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MIVACRON® Injection
(mivacurium chloride)
DESCRIPTION
MIVACRON (mivacurium chloride) is a short-acting, nondepolarizing skeletal muscle relaxant for intravenous (IV) administration. Mivacurium chloride is [R-[R*,R*-(E)]]-2,2'-[(1,8-dioxo-4-octene-1,8-diyl)bis(oxy-3,1-propanediyl)]bis[1,2,3,4-tetrahydro-6,7-dimethoxy-2-methyl-1-[(3,4,5-trimethoxyphenyl)methyl]isoquinolinium] dichloride. The molecular formula is C58H80Cl2N2O14 and the molecular weight is 1100.18. The structural formula is:
The partition coefficient of the compound is 0.015 in a 1-octanol/distilled water system at 25°C.
Mivacurium chloride is a mixture of three stereoisomers: (1R,1'R, 2S, 2'S), the trans-trans diester; (1R,1'R, 2R, 2'S), the cis-trans diester; and (1R,1'R, 2R, 2'R), the cis-cis diester. The trans-trans and cis-trans stereoisomers comprise 92% to 96% of mivacurium chloride and their neuromuscular blocking potencies are not significantly different from each other or from mivacurium chloride. The cis-cis diester has been estimated from studies in cats to have one-tenth the neuromuscular blocking potency of the other two stereoisomers.
MIVACRON Injection is a sterile, non-pyrogenic solution (pH 3.5 to 5.0) containing mivacurium chloride equivalent to 2 mg/mL mivacurium in Water for Injection. Hydrochloric acid may have been added to adjust pH. Multiple-dose vials contain 0.9% w/v benzyl alcohol.
CLINICAL PHARMACOLOGY
MIVACRON (a mixture of three stereoisomers) binds competitively to cholinergic receptors on the motor end-plate to antagonize the action of acetylcholine, resulting in a block of neuromuscular transmission. This action is antagonized by acetylcholinesterase inhibitors, such as neostigmine.
Pharmacodynamics
The time to maximum neuromuscular block is similarfor recommended doses of MIVACRON and intermediate-acting agents (e.g., atracurium), but longer than for the ultra-short-acting agent, succinylcholine. The clinically effective duration of action of MIVACRON (a mixture of three stereoisomers) is one-third to one-half that of intermediate-acting agents and 2 to 2.5 times that of succinylcholine.
The average ED95 (dose required to produce 95% suppression of the adductor pollicis muscle twitch response to ulnar nerve stimulation) of MIVACRON is 0.07 mg/kg (range: 0.05 to 0.09) in adults receiving opioid/nitrous oxide/oxygen anesthesia. The pharmacodynamics of doses of MIVACRON ≥ ED95 administered over 5 to 15 seconds during opioid/nitrous oxide/oxygen anesthesia are summarized in Table 1. The mean time for spontaneous recovery of the twitch response from 25% to 75% of control amplitude is about 6 minutes (range: 3 to 9, n = 32) following an initial dose of 0.15 mg/kg MIVACRON and 7 to 8 minutes (range: 4 to 24, n = 85) following initial doses of 0.20 or 0.25 mg/kg MIVACRON.
Volatile anesthetics may decrease the dosing requirement for MIVACRON and prolong the duration of action; the magnitude of these effects may be increased as the concentration of the volatile agent is increased. Isoflurane and enflurane (administered with nitrous oxide/oxygen to achieve 1.25 MAC [Minimum Alveolar Concentration]) may decrease the effective dose of MIVACRON by as much as 25%, and may prolong the clinically effective duration of action and decrease the average infusion requirement by as much as 35% to 40%. At equivalent MAC values, halothane has little or no effect on the ED50 of MIVACRON, but may prolong the duration of action and decrease the average infusion requirement by as much as 20% (see CLINICAL PHARMACOLOGY - Individualization of Dosages subsection and PRECAUTIONS - Drug Interactions).
| Time to Spontaneous Recovery† | ||||||
| Initial Dose of MIVACRON* (mg/kg) | Time to Maximum Block† (min) | 5% Recovery (min) | 25% Recovery‡ (min) | 95% Recovery§ (min) | T4/T 1 Ratio ≥ 75%§ (min) | |
* Doses administered over 5 to 15 seconds. † Values shown are medians of means from individual studies (range of individual patient values). ‡ Clinically effective duration of neuromuscular block. § Data available for as few as 40% of adults in specific dose groups and for 22% of children in the 0.20 mg/kg dose group due to administration of reversal agents or additional doses of MIVACRON prior to 95% recovery or T4/T1 ratio recovery to ≥ 75%. || Rapid administration not recommended due to possibility of decreased blood pressure. Administer 0.20 mg/kg over 30 seconds; administer 0.25 mg/kg as divided dose (0.15 mg/kg followed 30 seconds later by 0.10 mg/kg). (See DOSAGE AND ADMINISTRATION.) | ||||||
| Adults | ||||||
| 0.07 to 0.10 | [n = 47] | 4.9 (2.0-7.6) | 11 (7-19) | 13 (8-24) | 21 (10-36) | 21 (10-36) |
| 0.15 | [n = 50] | 3.3 (1.5-8.8) | 13 (6-31) | 16 (9-38) | 26 (16-41) | 26 (15-45) |
| 0.20|| | [n = 50] | 2.5 (1.2-6.0) | 16 (10-29) | 20 (10-36) | 31 (15-51) | 34 (19-56) |
| 0.25|| | [n = 48] | 2.3 (1.0-4.8) | 19 (11-29) | 23 (14-38) | 34 (22-64) | 43 (26-75) |
| Children 2 to 12 Years | ||||||
| 0.11 to 0.12 | [n = 17] | 2.8 (1.2-4.6) | 5 (3-9) | 7 (4-10) | – | – |
| 0.20 | [n = 18] | 1.9 (1.3-3.3) | 7 (3-12) | 10 (6-15) | 19 (14-26) | 16 (12-23) |
| 0.25 | [n = 9] | 1.6 (1.0-2.2) | 7 (4-9) | 9 (5-12) | – | – |
Administration of MIVACRON over 30 to 60 seconds does not alter the time to maximum neuromuscular block or the duration of action. The duration of action of MIVACRON may be prolonged in patients with reduced plasma cholinesterase (pseudocholinesterase) activity (see PRECAUTIONS - Reduced Plasma Cholinesterase Activity and CLINICAL PHARMACOLOGY - Individualization of Dosages subsection).
Interpatient variability in duration of action occurs with MIVACRON as with other neuromuscular blocking agents. However, analysis of data from 224 patients in clinical studies receiving various doses of MIVACRON during opioid/nitrous oxide/oxygen anesthesia with a variety of premedicants and varying lengths of surgery indicated that approximately 90% of the patients had clinically effective durations of block within 8 minutes of the median duration predicted from the dose-response data shown in Table 1. Variations in plasma cholinesterase activity, including values within the normal range and values as low as 20% below the lower limit of the normal range, were not associated with clinically significant effects on duration. The variability in duration, however, was greater in patients with plasma cholinesterase activity at or slightly below the lower limit of the normal range.
When administered during the induction of adequate anesthesia using thiopental or propofol, nitrous oxide/oxygen, and co-induction agents such as fentanyl and/or midazolam, doses of 0.15 mg/kg (2 x ED95) MIVACRON administered over 5 to 15 seconds or 0.20 mg/kg MIVACRON administered over 30 seconds produced generally good-to-excellent tracheal intubation conditions in 2.5 to 3 and 2 to 2.5 minutes, respectively. A dose of 0.25 mg/kg MIVACRON administered as a divided dose (0.15 mg/kg followed 30 seconds later by 0.10 mg/kg) produced generally good-to-excellent intubation conditions in 1.5 to 2 minutes after initiating the dosing regimen.
Repeated administration of maintenance doses or continuous infusion of MIVACRON for up to 2.5 hours is not associated with development of tachyphylaxis or cumulative neuromuscular blocking effects in ASA Physical Status I-II patients. Based on pharmacokinetic studies in 82 adults receiving infusions of MIVACRON for longer than 2.5 hours, spontaneous recovery of neuromuscular function after infusion is independent of the duration of infusion and comparable to recovery reported for single doses (Table 1).
MIVACRON was administered as an infusion for as long as 4 to 6 hours in 20 adult patients and 19 geriatric patients. In most patients, after a brief period of adjustment, the rate of MIVACRON required to maintain 89% to 99% T1 suppression remained relatively constant over time. There was a subset of patients in each group whose infusion rates did not stabilize quickly and decreased (by≥ 30%) over the period of infusion. The rate of spontaneous recovery in these patients was comparable with that of patients having stable infusion rates and not dependent on the duration of infusion. These patients, however, tended to have higher infusion requirements (i.e., > 8 mcg/kg/min) during the first 30 minutes of infusion than patients with stable infusion rates, although their final infusion rates were similar to those with stable infusion rates. There were no clinically important differences in infusion rate requirements between geriatric and young patients (see Pharmacokinetics -Special Populations - Geriatric Patients).
The neuromuscular block produced by MIVACRON is readily antagonized by anticholinesterase agents. As seen with other nondepolarizing neuromuscular blocking agents, the more profound the neuromuscular block at the time of reversal, the longer the time and the greater the dose of anticholinesterase agent required for recovery of neuromuscular function.
In children (2 to 12 years), MIVACRON has a higher ED95 (0.10 mg/kg), faster onset, and shorter duration of action than in adults. The mean time for spontaneous recovery of the twitch response from 25% to 75% of control amplitude is about 5 minutes (n = 4) following an initial dose of 0.20 mg/kg MIVACRON. Recovery following reversal is faster in children than in adults (Table 1).
Hemodynamics
Administration of MIVACRON in doses up to and including 0.15 mg/kg (2 x ED95) over 5 to 15 seconds to ASA Physical Status I-II patients during opioid/nitrous oxide/oxygen anesthesia is associated with minimal changes in mean arterial blood pressure (MAP) or heart rate (HR) (Table 2).
| % of Patients With ≥ 30% Change | |||||
| MAP | HR | ||||
| Initial Dose of MIVACRON* (mg/kg) | Dec | Inc | Dec | Inc | |
* Doses administered over 5 to 15 seconds. † Rapid administration not recommended due to possibility of decreased blood pressure. Administer 0.20 mg/kg over 30 seconds; administer 0.25 mg/kg as divided dose (0.15 mg/kg followed 30 seconds later by 0.10 mg/kg). (See DOSAGE AND ADMINISTRATION.) | |||||
| Adults | |||||
| 0.07 to 0.10 | [n = 49] | 0% | 2% | 0% | 0% |
| 0.15 | [n = 53] | 4% | 4% | 4% | 2% |
| 0.20† | [n = 53] | 30% | 0% | 0% | 8% |
| 0.25† | [n = 44] | 39% | 2% | 0% | 14% |
| Children 2 to 12 years | |||||
| 0.11 to 0.12 | [n = 17] | 0% | 6% | 0% | 0% |
| 0.20 | [n = 17] | 0% | 0% | 0% | 0% |
| 0.25 | [n = 8] | 13% | 0% | 0% | 0% |
Higher doses of ≥ 0.20 mg/kg (≥ 3 x ED95) may be associated with transient decreases in MAP and increases in HR in some patients. These decreases in MAP are usually maximal within 1 to 3 minutes following the dose, typically resolve without treatment in an additional 1 to 3 minutes, and are usually associated with increases in plasma histamine concentration. Decreases in MAP can be minimized by administering MIVACRON over 30 to 60 seconds (see CLINICAL PHARMACOLOGY - Individualization of Dosages subsection and PRECAUTIONS - General).
Analysis of 426 patients in clinical studies receiving initial doses of MIVACRON up to and including 0.30 mg/kg during opioid/nitrous oxide/oxygen anesthesia showed that highinitial doses and a rapid rate of injection contributed to a greater probability of experiencing a decrease of ≥ 30% in MAP after administration of MIVACRON. Obese patients also had a greater probability of experiencing a decrease of ≥ 30% in MAP when dosed on the basis of actual body weight, thereby receiving a larger dose than if dosed on the basis of ideal body weight (see CLINICAL PHARMACOLOGY - Individualization of Dosages subsection and PRECAUTIONS - General).
Children experience minimal changes in MAP or HR after administration of doses of MIVACRON up to and including 0.20 mg/kg over 5 to 15 seconds, but higher doses (≥ 0.25 mg/kg) may be associated with transient decreases in MAP (Table 2).
Following a dose of 0.15 mg/kg MIVACRON administered over 60 seconds, adult patients with significant cardiovascular disease undergoing coronary artery bypass grafting or valve replacement procedures showed no clinically important changes in MAP or HR. Transient decreases in MAP were observed in some patients after doses of 0.20 to 0.25 mg/kg MIVACRON administered over 60 seconds. The number of patients in whom these decreases in MAP required treatment was small.
Pharmacokinetics
MIVACRON is a mixture of isomers which do not interconvert in vivo. The cis-trans and trans-trans isomers (92% to 96% of the mixture) are equipotent. The steady-state concentrations of the cis-trans and trans-trans isomers doubled after the infusion rate was increased from 5 to 10 mcg/kg/min, indicating that their pharmacokinetics is dose-proportional.
| Parameter | trans-trans isomer | cis-trans isomer |
* Values shown are mean (range). † Ages 31 to 48 years. ‡ Volume of distribution during the terminal elimination phase. | ||
| Elimination Half-life (t½ min) | 2.0 (1.0-3.6) | 1.8 (0.8-4.8) |
| Volume of Distribution‡ (mL/kg) | 147 (67-254) | 276 (79-772) |
| Plasma Clearance (mL/min/kg) | 53 (26-98) | 99 (44-199) |
The cis-cis isomer (6% of the mixture) has approximately one-tenth the neuromuscular blocking potency of the trans-trans and cis-trans isomers in cats. Neuromuscular blocking effects due to the cis-cis isomer cannot be ruled out in humans; however, modeling of clinical pharmacokinetic-pharmacodynamic data suggests that the cis-cis isomer produces minimal (< 5%) neuromuscular block during a 2-hour infusion. In studies of ASA Physical Status I-II patients receiving infusions of MIVACRON lasting as long as 4 to 6 hours, the 5% to 25% and the 25% to 75% recovery indices were independent of the duration of infusion, suggesting that the cis-cis isomer does not affect the rate of post-infusion recovery.
Special Populations
Individualization of Dosages
DOSES OF MIVACRON SHOULD BE INDIVIDUALIZED AND A PERIPHERAL NERVE STIMULATOR SHOULD BE USED TO MEASURE NEUROMUSCULAR FUNCTION DURING ADMINISTRATION OF MIVACRON IN ORDER TO MONITOR DRUG EFFECT, DETERMINE THE NEED FOR ADDITIONAL DOSES, AND CONFIRM RECOVERY FROM NEUROMUSCULAR BLOCK.
Based on the known actions of MIVACRON (a mixture of three stereoisomers) and other neuromuscular blocking agents, the following factors should be considered when administering MIVACRON:
INDICATIONS AND USAGE
MIVACRON is a short-acting neuromuscular blocking agent indicated for inpatients and outpatients, as an adjunct to general anesthesia, to facilitate tracheal intubation and to provide skeletal muscle relaxation during surgery or mechanical ventilation.
CONTRAINDICATIONS
MIVACRON is contraindicated in patients known to have an allergic hypersensitivity to mivacurium chloride or other benzylisoquinolinium agents, as manifested by reactions such as urticaria or severe respiratory distress or hypotension. Use of MIVACRON from multiple-dose vials containing benzyl alcohol as a preservative is contraindicated in patients with a known hypersensitivity to benzyl alcohol.
WARNINGS
MIVACRON SHOULD BE ADMINISTERED IN CAREFULLY ADJUSTED DOSAGE BY OR UNDER THE SUPERVISION OF EXPERIENCED CLINICIANS WHO ARE FAMILIAR WITH THE DRUG'S ACTIONS AND THE POSSIBLE COMPLICATIONS OF ITS USE. THE DRUG SHOULD NOT BE ADMINISTERED UNLESS PERSONNEL AND FACILITIES FOR RESUSCITATION AND LIFE SUPPORT (TRACHEAL INTUBATION, ARTIFICIAL VENTILATION, OXYGEN THERAPY), AND AN ANTAGONIST OF MIVACRON ARE IMMEDIATELY AVAILABLE. IT IS RECOMMENDED THAT A PERIPHERAL NERVE STIMULATOR BE USED TO MEASURE NEUROMUSCULAR FUNCTION DURING THE ADMINISTRATION OF MIVACRON IN ORDER TO MONITOR DRUG EFFECT, DETERMINE THE NEED FOR ADDITIONAL DRUG, AND CONFIRM RECOVERY FROM NEUROMUSCULAR BLOCK.
MIVACRON HAS NO KNOWN EFFECT ON CONSCIOUSNESS, PAIN THRESHOLD, OR CEREBRATION. TO AVOID DISTRESS TO THE PATIENT, NEUROMUSCULAR BLOCK SHOULD NOT BE INDUCED BEFORE UNCONSCIOUSNESS.
MIVACRON IS METABOLIZED BY PLASMA CHOLINESTERASE AND SHOULD BE USED WITH GREAT CAUTION, IF AT ALL, IN PATIENTS KNOWN TO BE OR SUSPECTED OF BEING HOMOZYGOUS FOR THE ATYPICAL PLASMA CHOLINESTERASE GENE.
MIVACRON Injection is acidic (pH 3.5 to 5.0) and may not be compatible with alkaline solutions having a pH greater than 8.5 (e.g., barbiturate solutions).
Multiple-dose vials of MIVACRON contain benzyl alcohol. In newborn infants, benzyl alcohol has been associated with an increased incidence of neurological and other complications which are sometimes fatal. Single-use vials do not contain benzyl alcohol (see PRECAUTIONS - Pediatric Use).
PRECAUTIONS
General
Although MIVACRON (a mixture of three stereoisomers) is not a potent histamine releaser, the possibility of substantial histamine release must be considered. Release of histamine is related to the dose and speed of injection.
Caution should be exercised in administering MIVACRON to patients with clinically significant cardiovascular disease and patients with any history suggesting a greater sensitivity to the release of histamine or related mediators (e.g., asthma). In such patients, the initial dose of MIVACRON should be 0.15 mg/kg or less, administered over 60 seconds; assurance of adequate hydration and careful monitoring of hemodynamic status are important (see CLINICAL PHARMACOLOGY - Hemodynamics and Individualization of Dosages).
Obese patients may be more likely to experience clinically significant transient decreases in MAP than non-obese patients when the dose of MIVACRON is based on actual rather than ideal body weight. Therefore, in obese patients, the initial dose should be determined using the patient's ideal body weight (see CLINICAL PHARMACOLOGY - Hemodynamics and Individualization of Dosages).
Recommended doses of MIVACRON have no clinically significant effects on heart rate; therefore, MIVACRON will not counteract the bradycardia produced by many anesthetic agents or by vagal stimulation.
Neuromuscular blocking agents may have a profound effect in patients with neuromuscular diseases (e.g., myasthenia gravis and the myasthenic syndrome). In these and other conditions in which prolonged neuromuscular block is a possibility (e.g., carcinomatosis), the use of a peripheral nerve stimulator and a dose of not more than 0.015 to 0.020 mg/kg MIVACRON is recommended to assess the level of neuromuscular block and to monitor dosage requirements (see CLINICAL PHARMACOLOGY - Individualization of Dosages).
MIVACRON has not been studied in patients with burns. Resistance to nondepolarizing neuromuscular blocking agents may develop in patients with burns, depending upon the time elapsed since the injury and the size of the burn. Patients with burns may have reduced plasma cholinesterase activity which may offset this resistance (see CLINICAL PHARMACOLOGY - Individualization of Dosages).
Acid-base and/or serum electrolyte abnormalities may potentiate or antagonize the action of neuromuscular blocking agents. The action of neuromuscular blocking agents may be enhanced by magnesium salts administered for the management of toxemia of pregnancy (see CLINICAL PHARMACOLOGY - Individualization of Dosages).
No data are available to support the use of MIVACRON by intramuscular injection.
Renal and Hepatic Disease
The possibility of prolonged neuromuscular block must be considered when MIVACRON is used in patients with renal or hepatic disease (see CLINICAL PHARMACOLOGY - Pharmacokinetics). Most patients with chronic hepatic disease such as hepatitis, liver abscess, and cirrhosis of the liver exhibit a marked reduction in plasma cholinesterase activity. Patients with acute or chronic renal disease may also show a reduction in plasma cholinesterase activity (see CLINICAL PHARMACOLOGY - Individualization of Dosages).
Reduced Plasma Cholinesterase Activity
The possibility of prolonged neuromuscular block following administration of MIVACRON must be considered in patients with reduced plasma cholinesterase (pseudocholinesterase) activity.
Plasma cholinesterase activity may be diminished in the presence of genetic abnormalities of plasma cholinesterase (e.g., patients heterozygous or homozygous for the atypical plasma cholinesterase gene), pregnancy, liver or kidney disease, malignant tumors, infections, burns, anemia, decompensated heart disease, peptic ulcer, or myxedema. Plasma cholinesterase activity may also be diminished by chronic administration of oral contraceptives, glucocorticoids, or certain monoamine oxidase inhibitors and by irreversible inhibitors of plasma cholinesterase (e.g., organophosphate insecticides, echothiophate, and certain antineoplastic drugs).
MIVACRON has been used safely in patients heterozygous for the atypical plasma cholinesterase gene. At doses of 0.10 to 0.20 mg/kg MIVACRON, the clinically effective duration of action was 8 to 11 minutes longer in patients heterozygous for the atypical gene than in genotypically normal patients.
As with succinylcholine, patients homozygous for the atypical plasma cholinesterase gene (one in 2500 patients) are extremely sensitive to the neuromuscular blocking effect of MIVACRON. In three such adult patients, a small dose of 0.03 mg/kg (approximately the ED10-20 in genotypically normal patients) produced complete neuromuscular block for 26 to 128 minutes. Once spontaneous recovery had begun, neuromuscular block in these patients was antagonized with conventional doses of neostigmine. One adult patient, who was homozygous for the atypical plasma cholinesterase gene, received a dose of 0.18 mg/kg MIVACRON and exhibited complete neuromuscular block for about 4 hours. Response to post-tetanic stimulation was present after 4 hours, all four responses to train-of-four stimulation were present after 6 hours, and the patient was extubated after 8 hours. Reversal was not attempted in this patient.
Malignant Hyperthermia (MH)
In a study of MH-susceptible pigs, MIVACRON did not trigger MH. MIVACRON has not been studied in MH-susceptible patients. Because MH can develop in the absence of established triggering agents, the clinician should be prepared to recognize and treat MH in any patient undergoing general anesthesia.
Long-Term Use in the Intensive Care Unit (ICU)
No data are available on the long-term use of MIVACRON in patients undergoing mechanical ventilation in the ICU.
Drug Interactions
Although MIVACRON (a mixture of three stereoisomers) has been administered safely following succinylcholine-facilitated tracheal intubation, the interaction between MIVACRON and succinylcholine has not been systematically studied. Prior administration of succinylcholine can potentiate the neuromuscular blocking effects of nondepolarizing agents. Evidence of spontaneous recovery from succinylcholine should be observed before the administration of MIVACRON.
The use of MIVACRON before succinylcholine to attenuate some of the side effects of succinylcholine has not been studied.
There are no clinical data on the use of MIVACRON with other nondepolarizing neuromuscular blocking agents.
Isoflurane and enflurane (administered with nitrous oxide/oxygen to achieve 1.25 MAC) decrease the ED50 of MIVACRON by as much as 25% (see CLINICAL PHARMACOLOGY - Pharmacodynamics and Individualization of Dosages). These agents may also prolong the clinically effective duration of action and decrease the average infusion requirement of MIVACRON by as much as 35% to 40%. A greater potentiation of the neuromuscular blocking effects of MIVACRON may be expected with higher concentrations of enflurane or isoflurane. Halothane has little or no effect on the ED50, but may prolong the duration of action and decrease the average infusion requirement by as much as 20%.
Other drugs which may enhance the neuromuscular blocking action of nondepolarizing agents such as MIVACRON include certain antibiotics (e.g., aminoglycosides, tetracyclines, bacitracin, polymyxins, lincomycin, clindamycin, coulin, and sodium coulimethate), magnesium salts, lithium, local anesthetics, procainamide, and quinidine. The neuromuscular blocking effect of MIVACRON may be enhanced by drugs that reduce plasma cholinesterase activity (e.g., chronically administered oral contraceptives, glucocorticoids, or certain monoamine oxidase inhibitors) or by drugs that irreversibly inhibit plasma cholinesterase (see PRECAUTIONS - Reduced Plasma Cholinesterase Activity subsection).
Resistance to the neuromuscular blocking action of nondepolarizing neuromuscular blocking agents has been demonstrated in patients chronically administered phenytoin or carbamazepine. While the effects of chronic phenytoin or carbamazepine therapy on the action of MIVACRON are unknown, slightly shorter durations of neuromuscular block may be anticipated and infusion rate requirements may be higher.
Carcinogenesis, Mutagenesis, Impairment of Fertility
Carcinogenesis and fertility studies have not been performed. MIVACRON was evaluated in a battery of four short-term mutagenicity tests. It was non-mutagenic in the Ames Salmonella assay, the mouse lymphoma assay, the human lymphocyte assay, and the in vivo rat bone marrow cytogenetic assay.
Pregnancy
Teratogenic Effects
Labor and Delivery
The use of MIVACRON during labor, vaginal delivery, or cesarean section has not been studied in humans and it is not known whether MIVACRON administered to the mother has effects on the fetus. Doses of 0.08 and 0.20 mg/kg MIVACRON given to female beagles undergoing cesarean section resulted in negligible levels of the stereoisomers in MIVACRON in umbilical vessel blood of neonates and no deleterious effects on the puppies.
Nursing Mothers
It is not known whether any of the stereoisomers of mivacurium are excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised following administration of MIVACRON to a nursing woman.
Pediatric Use
MIVACRON has not been studied in pediatric patients below the age of 2 years (see CLINICAL PHARMACOLOGY and DOSAGE AND ADMINISTRATION for clinical experience and recommendations for use in children 2 to 12 years of age).
Geriatric Use
MIVACRON was safely administered during clinical trials to 64 geriatric (≥ 65 years) patients, including 31 patients with significant cardiovascular disease (see PRECAUTIONS - General subsection). In general, the clearances of MIVACRON are most likely lower, the duration may be longer, the rate of recovery may be slower, therefore, MIVACRON requirements may be lower in geriatric patients (see CLINICAL PHARMACOLOGY - Special Populations - Geriatric Patients).
ADVERSE REACTIONS
Observed in Clinical Trials
MIVACRON (a mixture of three stereoisomers) was well tolerated during extensive clinical trials in inpatients and outpatients. Prolonged neuromuscular block, which is an important adverse experience associated with neuromuscular blocking agents as a class, was reported as an adverse experience in three of 2074 patients administered MIVACRON. The most commonly reported adverse experience following the administration of MIVACRON was transient, dose-dependent cutaneous flushing about the face, neck, and/or chest. Flushing was most frequently noted after the initial dose of MIVACRON and was reported in about 25% of adult patients who received 0.15 mg/kg MIVACRON over 5 to 15 seconds. When present, flushing typically began within 1 to 2 minutes after the dose of MIVACRON and lasted for 3 to 5 minutes. Of 105 patients who experienced flushing after 0.15 mg/kg MIVACRON, two patients also experienced mild hypotension that was not treated, and one patient experienced moderate wheezing that was successfully treated.
Overall, hypotension was infrequently reported as an adverse experience in the clinical trials of MIVACRON. One of 332 (0.3%) healthy adults who received 0.15 mg/kg MIVACRON over 5 to 15 seconds and none of 37 cardiac surgery patients who received 0.15 mg/kg MIVACRON over 60 seconds were treated for a decrease in blood pressure in association with the administration of MIVACRON. One to two percent of healthy adults given ≥ 0.20 mg/kg MIVACRON over 5 to 15 seconds, 2% to 3% of healthy adults given 0.20 mg/kg over 30 seconds, none of 100 healthy adults given 0.25 mg/kg as a divided dose (0.15 mg/kg followed in 30 seconds by 0.10 mg/kg), and 2% to 4% of cardiac surgery patients given≥ 0.20 mg/kg over 60 seconds were treated for a decrease in blood pressure. None of the 63 children who received the recommended dose of 0.20 mg/kg MIVACRON was treated for a decrease in blood pressure in association with the administration of MIVACRON.
The following adverse experiences were reported in patients administered MIVACRON (all events judged by investigators during the clinical trials to have a possible causal relationship):
Incidence Greater Than 1%
Incidence Less Than 1%
Observed in Clinical Practice
Based on initial clinical practice experience in patients who received MIVACRON, spontaneously reported adverse events are uncommon. Some of these events occurred at recommended doses and required treatment. Anaphylaxis/Anaphylactoid Reactions: From post-marketing surveillance, MIVACRON has been associated with reports of anaphylactic/anaphylactoid reactions. In some of these reports, sensitivity to MIVACRON was confirmed using skin test procedures.
Other adverse reaction data from clinical practice are insufficient to establish a causal relationship or to support an estimate of their incidence. These adverse events include:
OVERDOSAGE
Overdosage with neuromuscular blocking agents may result in neuromuscular block beyond the time needed for surgery and anesthesia. The primary treatment is maintenance of a patent airway and controlled ventilation until recovery of normal neuromuscular function is assured. Once evidence of recovery from neuromuscular block is observed, further recovery may be facilitated by administration of an anticholinesterase agent (e.g., neostigmine, edrophonium) in conjunction with an appropriate anticholinergic agent (see Antagonism of Neuromuscular Block subsection below). Overdosage may increase the risk of hemodynamic side effects, especially decreases in blood pressure. If needed, cardiovascular support may be provided by proper positioning of the patient, fluid administration, and/or vasopressor agent administration.
Antagonism of Neuromuscular Block
ANTAGONISTS (SUCH AS NEOSTIGMINE) SHOULD NOT BE ADMINISTERED WHEN COMPLETE NEUROMUSCULAR BLOCK IS EVIDENT OR SUSPECTED. THE USE OF A PERIPHERAL NERVE STIMULATOR TO EVALUATE RECOVERY AND ANTAGONISM OF NEUROMUSCULAR BLOCK IS RECOMMENDED.
Administration of 0.030 to 0.064 mg/kg neostigmine or 0.5 mg/kg edrophonium at approximately 10% recovery from neuromuscular block (range: 1 to 15) produced 95% recovery of the muscle twitch response and a T4/T1 ratio ≥ 75% in about 10 minutes. The times from 25% recovery of the muscle twitch response to T4/T1 ratio ≥ 75% following these doses of antagonists averaged about 7 to 9 minutes. In comparison, average times for spontaneous recovery from 25% to T4/T1≥ 75% were 12 to 13 minutes.
Patients administered antagonists should be evaluated for adequate clinical evidence of antagonism, e.g., 5-second head lift and grip strength. Ventilation must be supported until no longer required.
Antagonism may be delayed in the presence of debilitation, carcinomatosis, and the concomitant use of certain broad spectrum antibiotics, or anesthetic agents and other drugs which enhance neuromuscular block or separately cause respiratory depression (see PRECAUTIONS - Drug Interactions). Under such circumstances the management is the same as that of prolonged neuromuscular block (see OVERDOSAGE).
DOSAGE AND ADMINISTRATION
MIVACRON SHOULD ONLY BE ADMINISTERED INTRAVENOUSLY.
The dosage information provided below is intended as a guide only. Doses of MIVACRON should be individualized (see CLINICAL PHARMACOLOGY -Individualization of Dosages). Factors that may warrant dosage adjustment include but may not be limited to: the presence of significant kidney, liver, or cardiovascular disease, obesity (patients weighing ≥ 30% more than ideal body weight for height), asthma, reduction in plasma cholinesterase activity, and the presence of inhalational anesthetic agents.
When using MIVACRON or other neuromuscular blocking agents to facilitate tracheal intubation, it is important to recognize that the most important factors affecting intubation are the depth of general anesthesia and the level of neuromuscular block. Satisfactory intubating conditions can usually be achieved before complete neuromuscular block is attained if there is adequate anesthesia.
The use of a peripheral nerve stimulator will permit the most advantageous use of MIVACRON, minimize the possibility of overdosage or underdosage, and assist in the evaluation of recovery. When using a stimulator to monitor onset of neuromuscular block, clinical studies have shown that all four twitches of the train-of-four response may be present, with little or no fade, at the times recommended for intubation. Therefore, as with other neuromuscular blocking agents, it is important to use other criteria, such as clinical evaluation of the status of relaxation of jaw muscles and vocal cords, in conjunction with peripheral muscle twitch monitoring, to guide the appropriate time of intubation.
The onset of conditions suitable for tracheal intubation occurs earlier after a conventional intubating dose of succinylcholine than after recommended doses of MIVACRON.
Adults
Children
Infusion Rate Tables
For adults and children the amount of infusion solution required per hour depends upon the clinical requirements of the patient, the concentration of MIVACRON in the infusion solution, and the patient's weight. The contribution of the infusion solution to the fluid requirements of the patient must be considered. Table 8 provides guidelines for delivery in mL/hr (equivalent to microdrops/min when 60 microdrops = 1 mL) of MIVACRON Injection (2 mg/mL).
| Drug Delivery Rate (mcg/kg/min) | ||||||||||
| 4 | 5 | 6 | 7 | 8 | 10 | 14 | 16 | 18 | 20 | |
| Patient Weight (kg) | Infusion Delivery Rate (mL/hr) | |||||||||
| 10 | 1.2 | 1.5 | 1.8 | 2.1 | 2.4 | 3.0 | 4.2 | 4.8 | 5.4 | 6.0 |
| 15 | 1.8 | 2.3 | 2.7 | 3.2 | 3.6 | 4.5 | 6.3 | 7.2 | 8.1 | 9.0 |
| 20 | 2.4 | 3.0 | 3.6 | 4.2 | 4.8 | 6.0 | 8.4 | 9.6 | 10.8 | 12.0 |
| 25 | 3.0 | 3.8 | 4.5 | 5.3 | 6.0 | 7.5 | 10.5 | 12.0 | 13.5 | 15.0 |
| 35 | 4.2 | 5.3 | 6.3 | 7.4 | 8.4 | 10.5 | 14.7 | 16.8 | 18.9 | 21.0 |
| 50 | 6.0 | 7.5 | 9.0 | 10.5 | 12.0 | 15.0 | 21.0 | 24.0 | 27.0 | 30.0 |
| 60 | 7.2 | 9.0 | 10.8 | 12.6 | 14.4 | 18.0 | 25.2 | 28.8 | 32.4 | 36.0 |
| 70 | 8.4 | 10.5 | 12.6 | 14.7 | 16.8 | 21.0 | 29.4 | 33.6 | 37.8 | 42.0 |
| 80 | 9.6 | 12.0 | 14.4 | 16.8 | 19.2 | 24.0 | 33.6 | 38.4 | 43.2 | 48.0 |
| 90 | 10.8 | 13.5 | 16.2 | 18.9 | 21.6 | 27.0 | 37.8 | 43.2 | 48.6 | 54.0 |
| 100 | 12.0 | 15.0 | 18.0 | 21.0 | 24.0 | 30.0 | 42.0 | 48.0 | 54.0 | 60.0 |
MIVACRON Injection Compatibility and Admixtures
HOW SUPPLIED
MIVACRON Injection, 2 mg mivacurium in each mL.
| List | Fill | Container | Quantity |
| 4365 | 5 mL | Single-Dose Fliptop Vial | 10 per Tray |
| 4365 | 10 mL | Single-Dose Fliptop Vial | 10 per Tray |
| 4375 | 20 mL | Multiple-Dose Fliptop Vial containing 0.9% w/v benzyl alcohol as a preservative (see WARNINGS concerning newborn infants) | 10 per Tray |
| 4375 | 50 mL | Multiple-Dose Fliptop Vial containing 0.9% w/v benzyl alcohol as a preservative (see WARNINGS concerning newborn infants) | 3 per Tray |
STORAGE
Store MIVACRON Injection at room temperature of 15° to 25°C (59° to 77°F). Avoid exposure to direct ultraviolet light. DO NOT FREEZE.