Xylac

Xylac is a typical antipsychotic indicated for the acute treatment of agitation associated with schizophrenia or bipolar I disorder in adults.

“Psychomotor agitation” is defined in DSM-IV as “excessive motor activity associated with a feeling of inner tension.” Patients experiencing agitation often manifest behaviors that interfere with their care (e.g., threatening behaviors, escalating or urgently distressing behavior, self-exhausting behavior), leading clinicians to the use of rapidly absorbed antipsychotic medications to achieve immediate control of the agitation.

The efficacy of Xylac was established in one study of acute agitation in patients with schizophrenia and one study of acute agitation in patients with bipolar I disorder.

Limitations Of Use

As part of the Xylac REMS Program to mitigate the risk of bronchospasm, Xylac must be administered only in an enrolled healthcare facility.

Dosing Information

Xylac must be administered only by a healthcare professional. Xylac is administered by oral inhalation only. The recommended dose for acute agitation is 10 mg administered by oral inhalation, using a single-use inhaler. Administer only a single dose within a 24-hour period.

Required Examination Prior To Dosing

Prior to administering Xylac, screen all patients for a history of asthma, COPD, or other pulmonary disease, and examine patients (including chest auscultation) for respiratory signs (e.g. wheezing).

Important Administration Instructions

Read all of these instructions prior to administering Xylac.

Step 1. Open the Pouch

When ready to use, tear open the foil pouch and remove the inhaler from the package (see Figure 1).

Figure 1: Tearing the pouch

When the Xylac inhaler is removed from the pouch, the indicator light is off (see Figure 2).

Figure 2: Xylac Inhaler with Indicator Light

Step 2. Pull Tab

Firmly pull the plastic tab from the rear of the inhaler (see Figure 3). Check that the green light turns on. This indicates that the inhaler is ready for use. Use the inhaler within 15 minutes after removing the tab to prevent automatic deactivation of the inhaler. The green light will turn off, indicating that the inhaler is not usable. Discard the inhaler after one use.

Figure 3

Step 3. Explain Procedures to the Patient

Explain the administration procedures to the patient prior to use, and advise the patient that it is important to follow the instructions. Inform the patient that the inhaler may produce a flash of light and a clicking sound, and it may become warm during use. These are normal.

Step 4. Instruct the Patient to Exhale

Instruct the patient to hold the inhaler away from the mouth and breathe out fully to empty the lungs (see Figure 4).

Figure 4: Exhale

Step 5. Instruct the Patient to Inhale

Instruct the patient to put the mouthpiece of the inhaler between the lips, close the lips, and inhale through the mouthpiece with a steady deep breath (see Figure 5). Check that the green light turns off indicating that the dose has been delivered.

Figure 5: Inhale

Step 6. Instruct the Patient to Hold Breath

Instruct the patient to remove the mouthpiece from the mouth and hold the breath for as long as possible, up to 10 seconds (see Figure 6).

Figure 6: Hold Breath

Important: If the green light remains on after the patient inhales, the dose of Xylac has NOT been delivered. Instruct the patient to repeat Step 4, Step 5, and Step 6 up to 2 additional times. If the green light still does not turn off, discard the inhaler and use a new one.

Monitoring To Assess Safety

Monitor the patient for signs and symptoms of bronchospasm after Xylac administration. Perform a physical examination, including chest auscultation, at least every 15 minutes for at least one hour after Xylac administration.

Xylac is contraindicated in patients with the following:

• Current diagnosis or history of asthma, COPD, or other lung disease associated with bronchospasm
• Acute respiratory symptoms or signs (e.g., wheezing)
• Current use of medications to treat airways disease, such as asthma or COPD
• History of bronchospasm following Xylac treatment

Known hypersensitivity to loxapine or amoxapine. Serious skin reactions have occurred with oral loxapine and amoxapine.

WARNINGS

Included as part of the PRECAUTIONS section.

PRECAUTIONS

Bronchospasm

Xylac can cause bronchospasm that has the potential to lead to respiratory distress and respiratory arrest. Administer Xylac only in an enrolled healthcare facility that has immediate access on-site to equipment and personnel trained to manage acute bronchospasm, including advanced airway management (intubation and mechanical ventilation). Prior to administering Xylac, screen patients regarding a current diagnosis or history of asthma, COPD, and other lung disease associated with bronchospasm, acute respiratory symptoms or signs, current use of medications to treat airways disease, such as asthma or COPD; and examine patients (including chest auscultation) for respiratory abnormalities (e.g., wheezing). Monitor patients for symptoms and signs of bronchospasm (i.e., vital signs and chest auscultation) at least every 15 minutes for a minimum of one hour following treatment with Xylac. Xylac can cause sedation, which can mask the symptoms of bronchospasm.

Because clinical trials in patients with asthma or COPD demonstrated that the degree of bronchospasm, as indicated by changes in forced expiratory volume in 1 second (FEV₁), was greater following a second dose of Xylac, limit Xylac use to a single dose within a 24 hour period.

Advise all patients of the risk of bronchospasm. Advise them to inform the healthcare professional if they develop any breathing problems such as wheezing, shortness of breath, chest tightness, or cough following treatment with Xylac.

Xylac REMS To Mitigate Bronchospasm

Because of the risk of bronchospasm, Xylac is available only through a restricted program under a REMS called the Xylac REMS. Required components of the Xylac REMS are:

• Healthcare facilities that dispense and administer Xylac must be enrolled and comply with the REMS requirements. Certified healthcare facilities must have on-site access to equipment and personnel trained to provide advance airway management, including intubation and mechanical ventilation.
• Wholesalers and distributors that distribute Xylac must enroll in the program and distribute only to enrolled healthcare facilities.

Further information is available at www.Xylacrems.com or 1-855-755-0492.

Increased Mortality In Elderly Patients With Dementia-Related Psychosis

Elderly patients with dementia-related psychosis treated with antipsychotic drugs are at increased risk of death. Analyses of 17 placebo-controlled trials (modal duration of 10 weeks), largely in patients taking atypical antipsychotic drugs, revealed a risk of death in drug-treated patients of 1.6 to 1.7 times the risk of death in placebo-treated patients. Over the course of a typical 10-week controlled trial, the rate of death in drug-treated patients was about 4.5%, compared to a rate of about 2.6% in the placebo group. Although the cases of death were varied, most of the deaths appeared to be either cardiovascular (e.g., heart failure, sudden death) or infectious (e.g., pneumonia) in nature. Observational studies suggest that, similar to atypical antipsychotic drugs, treatment with conventional antipsychotic drugs may increase mortality. The extent to which the findings of increased mortality in observational studies can be attributed to the antipsychotic drug as opposed to some characteristic(s) of the patients is not clear. Xylac is not approved for the treatment of elderly patients with dementia-related psychosis.

Neuroleptic Malignant Syndrome

Antipsychotic drugs can cause a potentially fatal symptom complex termed Neuroleptic Malignant Syndrome (NMS). Clinical manifestations of NMS include hyperpyrexia, muscle rigidity, altered mental status, and autonomic instability (irregular pulse or blood pressure, tachycardia, diaphoresis, and cardiac dysrhythmia). Associated features can include elevated serum creatine phosphokinase (CPK) concentration, rhabdomyolysis, elevated serum and urine myoglobin concentration, and renal failure. NMS did not occur in the Xylac clinical program.

The diagnostic evaluation of patients with this syndrome is complicated. It is important to consider the presence of other serious medical conditions (e.g., pneumonia, systemic infection, heat stroke, primary CNS pathology, central anticholinergic toxicity, extrapyramidal symptoms, or drug fever).

The management of NMS should include: 1) immediate discontinuation of antipsychotic drugs and other drugs that may contribute to the underlying disorder, 2) intensive symptomatic treatment and medical monitoring, and 3) treatment of any concomitant serious medical problems. There is no general agreement about specific pharmacological treatment regimens for NMS.

If a patient requires antipsychotic drug treatment after recovery from NMS, the potential reintroduction of drug therapy should be carefully considered. The patient should be carefully monitored, since recurrences of NMS have been reported.

Hypotension And Syncope

Xylac can cause hypotension, orthostatic hypotension, and syncope. Use Xylac with caution in patients with known cardiovascular disease (history of myocardial infarction or ischemic heart disease, heart failure or conduction abnormalities), cerebrovascular disease, or conditions that would predispose patients to hypotension (dehydration, hypovolemia, or treatment with antihypertensive medications or other drugs that affect blood pressure or reduce heart rate).

In the presence of severe hypotension requiring vasopressor therapy, the preferred drugs may be norepinephrine or phenylephrine. Epinephrine should not be used, because beta stimulation may worsen hypotension in the setting of Xylac-induced partial alpha blockade.

In short-term (24-hour) placebo-controlled trials of patients with agitation associated with schizophrenia or bipolar I disorder, hypotension occurred in 0.4% and 0.8% in the Xylac 10 mg and placebo groups, respectively. There were no cases of orthostatic hypotension, postural symptoms, presyncope or syncope. A systolic blood pressure ≤ 90 mm Hg with a decrease of ≥ 20 mm Hg occurred in 1.5% and 0.8% of the Xylac 10 mg and placebo groups, respectively. A diastolic blood pressure ≤ 50 mm Hg with a decrease of ≥ 15 mmHg occurred in 0.8% and 0.4% of the Xylac 10 mg and placebo groups, respectively.

In 5 Phase 1 studies in normal volunteers, the incidence of hypotension was 3% and 0% in Xylac 10 mg and the placebo groups, respectively. The incidence of syncope or presyncope in normal volunteers was 2.3% and 0% in the Xylac and placebo groups, respectively. In normal volunteers, a systolic blood pressure ≤ 90 mm Hg with a decrease of ≥ 20 mm Hg occurred in 5.3% and 1.1% in the Xylac and placebo groups, respectively. A diastolic blood pressure ≤ 50 mm Hg with a decrease of ≥ 15 mm Hg occurred in 7.5% and 3.3% in the Xylac and placebo groups, respectively.

Seizures

Xylac lowers the seizure threshold. Seizures have occurred in patients treated with oral loxapine. Seizures can occur in epileptic patients even during antiepileptic drug maintenance therapy. In short term (24 hour), placebo-controlled trials of Xylac, there were no reports of seizures.

Potential For Cognitive And Motor Impairment

Xylac can impair judgment, thinking, and motor skills. In short-term, placebocontrolled trials, sedation and/or somnolence were reported in 12% and 10% in the Xylac and placebo groups, respectively. No patients discontinued treatment because of sedation or somnolence.

The potential for cognitive and motor impairment is increased when Xylac is administered concurrently with other CNS depressants. Caution patients about operating hazardous machinery, including automobiles, until they are reasonably certain that therapy with Xylac does not affect them adversely.

Cerebrovascular Reactions, Including Stroke, In Elderly Patients With Dementia-Related Psychosis

In placebo-controlled trials with atypical antipsychotics in elderly patients with dementia- related psychosis, there was a higher incidence of cerebrovascular adverse reactions (stroke and transient ischemic attacks), including fatalities, compared to placebo-treated patients. Xylac is not approved for the treatment of patients with dementia-related psychosis.

Anticholinergic Reactions Including Exacerbation Of Glaucoma And Urinary Retention

Xylac has anticholinergic activity, and it has the potential to cause anticholinergic adverse reactions including exacerbation of glaucoma or urinary retention. The concomitant use of other anticholinergic drugs (e.g., antiparkinson drugs) with Xylac could have additive effects.

Patient Counseling Information

See FDA-approved patient labeling (Medication Guide)

Bronchospasm

Advise patients and caregivers that there is a risk of bronchospasm. Advise patients to inform their healthcare professional if they develop any breathing problems such as wheezing, shortness of breath, chest tightness, or cough following treatment with Xylac

Interference With Cognitive And Motor Performance

Caution patients and caregivers about performing activities requiring mental alertness, such as operating hazardous machinery or operating a motor vehicle, until they are reasonably certain that Xylac has not affected them adversely.

Caution patients and caregivers about the potential for sedation, especially when used concurrently with other CNS depressants (e.g., alcohol, opioid analgesics, benzodiazepines, tricyclic antidepressants, general anesthetics, phenothiazines, sedative/hypnotics, muscle relaxants, and/or illicit CNS depressants).

Neuroleptic Malignant Syndrome

Patients and caregivers should be counseled that a potentially fatal symptom complex sometimes referred to as NMS has been reported in association with administration of antipsychotic drugs. Signs and symptoms of NMS include hyperpyrexia, muscle rigidity, altered mental status, and evidence of autonomic instability (irregular pulse or blood pressure, tachycardia, diaphoresis, and cardiac dysrhythmia).

Hypotension And Syncope

Advise patients and caregivers of the risk of hypotension or orthostatic hypotension (symptoms include feeling dizzy or lightheaded upon standing).

Anticholinergic Reactions

Counsel patients and caregivers about the potential risks of anticholinergic reactions, such as exacerbation of glaucoma and urinary retention.

Pregnancy

Counsel patients and caregivers regarding the potential risk to the fetus or neonate.

Nursing Mothers

Counsel patients and caregivers regarding the potential risk to the infant.

Nonclinical Toxicology

Carcinogenesis, Mutagenesis, Impairment Of Fertility

Carcinogenesis

No adequate studies have been conducted.

Mutagenesis

Loxapine did not cause mutation or chromosomal aberration when tested in vitro and in vivo. Loxapine was negative in the Ames gene mutation assay, the human peripheral blood lymphocyte chromosomal aberration assay, and in the in vivo mouse bone marrow micronucleus assay up to 40 mg/kg (20-fold the MRHD on mg/m² basis). Loxapine metabolite 8-OH-loxapine was not mutagenic in the in vitro Ames reverse mutation assay and was not clastogenic in the in vitro human peripheral blood lymphocyte chromosomal aberration assay.

Impairment Of Fertility

Loxapine had no effects on fertility or early embryonic development in male rats or in male and female rabbits following oral administration. Mating was decreased in female rats because these animals were in persistent diestrus, an expected pharmacologic effect for this class of compounds. This occurred at doses approximately 0.2- and 1-fold the MRHD of 10 mg/day on a mg/m² basis.

Use In Specific Populations

In general, no dose adjustment for Xylac is required on the basis of a patient's age, gender, race, smoking status, hepatic function, or renal function.

Pregnancy

Pregnancy Category C

Risk Summary

There are no adequate and well-controlled studies of Xylac use in pregnant women. Neonates exposed to antipsychotic drugs during the third trimester of pregnancy are at risk for extrapyramidal and/or withdrawal symptoms following delivery. Loxapine, the active ingredient in Xylac, has demonstrated increased embryofetal toxicity and death in rat fetuses and offspring exposed to doses approximately 0.5-fold the maximum recommended human dose (MRHD) on a mg/m² basis. Xylac should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

Human Data

Neonates exposed to antipsychotic drugs during the third trimester of pregnancy are at risk for extrapyramidal and/or withdrawal symptoms following delivery. There have been reports of agitation, hypertonia, hypotonia, tremor, somnolence, respiratory distress, and feeding disorders in these neonates. These complications have varied in severity; in some cases symptoms have been self-limited, but in other cases neonates have required intensive care unit support and prolonged hospitalization.

Animal Data

In rats, embryofetal toxicity (increased fetal resorptions, reduced weights, and hydronephrosis with hydroureter) was observed following oral administration of loxapine during the period of organogenesis at a dose of 1 mg/kg/day. This dose is equivalent to the MRHD of 10 mg/day on a mg/m² basis. In addition, fetal toxicity (increased prenatal death, decreased postnatal survival, reduced fetal weights, delayed ossification, and/or distended renal pelvis with reduced or absent papillae) was observed following oral administration of loxapine from mid-pregnancy through weaning at doses of 0.6 mg/kg and higher. This dose is approximately half the MRHD of 10 mg/day on a mg/m² basis.

No teratogenicity was observed following oral administration of loxapine during the period of organogenesis in the rat, rabbit, or dog at doses up to 12, 60, and 10 mg/kg, respectively. These doses are approximately 12-, 120-, and 32-fold the MRHD of 10 mg/day on a mg/m² basis, respectively.

Nursing Mothers

It is not known whether Xylac is present in human milk. Loxapine and its metabolites are present in the milk of lactating dogs. Because many drugs are excreted in human milk and because of the potential for serious adverse reactions in nursing infants from Xylac, a decision should be made whether to discontinue nursing or discontinue Xylac, taking into account the importance of the drug to the mother.

Pediatric Use

The safety and effectiveness of Xylac in pediatric patients have not been established.

Geriatric Use

Elderly patients with dementia-related psychosis treated with antipsychotic drugs are at an increased risk of death. Xylac is not approved for the treatment of dementia-related psychosis. Placebocontrolled studies of Xylac in patients with agitation associated with schizophrenia or bipolar disorder did not include patients over 65 years of age.

The following adverse reactions are discussed in more detail in other sections of the labeling:

• Hypersensitivity (serious skin reactions)
• Bronchospasm
• Increased Mortality in Elderly Patients with Dementia-Related Psychosis
• Neuroleptic Malignant Syndrome
• Hypotension and syncope
• Seizure
• Potential for Cognitive and Motor Impairment
• Cerebrovascular Reactions, Including Stroke, in Elderly Patients with Dementia- Related Psychosis
• Anticholinergic Reactions Including Exacerbation of Glaucoma and Urinary Retention

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. The following findings are based on pooled data from three short-term (24-hour), randomized, double-blind, placebo-controlled clinical trials (Studies 1, 2, and 3) of Xylac 10 mg in the treatment of patients with acute agitation associated with schizophrenia or bipolar I disorder. In the 3 trials, 259 patients received Xylac 10 mg, and 263 received placebo.

Commonly Observed Adverse Reactions

In the 3 trials in acute agitation, the most common adverse reactions were dysgeusia, sedation, and throat irritation. These reactions occurred at a rate of at least 2% of the Xylac group and at a rate greater than in the placebo group. (Refer to Table 1).

Table 1: Adverse Reactions in 3 Pooled Short-Term, Placebo-Controlled Trials (Studies 1, 2, and 3) in Patients with Schizophrenia or Bipolar Disorder

Airway Adverse Reactions In The 3 Trials In Acute Agitation

Agitated patients with Schizophrenia or Bipolar Disorder: In the 3 short-term (24-hour), placebo-controlled trials in patients with agitation associated with schizophrenia or bipolar disorder (Studies 1, 2, and 3), bronchospasm (which includes reports of wheezing, shortness of breath and cough) occurred more frequently in the Xylac group, compared to the placebo group: 0% (0/263) in the placebo group and 0.8% (2/259) in the Xylac 10 mg group. One patient with schizophrenia, without a history of pulmonary disease, had significant bronchospasm requiring rescue treatment with a bronchodilator and oxygen.

Bronchospasm And Airway Adverse Reactions In Pulmonary Safety Trials

Clinical pulmonary safety trials demonstrated that Xylac can cause bronchospasm as measured by FEV₁, and as indicated by respiratory signs and symptoms in the trials. In addition, the trials demonstrated that patients with asthma or other pulmonary diseases, such as COPD are at increased risk of bronchospasm. The effect of Xylac on pulmonary function was evaluated in 3 randomized, double-blind, placebo-controlled clinical pulmonary safety trials in healthy volunteers, patients with asthma, and patients with COPD. Pulmonary function was assessed by serial FEV₁ tests, and respiratory signs and symptoms were assessed. In the asthma and COPD trials, patients with respiratory symptoms or FEV₁ decrease of ≥ 20% were administered rescue treatment with albuterol (metered dose inhaler or nebulizer) as required. These patients were not eligible for a second dose; however, they had continued FEV₁ monitoring in the trial.

Healthy Volunteers: In the healthy volunteer crossover trial, 30 subjects received 2 doses of either Xylac or placebo 8 hours apart, and 2 doses of the alternate treatment at least 4 days later. The results for maximum decrease in FEV₁ are presented in Table 2. No subjects in this trial developed airway related adverse reactions (cough, wheezing, chest tightness, or dyspnea).

Asthma Patients: In the asthma trial, 52 patients with mild-moderate persistent asthma (with FEV₁ ≥ 60% of predicted) were randomized to treatment with 2 doses of Xylac 10 mg or placebo. The second dose was to be administered 10 hours after the first dose. Approximately 67% of these patients had a baseline FEV₁ ≥ 80% of predicted. The remaining patients had an FEV₁ 60-80% of predicted. Nine patients (17%) were former smokers. As shown in Table 2 and Figure 7, there was a marked decrease in FEV₁ immediately following the first dose (maximum mean decreases in FEV₁ and % predicted FEV₁ were 303 mL and 9.1%, respectively). Furthermore, the effect on FEV₁ was greater following the second dose (maximum mean decreases in FEV₁ and % predicted FEV₁ were 537 mL and 14.7 %, respectively). Respiratory-related adverse reactions (bronchospasm, chest discomfort, cough, dyspnea, throat tightness, and wheezing) occurred in 54% of Xylac-treated patients and 12% of placebo-treated patients. There were no serious adverse events. Nine of 26 (35%) patients in the Xylac group, compared to one of 26 (4%) in the placebo group, did not receive a second dose of study medication, because they had a ≥ 20% decrease in FEV₁ or they developed respiratory symptoms after the first dose. Rescue medication (albuterol via metered dose inhaler or nebulizer) was administered to 54% of patients in the Xylac group [7 patients (27%) after the first dose and 7 of the remaining 17 patients (41%) after the second dose] and 12% in the placebo group (1 patient after the first dose and 2 patients after the second dose).

COPD Patients: In the COPD trial, 53 patients with mild to severe COPD (with FEV₁ ≥ 40% of predicted) were randomized to treatment with 2 doses of Xylac 10 mg or placebo. The second dose was to be administered 10 hours after the first dose. Approximately 57% of these patients had moderate COPD [Global Initiative for Chronic Obstructive Lung Disease (GOLD) Stage II]; 32% had severe disease (GOLD Stage III); and 11% had mild disease (GOLD Stage I). As illustrated in Table 2 there was a decrease in FEV₁ soon after the first dose (maximum mean decreases in FEV₁ and % predicted FEV₁ were 96 mL and 3.5%, respectively), and the effect on FEV₁ was greater following the second dose (maximum mean decreases in FEV₁ and % predicted FEV₁ were 125 mL and 4.5%, respectively). Respiratory adverse reactions occurred more frequently in the Xylac group (19%) than in the placebo group (11%). There were no serious adverse events. Seven of 25 (28%) patients in the Xylac group and 1of 27 (4%) in the placebo group did not receive a second dose of study medication because of a ≥ 20% decrease in FEV₁ or the development of respiratory symptoms after the first dose. Rescue medication (albuterol via MDI or nebulizer) was administered to 23% of patients in the Xylac group: 8% of patients after the first dose and 21% of patients after the second dose, and to 15% of patients in the placebo group.

Table 2: Maximum Decrease in FEV₁ from Baseline in the Healthy Volunteer, Asthma, and COPD Trials

FEV₁ categories are cumulative; i.e. a subject with a maximum decrease of 21% is included in all 3 categories. Patients with a ≥ 20% decrease in FEV₁ did not receive a second dose of study drug.

Figure 7: LS Mean Change from Baseline in FEV₁ in Patients with Asthma

Patients with a ≥ 20% decrease in FEV₁ did not receive a second dose of study drug and are not included in the curves beyond hour 10.

Extrapyramidal Symptoms (EPS): Extrapyramidal reactions have occurred during the administration of oral loxapine. In most patients, these reactions involved parkinsonian symptoms such as tremor, rigidity, and masked facies. Akathisia (motor restlessness) has also occurred.

In the 3 short-term (24-hour), placebo-controlled trials of Xylac in 259 patients with agitation associated with schizophrenia or bipolar disorder, extrapyramidal reactions occurred. One patient (0.4%) treated with Xylac developed neck dystonia and oculogyration. The incidence of akathisia was 0% and 0.4% in the placebo and Xylac groups, respectively.

Dystonia (Antipsychotic Class Effect): Symptoms of dystonia, prolonged abnormal contractions of muscle groups, may occur in susceptible individuals during treatment with Xylac. Dystonic symptoms include spasm of the neck muscles, sometimes progressing to tightness of the throat, difficulty swallowing or breathing, and/or protrusion of the tongue.

Acute dystonia tends to be dose-related, but can occur at low doses, and occurs more frequently with first generation antipsychotic drugs such as Xylac. The risk is greater in males and younger age groups.

Cardiovascular Reactions: Tachycardia, hypotension, hypertension, orthostatic hypotension, lightheadedness, and syncope have been reported with oral administration of loxapine.

Signs And Symptoms Of Overdosage

As would be expected from the pharmacologic actions of loxapine, the clinical findings may include CNS depression, unconsciousness, profound hypotension, respiratory depression, extrapyramidal symptoms, and seizure.

Management Of Overdosage

For the most up to date information on the management of Xylac overdosage, contact a certified poison control center (1-800-222-1222 or www.poison.org). Provide supportive care including close medical supervision and monitoring. Treatment should consist of general measures employed in the management of overdosage with any drug. Consider the possibility of multiple drug overdosage. Ensure an adequate airway, oxygenation, and ventilation. Monitor cardiac rhythm and vital signs. Use supportive and symptomatic measures.

Loxapine acts as an antagonist at central serotonin and dopamine receptors, with high affinity for serotonin 5-HT2A and dopamine D1, D2, D3, and D4 receptors (Ki values of 2 nM, 18 nM, 10 nM, 21 nM, 9 nM, respectively). Some of the adverse effects of loxapine may be related to the antagonism of histamine H1 (somnolence), muscarinic M1 (anticholinergic), and adrenergic a2 (orthostatic hypotension) receptors (Ki values of 15 nM, 117 nM and 250 nM, respectively).

Thorough QTc Study

Xylac did not prolong the QTc interval. The effect of Xylac on QTc prolongation was evaluated in a randomized, double-blinded, positive- (moxifloxacin 400 mg) and placebo-controlled parallel study in healthy subjects. A total of 48 healthy subjects were administered Xylac 10 mg. In this study with a demonstrated ability to detect small effects, the upper bound of the 90% confidence interval (CI) for the largest placeboadjusted, baseline-corrected QTc based on individual correction method was below 10 milliseconds, the threshold for regulatory concern.

Absorption

The single-dose pharmacokinetic parameters of loxapine following administration of single doses of Xylac 10 mg in healthy adult subjects are presented in Table 3 and Figure 8.

Administration of Xylac resulted in rapid absorption of loxapine, with a median time of maximum plasma concentration (Tmax) of 2 minutes. Loxapine exposure in the first 2 hours after administration (AUC0-2h) was 66.7 ng•h/mL for the 10 mg dose. As a consequence of the very rapid absorption of loxapine after oral inhalation, there is substantial variability in the early plasma concentrations of loxapine. The mean plasma loxapine concentrations following administration of Xylac were linear over the clinical dose range. AUC0-2h, AUCinf, and Cmax increased in a dose-dependent manner.

Table 3: Pharmacokinetics in Healthy Adult Subjects Administered a Single Dose of Xylac 10 mg

Figure 8: Mean Plasma Concentrations of Loxapine following Single-Dose Administration Xylac 10 mg in Healthy Subjects

Distribution

Loxapine is removed rapidly from the plasma and distributed in tissues. Animal studies following oral administration suggest an initial preferential distribution in the lungs, brain, spleen, heart, and kidney. Loxapine is 96.6% bound to human plasma proteins.

Metabolism

Loxapine is metabolized extensively in the liver following oral administration, with multiple metabolites formed. The main metabolic pathways include: 1) hydroxylation to form 8-OH-loxapine by CYP1A2 and 7-OH-loxapine by CYP3A4 and CYP2D6, 2) N-oxidation to form loxapine N-oxide by flavanoid monoamine oxidases (FMOs), and 3) de-methylation to form amoxapine. Because there are multiple metabolic pathways, the risk of metabolic interactions caused by an effect on an individual isoform is minimal. For Xylac, the order of metabolites observed in humans (based on systemic exposure) was 8-OH-loxapine > > loxapine N-oxide, 7-OH-loxapine > amoxapine. Plasma levels of 8-OH-loxapine are similar to those of the parent compound.

Excretion

Excretion occurs mainly in the first 24 hours. Metabolites are excreted in the urine in the form of conjugates and in the feces unconjugated. The terminal elimination half-life (T½) ranged from 6 to 8 hours.

Transporter Interaction

In vitro studies indicated that loxapine was not a substrate for p-glycoprotein (P-gp): however, loxapine inhibited P-gp.