Oxybate

INDICATIONS AND USAGE Sodium oxybate oral solution is indicated for the treatment of cataplexy or excessive daytime sleepiness (EDS) in patients with narcolepsy. Pediatric use information is approved for Jazz Pharmaceuticals Inc.’s XYREM (sodium oxybate) Oral Solution. However, due to Jazz Pharmaceuticals Inc.’s marketing exclusivity rights, this drug product is not labeled with that pediatric information. Sodium oxybate oral solution is a central nervous system depressant indicated for the treatment of cataplexy or excessive daytime sleepiness (EDS) in patients with narcolepsy (1) .

DOSAGE AND ADMINISTRATION Dosage for Adult Patients • Initiate dosage at 4.5 g per night orally, divided into two doses ( 2.1 ). • Titrate to effect in increments of 1.5 g per night at weekly intervals (0.75 g at bedtime and 0.75 g taken 2.5 to 4 hours later) ( 2.1 ). • Recommended dosage range: 6 g to 9 g per night orally ( 2.1 ). Total Nightly Dose Take at Bedtime Take 2.5 to 4 Hours Later 4.5 g per night 2.25 g 2.25 g 6 g per night 3 g 3 g 7.5 g per night 3.75 g 3.75 g 9 g per night 4.5 g 4.5 g Dosage for Pediatric Patients (7 years of Age and Older) • The recommended starting dosage, titration regimen, and maximum total nightly dosage are based on body weight (2.2 ). Important Administration Information • Prepare both doses prior to bedtime; dilute each dose with approximately ¼ cup of water in pharmacy-provided containers ( 2.3 ). • Allow 2 hours after eating before dosing ( 2.3 ). • Take each dose while in bed and lie down after dosing ( 2.3 ). Patients with Hepatic Impairment Recommended starting dosage is one-half of the original dosage per night administered orally, divided into two doses ( 2.4 ). 2.1 Adult Dosing Information The recommended starting dosage is 4.5 grams (g) per night administered orally, divided into two doses: 2.25 g at bedtime and 2.25 g taken 2.5 to 4 hours later (see Table 1). Increase the dosage by 1.5 g per night at weekly intervals (additional 0.75 g at bedtime and 0.75 g taken 2.5 to 4 hours later) to the effective dosage range of 6 g to 9 g per night orally. The dosage may be gradually titrated based on efficacy and tolerability. Doses higher than 9 g per night have not been studied and should not ordinarily be administered. Table 1: Recommended Adult Xyrem Dose Regimen (g = grams) If a Patient’s Total Nightly Dose is: Take at Bedtime: Take 2.5 to 4 Hours Later: 4.5 g per night 2.25 g 2.25 g 6 g per night 3 g 3 g 7.5 g per night 3.75 g 3.75 g 9 g per night 4.5 g 4.5 g 2.2 Pediatric Dosing Information Xyrem is administered orally twice nightly. The recommended starting pediatric dosage, titration regimen, and maximum total nightly dosage are based on patient weight, as specified in Table 2. The dosage may be gradually titrated based on efficacy and tolerability. Table 2: Recommended Pediatric Xyrem Dosage for Patients 7 Years of Age and Older* Patient Weight Initial Dosage Maximum Weekly Dosage Increase Maximum Recommended Dosage Take at Bedtime: Take 2.5 to 4 Hours Later: Take at Bedtime: Take 2.5 to 4 Hours Later: Take at Bedtime: Take 2.5 to 4 Hours Later: <20 kg** There is insufficient information to provide specific dosing recommendations for patients who weigh less than 20 kg. 20 kg to <30 kg ≤1 g ≤1 g 0.5 g 0.5 g 3 g 3 g 30 kg to <45 kg ≤1.5 g ≤1.5 g 0.5 g 0.5 g 3.75 g 3.75 g ≥45 kg ≤2.25 g ≤2.25 g 0.75 g 0.75 g 4.5 g 4.5 g * For patients who sleep more than 8 hours per night, the first dose of Xyrem may be given at bedtime or after an initial period of sleep. ** If Xyrem is used in patients 7 years of age and older who weigh less than 20 kg, a lower starting dosage, lower maximum weekly dosage increases, and lower total maximum nightly dosage should be considered. Note: Some patients may achieve better responses with unequal doses at bedtime and 2.5 to 4 hours later. 2.3 Important Administration Instructions for All Patients The total nightly dosage of Xyrem is divided into two doses. Prepare both doses of Xyrem prior to bedtime. Prior to ingestion, each dose of Xyrem should be diluted with approximately ¼ cup (approximately 60 mL) of water in the empty pharmacy containers provided. Take the first nightly dose of Xyrem at least 2 hours after eating [see Clinical Pharmacology ( 12.3 )] . Take the second nightly dose 2.5 to 4 hours after the first dose. Patients should take both doses of Xyrem while in bed and lie down immediately after dosing, and remain in bed following ingestion of each dose. Xyrem may cause patients to fall asleep abruptly without first feeling drowsy [see Adverse Reactions ( 6.2 )] . Patients will often fall asleep within 5 minutes of taking Xyrem, and will usually fall asleep within 15 minutes, though the time it takes any individual patient to fall asleep may vary from night to night. Patients may need to set an alarm to awaken for the second dose. Rarely, patients may take up to 2 hours to fall asleep. If the second dose is missed, that dose should be skipped and Xyrem should not be taken again until the next night. Both Xyrem doses should never be taken at one time. 2.4 Dosage Modification in Patients with Hepatic Impairment The recommended starting dosage in patients with hepatic impairment is one-half of the original dosage per night, administered orally divided into two doses [see Use in Specific Populations ( 8.6 ) and Clinical Pharmacology ( 12.3 )] . 2.5 Dosage Adjustment with Co-administration of Divalproex Sodium When initiating divalproex sodium in patients taking a stable dosage of Xyrem, a reduction of the Xyrem dosage by at least 20% is recommended with initial concomitant use [see Drug Interactions ( 7.2 ) and Clinical Pharmacology ( 12.3 )] . When initiating Xyrem in patients already taking divalproex sodium, a lower starting dosage of Xyrem is recommended. Subsequently, the dosage of Xyrem can be adjusted based on individual clinical response and tolerability.

WARNINGS AND PRECAUTIONS • CNS depression: Use caution when considering the concurrent use of LUMRYZ with other CNS depressants ( 5.1 ). • Caution patients against hazardous activities requiring complete mental alertness or motor coordination within the first 6 hours of dosing or after first initiating treatment until certain that LUMRYZ does not affect them adversely ( 5.1 ). • Depression and suicidality: Monitor patients for emergent or increased depression and suicidality ( 5.5 ). • Confusion/Anxiety: Monitor for impaired motor/cognitive function ( 5.6 ). • Parasomnias: Evaluate episodes of sleepwalking ( 5.7 ). • High sodium content in LUMRYZ: Monitor patients with heart failure, hypertension, or impaired renal function ( 5.8 ). 5.1 Central Nervous System Depression LUMRYZ is a central nervous system (CNS) depressant. Clinically significant respiratory depression and obtundation has occurred in patients treated with immediate-release sodium oxybate at recommended doses in clinical trials and may occur in patients treated with LUMRYZ at recommended doses. LUMRYZ is contraindicated in combination with alcohol and sedative hypnotics. The concurrent use of LUMRYZ with other CNS depressants, including but not limited to opioid analgesics, benzodiazepines, sedating antidepressants or antipsychotics, sedating antiepileptic drugs, general anesthetics, muscle relaxants, and/or illicit CNS depressants, may increase the risk of respiratory depression, hypotension, profound sedation, syncope, and death. If use of these CNS depressants in combination with LUMRYZ is required, dose reduction or discontinuation of one or more CNS depressants (including LUMRYZ) should be considered. In addition, if short-term use of an opioid (e.g., post- or perioperative) is required, interruption of treatment with LUMRYZ should be considered. In addition to coadministration of LUMRYZ and alcohol being contraindicated because of respiratory depression, consumption of alcohol while taking LUMRYZ may also result in a more rapid release of the dose of sodium oxybate [see Clinical Pharmacology (12.3) ] . Healthcare providers should caution patients about operating hazardous machinery, including automobiles or airplanes, until they are reasonably certain that LUMRYZ does not affect them adversely (e.g., impair judgment, thinking, or motor skills). Patients should not engage in hazardous occupations or activities requiring complete mental alertness or motor coordination, such as operating machinery or a motor vehicle or flying an airplane, for at least 6 hours after taking LUMRYZ. Patients should be queried about CNS depression-related events upon initiation of LUMRYZ therapy and periodically thereafter. LUMRYZ is available only through a restricted program under a REMS [see Warnings and Precautions (5.3) ]. 5.2 Abuse and Misuse LUMRYZ is a Schedule III controlled substance. The active ingredient of LUMRYZ, sodium oxybate, is the sodium salt of gamma-hydroxybutyrate (GHB), a Schedule I controlled substance. Abuse of illicit GHB, either alone or in combination with other CNS depressants, is associated with CNS adverse reactions, including seizure, respiratory depression, decreases in the level of consciousness, coma, and death. The rapid onset of sedation, coupled with the amnestic features of GHB, particularly when combined with alcohol, has proven to be dangerous for the voluntary and involuntary user (e.g., assault victim). Because illicit use and abuse of GHB have been reported, physicians should carefully evaluate patients for a history of drug abuse and follow such patients closely, observing them for signs of misuse or abuse of GHB (e.g., increase in size or frequency of dosing, drug-seeking behavior, feigned cataplexy) [see Warnings and Precautions (5.3) and Drug Abuse and Dependence (9.2) ]. LUMRYZ is available only through a restricted program under a REMS [see Warnings and Precautions (5.3) ]. 5.3 LUMRYZ REMS LUMRYZ is available only through a restricted distribution program called the LUMRYZ REMS because of the risks of central nervous system depression and abuse and misuse [see Warnings and Precautions (5.1 , 5.2) ] . Notable requirements of the LUMRYZ REMS include the following: ● Healthcare providers who prescribe LUMRYZ are specially certified. ● LUMRYZ will be dispensed only by pharmacies that are specially certified. ● LUMRYZ will be dispensed and shipped only to patients who are enrolled in the LUMRYZ REMS with documentation of safe use conditions. Further information is available at www.LUMRYZREMS.com or by calling 1-877-453-1029. 5.4 Respiratory Depression and Sleep-Disordered Breathing LUMRYZ may impair respiratory drive, especially in patients with compromised respiratory function. In overdoses of oxybate and with illicit use of GHB, life-threatening respiratory depression has been reported [see Overdosage (10) ] . Increased apnea and reduced oxygenation may occur with LUMRYZ administration. A significant increase in the number of central apneas and clinically significant oxygen desaturation may occur in patients with obstructive sleep apnea treated with LUMRYZ. During polysomnographic evaluation (PSG), central sleep apnea and oxygen desaturation were observed in pediatric patients with narcolepsy treated with immediate-release sodium oxybate. In adult clinical trials of LUMRYZ in patients with narcolepsy, no subjects with apnea/hypopnea indexes greater than 15 were allowed to enroll. In an adult study assessing the respiratory-depressant effects of immediate-release sodium oxybate at doses up to 9 g per night in 21 patients with narcolepsy, no dose-related changes in oxygen saturation were demonstrated in the group as a whole. One of four patients with preexisting moderate-to-severe sleep apnea had significant worsening of the apnea/hypopnea index during treatment. In an adult study assessing the effects of immediate-release sodium oxybate 9 g per night in 50 patients with obstructive sleep apnea, immediate-release sodium oxybate did not increase the severity of sleep-disordered breathing and did not adversely affect the average duration and severity of oxygen desaturation overall. However, there was a significant increase in the number of central apneas in patients taking immediate-release sodium oxybate, and clinically significant oxygen desaturation (≤55%) was measured in three patients (6%) after administration, with one patient withdrawing from the study and two continuing after single brief instances of desaturation. In adult clinical trials in 128 patients with narcolepsy administered immediate-release sodium oxybate, two subjects had profound CNS depression, which resolved after supportive respiratory intervention. Two other patients discontinued immediate-release sodium oxybate because of severe difficulty breathing and an increase in obstructive sleep apnea. In two controlled trials assessing polysomnographic (PSG) measures in adult patients with narcolepsy administered immediate-release sodium oxybate, 40 of 477 patients were included with a baseline apnea/hypopnea index of 16 to 67 events per hour, indicative of mild to severe sleep-disordered breathing. None of the 40 patients had a clinically significant worsening of respiratory function, as measured by apnea/hypopnea index and pulse oximetry at doses of 4.5 g to 9 g per night. Prescribers should be aware that sleep-related breathing disorders tend to be more prevalent in obese patients, in men, in postmenopausal women not on hormone replacement therapy, and among patients with narcolepsy. Increased central apneas and clinically relevant desaturation events have been observed with immediate-release sodium oxybate administration in adult and pediatric patients. 5.5 Depression and Suicidality Depression, and suicidal ideation and behavior, can occur in patients treated with LUMRYZ. In an adult clinical trial in patients with narcolepsy administered LUMRYZ [see Adverse Reactions (6.1) ] , there were

CONTRAINDICATIONS Sodium oxybate oral solution is contraindicated for use in: combination with sedative hypnotics [see Warnings and Precautions (5.1) ] . combination with alcohol [see Warnings and Precautions (5.1) ] . patients with succinic semialdehyde dehydrogenase deficiency [see Clinical Pharmacology (12.3) ] . In combination with sedative hypnotics or alcohol (4) Succinic semialdehyde dehydrogenase deficiency (4)

DRUG INTERACTIONS Concomitant use with divalproex sodium: An initial reduction in sodium oxybate oral solution dose of at least 20% is recommended (2.5, 7.2). 7.1 Alcohol, Sedative Hypnotics, and CNS Depressants Sodium oxybate oral solution is contraindicated for use in combination with alcohol or sedative hypnotics. Use of other CNS depressants may potentiate the CNS-depressant effects of sodium oxybate oral solution [see Warnings and Precautions (5.1)]. 7.2 Divalproex Sodium Concomitant use of sodium oxybate oral solution with divalproex sodium results in an increase in systemic exposure to GHB, which was shown to cause a greater impairment on some tests of attention and working memory in a clinical study [see Clinical Pharmacology (12.3)]. An initial dose reduction of sodium oxybate oral solution is recommended when used concomitantly with divalproex sodium [see Dosage and Administration (2.5)]. Prescribers are advised to monitor patient response closely and adjust dose accordingly if concomitant use of sodium oxybate oral solution and divalproex sodium is warranted.

ADVERSE REACTIONS The following clinically significant adverse reactions appear in other sections of the labeling: • CNS depression [see Warnings and Precautions ( 5.1 )] • Abuse and Misuse [see Warnings and Precautions ( 5.2 )] • Respiratory Depression and Sleep-Disordered Breathing [see Warnings and Precautions ( 5.4 )] • Depression and Suicidality [see Warnings and Precautions ( 5.5 )] • Other Behavioral or Psychiatric Adverse Reactions [see Warnings and Precautions ( 5.6 )] • Parasomnias [see Warnings and Precautions ( 5.7 )] • Use in Patients Sensitive to High Sodium Intake [see Warnings and Precautions ( 5.8 )] Most common adverse reactions in adults (≥5% and at least twice the incidence with placebo) were nausea, dizziness, vomiting, somnolence, enuresis, and tremor ( 6.1 ). Most common adverse reactions in pediatric patients (≥5%) were nausea, enuresis, vomiting, headache, weight decreased, decreased appetite, dizziness, and sleepwalking ( 6.1 ). To report SUSPECTED ADVERSE REACTIONS, contact Jazz Pharmaceuticals, Inc. at 1-800-520-5568, or FDA at 1-800-FDA-1088 or www.fda.gov/Medwatch . 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 clinical practice. Adult Patients Xyrem was studied in three placebo-controlled clinical trials (Trials N1, N3, and N4, described in Sections 14.1 and 14.2 ) in 611 patients with narcolepsy (398 subjects treated with Xyrem, and 213 with placebo). A total of 781 patients with narcolepsy were treated with Xyrem in controlled and uncontrolled clinical trials. Section 6.1 and Table 4 present adverse reactions from three pooled, controlled trials (N1, N3, N4) in patients with narcolepsy. Adverse Reactions Leading to Treatment Discontinuation: Of the 398 patients with narcolepsy treated with Xyrem, 10.3% of patients discontinued because of adverse reactions compared with 2.8% of patients receiving placebo. The most common adverse reaction leading to discontinuation was nausea (2.8%). The majority of adverse reactions leading to discontinuation began during the first few weeks of treatment. Commonly Observed Adverse Reactions in Controlled Clinical Trials: The most common adverse reactions (incidence ≥5% and twice the rate seen with placebo) in patients treated with Xyrem were nausea, dizziness, vomiting, somnolence, enuresis, and tremor. Adverse Reactions Occurring at an Incidence of 2% or Greater: Table 4 lists adverse reactions that occurred at a frequency of 2% or more in any treatment group for three controlled trials and were more frequent in any Xyrem treatment group than with placebo. Adverse reactions are summarized by dose at onset. Nearly all patients in these studies initiated treatment at 4.5 g per night. In patients who remained on treatment, adverse reactions tended to occur early and to diminish over time. Table 4 Adverse Reactions Occurring in ≥2% of Adult Patients and More Frequently with Xyrem than Placebo in Three Controlled Trials (N1, N3, N4) by Body System and Dose at Onset Adverse Reaction Placebo (n=213) % Xyrem 4.5g (n=185) % Xyrem 6g (n=258) % Xyrem 9g (n=178) % ANY ADVERSE REACTION 62 45 55 70 GASTROINTESTINAL DISORDERS Nausea 3 8 13 20 Vomiting 1 2 4 11 Diarrhea 2 4 3 4 Abdominal pain upper 2 3 1 2 Dry mouth 2 1 2 1 GENERAL DISORDERS AND ADMINISTRATIVE SITE CONDITIONS Pain 1 1 <1 3 Feeling drunk 1 0 <1 3 Edema peripheral 1 3 0 0 MUSCULOSKELETAL AND CONNECTIVE TISSUE DISORDERS Cataplexy 1 1 1 2 Muscle spasms 2 2 <1 2 Pain in extremity 1 3 1 1 NERVOUS SYSTEM DISORDERS Dizziness 4 9 11 15 Somnolence 4 1 3 8 Tremor 0 0 2 5 Disturbance in attention 0 1 0 4 Paresthesia 1 2 1 3 Sleep paralysis 1 0 1 3 PSYCHIATRIC DISORDERS Disorientation 1 1 2 3 Irritability 1 0 <1 3 Sleepwalking 0 0 0 3 Anxiety 1 1 1 2 RENAL AND URINARY DISORDERS Enuresis 1 3 3 7 SKIN AND SUBCUTANEOUS TISSUE DISORDERS Hyperhidrosis 0 1 1 3 Dose-Response Information In clinical trials in narcolepsy, a dose-response relationship was observed for nausea, vomiting, paresthesia, disorientation, irritability, disturbance in attention, feeling drunk, sleepwalking, and enuresis. The incidence of all these reactions was notably higher at 9 g per night. In controlled trials in narcolepsy, discontinuations of treatment due to adverse reactions were greater at higher doses of Xyrem. Pediatric Patients (7 Years of Age and Older) In the pediatric clinical trial (Trial N5), 104 patients aged 7 to 17 years (37 patients aged 7 to 11 years; 67 patients aged 12 to 17 years) with narcolepsy received Xyrem for up to one year. This study included an open-label safety continuation period in which eligible patients received Xyrem for up to an additional 2 years. The median and maximum exposure across the entire study were 371 and 987 days, respectively. Adverse Reactions Leading to Treatment Discontinuation In the pediatric clinical trial, 7 of 104 patients reported adverse reactions that led to withdrawal from the study (hallucination, tactile; suicidal ideation; weight decreased; sleep apnea syndrome; affect lability; anger, anxiety, depression; and headache). Adverse Reactions in the Pediatric Clinical Trial The most common adverse reactions (≥5%) were nausea (20%), enuresis (19%), vomiting (18%), headache (17%), weight decreased (13%), decreased appetite (9%), dizziness (8%), and sleepwalking (6%). Additional information regarding safety in pediatric patients appears in the following sections: • Respiratory Depression and Sleep-Disordered Breathing [see Warnings and Precautions ( 5.4 )] • Depression and Suicidality [see Warnings and Precautions ( 5.5 )] • Other Behavioral or Psychiatric Adverse Reactions [see Warnings and Precautions ( 5.6 )] • Parasomnias [see Warnings and Precautions ( 5.7 )] The overall adverse reaction profile of Xyrem in the pediatric clinical trial was similar to that seen in the adult clinical trial program. 6.2 Postmarketing Experience The following adverse reactions have been identified during postapproval use of Xyrem. 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: arthralgia, decreased appetite, fall*, fluid retention, hangover, headache, hypersensitivity, hypertension, memory impairment, nocturia, panic attack, vision blurred, and weight decreased. * The sudden onset of sleep in patients taking sodium oxybate, including in a standing position or while rising from bed, has led to falls complicated by injuries, in some cases requiring hospitalization.

CLINICAL PHARMACOLOGY 12.1 Mechanism of Action LUMRYZ is a CNS depressant. The mechanism of action of LUMRYZ in the treatment of narcolepsy is unknown. Sodium oxybate is the sodium salt of gamma-hydroxybutyrate (GHB), an endogenous compound and metabolite of the neurotransmitter GABA. It is hypothesized that the therapeutic effects of LUMRYZ on cataplexy and excessive daytime sleepiness are mediated through GABA B actions at noradrenergic and dopaminergic neurons, as well as at thalamocortical neurons. 12.3 Pharmacokinetics Following oral administration of LUMRYZ, the plasma levels of GHB increased dose-proportionally for C max and more than dose-proportionally for area under the plasma concentration-time curve (AUC inf ) (respectively, 2-fold and 2.3-fold increases as total daily dose is doubled from 4.5 g to 9 g). No clinically significant difference in oxybate pharmacokinetics was observed between a single 6 g dose of LUMRYZ and two 3 g doses of immediate-release sodium oxybate administered 4 hours apart. Absorption Following oral administration of a single 6 g dose of LUMRYZ, the peak plasma concentration (C max ) was 66 mcg/mL and the time to peak plasma concentration (T max ) was 1.5 hours. Effect of Food Administration of LUMRYZ immediately after a high-fat meal resulted in a mean reduction in C max and AUC of GHB by 33% and 14%, respectively; average T max increased from 0.5 hours to 1.5 hours [ see Dosage and Administration (2.3) ]. Effect of Ethanol An in vitro study showed alcohol-induced dose-dumping of sodium oxybate from extended-release oral suspension at 1 hour in the presence of 40% alcohol, and approximately 60% increase of drug release at 2 hours in the presence of 20% alcohol [see Contraindications (4) and Warnings and Precautions (5.1) ] . Effect of Water Temperature An in vitro dissolution study showed that LUMRYZ mixed with hot water (90°C) resulted in a dose-dumping phenomenon for the release of sodium oxybate, whereas warm water (50°C) did not significantly affect the drug release from the extended-release suspension [ see Dosage and Administration (2.3) ]. Effect of Water Flavoring An in vitro dissolution study showed that LUMRYZ mixed with water prepared with calorie-free drink mix (e.g., Crystal Light Raspberry Lemonade Drink Mix) or flavored water enhancer (e.g., Mio Fruit Punch Concentrate Liquid Water Enhancer) did not impact the drug release from the extended-release suspension [see Dosage and Administration (2.3) ]. Distribution GHB is a hydrophilic compound with an apparent volume of distribution averaging 190 mL/kg to 384 mL/kg. At GHB concentrations ranging from 3 mcg/mL to 300 mcg/mL, less than 1% is bound to plasma proteins. Elimination Metabolism Animal studies indicate that metabolism is the major elimination pathway for GHB, producing carbon dioxide and water via the tricarboxylic acid (Krebs) cycle, and secondarily by β-oxidation. The primary pathway involves a cytosolic NADP + -linked enzyme, GHB dehydrogenase, which catalyzes the conversion of GHB to succinic semialdehyde, which is then biotransformed to succinic acid by the enzyme succinic semialdehyde dehydrogenase. Succinic acid enters the Krebs cycle where it is metabolized to carbon dioxide and water. A second mitochondrial oxidoreductase enzyme, a transhydrogenase, also catalyzes the conversion to succinic semialdehyde in the presence of α-ketoglutarate. An alternate pathway of biotransformation involves β-oxidation via 3,4-dihydroxybutyrate to carbon dioxide and water. No active metabolites have been identified. Excretion The clearance of GHB is almost entirely by biotransformation to carbon dioxide, which is then eliminated by expiration. On average, less than 5% of unchanged drug appears in human urine within 6 to 8 hours after dosing. Fecal excretion is negligible. GHB has an elimination half-life of 0.5 to 1 hour. Specific Population Geriatric Patients There is limited experience with LUMRYZ in the elderly. Results from a pharmacokinetic study of immediate-release sodium oxybate (n=20) in another studied population indicate that the pharmacokinetic characteristics of GHB are consistent among younger (age 48 to 64 years) and older (age 65 to 75 years) adults. Pediatric Patients The pharmacokinetics of LUMRYZ has not been directly evaluated in pediatric patients. The pharmacokinetics of immediate-release sodium oxybate were evaluated in pediatric patients 7 to 17 years of age (n=29). The pharmacokinetic characteristics of immediate-release sodium oxybate were shown to be similar in adults and pediatric patients. Body weight was found to be the major intrinsic factor affecting oxybate pharmacokinetics. Male and Female Patients In a study of 18 female and 18 male healthy adult volunteers, no gender differences were detected in the pharmacokinetics of GHB following an immediate-release 4.5 g oral dose of sodium oxybate. Racial or Ethnic Groups There are insufficient data to evaluate any pharmacokinetic differences among races. Patients with Renal Impairment No pharmacokinetic study in patients with renal impairment has been conducted. Patients with Hepatic Impairment The pharmacokinetics of GHB in 16 cirrhotic patients, half without ascites (Child’s Class A) and half with ascites (Child’s Class C), were compared to the kinetics in 8 subjects with normal hepatic function, after a single sodium oxybate oral dose of 25 mg/kg. AUC values were doubled in cirrhotic patients, with apparent oral clearance reduced from 9.1 mL/min/kg in healthy adults to 4.5 and 4.1 mL/min/kg in Class A and Class C patients, respectively. Elimination half-life was significantly longer in Class C and Class A patients than in control patients (mean t 1/2 of 59 minutes and 32 minutes, respectively, versus 22 minutes in control patients). LUMRYZ should not be initiated in patients with liver impairment [see Use in Specific Populations (8.6) ]. Drug Interaction Studies In vitro studies with pooled human liver microsomes indicate that sodium oxybate does not significantly inhibit the activities of the human isoenzymes CYP1A2, CYP2C9, CYP2C19, CYP2D6, CYP2E1, or CYP3A, up to the concentration of 3 mM (378 mcg/mL), a level considerably higher than levels achieved with the maximum recommended dose. A drug interaction study in healthy adults (age 18 to 55 years) was conducted with LUMRYZ and divalproex sodium. Co-administration of a single dose of LUMRYZ (6 g) with divalproex sodium ER at steady state resulted in an approximate 18% increase in AUC (90% CI ratio range of 112%-123%), which is not expected to be clinically meaningful, while C max was comparable. A single dose of LUMRYZ (6 g) did not appear to affect the pharmacokinetics of divalproex sodium. However, a pharmacodynamic interaction between LUMRYZ and divalproex sodium, a sedative antiepileptic drug, cannot be ruled out [see Warnings and Precautions (5.1) and Drug Interactions (7.1) ] . Drug interaction studies in healthy adults (age 18 to 50 years) were conducted with immediate-release sodium oxybate and diclofenac and ibuprofen: ● Diclofenac: Co-administration of sodium oxybate (6 g per day as two equal doses of 3 grams dosed four hours apart) with diclofenac (50 mg/dose twice per day) showed no significant changes in systemic exposure to GHB. Co-administration did not appear to affect the pharmacokinetics of diclofenac. ● Ibuprofen: Co-administration of sodium oxybate (6 g per day as two equal doses of 3 grams dosed four hours apart) with ibuprofen (800 mg/dose four times per day also dosed four hours apart) resulted in comparable systemic exposure to GHB, as shown by plasma C max and AUC values. Co-administration did not affect the pharmacokinetics of ibuprofen. Drug interaction studies in healthy adults demonstrated no pharmacokinetic interactions between immediate-release sodium oxybate and protriptyline hydrochloride, zolpidem tartrate, and modafinil. Also, there were no pharmacokinetic interactions with the alcohol d