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451094A/Issued: February 2008
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DIPRIVAN
®
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(propofol) Injectable Emulsion
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FOR IV ADMINISTRATION
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Strict aseptic technique must always be maintained during handling. Diprivan
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Injectable Emulsion is a single-use parenteral product which contains 0.005% disodium
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edetate to inhibit the rate of growth of microorganisms, for up to 12 hours, in the event
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of accidental extrinsic contamination. However, Diprivan Injectable Emulsion can still
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support the growth of microorganisms, as it is not an antimicrobially preserved product
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under USP standards. Accordingly, strict aseptic technique must still be adhered to.
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Do not use if contamination is suspected. Discard unused portions as directed within the
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required time limits (see
DOSAGE AND ADMINSTRATION, Handling Procedures
).
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There have been reports in which failure to use aseptic technique when handling
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Diprivan Injectable Emulsion was associated with microbial contamination of the
15
product and with fever, infection/sepsis, other life-threatening illness, and/or death.
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DESCRIPTION
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DIPRIVAN
®
(propofol) Injectable Emulsion is a sterile, nonpyrogenic emulsion containing
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10 mg/mL of propofol suitable for intravenous administration. Propofol is chemically
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described as 2,6-diisopropylphenol and has a molecular weight of 178.27. The structural and
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molecular formulas are:
21
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1
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Propofol is slightly soluble in water and, thus, is formulated in a white, oil-in-water
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emulsion. The pKa is 11. The octanol/water partition coefficient for propofol is 6761:1 at a
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pH of 6-8.5. In addition to the active component, propofol, the formulation also contains
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soybean oil (100 mg/mL), glycerol (22.5 mg/mL), egg lecithin (12 mg/mL); and disodium
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edetate (0.005%); with sodium hydroxide to adjust pH. The DIPRIVAN Injectable Emulsion
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is isotonic and has a pH of 7-8.5.
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CLINICAL PHARMACOLOGY
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General
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DIPRIVAN Injectable Emulsion is an intravenous sedative-hypnotic agent for use in the
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induction and maintenance of anesthesia or sedation. Intravenous injection of a therapeutic
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dose of propofol induces hypnosis, with minimal excitation, usually within 40 seconds from
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the start of injection (the time for one arm-brain circulation). As with other rapidly acting
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intravenous anesthetic agents, the half-time of the blood-brain equilibration is approximately
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1 to 3 minutes, accounting for the rate of induction of anesthesia.
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Pharmacodynamics
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Pharmacodynamic properties of propofol are dependent upon the therapeutic blood propofol
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concentrations. Steady-state propofol blood concentrations are generally proportional to
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infusion rates. Undesirable side effects, such as cardiorespiratory depression, are likely to
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occur at higher blood concentrations which result from bolus dosing or rapid increases in
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infusion rates. An adequate interval (3 to 5 minutes) must be allowed between dose
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adjustments in order to assess clinical effects.
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The hemodynamic effects of DIPRIVAN Injectable Emulsion during induction of anesthesia
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vary. If spontaneous ventilation is maintained, the major cardiovascular effect is arterial
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hypotension (sometimes greater than a 30% decrease) with little or no change in heart rate
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and no appreciable decrease in cardiac output. If ventilation is assisted or controlled
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(positive pressure ventilation), there is an increase in the incidence and the degree of
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depression of cardiac output. Addition of an opioid, used as a premedicant, further decreases
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cardiac output and respiratory drive.
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If anesthesia is continued by infusion of DIPRIVAN Injectable Emulsion, the stimulation of
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endotracheal intubation and surgery may return arterial pressure towards normal. However,
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cardiac output may remain depressed. Comparative clinical studies have shown that the
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hemodynamic effects of DIPRIVAN Injectable Emulsion during induction of anesthesia are
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generally more pronounced than with other intravenous (IV) induction agents.
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Induction of anesthesia with DIPRIVAN Injectable Emulsion is frequently associated with
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apnea in both adults and pediatric patients. In adult patients who received DIPRIVAN
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Injectable Emulsion (2 to 2.5 mg/kg), apnea lasted less than 30 seconds in 7% of patients, 30-
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60 seconds in 24% of patients, and more than 60 seconds in 12% of patients. In pediatric
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patients from birth through 16 years of age assessable for apnea who received bolus doses of
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DIPRIVAN Injectable Emulsion (1 to 3.6 mg/kg), apnea lasted less than 30 seconds in 12%
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of patients, 30-60 seconds in 10% of patients, and more than 60 seconds in 5% of patients.
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During maintenance of general anesthesia, DIPRIVAN Injectable Emulsion causes a
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decrease in spontaneous minute ventilation usually associated with an increase in carbon
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dioxide tension which may be marked depending upon the rate of administration and
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concurrent use of other medications (e.g., opioids, sedatives, etc.).
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During monitored anesthesia care (MAC) sedation, attention must be given to the
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cardiorespiratory effects of DIPRIVAN Injectable Emulsion. Hypotension, oxyhemoglobin
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desaturation, apnea, and airway obstruction can occur, especially following a rapid bolus of
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DIPRIVAN Injectable Emulsion. During initiation of MAC sedation, slow infusion or slow
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injection techniques are preferable over rapid bolus administration. During maintenance of
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MAC sedation, a variable rate infusion is preferable over intermittent bolus administration in
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order to minimize undesirable cardiorespiratory effects. In the elderly, debilitated, or ASA-
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PS III or IV patients, rapid (single or repeated) bolus dose administration should not be used
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for MAC sedation (see
WARNINGS
).
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Clinical and preclinical studies suggest that DIPRIVAN Injectable Emulsion is rarely
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associated with elevation of plasma histamine levels.
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Preliminary findings in patients with normal intraocular pressure indicate that DIPRIVAN
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Injectable Emulsion produces a decrease in intraocular pressure which may be associated
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with a concomitant decrease in systemic vascular resistance.
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Clinical studies indicate that DIPRIVAN Injectable Emulsion when used in combination with
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hypocarbia increases cerebrovascular resistance and decreases cerebral blood flow, cerebral
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metabolic oxygen consumption, and intracranial pressure. DIPRIVAN Injectable Emulsion
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does not affect cerebrovascular reactivity to changes in arterial carbon dioxide tension (see
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Clinical Trials - Neuroanesthesia
).
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Clinical studies indicate that DIPRIVAN Injectable Emulsion does not suppress the adrenal
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response to ACTH.
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Animal studies and limited experience in susceptible patients have not indicated any
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propensity of DIPRIVAN Injectable Emulsion to induce malignant hyperthermia.
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Hemosiderin deposits have been observed in the livers of dogs receiving DIPRIVAN
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Injectable Emulsion containing 0.005% disodium edetate over a four-week period; the
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clinical significance of this is unknown.
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Pharmacokinetics
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The pharmacokinetics of propofol are well described by a three compartment linear model
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with compartments representing the plasma, rapidly equilibrating tissues, and slowly
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equilibrating tissues.
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Following an IV bolus dose, there is rapid equilibration between the plasma and the brain,
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accounting for the rapid onset of anesthesia. Plasma levels initially decline rapidly as a result
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of both distribution and metabolic clearance. Distribution accounts for about half of this
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decline following a bolus of propofol. However, distribution is not constant over time, but
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decreases as body tissues equilibrate with plasma and become saturated. The rate at which
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equilibration occurs is a function of the rate and duration of the infusion. When equilibration
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occurs there is no longer a net transfer of propofol between tissues and plasma.
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Discontinuation of the recommended doses of DIPRIVAN Injectable Emulsion after the
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maintenance of anesthesia for approximately one hour, or for sedation in the ICU for one
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day, results in a prompt decrease in blood propofol concentrations and rapid awakening.
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Longer infusions (10 days of ICU sedation) result in accumulation of significant tissue stores
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of propofol, such that the reduction in circulating propofol is slowed and the time to
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awakening is increased.
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By daily titration of DIPRIVAN Injectable Emulsion dosage to achieve only the minimum
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effective therapeutic concentration, rapid awakening within 10 to 15 minutes can occur even
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after long-term administration. If, however, higher than necessary infusion levels have been
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maintained for a long time, propofol redistribution from fat and muscle to the plasma can be
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significant and slow recovery.
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The figure below illustrates the fall of plasma propofol levels following infusions of various
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durations to provide ICU sedation.
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The large contribution of distribution (about 50%) to the fall of propofol plasma levels
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following brief infusions means that after very long infusions a reduction in the infusion rate
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is appropriate by as much as half the initial infusion rate in order to maintain a constant
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plasma level. Therefore, failure to reduce the infusion rate in patients receiving DIPRIVAN
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Injectable Emulsion for extended periods may result in excessively high blood concentrations
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of the drug. Thus, titration to clinical response and daily evaluation of sedation levels are
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important during use of DIPRIVAN Injectable Emulsion infusion for ICU sedation..
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Adults: Propofol clearance ranges from 23-50 mL/kg/min (1.6 to 3.4 L/min in 70 kg adults).
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It is chiefly eliminated by hepatic conjugation to inactive metabolites which are excreted by
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the kidney. A glucuronide conjugate accounts for about 50% of the administered dose.
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Propofol has a steady state volume of distribution (10-day infusion) approaching 60 L/kg in
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healthy adults. A difference in pharmacokinetics due to gender has not been observed. The
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terminal half-life of propofol after a 10-day infusion is 1 to 3 days.
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Geriatrics: With increasing patient age, the dose of propofol needed to achieve a defined
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anesthetic end point (dose-requirement) decreases. This does not appear to be an age-related
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change in pharmacodynamics or brain sensitivity, as measured by EEG burst suppression.
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With increasing patient age, pharmacokinetic changes are such that, for a given IV bolus
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dose, higher peak plasma concentrations occur, which can explain the decreased dose
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requirement. These higher peak plasma concentrations in the elderly can predispose patients
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to cardiorespiratory effects including hypotension, apnea, airway obstruction, and/or arterial
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oxygen desaturation. The higher plasma levels reflect age-related decreased in volume of
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distribution and intercompartmental clearance. Lower doses are therefore recommended for
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initiation and maintenance of sedation and anesthesia in elderly patients. (See
DOSAGE
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AND ADMINISTRATION.
)
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Pediatrics: The pharmacokinetics of propofol were studied in children between 3 and 12
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years of age who received DIPRIVAN Injectable Emulsion for periods of approximately 1-2
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hours. The observed distribution and clearance of propofol in these children were similar to
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adults.
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Organ Failure: The pharmacokinetics of propofol do not appear to be different in people
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with chronic hepatic cirrhosis or chronic renal impairment compared to adults with normal
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hepatic and renal function. The effects of acute hepatic or renal failure on the
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pharmacokinetics of propofol have not been studied.
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Clinical Trials
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Anesthesia and Monitored Anesthesia Care (MAC) Sedation
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Pediatric Anesthesia:
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DIPRIVAN Injectable Emulsion was studied in clinical trials which included cardiac surgical
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patients. Most patients were 3 years of age or older. The majority of the patients were
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healthy ASA-PS I or II patients The range of doses in these studies are described in Tables 1
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and
2
.
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TABLE 1. PEDIATRIC INDUCTION OF ANESTHESIA
Age Range
Induction Dose
Injection Duration
Median (range)
Median (range)
Birth through 16 years
2.5 mg/kg
20 sec.
(1-3.6)
(6-45)
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1
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TABLE 2. PEDIATRIC MAINTENANCE OF ANESTHESIA
Age Range
2 months to 2 years
2 to 12 years
>12 through 16 years
Neuroanesthesia:
Maintenance Dosage
Duration
(mcg/kg/min)
199 (82 – 394)
188 (12 – 1041)
161 (84 – 359)
(minutes)
65 (12 - 282)
69 (23 – 374)
69 (26 – 251)
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DIPRIVAN Injectable Emulsion was studied in patients undergoing craniotomy for
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supratentorial tumors in two clinical trials. The mean lesion size (anterior/posterior x lateral)
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was 31 mm x 32 mm in one trial and 55 mm x 42 mm in the other trial respectively.
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Anesthesia was induced with a median Diprivan dose of 1.4 mg/kg (range: 0.9-6.9 mg/kg)
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and maintained with a median maintenance Diprivan dose of 146 mcg/kg/min (range: 68-425
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mcg/kg/min). The median duration of the Diprivan maintenance infusion was 285 minutes
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(range: 48-622 minutes).
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DIPRIVAN Injectable Emulsion was administered by infusion in a controlled clinical trial to
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evaluate its effect on cerebrospinal fluid pressure (CSFP). The mean arterial pressure was
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maintained relatively constant over 25 minutes with a change from baseline of -4% ± 17%
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(mean ± SD). The change in CSFP was -46% ± 14%. As CSFP is an indirect measure of
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intracranial pressure (ICP), DIPRIVAN Injectable Emulsion, when given by infusion or slow
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bolus in combination with hypocarbia, is capable of decreasing ICP independent of changes
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in arterial pressure.
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Intensive Care Unit (ICU) Sedation
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Adult Patients:
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DIPRIVAN Injectable Emulsion was compared to benzodiazepines and opioids in clinical
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trials involving ICU patients. Of these, 302 received DIPRIVAN Injectable Emulsion and
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comprise the overall safety database for ICU sedation.
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Across all clinical studies, the mean infusion maintenance rate for all DIPRIVAN Injectable
7
Emulsion patients was 27 ± 21 mcg/kg/min. The maintenance infusion rates required to
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maintain adequate sedation ranged from 2.8 mcg/kg/min to 130 mcg/kg/min. The infusion
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rate was lower in patients over 55 years of age (approximately 20 mcg/kg/min) compared to
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patients under 55 years of age (approximately 38 mcg/kg/min). Although there are reports of
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reduced analgesic requirements, most patients received opioids for analgesia during
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maintenance of ICU sedation. In these studies, morphine or fentanyl was used as needed for
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analgesia. Some patients also received benzodiazepines and/or neuromuscular blocking
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agents. During long-term maintenance of sedation, some ICU patients were awakened once
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or twice every 24 hours for assessment of neurologic or respiratory function.
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In Medical and Postsurgical ICU studies comparing DIPRIVAN Injectable Emulsion to
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benzodiazepine infusion or bolus, there were no apparent differences in maintenance of
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adequate sedation, mean arterial pressure, or laboratory findings. Like the comparators,
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DIPRIVAN Injectable Emulsion reduced blood cortisol during sedation while maintaining
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responsivity to challenges with adrenocorticotropic hormone (ACTH). Case reports from
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the published literature generally reflect that DIPRIVAN Injectable Emulsion has been used
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safely in patients with a history of porphyria or malignant hyperthermia.
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In hemodynamically stable head trauma patients ranging in age from 19-43 years, adequate
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sedation was maintained with DIPRIVAN Injectable Emulsion or morphine. There were no
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apparent differences in adequacy of sedation, intracranial pressure, cerebral perfusion
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pressure, or neurologic recovery between the treatment groups. In literature reports of
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severely head-injured patients in Neurosurgical ICUs, DIPRIVAN Injectable Emulsion
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infusion and hyperventilation, both with and without diuretics, controlled intracranial
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pressure while maintaining cerebral perfusion pressure. In some patients, bolus doses
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resulted in decreased blood pressure and compromised cerebral perfusion pressure.
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DIPRIVAN Injectable Emulsion was found to be effective in status epilepticus which was
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refractory to the standard anticonvulsant therapies. For these patients, as well as for
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ARDS/respiratory failure and tetanus patients, sedation maintenance dosages were generally
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higher than those for other critically ill patient populations.
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Pediatric Patients:
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A single, randomized, controlled, clinical trial that evaluated the safety and effectiveness of
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DIPRIVAN versus standard sedative agents (SSA) was conducted on 327 pediatric ICU
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patients. Patients were randomized to receive either DIPRIVAN 2%, (113 patients),
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DIPRIVAN 1%, (109 patients), or an SSA (eg, lorazepam, chloral hydrate, fentanyl,
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ketamine, morphine, or phenobarbital). DIPRIVAN therapy was initiated at an infusion rate
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of 5.5 mg/kg/hr and titrated as needed to maintain sedation at a standardized level. The
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results of the study showed an increase in the number of deaths in patients treated with
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DIPRIVAN as compared to SSAs. Of the 25 patients who died during the trial or within the
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28-day follow-up period: 12 (11% were) in the DIPRIVAN 2% treatment group, 9 (8% were)
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in the DIPRIVAN 1% treatment group, and 4% were (4%) in the SSA treatment group. The
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differences in mortality rate between the groups were not statistically significant. Review of
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the deaths failed to reveal a correlation with underlying disease status or a correlation to the
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drug or a definitive pattern to the causes of death.
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Cardiac Anesthesia
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DIPRIVAN Injectable Emulsion was evaluated in clinical trials involving patients
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undergoing coronary artery bypass graft (CABG).
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In post-CABG (coronary artery bypass graft) patients, the maintenance rate of propofol
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administration was usually low (median 11 mcg/kg/min) due to the intraoperative
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administration of high opioid doses. Patients receiving DIPRIVAN Injectable Emulsion
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required 35% less nitroprusside than midazolam patients. During initiation of sedation in
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post-CABG patients, a 15% to 20% decrease in blood pressure was seen in the first 60
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minutes. It was not possible to determine cardiovascular effects in patients with severely
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compromised ventricular function.
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