2 DOSAGE AND ADMINISTRATION
ZEMURON is for intravenous use only. This drug should only be administered by experienced clinicians or trained individuals supervised by an experienced clinician familiar with the use, actions, characteristics, and complications of neuromuscular blocking agents. Doses of ZEMURON injection should be individualized and a peripheral nerve stimulator should be used to monitor drug effect, need for additional doses, adequacy of spontaneous recovery or antagonism, and to decrease the complications of overdosage if additional doses are administered.
The dosage information which follows is derived from studies based upon units of drug per unit of body weight. It is intended to serve as an initial guide to clinicians familiar with other neuromuscular blocking agents to acquire experience with ZEMURON.
In patients in whom potentiation of, or resistance to, neuromuscular block is anticipated, a dose adjustment should be considered [see Dosage and Administration (2.5), Warnings and Precautions (5.9, 5.12), Drug Interactions (7.2, 7.3, 7.4, 7.5, 7.6, 7.8, 7.10), and Use in Specific Populations (8.6)].
2.1 Dose for Tracheal Intubation
The recommended initial dose of ZEMURON, regardless of anesthetic technique, is 0.6 mg/kg. Neuromuscular block sufficient for intubation (80% block or greater) is attained in a median (range) time of 1 (0.4-6) minute(s) and most patients have intubation completed within 2 minutes. Maximum blockade is achieved in most patients in less than 3 minutes. This dose may be expected to provide 31 (15-85) minutes of clinical relaxation under opioid/nitrous oxide/oxygen anesthesia. Under halothane, isoflurane, and enflurane anesthesia, some extension of the period of clinical relaxation should be expected [see Drug Interactions (7.3)].
A lower dose of ZEMURON (0.45 mg/kg) may be used. Neuromuscular block sufficient for intubation (80% block or greater) is attained in a median (range) time of 1.3 (0.8-6.2) minute(s), and most patients have intubation completed within 2 minutes. Maximum blockade is achieved in most patients in less than 4 minutes. This dose may be expected to provide 22 (12-31) minutes of clinical relaxation under opioid/nitrous oxide/oxygen anesthesia. Patients receiving this low dose of 0.45 mg/kg who achieve less than 90% block (about 16% of these patients) may have a more rapid time to 25% recovery, 12 to 15 minutes.
A large bolus dose of 0.9 or 1.2 mg/kg can be administered under opioid/nitrous oxide/oxygen anesthesia without adverse effects to the cardiovascular system [see Clinical Pharmacology (12.2)].
2.2 Rapid Sequence Intubation
In appropriately premedicated and adequately anesthetized patients, ZEMURON 0.6 to 1.2 mg/kg will provide excellent or good intubating conditions in most patients in less than 2 minutes [see Clinical Studies (14.1)].
2.3 Maintenance Dosing
Maintenance doses of 0.1, 0.15, and 0.2 mg/kg ZEMURON, administered at 25% recovery of control T1 (defined as 3 twitches of train-of-four), provide a median (range) of 12 (2-31), 17 (6-50), and 24 (7-69) minutes of clinical duration under opioid/nitrous oxide/oxygen anesthesia [see Clinical Pharmacology (12.2)]. In all cases, dosing should be guided based on the clinical duration following initial dose or prior maintenance dose and not administered until recovery of neuromuscular function is evident. A clinically insignificant cumulation of effect with repetitive maintenance dosing has been observed [see Clinical Pharmacology (12.2)].
2.4 Use by Continuous Infusion
Infusion at an initial rate of 10 to 12 mcg/kg/min of ZEMURON should be initiated only after early evidence of spontaneous recovery from an intubating dose. Due to rapid redistribution [see Clinical Pharmacology (12.3)] and the associated rapid spontaneous recovery, initiation of the infusion after substantial return of neuromuscular function (more than 10% of control T1) may necessitate additional bolus doses to maintain adequate block for surgery.
Upon reaching the desired level of neuromuscular block, the infusion of ZEMURON must be individualized for each patient. The rate of administration should be adjusted according to the patient's twitch response as monitored with the use of a peripheral nerve stimulator. In clinical trials, infusion rates have ranged from 4 to 16 mcg/kg/min.
Inhalation anesthetics, particularly enflurane and isoflurane, may enhance the neuromuscular blocking action of nondepolarizing muscle relaxants. In the presence of steady-state concentrations of enflurane or isoflurane, it may be necessary to reduce the rate of infusion by 30% to 50%, at 45 to 60 minutes after the intubating dose.
Spontaneous recovery and reversal of neuromuscular blockade following discontinuation of ZEMURON infusion may be expected to proceed at rates comparable to that following comparable total doses administered by repetitive bolus injections [see Clinical Pharmacology (12.2)].
Infusion solutions of ZEMURON can be prepared by mixing ZEMURON with an appropriate infusion solution such as 5% glucose in water or lactated Ringers [see Dosage and Administration (2.6)]. These infusion solutions should be used within 24 hours of mixing. Unused portions of infusion solutions should be discarded.
Infusion rates of ZEMURON can be individualized for each patient using the following tables for 3 different concentrations of ZEMURON solution as guidelines:
Table 1: Infusion Rates Using ZEMURON Injection (0.5 mg/mL)*
|
Patient Weight |
Drug Delivery Rate (mcg/kg/min) |
|
(kg) |
(lbs) |
4 |
5 |
6 |
7 |
8 |
9 |
10 |
12 |
14 |
16 |
|
Infusion Delivery Rate (mL/hr) |
|
|
|
10 |
22 |
4.8 |
6 |
7.2 |
8.4 |
9.6 |
10.8 |
12 |
14.4 |
16.8 |
19.2 |
|
15 |
33 |
7.2 |
9 |
10.8 |
12.6 |
14.4 |
16.2 |
18 |
21.6 |
25.2 |
28.8 |
|
20 |
44 |
9.6 |
12 |
14.4 |
16.8 |
19.2 |
21.6 |
24 |
28.8 |
33.6 |
38.4 |
|
25 |
55 |
12 |
15 |
18 |
21 |
24 |
27 |
30 |
36 |
42 |
48 |
|
35 |
77 |
16.8 |
21 |
25.2 |
29.4 |
33.6 |
37.8 |
42 |
50.4 |
58.8 |
67.2 |
|
&nb |
