism by CYP2C19 may be substantially increased. Modafinil tablets may cause elevation of the levels of the tricyclics in this subset of patients [see Drug Interactions (7)].
  • Concomitant administration of armodafinil with quetiapine reduced the systemic exposure of quetiapine.
• Interaction with P-Glycoprotein
• An in vitro study demonstrated that armodafinil is a substrate of P-glycoprotein. The impact of inhibition of P-glycoprotein is not known.

13.1 Carcinogenesis, Mutagenesis, Impairment of Fertility

Carcinogenesis

Carcinogenicity studies were conducted in which modafinil (a mixture of R-and S-modafinil) was administered in the diet to mice for 78 weeks and to rats for 104 weeks at doses of 6, 30, and 60 mg/kg/day. The highest doses studied were associated with plasma modafinil exposures (AUC) less than that in humans at the recommended human dose (RHD) of modafinil tablets (200 mg/day). There was no evidence of tumorigenesis associated with modafinil administration in these studies. However, the mouse study was inadequate because the high dose was not a maximum tolerated dose (MTD). In a mouse carcinogenicity study in which armodafinil (the R-enantiomer of modafinil) was administered at oral doses of up to 300 mg/kg/day in males and 100 mg/kg/day in females for approximately 2 years, no tumorigenic effects were observed. The highest doses studied, which were considered MTDs, were associated with plasma armodafinil exposures less than (females) or 2 times (males) that in humans at the RHD of modafinil tablets.

Mutagenesis

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) or in vivo (mouse bone marrow micronucleus) assays.

Impairment of Fertility

Oral administration of modafinil (doses of up to 480 mg/kg/day) to male and female rats prior to and throughout mating, and continuing in females through day 7 of gestation produced an increase in the time to mate at the highest dose; no effects were observed on other fertility or reproductive parameters. The no-effect dose of 240 mg/kg/day was associated with a plasma modafinil AUC less than that in humans at the RHD of modafinil tablets.

14.1 Narcolepsy

The effectiveness of modafinil tablets in improving wakefulness in adult patients with excessive sleepiness associated with narcolepsy was established in two US 9-week, multi-center, placebo-controlled, parallel-group, double-blind studies of outpatients who met the criteria for narcolepsy. A total of 558 patients were randomized to receive modafinil tablets 200 or 400 mg/day, or placebo. The criteria for narcolepsy include either: 1) 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 2) a complaint of excessive sleepiness or sudden muscle weakness with associated features: sleep paralysis, hypnagogic hallucinations, automatic behaviors, 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. For entry into these studies, all patients were required to have objectively documented excessive daytime sleepiness, via a Multiple Sleep Latency Test (MSLT) with two or more sleep onset REM periods 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 15 minutes after sleep onset.

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). For a successful trial, both measures had to show statistically significant improvement.

The MWT measures latency (in minutes) to sleep onset averaged over 4 test sessions at 2 hour intervals following nocturnal polysomnography. For each test session, the subject was asked to attempt to remain awake without using extraordinary measures. Each test session was terminated after 20 minutes if no sleep occurred or 10 minutes 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. Patients were rated by evaluators who had no access to any data about the patients other than a measure of their baseline severity. Evaluators were not given any specific guidance about the criteria they were to apply when rating patients.

Both studies demonstrated improvement in objective and subjective measures of excessive daytime sleepiness for both the 200 mg and 400 mg doses compared to placebo. Patients treated with modafinil tablets showed a statistically significantly enhanced ability to remain awake on the MWT at each dose compared to placebo at final visit (Table 2). A statistically significantly greater number of patients treated with modafinil tablets at each dose showed improvement in overall clinical condition as rated by the CGI-C scale at final visit (Table 3).

Nighttime sleep measured with polysomnography was not affected by the use of modafinil tablets.

14.2 Obstructive Sleep Apnea (OSA)

The effectiveness of modafinil tablets in improving wakefulness in patients with excessive sleepiness associated with OSA was established in two multi-center, placebo-controlled clinical studies of patients who met the criteria for OSA.The criterial include either: 1) excessive sleepiness or insomnia, plus frequent episodes of impaired breathing during sleep, and associated features such as loud snoring, morning headaches and dry mouth upon awakening; or 2) excessive sleepiness or insomnia and polysomnography demonstrating one of the following: more than five obstructive apneas, 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 apneas, bradytachycardia, and arterial oxygen desaturation in association with the apneas. 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 (ESS), despite treatment with continuous positive airway pressure (CPAP). Evidence that CPAP was effective in reducing episodes of apnea/hypopnea was required along with documentation of CPAP use.

In the first study, a 12-week trial, a total of 327 patients with OSA were randomized to receive modafinil tablets 200 mg/day, modafinil tablets 400 mg/day, or matching placebo. The majority of patients (80%) were fully compliant with CPAP, defined as CPAP use greater than 4 hours/night on > 70% of nights. The remainder were partially CPAP compliant, defined as CPAP use < 4 hours/night on >30% of nights. CPAP use continued throughout the study. 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[see Clinical Studies (14.1) for a description of these measures].

Patients treated with modafinil tablets showed a statistically significant improvement in the ability to remain awake compared to placebo-treated patients as measured by the MWT at final visit (Table 2). A statistically significant greater number of patients treated with modafinil tablets showed improvement in overall clinical condition as rated by the CGI-C scale at final visit (Table 3). The 200 mg and 400 mg doses of modafinil tablets produced statistically significant effects of similar magnitude on the MWT, and also on the CGI-C.

In the second study, a 4-week trial, 157 patients with OSA were randomized to receive modafinil tablets 400 mg/day or placebo. Documentation of regular CPAP use (at least 4 hours/night on 70% of nights) was required for all patients. The primary measure of effectiveness was the change from baseline on the ESS at final visit. The baseline ESS scores for the modafinil tablets and placebo groups were 14.2 and 14.4, respectively. At week 4, the ESS was reduced by 4.6 in the modafinil tablets group and by 2.0 in the placebo group, a difference that was statistically significant.

Nighttime sleep measured with polysomnography was not affected by the use of modafinil tablets.

14.3 Shift Work Disorder (SWD)

The effectiveness of modafinil tablets in improving wakefulness in patients with excessive sleepiness associated with SWD was demonstrated in a 12-week placebo-controlled clinical trial. A total of 209 patients with chronic SWD were randomized to receive modafinil tablets 200 mg/day or placebo. All patients met the criteria for chronic SWD. The 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 SWD. 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.
The primary measures of effectiveness were 1) sleep latency, as assessed by the 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 [see Clinical Studies (14.1)for a description of these measures.].
Patients treated with modafinil tablets showed a statistically significant prolongation in the time to sleep onset compared to placebo-treated patients, as measured by the nighttime MSLT at final visit (Table 2). A statistically significant greater number of patients treated with modafinil tablets showed improvement in overall clinical condition as rated by the CGI-C scale at final visit (Table 3). 

Daytime sleep measured with polysomnography was not affected by the use of modafinil tablets.