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|Mivacron |
Drugs search, click the first letter of a drug name: | A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | 1 | 2 | 3 | 4 | 5 | 6 | 8 | 9 Home MivacronGeneric Name: mivacurium chloride Dosage Form: Injection This drug should be administered only by adequately trained individuals familiar with its actions, characteristics, and hazards. Mivacron DescriptionMivacron (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. Mivacron - Clinical PharmacologyMivacron (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. PharmacodynamicsThe 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).
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