Remifentanil Drug Information

• Remifentanil hydrochloride (HCl) for injection is indicated for intravenous (IV) administration:
• As an analgesic agent for use during the induction and maintenance of general anesthesia for inpatient and outpatient procedures.
• For continuation as an analgesic into the immediate postoperative period in adult patients under the direct supervision of an anesthesia practitioner in a postoperative anesthesia care unit or intensive care setting.
• As an analgesic component of monitored anesthesia care in adult patients. Remifentanil hydrochloride for injection is an opioid agonist indicated for intravenous administration:
• As an analgesic component of monitored anesthesia care in adult patients.

Important Dosage and Administration Instructions

Monitor patients closely for respiratory depression when initiating therapy and following dosage increases with remifentanil HCl and adjust the dosage accordingly. Remifentanil HCl is for intravenous use only. Continuous infusions of remifentanil HCl should be administered only by an infusion device.

The injection site should be close to the venous cannula and all IV tubing should be cleared at the time of discontinuation of infusion. Remifentanil HCl should not be administered without dilution. Consider an alternative to remifentanil HCl for patients taking mixed agonist/antagonist and partial agonist opioid analgesics due to reduced analgesic effect or potential withdrawal symptoms.

If concomitant use is warranted, carefully observe the patient, particularly during treatment initiation and dose adjustment. Discontinue remifentanil HCl if patient is not responding appropriately to treatment. Discard unused portion.

General Anesthesia Remifentanil HCl is not recommended as the sole agent in general anesthesia because loss of consciousness cannot be assured and because of a high incidence of apnea, muscle rigidity, and tachycardia. Remifentanil HCl is synergistic with other anesthetics; therefore, clinicians may need to reduce doses of thiopental, propofol, isoflurane, and midazolam by up to 75% with the coadministration of remifentanil HCl. The administration of remifentanil HCl must be individualized based on the patient's response.

Induction of Anesthesia Remifentanil HCl should be administered at an infusion rate of 0.5 to 1 mcg/kg/min with a hypnotic or volatile agent for the induction of anesthesia. If endotracheal intubation is to occur less than 8 minutes after the start of the infusion of remifentanil HCl, then an initial dose of 1 mcg/kg may be administered over 30 to 60 seconds. Remifentanil HCl should not be used as a sole agent for induction of anesthesia because loss of consciousness cannot be assured and because of a high incidence of apnea, muscle rigidity, and tachycardia.

Maintenance of Anesthesia After endotracheal intubation, the infusion rate of remifentanil HCl should be decreased in accordance with the dosing guidelines in Tables 1 (adults, predominately ASA physical status I, II, or III) and 2 (pediatric patients). • Due to the fast onset and short duration of action of remifentanil HCl, the rate of administration during anesthesia can be titrated upward in 25% to 100% increments in adult patients or up to 50% increments in pediatric patients, or downward in 25% to 50% decrements every 2 to 5 minutes to attain the desired level of μ-opioid effect. • In response to light anesthesia or transient episodes of intense surgical stress, supplemental bolus doses of 1 mcg/kg may be administered every 2 to 5 minutes. • At infusion rates > 1 mcg/kg/min, increases in the concomitant anesthetic agents should be considered to increase the depth of anesthesia. Table 1: Dosing Guidelines in Adults – General Anesthesia and Continuing as an Analgesic into the Postoperative Care Unit or Intensive Care Setting a a An initial dose of 1 mcg/kg may be administered over 30 to 60 seconds. Table 2 summarizes the recommended doses in pediatric patients, predominantly ASA physical status I, II, or III.

In pediatric patients, remifentanil was administered with nitrous oxide or nitrous oxide in combination with halothane, sevoflurane, or isoflurane. The use of atropine may blunt the potential for bradycardia that can occur upon administration of remifentanil HCl. Table 2: Dosing Guidelines in Pediatric Patients – a An initial dose of 1 mcg/kg may be administered over 30 to 60 seconds. b The clearance rate in neonates is highly variable, on average two times higher than in the young healthy adult population.

Therefore, an increased infusion rate may be necessary to maintain adequate surgical anesthesia, and additional bolus doses may be required. Neonates receiving supplementation with potent inhalation agents or neuraxial anesthesia, those with significant co-morbidities or undergoing significant fluid shifts, or those who have not been pretreated with atropine, may require smaller bolus doses to avoid hypotension and/or bradycardia.

Continuation as an Analgesic into the Immediate Postoperative Period Under the Direct Supervision of an Anesthesia Practitioner Infusions of remifentanil HCl may be continued into the immediate postoperative period for select patients for whom later transition to longer acting analgesics may be desired. • Remifentanil HCl has not been studied in pediatric patients for use in the immediate postoperative period. • The use of bolus injections of remifentanil HCl to treat pain during the postoperative period is not recommended. • When used as an IV analgesic in the immediate postoperative period, remifentanil HCl should be initially administered by continuous infusion at a rate of 0.1 mcg/kg/min. • The infusion rate may be adjusted every 5 minutes in 0.025 mcg/kg/min increments to balance the patient's level of analgesia and respiratory rate. • Infusion rates greater than 0.2 mcg/kg/min are associated with respiratory depression (respiratory rate less than 8 breaths/min). Due to the rapid offset of action of remifentanil HCl, no residual analgesic activity will be present within 5 to 10 minutes after discontinuation. For patients undergoing surgical procedures where postoperative pain is generally anticipated, alternative analgesics should be administered prior to discontinuation of remifentanil HCl.

The choice of analgesic should be appropriate for the patient's surgical procedure and the level of follow-up care.

Analgesic Component of Monitored Anesthesia Care It is strongly recommended that supplemental oxygen be supplied to the patient whenever remifentanil HCl is administered. • Remifentanil HCl has not been studied for use in children in monitored anesthesia care. Continuous Infusion When used alone as an IV analgesic component of monitored anesthesia care, remifentanil HCl should be initially administered by continuous infusion at a rate of 0.1 mcg/kg/min beginning 5 minutes before placement of the local or regional anesthetic block. • Because of the risk for hypoventilation, the infusion rate of remifentanil HCl should be decreased to 0.05 mcg/kg/min following placement of the block. • Thereafter, rate adjustments of 0.025 mcg/kg/min at 5 minute intervals may be used to balance the patient's level of analgesia and respiratory rate. • Rates greater than 0.2 mcg/kg/min are generally associated with respiratory depression (respiratory rates less than 8 breaths/min). • Bolus doses of remifentanil HCl administered simultaneously with a continuous infusion of remifentanil HCl to spontaneously breathing patients are not recommended. Table 3 summarizes the recommended doses for monitored anesthesia care in adult patients, predominately ASA physical status I, II, or III.

Table 3: Dosing Guidelines in Adults – Monitored Anesthesia Care

Discontinuation

Upon discontinuation of remifentanil HCl, the IV tubing should be cleared to prevent the inadvertent administration of remifentanil HCl at a later time.

Dosage Modifications in Geriatric Patients

The starting doses of remifentanil HCl should be decreased by 50% in elderly patients (> 65 years). Remifentanil HCl should then be cautiously titrated to effect.

Dosage Modifications in Pediatric Patients See Table 2 for dosing recommendations for use of remifentanil HCl in pediatric patients from birth to 12 years of age for maintenance of anesthesia. Remifentanil HCl has not been studied in pediatric patients for use in the immediate postoperative period or for use as a component of monitored anesthesia care.

Dosage Modifications in Coronary Artery Bypass Surgery Table 4 summarizes the recommended doses for induction, maintenance, and continuation as an analgesic into the ICU in adult patients, predominantly ASA physical status III or IV. To avoid hypotension during the induction phase, it is important to consider the concomitant medication regimens. Table 4: Dosing Recommendations a – Coronary Artery Bypass Surgery a See Clinical Studies: Coronary Artery Bypass Surgery subsection for concomitant medication regimens.

Dosage Modifications in Obese Patients

The starting doses of remifentanil HCl should be based on ideal body weight (IBW) in obese patients (greater than 30% over their IBW).

Dosage Modifications in Preanesthetic Medication

The need for premedication and the choice of anesthetic agents must be individualized. In clinical studies, patients who received remifentanil HCl frequently received a benzodiazepine premedication.

Preparation for Administration

To reconstitute solution, add 1 mL of diluent per mg of remifentanil. Shake well to dissolve. When reconstituted as directed, the solution contains approximately 1 mg of remifentanil activity per 1 mL. • Remifentanil HCl should be diluted to a recommended final concentration of mcg/mL prior to administration (see Table 5).

Infusion rates of remifentanil HCl can be individualized for each patient using Table 6: Table 6: IV Infusion Rates of Remifentanil HCl (mL/kg/h ) When remifentanil HCl is used as an analgesic component of monitored analgesia care, a final concentration of 25 mcg/mL is recommended. When remifentanil HCl is used for pediatric patients 1 year of age and older, a final concentration of 20 or 25 mcg/mL is recommended. Table 7 is a guideline for milliliter-per-hour delivery for a solution of 20 mcg/mL with an infusion device.

Table 8: IV Infusion Rates of Remifentanil HCl (mL/h) for a Table 9 is a guideline for milliliter-per-hour delivery for a solution of 50 mcg/mL with an infusion device. Table 10: IV Infusion Rates of Remifentanil HCl (mL/h) for a 2 Compatibility and Stability Reconstitution and Dilution Prior to Administration Remifentanil HCl is stable for 24 hours at room temperature after reconstitution and further dilution to concentrations of 20 to 250 mcg/mL with the IV fluids listed below. Remifentanil HCl has been shown to be compatible with these IV fluids when coadministered into a running IV administration set.

Compatibility with Other Therapeutic Agents Remifentanil HCl has been shown to be compatible with Diprivan ® (propofol) Injection when coadministered into a running IV administration set. The compatibility of remifentanil HCl with other therapeutic agents has not been evaluated. Incompatibilities Nonspecific esterases in blood products may lead to the hydrolysis of remifentanil to its carboxylic acid metabolite.

Therefore, administration of remifentanil HCl into the same IV tubing with blood is not recommended. Note: Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration whenever solution and container permit. Product should be a clear, colorless liquid after reconstitution and free of visible particulate matter.

Remifentanil HCl does not contain any antimicrobial preservative and thus care must be taken to assure the sterility of prepared solutions.

Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction 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. Adverse event information is derived from controlled clinical studies that were conducted in a variety of surgical procedures of varying duration, using a variety of premedications and other anesthetics, and in patient populations with diverse characteristics including underlying disease. Adults Approximately 2,770 adult patients were exposed to remifentanil HCl in controlled clinical studies.

The frequencies of adverse events during general anesthesia with the recommended doses of remifentanil HCl are given in Table 11. Each patient was counted once for each type of adverse event. Table 11: Adverse Events Reported in ≥ 1% of Adult Patients in General Anesthesia Studies a at the Recommended Doses b of a Does not include adverse events from cardiac studies or the neonatal study.

Not all doses of remifentanil HCl were equipotent to the comparator opioid. The overall muscle rigidity incidence is < 1% when remifentanil is administered concurrently or after a hypnotic induction agent. In the elderly population (> 65 years), the incidence of hypotension is higher, whereas the incidence of nausea and vomiting is lower.

Table 12: Incidence (%) of Most Common Adverse Events by Gender in General Anesthesia Studies a at the Recommended Doses b of a Does not include adverse events from cardiac studies or the neonatal study. b See Table 1 for recommended doses. The frequencies of adverse events from the clinical studies at the recommended doses of remifentanil HCl in monitored anesthesia care are given in Table 13. Table 13: Adverse Events Reported in ≥ 1% of Adult Patients in Monitored Anesthesia Care Studies at the Recommended Doses a of a See Table 3 for recommended doses.

Administration of remifentanil HCl in excess of the recommended infusion rate (i.e., starting doses > 0.1 mcg/kg/min) resulted in a higher incidence of some adverse events: nausea (60%), apnea (8%), and muscle rigidity (5%). b With higher midazolam doses, higher incidences of respiratory depression and apnea were observed. Other Adverse Events in Adult Patients The frequencies of less commonly reported adverse clinical events from all controlled general anesthesia and monitored anesthesia care studies are presented below. Event frequencies are calculated as the number of patients who were administered remifentanil HCl and reported an event divided by the total number of patients exposed to remifentanil HCl in all controlled studies including cardiac dose-ranging and neurosurgery studies (n = 1,883 general anesthesia, n = 609 monitored anesthesia care).

Incidence Less than 1% Digestive: constipation, abdominal discomfort, xerostomia, gastro-esophageal reflux, dysphagia, diarrhea, ileus. Cardiovascular: various atrial and ventricular arrhythmias, heart block, ECG change consistent with myocardial ischemia, elevated CPK-MB level, syncope. Musculoskeletal: muscle stiffness, musculoskeletal chest pain.

Respiratory: cough, dyspnea, bronchospasm, laryngospasm, rhonchi, stridor, nasal congestion, pharyngitis, pleural effusion, hiccup(s), pulmonary edema, rales, bronchitis, rhinorrhea. Nervous: anxiety, involuntary movement, prolonged emergence from anesthesia, confusion, awareness under anesthesia without pain, rapid awakening from anesthesia, tremors, disorientation, dysphoria, nightmare(s), hallucinations, paresthesia, nystagmus, twitch, seizure, amnesia. Body as a Whole: decreased body temperature, anaphylactic reaction, delayed recovery from neuromuscular block.

Skin: rash, urticaria. Urogenital: urine retention, oliguria, dysuria, urine incontinence. Infusion Site Reaction: erythema, pruritus, rash.

Metabolic and Nutrition: abnormal liver function, hyperglycemia, electrolyte disorders, increased CPK level. Hematologic and Lymphatic: anemia, lymphopenia, leukocytosis, thrombocytopenia. The frequencies of adverse events from the clinical studies at the recommended doses of remifentanil HCl in cardiac surgery are given in Tables 14, 15, and 16.

These tables represent adverse events collected during discrete phases of cardiac surgery. Any event should be viewed as temporally associated with drug administration and the phase indicated should not be perceived as the only time the event might occur. Table 14: Adverse Events Reported in ≥ 1% of Patients in the Induction/Intubation and Maintenance Phases of Cardiac Surgery Studies at the Recommended Doses a of 0 a See Table 4 for recommended doses.

Table 16: Adverse Events Reported in ≥ 1% of Patients in the Post-Study Drug Phase of Cardiac Surgery Studies at the Recommended Doses a of a See Table 4 for recommended doses. Pediatrics Remifentanil HCl has been studied in 342 pediatric patients in controlled clinical studies for maintenance of general anesthesia. In the pediatric population (birth to 12 years), the most commonly reported events were nausea, vomiting, and shivering.

There were no adverse events ≥ 1% for any treatment group during the maintenance period in the pediatric patient general anesthesia studies. Table 17: Adverse Events Reported in ≥ 1% of Pediatric Patients Receiving remifentanil HCl in General Anesthesia Studies at the Recommended Doses a of a See Table 2 for recommended doses. b In subjects receiving halothane (n = 22), 10 (45%) experienced vomiting.

Postmarketing Experience

The following adverse reactions have been identified during post approval use of remifentanil. 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. Cardiovascular: Asystole Serotonin syndrome: Cases of serotonin syndrome, a potentially life-threatening condition, have been reported during concomitant use of opioids with serotonergic drugs.

Anaphylaxis: Anaphylaxis has been reported with ingredients contained in remifentanil HCl.

Table 18 includes clinically significant drug interactions with remifentanil HCl. Intervention: Limit dosages and durations to the minimum required. Patients should be advised to avoid alcohol for 24 hours after surgery.

Examples: Benzodiazepines and other sedatives/hypnotics, anxiolytics, tranquilizers, muscle relaxants, general anesthetics, antipsychotics, other opioids, alcohol. Serotonergic Drugs Clinical Impact: The concomitant use of opioids with other drugs that affect the serotonergic neurotransmitter system has resulted in serotonin syndrome. MAOI interactions with opioids may manifest as serotonin syndrome or opioid toxicity (e.g., respiratory depression, coma).

If urgent use of remifentanil HCl is necessary, use test doses and frequent titration of small doses while closely monitoring blood pressure and signs and symptoms of CNS and respiratory depression.: May reduce the analgesic effect of Remifentanil hydrochloride for injection and/or precipitate withdrawal symptoms.

Pregnancy Risk Summary Prolonged use of opioid analgesics during pregnancy may cause neonatal opioid withdrawal syndrome. Available data with remifentanil hydrochloride in pregnant women are insufficient to inform a drug-associated risk for major birth defects and miscarriage. In animal reproduction studies, reduced fetal rat body weight and pup weights were reported at 2.2 times a human intravenous infusion of an induction dose of 1 mcg/kg with a maintenance dose of 2 mcg/kg/min for a surgical procedure lasting 3 hours.

There were no malformations noted when remifentanil was administered via bolus injection to pregnant rats or rabbits during organogenesis at doses approximately 5 times and approximately equal, respectively, to a human intravenous infusion of an induction dose of 1 mcg/kg with a maintenance dose of 2 mcg/kg/min for a surgical procedure lasting 3 hours.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.

Clinical Considerations Labor or Delivery Opioids cross the placenta and may produce respiratory depression and psycho-physiologic effects in neonates. An opioid antagonist, such as naloxone, must be available for reversal of opioid-induced respiratory depression in the neonate. Remifentanil HCl is not recommended for use in pregnant women during or immediately prior to labor, when other analgesic techniques are more appropriate.

Opioid analgesics, including remifentanil HCl, can prolong labor through actions which temporarily reduce the strength, duration, and frequency of uterine contractions. However, this effect is not consistent and may be offset by an increased rate of cervical dilation, which tends to shorten labor. Monitor neonates exposed to opioid analgesics during labor for signs of excess sedation and respiratory depression.

Data Human Data In a human clinical trial, the average maternal remifentanil concentrations were approximately twice those seen in the fetus. In some cases, however, fetal concentrations were similar to those in the mother. The umbilical arteriovenous ratio of remifentanil concentrations was approximately 30% suggesting metabolism of remifentanil in the neonate.

Reduced fetal weights were reported in the high dose group; however, no malformations were reported in surviving fetuses despite a non-dose dependent increase in maternal mortality. No malformations were reported in surviving fetuses despite clear maternal toxicity (decreased food consumption and body weights and increased mortality in all treatment groups). Reduced birth weights were noted in the high-dose groups in the presence of maternal toxicity (increased mortality in all groups).

Pediatric Use The efficacy and safety of remifentanil HCl as an analgesic agent for use in the maintenance of general anesthesia in outpatient and inpatient pediatric surgery have been established in controlled clinical studies in pediatric patients from birth to 12 years. The initial maintenance infusion regimen of remifentanil HCl evaluated in pediatric patients from birth to 2 months of age was 0.4 mcg/kg/min, the approved adult regimen for use with N 2 O. The clearance rate observed in neonates was highly variable and on average was 2 times higher than in the young healthy adult population.

Therefore, while a starting infusion rate of 0.4 mcg/kg/min may be appropriate for some neonates, an increased infusion rate may be necessary to maintain adequate surgical anesthesia, and additional bolus doses may be required. The individual dose for each patient should be carefully titrated. Remifentanil HCl has not been studied in pediatric patients for use as a postoperative analgesic or as an analgesic component of monitored anesthesia care.

• Remifentanil HCl is contraindicated:
• For epidural or intrathecal administration due to the presence of glycine in the formulation.
• In patients with hypersensitivity to remifentanil (e.g., anaphylaxis). Remifentanil hydrochloride for injection is contraindicated:
• In patients with hypersensitivity to remifentanil (e.g., anaphylaxis).

Clinical Presentation Acute overdose with remifentanil HCl can be manifested by respiratory depression, somnolence progressing to stupor or coma, skeletal muscle flaccidity, cold and clammy skin, constricted pupils, and, in some cases, pulmonary edema, bradycardia, hypotension, partial or complete airway obstruction, atypical snoring, and death. Marked mydriasis rather than miosis may be seen with hypoxia in overdose situations. Treatment of Overdose In case of overdose, priorities are the reestablishment of a patent and protected airway and institution of assisted or controlled ventilation, if needed.

Employ other supportive measures (including oxygen and vasopressors) in the management of circulatory shock and pulmonary edema as indicated. Cardiac arrest or arrhythmias will require advanced life-support techniques. The opioid antagonists, naloxone or nalmefene, are specific antidotes to respiratory depression resulting from opioid overdose.

For clinically significant respiratory or circulatory depression secondary to remifentanil overdose, stop the infusion or administer an opioid antagonist. Opioid antagonists should not be administered in the absence of clinically significant respiratory or circulatory depression secondary to remifentanil overdose. In an individual physically dependent on opioids, administration of the recommended usual dosage of the antagonist will precipitate an acute withdrawal syndrome.

The severity of the withdrawal symptoms experienced will depend on the degree of physical dependence and the dose of the antagonist administered. If a decision is made to treat serious respiratory depression in the physically dependent patient, administration of the antagonist should be begun with care and by titration with smaller than usual doses of the antagonist.