Sodium Oxybate

Xyrem is indicated for the treatment of cataplexy or excessive daytime sleepiness (EDS) in patients 7 years of age and older with narcolepsy. Xyrem is a central nervous system depressant indicated for the treatment of cataplexy or excessive daytime sleepiness (EDS) in patients 7 years of age and older with narcolepsy ( 1 ).

Xyrem is a clear to slightly opalescent oral solution, in a concentration of 0.5 g per mL (0.5 g/mL of sodium oxybate equivalent to 0.413 g/mL of oxybate). Oral solution, 0.5 g per mL ( 3 )

Xyrem 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 )

• CNS depression: Use caution when considering the concurrent use of Xyrem 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 Xyrem 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 Xyrem: Monitor patients with heart failure, hypertension, or impaired renal function ( 5.8 ).

5.1 Central Nervous System Depression Xyrem is a central nervous system (CNS) depressant. In adult clinical trials at recommended doses, obtundation and clinically significant respiratory depression occurred in patients treated with Xyrem. Xyrem is contraindicated in combination with alcohol and sedative hypnotics. The concurrent use of Xyrem with other CNS depressants, including but not limited to opioid analgesics, benzodiazepines, sedating antidepressants or antipsychotics, sedating anti-epileptic 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 Xyrem is required, dose reduction or discontinuation of one or more CNS depressants (including Xyrem) should be considered. In addition, if short-term use of an opioid (e.g., post- or perioperative) is required, interruption of treatment with Xyrem should be considered. Healthcare providers should caution patients about operating hazardous machinery, including automobiles or airplanes, until they are reasonably certain that Xyrem 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 Xyrem. Patients should be queried about CNS depression‐related events upon initiation of Xyrem therapy and periodically thereafter. Xyrem is available only through a restricted program under a REMS [see Warnings and Precautions ( 5.3 )] .

5.2 Abuse and Misuse Xyrem is a Schedule III controlled substance. The active ingredient of Xyrem, sodium oxybate or gamma-hydroxybutyrate (GHB), is 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 Xyrem, 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 Drug Abuse and Dependence ( 9.2 )]. Xyrem is available only through a restricted program under a REMS [see Warnings and Precautions ( 5.3 )] . 5.3 XYWAV and XYREM REMS Xyrem is available only through a restricted distribution program called the XYWAV and XYREM 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 XYWAV and XYREM REMS include the following:

• Healthcare Providers who prescribe Xyrem are specially certified
• Xyrem will be dispensed only by the central pharmacy that is specially certified
• Xyrem will be dispensed and shipped only to patients who are enrolled in the XYWAV and XYREM REMS with documentation of safe use Further information is available at www.XYWAVXYREMREMS.com or 1-866-997-3688.

5.4 Respiratory Depression and Sleep-Disordered Breathing Xyrem may impair respiratory drive, especially in patients with compromised respiratory function. In overdoses, life-threatening respiratory depression has been reported [see Overdosage ( 10 )]. In an adult study assessing the respiratory-depressant effects of Xyrem 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 the 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 Xyrem 9 g per night in 50 patients with obstructive sleep apnea, Xyrem 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 Xyrem, and clinically significant oxygen desaturation (≤55%) was measured in three patients (6%) after Xyrem administration, with one patient withdrawing from the study and two continuing after single brief instances of desaturation. During polysomnographic evaluation (PSG), central sleep apnea and oxygen desaturation were observed in pediatric patients with narcolepsy treated with Xyrem. Prescribers should be aware that increased central apneas and clinically relevant desaturation events have been observed with Xyrem administration in adult and pediatric patients. In adult clinical trials in 128 patients with narcolepsy, two subjects had profound CNS depression, which resolved after supportive respiratory intervention. Two other patients discontinued sodium oxybate because of severe difficulty breathing and an increase in obstructive sleep apnea. In two controlled trials assessing PSG measures in adult patients with narcolepsy, 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.

5.5 Depression and Suicidality In adult clinical trials in patients with narcolepsy (n=781), there were two suicides and two attempted suicides in patients treated with Xyrem, including three patients with a previous history of depressive psychiatric disorder. Of the two suicides, one patient used Xyrem in conjunction with other drugs. Xyrem was not involved in the second suicide. Adverse reactions of depression were reported by 7% of 781 patients treated with Xyrem, with four patients (<1%) discontinuing because of depression. In most cases, no change in Xyrem treatment was required. In a controlled adult trial, with patients randomized to fixed doses of 3 g, 6 g, or 9 g per night Xyrem or placebo, there was a single event of depression at the 3 g per night dose. In another adult controlled trial, with patients titrated from an initial 4.5 g per night starting dose, the incidences of depression were 1 (1.7%), 1 (1.5%), 2 (3.2%), and 2 (3.6%) for the placebo, 4.5 g, 6 g, and 9 g per night doses, respectively. In the pediatric clinical trial in patients with narcolepsy (n=104), one patient experienced suicidal ideation and two patients reported depression while taking Xyrem. The emergence of depression in patients treated with Xyrem requires careful and immediate evaluation. […]

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.

• Concomitant use with divalproex sodium: An initial reduction in Xyrem dose of at least 20% is recommended ( 2.5 , 7.2 ).

7.1 Alcohol, Sedative Hypnotics, and CNS Depressants Xyrem is contraindicated for use in combination with alcohol or sedative hypnotics. Use of other CNS depressants may potentiate the CNS-depressant effects of Xyrem [see Warnings and Precautions ( 5.1 )] .

7.2 Divalproex Sodium Concomitant use of Xyrem 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 Xyrem 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 Xyrem and divalproex sodium is warranted.

• Pregnancy: Based on animal data, may cause fetal harm ( 8.1 ).
• Geriatric patients: Monitor for impaired motor and/or cognitive function when taking Xyrem ( 8.5 ).

8.1 Pregnancy Risk Summary There are no adequate data on the developmental risk associated with the use of sodium oxybate in pregnant women. Oral administration of sodium oxybate to pregnant rats (150, 350, or 1,000 mg/kg/day) or rabbits (300, 600, or 1,200 mg/kg/day) throughout organogenesis produced no clear evidence of developmental toxicity; however, oral administration to rats throughout pregnancy and lactation resulted in increased stillbirths and decreased offspring postnatal viability and growth, at a clinically relevant dose [see Data] . In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2-4% and 15-20%, respectively. The background risk of major birth defects and miscarriage for the indicated population is unknown. Clinical Considerations Labor or Delivery Xyrem has not been studied in labor or delivery. In obstetric anesthesia using an injectable formulation of sodium oxybate, newborns had stable cardiovascular and respiratory measures but were very sleepy, causing a slight decrease in Apgar scores. There was a fall in the rate of uterine contractions 20 minutes after injection. Placental transfer is rapid and gamma-hydroxybutyrate (GHB) has been detected in newborns at delivery after intravenous administration of GHB to mothers. Subsequent effects of sodium oxybate on later growth, development, and maturation in humans are unknown. Data Animal Data Oral administration of sodium oxybate to pregnant rats (150, 350, or 1,000 mg/kg/day) or rabbits (300, 600, or 1,200 mg/kg/day) throughout organogenesis produced no clear evidence of developmental toxicity. The highest doses tested in rats and rabbits were approximately 1 and 3 times, respectively, the maximum recommended human dose (MRHD) of 9 g per night on a body surface area (mg/m 2 ) basis. Oral administration of sodium oxybate (150, 350, or 1,000 mg/kg/day) to rats throughout pregnancy and lactation resulted in increased stillbirths and decreased offspring postnatal viability and body weight gain at the highest dose tested. The no-effect dose for pre- and post-natal developmental toxicity in rats is less than the MRHD on a mg/m 2 basis.

8.2 Lactation Risk Summary GHB is excreted in human milk after oral administration of sodium oxybate. There is insufficient information on the risk to a breastfed infant, and there is insufficient information on milk production in nursing mothers. The developmental and health benefits of breastfeeding should be considered along with the mother's clinical need for Xyrem and any potential adverse effects on the breastfed infant from Xyrem or from the underlying maternal condition.

8.4 Pediatric Use The safety and effectiveness of Xyrem in the treatment of cataplexy or excessive daytime sleepiness in pediatric patients (7 years of age and older) with narcolepsy have been established in a double-blind, placebo-controlled, randomized-withdrawal study [see Adverse Reactions ( 6.1 ) and Clinical Studies ( 14.3 )] . In the pediatric clinical trial with Xyrem administration in patients with narcolepsy, serious adverse reactions of central sleep apnea and oxygen desaturation documented by polysomnography evaluation; depression; suicidal ideation; neuropsychiatric reactions including acute psychosis, confusion, and anxiety; and parasomnias, including sleepwalking, have been reported [see Warnings and Precautions ( 5.4 , 5.5 , 5.6 , 5.7 ) and Adverse Reactions ( 6.1 )] . Safety and effectiveness of Xyrem in pediatric patients below the age of 7 years have not been established. Juvenile Animal Toxicity Data In a study in which sodium oxybate (0, 100, 300, or 900 mg/kg/day) was orally administered to rats during the juvenile period of development (postnatal days 21 through 90), mortality was observed at the two highest doses tested. Deaths occurred during the first week of dosing and were associated with clinical signs (including decreased activity and respiratory rate) consistent with the pharmacological effects of the drug. Reduced body weight gain in males and females and delayed sexual maturation in males were observed at the highest dose tested. The no-effect dose for adverse effects in juvenile rats is associated with plasma exposures (AUC) less than that at the maximum recommended human dose (9 g/night).

8.5 Geriatric Use Clinical studies of Xyrem in patients with narcolepsy did not include sufficient numbers of subjects age 65 years and older to determine whether they respond differently from younger subjects. In controlled trials in another population, 39 (5%) of 874 patients were 65 years or older. Discontinuations of treatment due to adverse reactions were increased in the elderly compared to younger adults (21% vs. 19%). Frequency of headaches was markedly increased in the elderly (39% vs. 19%). The most common adverse reactions were similar in both age categories. In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy.

8.6 Hepatic Impairment Because of an increase in exposure to Xyrem, the starting dose should be reduced by half in patients with hepatic impairment [see Dosage and Administration ( 2.4 ) and Clinical Pharmacology ( 12.3 )].

Xyrem is a CNS depressant. The mechanism of action of Xyrem 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 Xyrem on cataplexy and excessive daytime sleepiness are mediated through GABA B actions at noradrenergic and dopaminergic neurons, as well as at thalamocortical neurons.