warnings and cautions
5 WARNINGS AND PRECAUTIONS Monitoring: Continuously monitor patients while receiving dexmedetomidine hydrochloride injection. ( 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 ) Prolonged exposure to dexmedetomidine beyond 24 hours may be associated with tolerance and tachyphylaxis and a dose-related increase in adverse events. ( 5.6 ) 5.1 Drug Administration Dexmedetomidine hydrochloride injection should be administered only by persons skilled in the management of patients in the operating room setting. Due to the known pharmacological effects of dexmedetomidine hydrochloride injection, patients should be continuously monitored while receiving dexmedetomidine hydrochloride injection. 5.2 Hypotension, Bradycardia, and Sinus Arrest Clinically significant episodes of bradycardia and sinus arrest have been reported with dexmedetomidine hydrochloride injection 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 hydrochloride infusion. Some of these cases have resulted in fatalities. If medical intervention is required, treatment may include decreasing or stopping the infusion of dexmedetomidine hydrochloride injection, increasing the rate of intravenous fluid administration, elevation of the lower extremities, and use of pressor agents. Because dexmedetomidine hydrochloride injection 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 hydrochloride-induced bradycardia. However, in some patients with significant cardiovascular dysfunction, more advanced resuscitative measures were required. Caution should be exercised when administering dexmedetomidine hydrochloride injection to patients with advanced heart block and/or severe ventricular dysfunction. Because dexmedetomidine hydrochloride injection 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 hydrochloride injection an additive pharmacodynamic effect was not observed. Nonetheless, caution should be used when such agents are administered concomitantly with dexmedetomidine hydrochloride injection. 5.3 Transient Hypertension Transient hypertension has been observed primarily during the loading dose in association with the initial peripheral vasoconstrictive effects of dexmedetomidine hydrochloride injection. 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 hydrochloride injection 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 Procedural Sedation In adult subjects, withdrawal symptoms were not seen after discontinuation of short term infusions of dexmedetomidine hydrochloride injection (<6 hours). 5.6 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 ) ]. 5.7 Hepatic Impairment Since dexmedetomidine hydrochloride injection clearance decreases with severity of hepatic impairment, dose reduction should be considered in patients with impaired hepatic function [ see Dosage and Administration ( 2.2 ) ].