Precedex (dexmedetomidine hydrochloride) injection is a sterile, nonpyrogenic solution suitable for intravenous infusion following dilution. Dexmedetomidine hydrochloride is the S-enantiomer of medetomidine and is chemically described as (+)-4-(S)-[1-(2,3-dimethylphenyl)ethyl]-1H-imidazole monohydrochloride. Precedex has a molecular weight of 236.7 and the empirical formula is C₁₃H₁₆N₂• HCl and the structural formula is:

Dexmedetomidine hydrochloride is a white or almost white powder that is freely soluble in water and has a pKa of 7.1. Its partition coefficient in-octanol: water at pH 7.4 is 2.89. Precedex is supplied as a clear, colorless, isotonic solution with a pH of 4.5 to 7.0. Each mL contains 118 mcg of dexmedetomidine hydrochloride equivalent to 100 mcg of dexmedetomidine and 9 mg of sodium chloride in water. The solution is preservative-free and contains no additives or chemical stabilizers.

Last updated on RxList: 2/9/2009

Intensive Care Unit Sedation

Precedex® is indicated for sedation of initially intubated and mechanically ventilated patients during treatment in an intensive care setting. Precedex should be administered by continuous infusion not to exceed 24 hours.

Precedex has been continuously infused in mechanically ventilated patients prior to extubation, during extubation, and post-extubation. It is not necessary to discontinue Precedex prior to extubation.

Procedural Sedation

Precedex is indicated for sedation of non-intubated patients prior to and/or during surgical and other procedures.

Dosing Guidelines

• Precedex dosing should be individualized and titrated to desired clinical response.
• Precedex is not indicated for infusions lasting longer than 24 hours
• Precedex should be administered using a controlled infusion device.

Dosage Information

Table 1. Dosage Information

Dosage Adjustment

Due to possible pharmacodynamic interactions, a reduction in dosage of Precedex or other concomitant anesthetics, sedatives, hypnotics or opioids may be required when co-administered. [see DRUG INTERACTIONS].

Dosage reductions may need to be considered for patients with renal or hepatic impairment, and geriatric patients [see WARNINGS AND PRECAUTIONS, Use in Specific Populations, CLINICAL PHARMACOLOGY].

Preparation of Solution

Precedex must be diluted in 0.9% sodium chloride solution to achieve required concentration (4 mcg/mL) prior to administration. Preparation of solutions is the same, whether for the loading dose or maintenance infusion.

Strict aseptic technique must always be maintained during handling of Precedex.

To prepare the infusion, withdraw 2 mL of Precedex and add to 48 mL of 0.9% sodium chloride injection to a total of 50 mL. Shake gently to mix well.

Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit.

Administration with Other Fluids

Precedex infusion should not be co-administered through the same intravenous catheter with blood or plasma because physical compatibility has not been established.

Precedex has been shown to be incompatible when administered with the following drugs: amphotericin B, diazepam.

Precedex has been shown to be compatible when administered with the following intravenous fluids and drugs:

0.9% sodium chloride in water, 5% dextrose in water, 20% mannitol, alfentanil hydrochloride, amikacin sulfate, aminophylline, amiodarone hydrochloride, ampicillin sodium, ampicillin sodium-sulbactam sodium, atracurium besylate, atropine sulfate, azithromycin, aztreonam, bretylium tosylate, bumetanide, butorphanol tartrate, calcium gluconate, cefazolin sodium, cefepime hydrochloride, cefoperazone sodium, cefotaxime sodium, cefotetan sodium, cefoxitin sodium, ceftazidime, ceftizoxime sodium, ceftriaxone sodium, cefuroxime sodium, chlorpromazine hydrochloride, cimetidine hydrochloride, ciprofloxacin, cisatracurium besylate, clindamycin phosphate, dexamethasone sodium phosphate, digoxin, diltiazem hydrochloride, diphenhydramine hydrochloride, dobutamine hydrochloride, dolasetron mesylate, dopamine hydrochloride, doxycycline hyclate, droperidol, enalaprilat, ephedrine hydrochloride, epinephrine hydrochloride, erythromycin lactobionate, esmolol, etomidate, famotidine, fenoldopam mesylate, fentanyl citrate, fluconazole, furosemide, gatifloxacin, gentamicin sulfate, glycopyrrolate bromide, granisetron hydrochloride, haloperidol lactate, heparin sodium, hydrocortisone sodium succinate, hydromorphone hydrochloride, hydroxyzine hydrochloride, inamrinone lactate, isoproterenol hydrochloride, ketorolac tromethamine, labetalol, lactated Ringer's solution, levofloxacin, lidocaine hydrochloride, linezolid, lorazepam, magnesium sulfate, meperidine hydrochloride, methylprednisolone sodium succinate, metoclopramide hydrochloride, metronidazole, midazolam, milrinone lactate, mivacurium chloride, morphine sulfate, nalbuphine hydrochloride, nitroglycerin, norepinephrine bitartrate, ofloxacin, ondansetron hydrochloride, pancuronium bromide, phenylephrine hydrochloride, piperacillin sodium, piperacillin sodium-tazobactam sodium, potassium chloride, procainamide hydrochloride, prochlorperazine edisylate, promethazine hydrochloride, propofol, ranitidine hydrochloride, rapacuronium bromide, remifentanil hydrochloride, rocuronium bromide, sodium bicarbonate, sodium nitroprusside, succinylcholine, sufentanil citrate, sulfamethoxazole-trimethoprim, theophylline, thiopental sodium, ticarcillin disodium, ticarcillin disodium-clavulanate potassium, tobramycin sulfate, vancomycin hydrochloride, vecuronium bromide, verapamil hydrochloride, and a plasma-substitute.

Compatibility with Natural Rubber

Compatibility studies have demonstrated the potential for absorption of Precedex to some types of natural rubber. Although Precedex is dosed to effect, it is advisable to use administration components made with synthetic or coated natural rubber gaskets.

Dosage Forms And Strengths

200 mcg/2 mL (100 mcg/mL) in a glass vial

Storage And Handling

Precedex (dexmedetomidine hydrochloride) injection, 200 mcg/2 mL (100 mcg/mL) is available in 2 mL clear glass vial. Vials are intended for single use only.

Store at controlled room temperature, 25°C (77°F) with excursions allowed from 15 to 30°C (59 to 86°F). [See USP.]

Manufactured and Distributed by: Hospira, Inc. Lake Forest, IL 60045, USA. FDA revision date: 10/17/2008

Last updated on RxList: 2/9/2009

Clinical Studies 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 clinical trials of another drug and may not reflect the rates observed in practice.

Use of Precedex has been associated with the following serious adverse reactions:

• Hypotension, bradycardia and sinus arrest [see WARNINGS AND PRECAUTIONS]
• Transient hypertension [see WARNINGS AND PRECAUTIONS]

Most common treatment-emergent adverse reactions, occurring in greater than 2% of 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 Precedex for sedation in the Intensive Care Unit setting in which 1007 patients received Precedex. 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] .

Table 2. Adverse Reactions With an Incidence > 2%— Intensive Care Unit Sedation Population

Procedural Sedation

Adverse reaction information is derived from the two trials for procedural sedation in which 318 patients received Precedex. 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, 30% ≥ 65 years of age, 52% male and 61% Caucasian.

Treatment-emergent adverse reactions occurring at an incidence of > 2% are provided in Table 3. The most frequent adverse reactions were hypotension, bradycardia, and dry mouth [see WARNINGS AND PRECAUTIONS] . 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 Precedex and comparator groups in both studies.

Table 3. Adverse Reactions With an Incidence > 2%— Procedural Sedation Population

Postmarketing Experience

The following adverse reactions have been identified during post approval use of Precedex. 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 Precedex during post approval use of the drug.

Table 4: Adverse Reactions Experienced During Post-approval Use of Precedex

Drug Abuse And Dependence

Controlled Substance

Precedex (dexmedetomidine hydrochloride) is not a controlled substance.

Dependence

The dependence potential of Precedex has not been studied in humans. However, since studies in rodents and primates have demonstrated that Precedex exhibits pharmacologic actions similar to those of clonidine, it is possible that Precedex may produce a clonidine-like withdrawal syndrome upon abrupt discontinuation[see WARNINGS AND PRECAUTIONS] .

Anesthetics, Sedatives, Hypnotics, Opioids

Co-administration of Precedex with anesthetics, sedatives, hypnotics, and opioids is likely to lead to an enhancement of effects. Specific studies have confirmed these effects with sevoflurane, isoflurane, propofol, alfentanil, and midazolam. No pharmacokinetic interactions between Precedex and isoflurane, propofol, alfentanil and midazolam have been demonstrated. However, due to possible pharmacodynamic interactions, when co-administered with Precedex, a reduction in dosage of Precedex or the concomitant anesthetic, sedative, hypnotic or opioid may be required.

Neuromuscular Blockers

In one study of 10 healthy volunteers, administration of Precedex for 45 minutes at a plasma concentration of one ng/mL resulted in no clinically meaningful increases in the magnitude of neuromuscular blockade associated with rocuronium administration.

Last updated on RxList: 2/9/2009

Included as part of the PRECAUTIONS section.

Drug Administration

Precedex 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 Precedex, patients should be continuously monitored while receiving Precedex.

Hypotension, Bradycardia, and Sinus Arrest

Clinically significant episodes of bradycardia and sinus arrest have been reported with Precedex administration in young, healthy 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 Precedex infusion. If medical intervention is required, treatment may include decreasing or stopping the infusion of Precedex, increasing the rate of intravenous fluid administration, elevation of the lower extremities, and use of pressor agents. Because Precedex 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 Precedex-induced bradycardia. However, in some patients with significant cardiovascular dysfunction, more advanced resuscitative measures were required.

Caution should be exercised when administering Precedex to patients with advanced heart block and/or severe ventricular dysfunction. Because Precedex 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 situations where other vasodilators or negative chronotropic agents are administered, co-administration of Precedex could have an additive pharmacodynamic effect and should be administered with caution.

Transient Hypertension

Transient hypertension has been observed primarily during the loading dose in association with the initial peripheral vasoconstrictive effects of Precedex. Treatment of the transient hypertension has generally not been necessary, although reduction of the loading infusion rate may be desirable.

Arousability

Some patients receiving Precedex 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.

Withdrawal

Intensive Care Unit Sedation

If Precedex were to be administered for more than 24 hours and stopped abruptly, withdrawal symptoms similar to those reported for another alpha-2-adrenergic agent, clonidine, may result. These symptoms include nervousness, agitation, and headaches, accompanied or followed by a rapid rise in blood pressure and elevated catecholamine concentrations in the plasma.

Procedural Sedation

Withdrawal symptoms were not seen after discontinuation of short term infusions of Precedex ( < 6 hours).

Hepatic Impairment

Since Precedex clearance decreases with severity of hepatic impairment, dose reduction should be considered in patients with impaired hepatic function [see DOSAGE AND ADMINISTRATION].

Nonclinical Toxicology

Carcinogenesis, Mutagenesis, Impairment of Fertility

Animal carcinogenicity studies have not been performed with Precedex.

Dexmedetomidine was not mutagenic in vitro, in either the bacterial reverse mutation assay (E. coli and Salmonella typhimurium) or the mammalian cell forward mutation assay (mouse lymphoma). Dexmedetomidine was clastogenic in the in vitro human lymphocyte chromosome aberration test with, but not without, rat S9 metabolic activation. In contrast, dexmedetomidine was not clastogenic in the in vitro human lymphocyte chromosome aberration test with or without human S9 metabolic activation. Although dexmedetomidine was clastogenic in an in vivo mouse micronucleus test in NMRI mice, there was no evidence of clastogenicity in CD-1 mice,

Fertility in male or female rats was not affected after daily subcutaneous injections at doses up to 54 mcg/kg (less than the maximum recommended human intravenous dose on a mcg/m² basis). Precedex was dosed from 10 weeks prior to mating in males and 3 weeks prior to mating and during mating in females.

Use In Specific Populations

Pregnancy

Pregnancy Category C: Teratogenic effects were not observed following administration of Precedex at subcutaneous doses up to 200 mcg/kg in rats from day 5 to day 16 of gestation and intravenous doses up to 96 mcg/kg in rabbits from day 6 to day 18 of gestation. The dose in rats is approximately 2 times the maximum recommended human intravenous dose on a mcg/m² basis. The exposure in rabbits is approximately equal to that in humans at the maximum recommended intravenous dose based on plasma area-under-the-curve values. However, fetal toxicity, as evidenced by increased post-implantation losses and reduced live pups, was observed in rats at subcutaneous dose of 200 mcg/kg. The no-effect dose was 20 mcg/kg (less than the maximum recommended human intravenous dose on a mcg/m² basis). In another reproductive study when Precedex was administered subcutaneously to pregnant rats from gestation day 16 through nursing, it caused lower pup weights at 8 and 32 mcg/kg as well as fetal and embryocidal toxicity of second generation offspring at a dose of 32 mcg/kg (less than the maximum recommended human intravenous dose on a mcg/m² basis). Precedex also produced delayed motor development in pups at a dose of 32 mcg/kg (less than the maximum recommended human intravenous dose on a mcg/m² basis). No such effects were observed at a dose of 2 mcg/kg (less than the maximum recommended intravenous dose on a mcg/m² basis).

Placental transfer of Precedex was observed when radiolabeled Precedex was administered subcutaneously to pregnant rats.

There are no adequate and well-controlled studies in pregnant women. Precedex should be used during pregnancy only if the potential benefits justify the potential risk to the fetus.

Labor and Delivery

The safety of Precedex during labor and delivery has not been studied. Therefore, Precedex is not recommended during labor and delivery including cesarean section deliveries.

Nursing Mothers

It is not known whether Precedex is excreted in human milk. Radio-labeled Precedex administered subcutaneously to lactating female rats was excreted in milk. Because many drugs are excreted in human milk, caution should be exercised when Precedex is administered to a nursing woman.

Pediatric Use

There have been no clinical studies to establish the safety and efficacy of Precedex in pediatric patients below 18 years of age. Therefore, Precedex should not be used in this population.

Geriatric Use

Precedex is known to be substantially excreted by the kidney, and the risk of adverse reactions to this drug may be greater in patients with impaired renal function. Because elderly patients are more likely to have decreased renal function, care should be taken in dose selection in elderly patients, and it may be useful to monitor renal function.

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 Precedex [see WARNINGS AND PRECAUTIONS] . Therefore a dose reduction may be considered in patients over 65 years of age [see DOSING AND ADMINISTRATION and CLINICAL PHARMACOLOGY].

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 Precedex-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.

Hepatic Impairment

Since Precedex clearance decreases with severity of hepatic impairment, dose reduction should be considered in patients with impaired hepatic function [see DOSING AND ADMINISTRATION and CLINICAL PHARMACOLOGY].

Renal Impairment

[see Use in Special Populations and CLINICAL PHARMACOLOGY].

Last updated on RxList: 2/9/2009

The tolerability of Precedex was studied in one study in which healthy subjects were administered doses at and above the recommended dose of 0.2 to 0.7 mcg/kg/hr. The maximum blood concentration achieved in this study was approximately 13 times the upper boundary of the therapeutic range. The most notable effects observed in two subjects who achieved the highest doses were first degree atrioventricular block and second degree heart block. No hemodynamic compromise was noted with the atrioventricular block and the heart block resolved spontaneously within one minute.

Five patients received an overdose of Precedex in the intensive care unit sedation studies. Two of these patients had no symptoms reported; one patient received a 2 mcg/kg loading dose over 10 minutes (twice the recommended loading dose) and one patient received a maintenance infusion of 0.8 mcg/kg/hr. Two other patients who received a 2 mcg/kg loading dose over 10 minutes, experienced bradycardia and/or hypotension. One patient who received a loading bolus dose of undiluted Precedex (19.4 mcg/kg), had cardiac arrest from which he was successfully resuscitated.

None

Last updated on RxList: 2/9/2009

Mechanismof Action

Precedex is a relatively selective alpha₂-adrenergic agonist with sedative properties. Alpha₂ selectivity is observed in animals following slow intravenous infusion of low and medium doses (10-300 mcg/kg). Both alpha1 and alpha₂ activity is observed following slow intravenous infusion of high doses ( ≥ 1000 mcg/kg) or with rapid intravenous administration.

Pharmacodynamics

In a study in healthy volunteers (N=10), respiratory rate and oxygen saturation remained within normal limits and there was no evidence of respiratory depression when Precedex was administered by intravenous infusion at doses within the recommended dose range (0.2 - 0.7 mcg/kg/hr).

Pharmacokinetics

Following intravenous administration, dexmedetomidine exhibits the following pharmacokinetic parameters: a rapid distribution phase with a distribution half-life (t½) of approximately 6 minutes; a terminal elimination half-life (t½) of approximately 2 hours; and steady-state volume of distribution (V_ss) of approximately 118 liters. Clearance is estimated to be approximately 39 L/h. The mean body weight associated with this clearance estimate was 72 kg.

Dexmedetomidine exhibits linear pharmacokinetics in the dosage range of 0.2 to 0.7 mcg/kg/hr when administered by intravenous infusion for up to 24 hours. Table 5 shows the main pharmacokinetic parameters when Precedex was infused (after appropriate loading doses) at maintenance infusion rates of 0.17 mcg/kg/hr (target plasma concentration of 0.3 ng/mL) for 12 and 24 hours, 0.33 mcg/kg/hr (target plasma concentration of 0.6 ng/mL) for 24 hours, and 0.70 mcg/kg/hr (target plasma concentration of 1.25 ng/mL) for 24 hours.

Table 5. Mean ± SD Pharmacokinetic Parameters

Distribution

The steady-state volume of distribution (Vss) of dexmedetomidine is approximately 118 liters. Dexmedetomidine protein binding was assessed in the plasma of normal healthy male and female subjects. The average protein binding was 94% and was constant across the different plasma concentrations tested. Protein binding was similar in males and females. The fraction of Precedex that was bound to plasma proteins was significantly decreased in subjects with hepatic impairment compared to healthy subjects.

The potential for protein binding displacement of dexmedetomidine by fentanyl, ketorolac, theophylline, digoxin and lidocaine was explored in vitro, and negligible changes in the plasma protein binding of Precedex were observed. The potential for protein binding displacement of phenytoin, warfarin, ibuprofen, propranolol, theophylline and digoxin by Precedex was explored in vitro and none of these compounds appeared to be significantly displaced by Precedex.

Metabolism

Dexmedetomidine undergoes almost complete biotransformation with very little unchanged dexmedetomidine excreted in urine and feces. Biotransformation involves both direct glucuronidation as well as cytochrome P450 mediated metabolism. The major metabolic pathways of dexmedetomidine are: direct N-glucuronidation to inactive metabolites; aliphatic hydroxylation (mediated primarily by CYP2A6) of dexmedetomidine to generate 3-hydroxy-dexmedetomidine, the glucuronide of 3-hydroxy-dexmedetomidine, and 3-carboxy-dexmedetomidine; and N methylation of dexmedetomidineto generate 3-hydroxy N-methyl-dexmedetomidine, 3-carboxy N-methyl-dexmedetomidine, and dexmedetomidine-N-methyl O-glucuronide.

Elimination

The terminal elimination half-life (t½) of dexmedetomidine is approximately 2 hours and clearance is estimated to be approximately 39 L/h. A mass balance study demonstrated that after nine days an average of 95% of the radioactivity, following intravenous administration of radiolabeled dexmedetomidine, was recovered in the urine and 4% in the feces. No unchanged dexmedetomidine was detected in the urine. Approximately 85% of the radioactivity recovered in the urine was excreted within 24 hours after the infusion. Fractionation of the radioactivity excreted in urine demonstrated that products of N-glucuronidation accounted for approximately 34% of the cumulative urinary excretion. In addition, aliphatic hydroxylation of parent drug to form 3-hydroxy-dexmedetomidine, the glucuronide of 3-hydroxy-dexmedetomidine, and 3-carboxylic acid-dexmedetomidine together represented approximately 14% of the dose in urine. N-methylation of dexmedetomidine to form 3 hydroxy N-methyl dexmedetomidine, 3-carboxy N-methyl dexmedetomidine, and N methyl O glucuronide dexmedetomidine accounted for approximately 18% of the dose in urine. The N Methyl metabolite itself was a minor circulating component and was undetected in urine. Approximately 28% of the urinary metabolites have not been identified.

Gender

There was no observed difference in Precedex pharmacokinetics due to gender.

Geriatrics

The pharmacokinetic profile of Precedex was not altered by age. There were no differences in the pharmacokinetics of Precedex in young (18 - 40 years), middle age (41 - 65 years), and elderly ( > 65 years) subjects.

Pediatrics

The pharmacokinetic profile of Precedex has not been studied in pediatric patients.

Hepatic Impairment

In subjects with varying degrees of hepatic impairment (Child-Pugh Class A, B, or C), clearance values for Precedex were lower than in healthy subjects. The mean clearance values for patients with mild, moderate, and severe hepatic impairment were 74%, 64% and 53% of those observed in the normal healthy subjects, respectively. Mean clearances for free drug were 59%, 51% and 32% of those observed in the normal healthy subjects, respectively.

Although Precedex is dosed to effect, it may be necessary to consider dose reduction in subjects with hepatic impairment [see DOSAGE AND ADMINISTRATION, WARNINGS AND PRECAUTIONS]

Renal Impairment

Precedex pharmacokinetics (Cmax, Tmax, AUC, t½, CL, and VSS) were not significantly different in patients with severe renal impairment (creatinine clearance: < 30 mL/min) compared to healthy subjects. However, the pharmacokinetics of the metabolites of Precedex have not been evaluated in patients with impaired renal function. Since the majority of metabolites are excreted in the urine, it is possible that the metabolites may accumulate upon long-term infusions in patients with impaired renal function.[see DOSAGE AND ADMINISTRATION and Use in Specific Populations]

Drug Interactions

In vitro studies: In vitro studies in human liver microsomes demonstrated no evidence of cytochrome P450 mediated drug interactions that are likely to be of clinical relevance.

Animal Toxicology and/or Pharmacology

Dexmedetomidine had no effect on adrenocorticotropic hormone-stimulated cortisol release in dogs after a single dose; however, after the subcutaneous infusion of Precedex for one week, the cortisol response to adrenocorticotropic hormone was diminished by approximately 40%, indicating adrenal insufficiency.

Clinical Studies

The safety and efficacy of Precedex has been evaluated in four randomized, double-blind, placebo-controlled multicenter clinical trials in 1185 patients.

Intensive Care Unit Sedation

Two randomized, double-blind, parallel-group, placebo-controlled multicenter clinical trials included 754 patients being treated in a surgical intensive care unit. All patients were initially intubated and received mechanical ventilation. These trials evaluated the sedative properties of Precedex by comparing the amount of rescue medication (midazolam in one trial and propofol in the second) required to achieve a specified level of sedation (using the standardized Ramsay sedation scale) between Precedex and placebo from onset of treatment to extubation or to a total treatment duration of 24 hours. The Ramsay Level of Sedation Scale is displayed in Table 6.

Table 6: Ramsay Level of Sedation Scale

In the first study, 175 patients were randomized to receive placebo and 178 to receive Precedex by intravenous infusion at a dose of 0.4 mcg/kg/hr (with allowed adjustment between 0.2 and 0.7 mcg/kg/hr) following an initial loading infusion of one mcg/kg intravenous over 10 minutes. The study drug infusion rate was adjusted to maintain a Ramsay sedation score of ≥ 3. Patients were allowed to receive “rescue” midazolam as needed to augment the study drug infusion. In addition, morphine sulfate was administered for pain as needed. The primary outcome measure for this study was the total amount of rescue medication (midazolam) needed to maintain sedation as specified while intubated. Patients randomized to placebo received significantly more midazolam than patients randomized to Precedex (see Table 7).

A second prospective primary analysis assessed the sedative effects of Precedex by comparing the percentage of patients who achieved a Ramsay sedation score of ≥ 3 during intubation without the use of additional rescue medication. A significantly greater percentage of patients in the Precedex group maintained a Ramsay sedation score of ≥ 3 without receiving any midazolam rescue compared to the placebo group (see Table 7).

Table 7: Midazolam use as rescue medication during intubation (ITT) Study One

A prospective secondary analysis assessed the dose of morphine sulfate administered to patients in the Precedex and placebo groups. On average, Precedex-treated patients received less morphine sulfate for pain than placebo-treated patients (0.47 versus 0.83 mg/h). In addition, 44% (79 of 178 patients) of Precedex patients received no morphine sulfate for pain versus 19% (33 of 175 patients) in the placebo group.

In a second study, 198 patients were randomized to receive placebo and 203 to receive Precedex by intravenous infusion at a dose of 0.4 mcg/kg/hr (with allowed adjustment between 0.2 and 0.7 mcg/kg/hr) following an initial loading infusion of one mcg/kg intravenous over 10 minutes. The study drug infusion was adjusted to maintain a Ramsay sedation score of ≥ 3. Patients were allowed to receive “rescue” propofol as needed to augment the study drug infusion. In addition, morphine sulfate was administered as needed for pain. The primary outcome measure for this study was the total amount of rescue medication (propofol) needed to maintain sedation as specified while intubated.

Patients randomized to placebo received significantly more propofol than patients randomized to Precedex (see Table 8).

A significantly greater percentage of patients in the Precedex group compared to the placebo group maintained a Ramsay sedation score of ≥ 3 without receiving any propofol rescue (see Table 8).

Table 8: Propofol use as rescue medication during intubation (ITT) Study Two

A prospective secondary analysis assessed the dose of morphine sulfate administered to patients in the Precedex and placebo groups. On average, Precedex-treated patients received less morphine sulfate for pain than placebo-treated patients (0.43 versus 0.89 mg/h). In addition, 41% (83 of 203 patients) of Precedex patients received no morphine sulfate for pain versus 15% (30 of 198 patients) in the placebo group.

Procedural Sedation

The safety and efficacy of Precedex for sedation of non-intubated patients prior to and/or during surgical and other procedures was evaluated in two randomized, double-blind, placebo-controlled multicenter clinical trials. Study 1 evaluated the sedative properties of Precedex in patients having a variety of elective surgeries/procedures performed under monitored anesthesia care. Study 2 evaluated Precedex in patients undergoing awake fiberoptic intubation prior to a surgical or diagnostic procedure.

In Study 1, the sedative properties of Precedex were evaluated by comparing the percent of patients not requiring rescue midazolam to achieve a specified level of sedation using the standardized Observer's Assessment of Alertness/Sedation Scale (Table 9).

Table 9: Observer's Assessment of Alertness/Sedation

Patients were randomized to receive a loading infusion of either Precedex 1 mcg/kg, Precedex 0.5 mcg/kg, or placebo (normal saline) given over 10 minutes and followed by a maintenance infusion started at 0.6 mcg/kg/hr. The maintenance infusion of study drug could be titrated from 0.2 mcg/kg/hr to 1 mcg/kg/hr to achieve the targeted sedation score (Observer's Assessment of Alertness/Sedation Scale ≤ 4). Patients were allowed to receive rescue midazolam as needed to achieve and/or maintain an Observer's Assessment of Alertness/Sedation Scale ≤ 4. After achieving the desired level of sedation, a local or regional anesthetic block was performed. Demographic characteristics were similar between the Precedex and comparator groups. Efficacy results showed that Precedex was more effective than the comparator group when used to sedate non-intubated patients requiring monitored anesthesia care during surgical and other procedures. (see Table 10)

In Study 2, the sedative properties of Precedex were evaluated by comparing the percent of patients requiring rescue midazolam to achieve or maintain a specified level of sedation using the Ramsay Sedation Scale score ≥ 2 (Table 6). Patients were randomized to receive a loading infusion of Precedex 1 mcg/kg or placebo (normal saline) given over 10 minutes and followed by a fixed maintenance infusion of 0.7 mcg/kg/hr. After achieving the desired level of sedation, topicalization of the airway occurred. Patients were allowed to receive rescue midazolam as needed to achieve and/or maintain an Ramsay Sedation Scale ≥ 2. Demographic characteristics were similar between the Precedex and comparator groups. For efficacy results see Table 10.

Table 10: Key Efficacy Results of Procedural Sedation Studies

Last updated on RxList: 2/9/2009

Precedex is indicated for short-term intravenous sedation. Dosage must be individualized and titrated to the desired clinical effect. Blood pressure, heart rate and oxygen levels will be monitored both continuously during the infusion of Precedex and as clinically appropriate after discontinuation.

• When Precedex is infused for more than 6 hours, patients should be informed to report nervousness, agitation, and headaches that may occur for up to 48 hours.
• Additionally, patients should be informed to report symptoms that may occur within 48 hours after the administration of Precedex such as: weakness, confusion, excessive sweating, weight loss, abdominal pain, salt cravings, diarrhea, constipation, dizziness or light-headedness.

Last updated on RxList: 2/9/2009