Varenicline

Varenicline tablets are indicated for use as an aid to smoking cessation treatment. Varenicline tablets are nicotinic receptor partial agonist indicated for use as an aid to smoking-cessation treatment. ( 1 and 2.1 )

Varenicline Tablets: 0.5 mg (white to off white, round, biconvex-coated tablets, debossed with "T" on one side and "2" on the other side) and 1 mg (yellow, round, biconvex-coated tablets, debossed with "T" on one side and "1" on the other side). Tablets: 0.5 mg and 1 mg ( 3 )

Varenicline tablets is contraindicated in patients with a known history of serious hypersensitivity reactions or skin reactions to varenicline tablets. History of serious hypersensitivity or skin reactions to varenicline tablets. ( 4 )

Neuropsychiatric Adverse Events: Postmarketing reports of serious or clinically significant neuropsychiatric adverse events have included changes in mood (including depression and mania), psychosis, hallucinations, paranoia, delusions, homicidal ideation, aggression, hostility, agitation, anxiety, and panic, as well as suicidal ideation, suicide attempt, and completed suicide. Observe patients attempting to quit smoking with varenicline tablets for the occurrence of such symptoms and instruct them to discontinue varenicline tablets and contact a healthcare provider if they experience such adverse events. ( 5.1 ) Seizures: New or worsening seizures have been observed in patients taking varenicline tablets. Varenicline tablets should be used cautiously in patients with a history of seizures or other factors that can lower the seizure threshold. ( 5.2 ) Interaction with Alcohol: Increased effects of alcohol have been reported. Instruct patients to reduce the amount of alcohol they consume until they know whether varenicline tablet affects them. ( 5.3 ) Accidental Injury: Accidental injuries (e.g., traffic accidents) have been reported. Instruct patients to use caution driving or operating machinery until they know how varenicline tablet may affects them. ( 5.4 ) Cardiovascular Events: Patients with underlying cardiovascular (CV) disease may be at increased risk of CV events; however, these concerns must be balanced with the health benefits of smoking cessation. Instruct patients to notify their healthcare providers of new or worsening CV symptoms and to seek immediate medical attention if they experience signs and symptoms of myocardial infarction (MI) or stroke. ( 5.5 and 6.1 ) Somnambulism: Cases of somnambulism have been reported in patients taking varenicline tablets. Some cases described harmful behavior to self, others, or property. Instruct patients to discontinue varenicline tablets and notify their healthcare provider if they experience somnambulism. (5.6 and 6.2 ) Angioedema and Hypersensitivity Reactions: Such reactions, including angioedema, infrequently life-threatening, have been reported. Instruct patients to discontinue varenicline tablets and immediately seek medical care if symptoms occur. ( 5.7 and 6.2 ) Serious Skin Reactions: Rare, potentially life-threatening skin reactions have been reported. Instruct patients to discontinue varenicline tablets and contact a healthcare provider immediately at first appearance of skin rash with mucosal lesions. ( 5.8 and 6.2 ) Nausea: Nausea is the most common adverse reaction (up to 30% incidence rate). Dose reduction may be helpful. ( 5.9 )

5.1 Neuropsychiatric Adverse Events including Suicidality Serious neuropsychiatric adverse events have been reported in patients being treated with varenicline tablets [see Adverse Reactions ( 6.2 )]. These postmarketing reports have included changes in mood (including depression and mania), psychosis, hallucinations, paranoia, delusions, homicidal ideation, aggression, hostility, agitation, anxiety, and panic, as well as suicidal ideation, suicide attempt, and completed suicide. Some patients who stopped smoking may have been experiencing symptoms of nicotine withdrawal, including depressed mood. Depression, rarely including suicidal ideation, has been reported in smokers undergoing a smoking cessation attempt without medication. However, some of these adverse events occurred in patients taking varenicline tablets who continued to smoke. Neuropsychiatric adverse events occurred in patients without and with pre-existing psychiatric disease; some patients experienced worsening of their psychiatric illnesses. Some neuropsychiatric adverse events, including unusual and sometimes aggressive behavior directed to oneself or others, may have been worsened by concomitant use of alcohol [see Warnings and Precautions ( 5.3 ), Adverse Reactions ( 6.2 )] . Observe patients for the occurrence of neuropsychiatric adverse events. Advise patients and caregivers that the patient should stop taking varenicline tablets and contact a healthcare provider immediately if agitation, depressed mood, or changes in behavior or thinking that are not typical for the patient are observed, or if the patient develops suicidal ideation or suicidal behavior. The healthcare provider should evaluate the severity of the symptoms and the extent to which the patient is benefiting from treatment, and consider options including dose reduction, continued treatment under closer monitoring, or discontinuing treatment. In many postmarketing cases, resolution of symptoms after discontinuation of varenicline tablets were reported. However, the symptoms persisted in some cases; therefore, ongoing monitoring and supportive care should be provided until symptoms resolve. The neuropsychiatric safety of varenicline tablets was evaluated in a randomized, double-blind, active and placebo-controlled study that included patients without a history of psychiatric disorder (non-psychiatric cohort, N=3912) and patients with a history of psychiatric disorder (psychiatric cohort, N=4003). In the non-psychiatric cohort, varenicline tablets were not associated with an increased incidence of clinically significant neuropsychiatric adverse events in a composite endpoint comprising anxiety, depression, feeling abnormal, hostility, agitation, aggression, delusions, hallucinations, homicidal ideation, mania, panic, and irritability. In the psychiatric cohort, there were more events reported in each treatment group compared to the non-psychiatric cohort, and the incidence of events in the composite endpoint was higher for each of the active treatments compared to placebo: Risk Differences (RDs) (95%CI) vs. placebo were 2.7% (-0.05, 5.4) for varenicline tablets, 2.2% (-0.5, 4.9) for bupropion, and 0.4% (-2.2, 3.0) for transdermal nicotine. In the non-psychiatric cohort, neuropsychiatric adverse events of a serious nature were reported in 0.1% of varenicline tablets -treated patients and 0.4% of placebo-treated patients. In the psychiatric cohort, neuropsychiatric events of a serious nature were reported in 0.6% of varenicline tablets -treated patients, with 0.5% involving psychiatric hospitalization. In placebo-treated patients, serious neuropsychiatric events occurred in 0.6%, with 0.2% requiring psychiatric hospitalization [see Clinical Studies ( 14.10 )].

5.2 Seizures During clinical trials and the postmarketing experience, there have been reports of seizures in patients treated with varenicline tablets. Some patients had no history of seizures, whereas others had a history of seizure disorder that was remote or well-controlled. In most cases, the seizure occurred within the first month of therapy. Weigh this potential risk against the potential benefits before prescribing varenicline tablets in patients with a history of seizures or other factors that can lower the seizure threshold. Advise patients to discontinue varenicline tablets and contact a healthcare provider immediately if they experience a seizure while on treatment [see Adverse Reactions ( 6.2 )].

5.3 Interaction with Alcohol There have been postmarketing reports of patients experiencing increased intoxicating effects of alcohol while taking varenicline tablets. Some cases described unusual and sometimes aggressive behavior, and were often accompanied by amnesia for the events. Advise patients to reduce the amount of alcohol they consume while taking varenicline tablets until they know whether varenicline tablet affects their tolerance for alcohol [see Adverse Reactions ( 6.2 )].

5.4 Accidental Injury There have been postmarketing reports of traffic accidents, near-miss incidents in traffic, or other accidental injuries in patients taking varenicline tablets. […]

The following serious adverse reactions were reported in postmarketing experience and are discussed in greater detail in other sections of the labeling: Neuropsychiatric Adverse Events including Suicidality [see Warnings and Precautions ( 5.1 )] Seizures [see Warnings and Precautions ( 5.2 )] Interaction with Alcohol [see Warnings and Precautions ( 5.3 )] Accidental Injury [see Warnings and Precautions ( 5.4 )] Cardiovascular Events [see Warnings and Precautions ( 5.5 )] Somnambulism [see Warnings and Precautions ( 5.6 )] Angioedema and Hypersensitivity Reactions [see Warnings and Precautions ( 5.7 )] Serious Skin Reactions [see Warnings and Precautions ( 5.8 )] In the placebo-controlled premarketing studies, the most common adverse events associated with Varenicline tablets (>5% and twice the rate seen in placebo-treated patients) were nausea, abnormal (vivid, unusual, or strange) dreams, constipation, flatulence, and vomiting. The treatment discontinuation rate due to adverse events in patients dosed with 1 mg twice daily was 12% for varenicline tablets, compared to 10% for placebo in studies of three months' treatment. In this group, the discontinuation rates that are higher than placebo for the most common adverse events in varenicline tablets -treated patients were as follows: nausea (3% vs. 0.5% for placebo), insomnia (1.2% vs. 1.1% for placebo), and abnormal dreams (0.3% vs. 0.2% for placebo). Smoking cessation, with or without treatment, is associated with nicotine withdrawal symptoms and has also been associated with the exacerbation of underlying psychiatric illness. Most common adverse reactions (>5% and twice the rate seen in placebo-treated patients) were nausea, abnormal (e.g., vivid, unusual, or strange) dreams, constipation, flatulence, and vomiting. ( 6 ) To report SUSPECTED ADVERSE REACTIONS, contact Lupin Pharmaceuticals, Inc. at 1-800-399-2561 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, the adverse reactions rates observed in the clinical studies 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. During the premarketing development of varenicline tablets, over 4500 subjects were exposed to varenicline tablets, with over 450 treated for at least 24 weeks and approximately 100 for a year. Most study participants were treated for 12 weeks or less. The most common adverse event associated with varenicline tablets treatment is nausea, occurring in 30% of patients treated at the recommended dose, compared with 10% in patients taking a comparable placebo regimen [see Warnings and Precautions ( 5.9 )]. Table 1 shows the adverse events for varenicline tablets and placebo in the 12- week fixed dose premarketing studies with titration in the first week [Studies 2 (titrated arm only), 4, and 5]. Adverse events were categorized using the Medical Dictionary for Regulatory Activities (MedDRA, Version 7.1). MedDRA High Level Group Terms (HLGT) reported in ≥ 5% of patients in the varenicline tablets 1 mg twice daily dose group, and more commonly than in the placebo group, are listed, along with subordinate Preferred Terms (PT) reported in ≥ 1% of varenicline tablets patients (and at least 0.5% more frequent than placebo). Closely related Preferred Terms such as 'Insomnia', 'Initial insomnia', 'Middle insomnia', 'Early morning awakening' were grouped, but individual patients reporting two or more grouped events are only counted once. Table 1: Common Treatment Emergent AEs (%) in the Fixed-Dose, Placebo-Controlled Studies (HLGTs ≥5% of Patients in the 1 mg BID Varenicline Tablets Group and More Commonly than Placebo and PT ≥ 1% in the 1 mg BID Varenicline Tablets Group, and 1 mg BID Varenicline Tablets at Least 0.5% More than Placebo) * Includes PTs Abdominal (pain, pain upper, pain lower, discomfort, tenderness, distension) and Stomach discomfort ** Includes PTs Insomnia/Initial insomnia/Middle insomnia/Early morning awakening SYSTEM ORGAN CLASS High Level Group Term Preferred Term Varenicline Tablets 0.5 mg BID N=129 Varenicline Tablets 1 mg BID N=821 Placebo N=805 GASTROINTESTINAL (GI) GI Signs and Symptoms Nausea 16 30 10 Abdominal Pain * 5 7 5 Flatulence 9 6 3 Dyspepsia 5 5 3 Vomiting 1 5 2 GI Motility/Defecation Conditions Constipation 5 8 3 Gastroesophageal reflux disease 1 1 0 Salivary Gland Conditions Dry mouth 4 6 4 PSYCHIATRIC DISORDERS Sleep Disorder/Disturbances Insomnia ** 19 18 13 Abnormal dreams 9 13 5 Sleep disorder 2 5 3 Nightmare 2 1 0 NERVOUS SYSTEM Headaches Headache 19 15 13 Neurological Disorders NEC Dysgeusia 8 5 4 Somnolence 3 3 2 Lethargy 2 1 0 GENERAL DISORDERS General Disorders NEC Fatigue/Malaise/Asthenia 4 7 6 RESPIR/THORACIC/MEDIAST Respiratory Disorders NEC Rhinorrhea 0 1 0 Dyspnea 2 1 1 Upper Respiratory Tract Disorder 7 5 4 SKIN/SUBCUTANEOUS TISSUE Epidermal and Dermal Conditions Rash 1 3 2 Pruritis 0 1 1 METABOLISM & NUTRITION Appetite/General Nutrition Disorders Increased appetite 4 3 2 Decreased appetite/ Anorexia 1 2 1 The overall pattern and frequency of adverse events during the longer-term premarketing trials was similar to those described in Table 1, though several of the most common events were reported by a greater proportion of patients with long-term use (e.g., nausea was reported in 40% of patients treated with varenicline tablets 1 mg twice daily in a one year study, compared to 8% of placebo-treated patients). Following is a list of treatment-emergent adverse events reported by patients treated with varenicline tablets during all premarketing clinical trials and updated based on pooled data from 18 placebo-controlled pre- and postmarketing studies, including approximately 5,000 patients treated with varenicline. Adverse events were categorized using MedDRA, Version 16.0. The listing does not include those events already listed in the previous tables or elsewhere in labeling, those events for which a drug cause was remote, those events which were so general as to be uninformative, and those events reported only once which did not have a substantial probability of being acutely life-threatening. Blood and Lymphatic System Disorders . Infrequent : anemia, lymphadenopathy. Rare : leukocytosis, splenomegaly, thrombocytopenia. Cardiac Disorders . Infrequent: angina pectoris, myocardial infarction, palpitations, tachycardia. Rare: acute coronary syndrome, arrhythmia, atrial fibrillation, bradycardia, cardiac flutter, cor pulmonale, coronary artery disease, ventricular extrasystoles. Ear and Labyrinth Disorders . Infrequent: tinnitus, vertigo. Rare: deafness, Meniere's disease. Endocrine Disorders . Infrequent: thyroid gland disorders. Eye Disorders . Infrequent : conjunctivitis, eye irritation, eye pain, vision blurred, visual impairment. Rare: blindness transient, cataract subcapsular, dry eye, night blindness, ocular vascular disorder, photophobia, vitreous floaters. Gastrointestinal Disorders . Frequent: diarrhea, toothache. Infrequent: dysphagia, eructation, gastritis, gastrointestinal hemorrhage, mouth ulceration. Rare: enterocolitis, esophagitis, gastric ulcer, intestinal obstruction, pancreatitis acute. General Disorders and Administration Site Conditions . Frequent: chest pain. Infrequent: chest discomfort, chills, edema, influenza-like illness, pyrexia. Hepatobiliary Disorders . Rare: gall bladder disorder. Investigations . Frequent: liver function test abnormal, weight increased. Infrequent: electrocardiogram abnormal. Rare: muscle enzyme increased, urine analysis abnormal. Metabolism and Nutrition Disorders . Infrequent: diabetes mellitus, hypoglycemia. Rare: hyperlipidemia, hypokalemia. Musculoskeletal and Connective Tissue Disorders. Frequent: arthralgia, back pain, myalgia. Infrequent : arthritis, muscle cramp, musculoskeletal pain. Rare: myositis, osteoporosis. Nervous System Disorders . […]

Based on varenicline characteristics and clinical experience to date, varenicline tablets have no clinically meaningful pharmacokinetic drug interactions [see Clinical Pharmacology ( 12.3 )] . Other Smoking-Cessation Therapies: Safety and efficacy in combination with other smoking-cessation therapies has not been established. Coadministration of varenicline and transdermal nicotine resulted in a high rate of discontinuation due to adverse events. ( 7.1 ) Effect of Smoking Cessation on Other Drugs: Pharmacokinetics or pharmacodynamics of certain drugs (e.g., theophylline, warfarin, insulin) may be altered, necessitating dose adjustment. ( 7.2 )

7.1 Use with Other Drugs for Smoking Cessation Safety and efficacy of varenicline tablets in combination with other smoking cessation therapies have not been studied. Bupropion Varenicline (1 mg twice daily) did not alter the steady-state pharmacokinetics of bupropion (150 mg twice daily) in 46 smokers. The safety of the combination of bupropion and varenicline has not been established. Nicotine replacement therapy (NRT) Although co-administration of varenicline (1 mg twice daily) and transdermal nicotine (21 mg/day) for up to 12 days did not affect nicotine pharmacokinetics, the incidence of nausea, headache, vomiting, dizziness, dyspepsia, and fatigue was greater for the combination than for NRT alone. In this study, eight of twenty-two (36%) patients treated with the combination of varenicline and NRT prematurely discontinued treatment due to adverse events, compared to 1 of 17 (6%) of patients treated with NRT and placebo.

7.2 Effect of Smoking Cessation on Other Drugs Physiological changes resulting from smoking cessation, with or without treatment with varenicline tablets, may alter the pharmacokinetics or pharmacodynamics of certain drugs (e.g., theophylline, warfarin, insulin) for which dosage adjustment may be necessary.

8.1 Pregnancy Risk Summary Available data have not suggested an increased risk for major birth defects following exposure to varenicline in pregnancy, compared with women who smoke [see Data] . Smoking during pregnancy is associated with maternal, fetal, and neonatal risks (see Clinical Considerations) . In animal studies, varenicline did not result in major malformations but caused decreased fetal weights in rabbits when dosed during organogenesis at exposures equivalent to 50 times the exposure at the maximum recommended human dose (MRHD). Additionally, administration of varenicline to pregnant rats during organogenesis through lactation produced developmental toxicity in offspring at maternal exposures equivalent to 36 times human exposure at the MRHD [see Data] . The estimated background risk of oral clefts is increased by approximately 30% in infants of women who smoke during pregnancy, compared to pregnant women who do not smoke. The background risk of other major birth defects and miscarriage for the indicated population are unknown. In the US general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2-4% and 15-20%, respectively. Clinical Considerations Disease-Associated Maternal and/or Embryo/Fetal Risk Smoking during pregnancy causes increased risks of orofacial clefts, premature rupture of membranes, placenta previa, placental abruption, ectopic pregnancy, fetal growth restriction and low birth weight, stillbirth, preterm delivery and shortened gestation, neonatal death, sudden infant death syndrome and reduction of lung function in infants. It is not known whether quitting smoking with varenicline tablets during pregnancy reduces these risks. Data Human Data A population-based observational cohort study using the national registers of Denmark and Sweden compared pregnancy and birth outcomes among women exposed to varenicline (N=335, includes 317 first trimester exposed) with women who smoked during pregnancy (N=78,412) and with non-smoking pregnant women (N=806,438). The prevalence of major malformations, the primary outcome, was similar in all groups, including between smoking and non-smoking groups. The prevalence of adverse perinatal outcomes in the varenicline-exposed cohort was not greater than in the cohort of women who smoked, and differed somewhat between the three cohorts. The prevalences of the primary and secondary outcomes are shown in Table 6. Table 6: Summary of Primary and Secondary Outcomes for Three Birth Cohorts *Included only live births in the cohorts. Prevalence among first trimester varenicline-exposed pregnancies (11/317 [3.5%]). **There was a lag in death data in Denmark, so the cohorts were smaller. Outcome Varenicline Cohort (n=335) Smoking Cohort (n=78,412) Non-Smoking Cohort (n=806,438) Major congenital malformation* 12 / 334 (3.6%) 3,382 / 78,028 (4.3%) 33,950 /804,020 (4.2%) Stillbirth 1 (0.3%) 384 (0.5%) 2,418 (0.3%) Small for gestational age 42 (12.5%) 13,433 (17.1%) 73,135 (9.1%) Preterm birth 25 (7.5%) 6,173 (7.9%) 46,732 (5.8%) Premature rupture of membranes 12 (3.6%) 4,246 (5.4%) 30,641 (3.8%) Sudden infant death syndrome** 0/307 (0.0%) 51/71,720 (0.1%) 58/755,939 (<0.1%) The study limitations include the inability to capture malformations in pregnancies that do not result in a live birth, and possible misclassification of outcome and of exposure to varenicline or to smoking. Other small epidemiological studies of pregnant women exposed to varenicline did not identify an association with major malformations, consistent with the Danish and Swedish observational cohort study. Methodological limitations of these studies include small samples and lack of adequate controls. Overall, available studies cannot definitely establish or exclude any varenicline-associated risk during pregnancy. Animal Data Pregnant rats and rabbits received varenicline succinate during organogenesis at oral doses up to 15 and 30 mg/kg/day, respectively. While no fetal structural abnormalities occurred in either species, maternal toxicity, characterized by reduced body weight gain, and reduced fetal weights occurred in rabbits at the highest dose (exposures 50 times the human exposure at the MRHD of 1 mg twice daily based on AUC). Fetal weight reduction did not occur in rabbits at exposures 23 times the human exposure at the MRHD based on AUC. In a pre- and postnatal development study, pregnant rats received up to 15 mg/kg/day of oral varenicline succinate from organogenesis through lactation. Maternal toxicity, characterized by a decrease in body weight gain was observed at 15 mg/kg/day (36 times the human exposure at the MRHD based on AUC). However, decreased fertility and increased auditory startle response occurred in offspring at the highest maternal dose of 15 mg/kg/day.

8.2 Lactation Risk Summary There are no data on the presence of varenicline in human milk, the effects on the breastfed infant, or the effects on milk production. In animal studies varenicline was present in milk of lactating rats [see Data] . However, due to species-specific differences in lactation physiology, animal data may not reliably predict drug levels in human milk. The lack of clinical data during lactation precludes a clear determination of the risk of varenicline tablets to an infant during lactation; however the developmental and health benefits of breastfeeding should be considered along with the mother's clinical need for varenicline tablets and any potential adverse effects on the breastfed child from varenicline tablets or from the underlying maternal condition. Clinical Considerations Because there are no data on the presence of varenicline in human milk and the effects on the breastfed infant, breastfeeding women should monitor their infant for seizures and excessive vomiting, which are adverse reactions that have occurred in adults that may be clinically relevant in breastfeeding infants. Data In a pre- and postnatal development study, pregnant rats received up to 15 mg/kg/day of oral varenicline succinate through gestation and lactation Mean serum concentrations of varenicline in the nursing pups were 5-22% of maternal serum concentrations.

8.4 Pediatric Use Varenicline is not recommended for use in pediatric patients 16 years of age or younger because its efficacy in this population was not demonstrated. Single and multiple-dose pharmacokinetics of varenicline have been investigated in pediatric patients aged 12 to 17 years old (inclusive) and were approximately dose-proportional over the 0.5 mg to 2 mg daily dose range studied. Steady-state systemic exposure in adolescent patients of bodyweight >55 kg, as assessed by AUC (0-24), was comparable to that noted for the same doses in the adult population. When 0.5 mg BID was given, steady-state daily exposure of varenicline was, on average, higher (by approximately 40%) in adolescent patients with bodyweight ≤ 55 kg compared to that noted in the adult population. The efficacy and safety of varenicline was evaluated in a randomized, double-blind, placebo-controlled study of 312 patients aged 12 to 19 years, who smoked an average of at least 5 cigarettes per day during the 30 days prior to recruitment, had a score of at least 4 on the Fagerstrom Test for Nicotine Dependence scale, and at least one previous failed quit attempt. Patients were stratified by age (12 to 16 years of age, n=216 and 17 to 19 years of age, n=96) and by body weight (≤55 kg and >55 kg). Patients were randomized to one of two doses of varenicline, adjusted by weight to provide plasma levels in the efficacious range (based on adult studies) and placebo. Patients received treatment for 12 weeks, followed by a non-treatment period of 40 weeks, along with age-appropriate counseling throughout the study. […]

Varenicline binds with high affinity and selectivity at α4β2 neuronal nicotinic acetylcholine receptors. The efficacy of varenicline tablets in smoking cessation is believed to be the result of varenicline's activity at α4β2 sub-type of the nicotinic receptor where its binding produces agonist activity, while simultaneously preventing nicotine binding to these receptors. Electrophysiology studies in vitro and neurochemical studies in vivo have shown that varenicline binds to α4β2 neuronal nicotinic acetylcholine receptors and stimulates receptor-mediated activity, but at a significantly lower level than nicotine. Varenicline blocks the ability of nicotine to activate α4β2 receptors and thus to stimulate the central nervous mesolimbic dopamine system, believed to be the neuronal mechanism underlying reinforcement and reward experienced upon smoking. Varenicline is highly selective and binds more potently to α4β2 receptors than to other common nicotinic receptors (>500-fold α3β4, >3,500-fold α7, >20,000-fold α1βγδ), or to non nicotinic receptors and transporters (>2,000-fold). Varenicline also binds with moderate affinity (Ki = 350 nM) to the 5-HT3 receptor.