Dexmedetomidine

5 WARNINGS AND PRECAUTIONS • Monitoring: Continuously monitor patients while receiving dexmedetomidine. (5.1) • Bradycardia and Sinus Arrest: Have occurred in young healthy volunteers with high vagal tone or with different routes of administration, e.g., rapid intravenous or bolus administration. (5.2) • Hypotension and Bradycardia: May necessitate medical intervention. May be more pronounced in patients with hypovolemia, diabetes mellitus, or chronic hypertension, and in the elderly. Use with caution in patients with advanced heart block or severe ventricular dysfunction. (5.2) • Co-administration with Other Vasodilators or Negative Chronotropic Agents: Use with caution due to additive pharmacodynamic effects. (5.2) • Transient Hypertension: Observed primarily during the loading dose. Consider reduction in loading infusion rate. (5.3) • Arousability: Patients can become aroused/alert with stimulation; this alone should not be considered as lack of efficacy. (5.4) • Tolerance and Tachyphylaxis: Prolonged exposure to dexmedetomidine beyond 24 hours may be associated with tolerance and tachyphylaxis and a dose-related increase in adverse events. (5.7) 5.1 Drug Administration Dexmedetomidine should be administered only by persons skilled in the management of patients in the intensive care or operating room setting. Due to the known pharmacological effects of dexmedetomidine, patients should be continuously monitored while receiving dexmedetomidine. 5.2 Hypotension, Bradycardia, and Sinus Arrest Clinically significant episodes of bradycardia and sinus arrest have been reported with dexmedetomidine administration in young, healthy adult volunteers with high vagal tone or with different routes of administration including rapid intravenous or bolus administration. Reports of hypotension and bradycardia have been associated with dexmedetomidine infusion. Some of these cases have resulted in fatalities. If medical intervention is required, treatment may include decreasing or stopping the infusion of dexmedetomidine, increasing the rate of intravenous fluid administration, elevation of the lower extremities, and use of pressor agents. Because dexmedetomidine has the potential to augment bradycardia induced by vagal stimuli, clinicians should be prepared to intervene. The intravenous administration of anticholinergic agents (e.g., glycopyrrolate, atropine) should be considered to modify vagal tone. In clinical trials, glycopyrrolate or atropine were effective in the treatment of most episodes of dexmedetomidine-induced bradycardia. However, in some patients with significant cardiovascular dysfunction, more advanced resuscitative measures were required. Caution should be exercised when administering dexmedetomidine to patients with advanced heart block and/or severe ventricular dysfunction. Because dexmedetomidine decreases sympathetic nervous system activity, hypotension and/or bradycardia may be expected to be more pronounced in patients with hypovolemia, diabetes mellitus, or chronic hypertension and in elderly patients. In clinical trials where other vasodilators or negative chronotropic agents were co-administered with dexmedetomidine an additive pharmacodynamic effect was not observed. Nonetheless, caution should be used when such agents are administered concomitantly with dexmedetomidine. 5.3 Transient Hypertension Transient hypertension has been observed primarily during the loading dose in association with the initial peripheral vasoconstrictive effects of dexmedetomidine. Treatment of the transient hypertension has generally not been necessary, although reduction of the loading infusion rate may be desirable. 5.4 Arousability Some patients receiving dexmedetomidine have been observed to be arousable and alert when stimulated. This alone should not be considered as evidence of lack of efficacy in the absence of other clinical signs and symptoms. 5.5 Withdrawal Intensive Care Unit Sedation With administration up to 7 days, regardless of dose, 12 (5%) dexmedetomidine adult subjects experienced at least 1 event related to withdrawal within the first 24 hours after discontinuing study drug and 7 (3%) dexmedetomidine adult subjects experienced at least 1 event 24 to 48 hours after end of study drug. The most common events were nausea, vomiting, and agitation [see Adverse Reactions (6.1)] . In adult subjects, tachycardia and hypertension requiring intervention in the 48 hours following study drug discontinuation occurred at frequencies of <5%. Procedural Sedation In adult subjects, withdrawal symptoms were not seen after discontinuation of short-term infusions of dexmedetomidine (<6 hours). In pediatric patients, mild transient withdrawal symptoms of emergence delirium or agitation were seen after discontinuation of short-term infusions of dexmedetomidine ( 125 mL/hr), diluted urine (osmolality 145 mmol/L). If unrecognized, this condition can lead to hemodynamic instability including unstable blood pressure and increased risk of other cardiovascular sequelae. In reported cases, signs of DI have spontaneously resolved following discontinuation of dexmedetomidine, with resolution often occurring after 24 hours. Monitor urine output and laboratory data for signs of DI during and after dexmedetomidine administration. If DI is suspected, adjust fluid management, provide supportive care, and consider discontinuing dexmedetomidine. If such care is insufficient, or in a setting where dexmedetomidine is used for an extended treatment period, consider expert consultation to assist with patient management. 5.7 Tolerance and Tachyphylaxis Use of dexmedetomidine beyond 24 hours has been associated with tolerance and tachyphylaxis and a dose-related increase in adverse reactions. [see Adverse Reactions (6.1)] . 5.8 Hyperthermia or Pyrexia Dexmedetomidine may induce hyperthermia or pyrexia, which may be resistant to traditional cooling methods, such as administration of cooled intravenous fluids and antipyretic medications. Discontinue dexmedetomidine if drug-related hyperthermia or pyrexia is suspected and monitor patients until body temperature normalizes. 5.9 Hepatic Impairment Since dexmedetomidine clearance decreases with severity of hepatic impairment, dose reduction should be considered in patients with impaired hepatic function [see Dosage and Administration (2.2, 2.3)] .

6 ADVERSE REACTIONS The following clinically significant adverse reactions are described elsewhere in the labeling: • Hypotension, bradycardia and sinus arrest [see Warnings and Precautions (5.2)] • Transient hypertension [see Warnings and Precautions (5.3)] • The most common adverse reactions (incidence >2%) in adults are hypotension, bradycardia, and dry mouth. (6.1) • Adverse reactions in adults, associated with infusions >24 hours in duration include ARDS, respiratory failure, and agitation. (6.1) To report SUSPECTED ADVERSE REACTIONS, contact WG Critical Care at 1-866-562-4708 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 reactions rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. Most common treatment-emergent adverse reactions, occurring in greater than 2% of adult patients in both Intensive Care Unit and procedural sedation studies include hypotension, bradycardia and dry mouth. Intensive Care Unit Sedation Adverse reaction information is derived from the continuous infusion trials of dexmedetomidine for sedation in the Intensive Care Unit setting in which 1,007 adult patients received dexmedetomidine. The mean total dose was 7.4 mcg/kg (range: 0.8 to 84.1), mean dose per hour was 0.5 mcg/kg/hr (range: 0.1 to 6.0) and the mean duration of infusion of 15.9 hours (range: 0.2 to 157.2). The population was between 17 to 88 years of age, 43% ≥65 years of age, 77% male and 93% Caucasian. Treatment-emergent adverse reactions occurring at an incidence of >2% are provided in Table 2. The most frequent adverse reactions were hypotension, bradycardia and dry mouth [see Warnings and Precautions (5.2)] . Table 2: Adverse Reactions with an Incidence >2%— Adult Intensive Care Unit Sedation Population <24 hours * Adverse Event All Dexmedetomidine (N = 1007) (%) Randomized Dexmedetomidine (N = 798) (%) Placebo (N = 400) (%) Propofol (N = 188) (%) Hypotension 25% 24% 12% 13% Hypertension 12% 13% 19% 4% Nausea 9% 9% 9% 11% Bradycardia 5% 5% 3% 0 Atrial Fibrillation 4% 5% 3% 7% Pyrexia 4% 4% 4% 4% Dry Mouth 4% 3% 1% 1% Vomiting 3% 3% 5% 3% Hypovolemia 3% 3% 2% 5% Atelectasis 3% 3% 3% 6% Pleural Effusion 2% 2% 1% 6% Agitation 2% 2% 3% 1% Tachycardia 2% 2% 4% 1% Anemia 2% 2% 2% 2% Hyperthermia 2% 2% 3% 0 Chills 2% 2% 3% 2% Hyperglycemia 2% 2% 2% 3% Hypoxia 2% 2% 2% 3% Post-procedural Hemorrhage 2% 2% 3% 4% Pulmonary Edema 1% 1% 1% 3% Hypocalcemia 1% 1% 0 2% Acidosis 1% 1% 1% 2% Urine Output Decreased 1% 1% 0 2% Sinus Tachycardia 1% 1% 1% 2% Ventricular Tachycardia <1% 1% 1% 5% Wheezing <1% 1% 0 2% Edema Peripheral 1% of All Dexmedetomidine-Treated Adult Patients in the Randomized Placebo-Controlled Continuous Infusion <24 Hours ICU Sedation Studies Adverse Event Randomized Dexmedetomidine (N = 387) Placebo (N = 379) Hypotension 28% 13% Hypertension 16% 18% Nausea 11% 9% Bradycardia 7% 3% Fever 5% 4% Vomiting 4% 6% Atrial Fibrillation 4% 3% Hypoxia 4% 4% Tachycardia 3% 5% Hemorrhage 3% 4% Anemia 3% 2% Dry Mouth 3% 1% Rigors 2% 3% Agitation 2% 3% Hyperpyrexia 2% 3% Pain 2% 2% Hyperglycemia 2% 2% Acidosis 2% 2% Pleural Effusion 2% 1% Oliguria 2% <1% Thirst 2% <1% In a controlled clinical trial, dexmedetomidine was compared to midazolam for ICU sedation exceeding 24 hours duration in adult patients. Key treatment emergent adverse events occurring in dexmedetomidine or midazolam treated adult patients in the randomized active comparator continuous infusion long-term intensive care unit sedation study are provided in Table 4. The number (%) of adult subjects who had a dose-related increase in treatment-emergent adverse events by maintenance adjusted dose rate range in the dexmedetomidine group is provided in Table 5. Table 4: Key Treatment-Emergent Adverse Events Occurring in Dexmedetomidine- or Midazolam-Treated Adult Patients in the Randomized Active Comparator Continuous Infusion Long-Term Intensive Care Unit Sedation Study Adverse Event Dexmedetomidine (N = 244) Midazolam (N = 122) Hypotension 1 56% 56% Hypotension Requiring Intervention 28% 27% Bradycardia 2 42% 19% Bradycardia Requiring Intervention 5% 1% Systolic Hypertension 3 28% 42% Tachycardia 4 25% 44% Tachycardia Requiring Intervention 10% 10% Diastolic Hypertension 3 12% 15% Hypertension 3 11% 15% Hypertension Requiring Intervention† 19% 30% Hypokalemia 9% 13% Pyrexia 7% 2% Agitation 7% 6% Hyperglycemia 7% 2% Constipation 6% 6% Hypoglycemia 5% 6% Respiratory Failure 5% 3% Renal Failure Acute 2% 1% Acute Respiratory Distress Syndrome 2% 1% Generalized Edema 2% 6% Hypomagnesemia 1% 7% † Includes any type of hypertension. 1 Hypotension was defined in absolute terms as Systolic blood pressure of <80 mmHg or Diastolic blood pressure of <50 mmHg or in relative terms as ≤30% lower than pre-study drug infusion value. 2 Bradycardia was defined in absolute terms as 180 mmHg or Diastolic blood pressure of >100 mmHg or in relative terms as ≥30% higher than pre-study drug infusion value. 4 Tachycardia was defined in absolute terms as >120 bpm or in relative terms as ≥30% greater than pre-study drug infusion value. The following adverse events occurred between 2 and 5% for dexmedetomidine and Midazolam, respectively: renal failure acute (2.5%, 0.8%), acute respiratory distress syndrome (2.5%, 0.8%), and respiratory failure (4.5%, 3.3%). Table 5. Number (%) of Adult Subjects Who Had a Dose-Related Increase in Treatment Emergent Adverse Events by Maintenance Adjusted Dose Rate Range in the Dexmedetomidine Group Dexmedetomidine mcg/kg/hr Adverse Event ≤0.7* (N = 95) >0.7 to ≤1.1* (N = 78) >1.1* (N = 71) Constipation 6% 5% 14% Agitation 5% 8% 14% Anxiety 5% 5% 9% Edema Peripheral 3% 5% 7% Atrial Fibrillation 2% 4% 9% Respiratory Failure 2% 6% 10% Acute Respiratory Distress Syndrome 1% 3% 9% *Average maintenance dose over the entire study drug administration Adult Procedural Sedation Adverse reaction information is derived from the two trials for adult procedural sedation [see Clinical Studies (14.2)] in which 318 adult patients received dexmedetomidine. The mean total dose was 1.6 mcg/kg (range: 0.5 to 6.7), mean dose per hour was 1.3 mcg/kg/hr (range: 0.3 to 6.1) and the mean duration of infusion of 1.5 hours (range: 0.1 to 6.2). The population was between 18 to 93 years of age, ASA I-IV, 30% ≥ 65 years of age, 52% male and 61% Caucasian. Treatment-emergent adverse reactions occurring in adults at an incidence of >2% are provided in Table 6. The most frequent adverse reactions were hypotension, bradycardia, and dry mouth [see Warnings and Precautions (5.2)] . Pre-specified criteria for the vital signs to be reported as adverse reactions are footnoted below the table. The decrease in respiratory rate and hypoxia was similar between dexmedetomidine and comparator groups in both studies. Table 6: Adverse Reactions that Occurred with an Incidence of Greater than 2% and Greater in the Placebo Group in Clinical Trials of Dexmedetomidine for Adult Procedural Adverse Event Dexmedetomidine (N = 318) (%) Placebo (N = 113) (%) Hypotension 1 54% 30% Respiratory Depression 2 37% 32% Bradycardia 3 14% 4% Hypertension 4 13% 24% Tachycardia 5 5% 17% Nausea 3% 2% Dry Mouth 3% 1% Hypoxia 6 2% 3% Bradypnea 2% 4% 1 Hypotension was defined in absolute and relative terms as Systolic blood pressure of <80 mmHg or ≤30% lower than pre-study drug infusion value, or Diastolic blood pressure of <50 mmHg. 2 Respiratory depression was defined in absolute and relative terms as respiratory rate (RR) 25% decrease from baseline. 3 Bradycardia was defined in absolute and relative terms as 180 mmHg or ≥30% higher than pre-study drug infusion value or Diastolic blood pressure of >100 mmHg. 5 Tachycardia was defined in absolute and relative terms as >120 beats per minute or ≥30% greater than pre-study drug infusion value. 6 Hypoxia was defined in absolute and relative terms as SpO2 <90% or 10% decrease from baseline. 6.2 Postmarketing Experience The following adverse reactions have been identified during post-approval use of dexmedetomidine. 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. Hypotension and bradycardia were the most common adverse reactions associated with the use of dexmedetomidine during post approval use of the drug. Table 7: Adverse Reactions Experienced During Post-Approval Use of Dexmedetomidine System Organ Class Preferred Term Blood and Lymphatic System Disorders Anemia Cardiac Disorders Arrhythmia, atrial fibrillation, atrioventricular block, bradycardia, cardiac arrest, cardiac disorder, extrasystoles, myocardial infarction, supraventricular tachycardia, tachycardia, ventricular arrhythmia, ventricular tachycardia Eye Disorders Photopsia, visual impairment Gastrointestinal Disorders Abdominal pain, diarrhea, nausea, vomiting General Disorders and Administration Site Conditions Chills, hyperpyrexia, pain, pyrexia, thirst Hepatobiliary Disorders Hepatic function abnormal, hyperbilirubinemia Investigations Alanine aminotransferase increased, aspartate aminotransferase increased, blood alkaline phosphatase increased, blood urea increased, electrocardiogram T wave inversion, gammaglutamyltransferase increased, electrocardiogram QT prolonged Metabolism and Nutrition Disorders Acidosis, hyperkalemia, hypoglycemia, hypovolemia, hypernatremia, diabetes insipidus (Cases of diabetes insipidus, with associated polyuria, dilute urine, and hypernatremia have been reported.) Nervous System Disorders Convulsion, dizziness, headache, neuralgia, neuritis, speech disorder Psychiatric Disorders Agitation, confusional state, delirium, hallucination, illusion Renal and Urinary Disorders Oliguria, polyuria Respiratory, Thoracic and Mediastinal Disorders Apnea, bronchospasm, dyspnea, hypercapnia, hypoventilation, hypoxia, pulmonary congestion, respiratory acidosis Skin and Subcutaneous Tissue Disorders Hyperhidrosis, pruritus, rash, urticaria Surgical and Medical Procedures Light anesthesia Vascular Disorders Blood pressure fluctuation, hemorrhage, hypertension, hypotension

8 USE IN SPECIFIC POPULATIONS • Geriatric Patients: Dose reduction should be considered. (2.2, 2.3, 5.2, 8.5) • Hepatic Impairment: Dose reduction should be considered. (2.2, 2.3, 5.9, 8.6) 8.1 Pregnancy Risk Summary Available data from published randomized controlled trials and case reports over several decades of use with intravenously administered dexmedetomidine during pregnancy have not identified a drug-associated risk of major birth defects and miscarriage; however, the reported exposures occurred after the first trimester. Most of the available data are based on studies with exposures that occurred at the time of caesarean section delivery, and these studies have not identified an adverse effect on maternal outcomes or infant Apgar scores. Available data indicate that dexmedetomidine crosses the placenta. In animal reproduction studies, fetal toxicity that lower fetal viability and reduced live fetuses occurred with subcutaneous administration of dexmedetomidine to pregnant rats during organogenesis at doses 1.8 times the maximum recommended human dose (MRHD) of 17.8 mcg/kg/day. Developmental toxicity (low pup weights and adult offspring weights, decreased F1 grip strength, increased early implantation loss and decreased viability of second-generation offspring) occurred when pregnant rats were subcutaneously administered dexmedetomidine at doses less than the clinical dose from late pregnancy through lactation and weaning ( see Data ). The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. 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. Data Animal Data Increased post-implantation losses and reduced live fetuses in the presence of maternal toxicity (i.e. decreased body weight) were noted in a rat embryo-fetal development study in which pregnant dams were administered subcutaneous doses of dexmedetomidine 200 mcg/kg/day (equivalent to 1.8 times the intravenous MRHD of 17.8 mcg/kg/day based on body surface area [BSA]) during the period of organogenesis (Gestation Day [GD] 6 to 15). No malformations were reported. No malformations or embryo-fetal toxicity were noted in a rabbit embryo-fetal development study in which pregnant does were administered dexmedetomidine intravenously at doses of up to 96 mcg/kg/day (approximately half the human exposure at the MRHD based on AUC) during the period of organogenesis (GD 6 to 18). Reduced pup and adult offspring birth weights, and grip strength were reported in a rat developmental toxicology study in which pregnant females were administered dexmedetomidine subcutaneously at doses of 8 mcg/kg/day (0.07 times the MRHD based on BSA) during late pregnancy through lactation and weaning (GD 16 to postnatal day [PND] 25). Decreased viability of second generation offspring and an increase in early implantation loss along with delayed motor development occurred in the 32 mcg/kg/day group (equivalent to less than the clinical dose based on BSA) when first generation offspring were allowed to mate. This study limited dosing to hard palate closure (GD 15 to 18) through weaning instead of dosing from implantation (GD 6 to 7) to weaning (PND 21). In a study in the pregnant rat, placental transfer of dexmedetomidine was observed when radiolabeled dexmedetomidine was administered subcutaneously. 8.2 Lactation Risk Summary Available published literature reports the presence of dexmedetomidine in human milk following intravenous administration (see Data). There is no information regarding the effects of dexmedetomidine on the breastfed infant or the effects on milk production. Advise women to monitor the breastfed infant for irritability. The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for dexmedetomidine and any potential adverse effects on the breastfed infant from dexmedetomidine or from the underlying condition. Data In two published clinical studies, a total of 14 women were given intravenous dexmedetomidine 6 mcg/kg/hour for 10 minutes after delivery followed by continuous infusion of 0.2–0.7 mcg/kg/hour. Breast milk and maternal blood samples were collected at 0, 6, 12, and 24 hours after discontinuation of dexmedetomidine. Plasma and milk dexmedetomidine concentrations were detectable up to 6 hours in most subjects, up to 12 hours in one subject and undetectable in all at 24 hours. The milk-to-plasma ratio from single paired maternal milk and plasma concentrations at each time point ranged from 0.53 to 0.95. The relative infant dose was estimated to range from 0.02 to 0.098%. 8.4 Pediatric Use Safety and efficacy of dexmedetomidine have not been established for Procedural or ICU Sedation in pediatric patients. 8.5 Geriatric Use Intensive Care Unit Sedation A total of 729 patients in the clinical studies were 65 years of age and over. A total of 200 patients were 75 years of age and over. In patients greater than 65 years of age, a higher incidence of bradycardia and hypotension was observed following administration of dexmedetomidine [ see Warnings and Precautions (5.1, 5.2)]. Therefore a dose reduction may be considered in patients over 65 years of age [see Dosage and Administration (2.3) and Clinical Pharmacology (12.3)]. Procedural Sedation A total of 131 patients in the clinical studies were 65 years of age and over. A total of 47 patients were 75 years of age and over. Hypotension occurred in a higher incidence in dexmedetomidine-treated patients 65 years or older (72%) and 75 years or older (74%) as compared to patients <65 years (47%). A reduced loading dose of 0.5 mcg/kg given over 10 minutes is recommended and a reduction in the maintenance infusion should be considered for patients greater than 65 years of age. 8.6 Hepatic Impairment Since dexmedetomidine clearance decreases with increasing severity of hepatic impairment, dose reduction should be considered in patients with impaired hepatic function [see Dosage and Administration (2.2, 2.3), Clinical Pharmacology (12.3)] .

8.1 Pregnancy Risk Summary Available data from published randomized controlled trials and case reports over several decades of use with intravenously administered dexmedetomidine during pregnancy have not identified a drug-associated risk of major birth defects and miscarriage; however, the reported exposures occurred after the first trimester. Most of the available data are based on studies with exposures that occurred at the time of caesarean section delivery, and these studies have not identified an adverse effect on maternal outcomes or infant Apgar scores. Available data indicate that dexmedetomidine crosses the placenta. In animal reproduction studies, fetal toxicity that lower fetal viability and reduced live fetuses occurred with subcutaneous administration of dexmedetomidine to pregnant rats during organogenesis at doses 1.8 times the maximum recommended human dose (MRHD) of 17.8 mcg/kg/day. Developmental toxicity (low pup weights and adult offspring weights, decreased F1 grip strength, increased early implantation loss and decreased viability of second-generation offspring) occurred when pregnant rats were subcutaneously administered dexmedetomidine at doses less than the clinical dose from late pregnancy through lactation and weaning ( see Data ). The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. 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. Data Animal Data Increased post-implantation losses and reduced live fetuses in the presence of maternal toxicity (i.e. decreased body weight) were noted in a rat embryo-fetal development study in which pregnant dams were administered subcutaneous doses of dexmedetomidine 200 mcg/kg/day (equivalent to 1.8 times the intravenous MRHD of 17.8 mcg/kg/day based on body surface area [BSA]) during the period of organogenesis (Gestation Day [GD] 6 to 15). No malformations were reported. No malformations or embryo-fetal toxicity were noted in a rabbit embryo-fetal development study in which pregnant does were administered dexmedetomidine intravenously at doses of up to 96 mcg/kg/day (approximately half the human exposure at the MRHD based on AUC) during the period of organogenesis (GD 6 to 18). Reduced pup and adult offspring birth weights, and grip strength were reported in a rat developmental toxicology study in which pregnant females were administered dexmedetomidine subcutaneously at doses of 8 mcg/kg/day (0.07 times the MRHD based on BSA) during late pregnancy through lactation and weaning (GD 16 to postnatal day [PND] 25). Decreased viability of second generation offspring and an increase in early implantation loss along with delayed motor development occurred in the 32 mcg/kg/day group (equivalent to less than the clinical dose based on BSA) when first generation offspring were allowed to mate. This study limited dosing to hard palate closure (GD 15 to 18) through weaning instead of dosing from implantation (GD 6 to 7) to weaning (PND 21). In a study in the pregnant rat, placental transfer of dexmedetomidine was observed when radiolabeled dexmedetomidine was administered subcutaneously.