Download Introduction of two new anaesthetic agents

INTRODUCTION
OF TWO NEW
ANESTHETIC AGENTS
Dr.G.k.kumar
Ropivacaine
Dexmeditomedine
Ropivacaine
Ropivacaine
• New local anesthetic agent
• Introduced in 1996.
• In India 2009.
Ropivacaine
• Lower systemic toxicity
• Safest long acting
local anesthetic
agent.
* Groban et al. Anesth Analg, 2001.
Ohmura et al. Anesth Analg, 2001.
Santos et al. Anesthesiology, 2001.
Ropivacaine -Pharmacology
Ropivacaine-Pharmacology
• Long acting LA agent.
• Aminio amide.
• Pure enantiomer
-S isomer.
Ropivacaine-Pharmacology
• Greater selectivity for
sensory blockade
-binds selectively to
Na⁺channels 1.7
• Shorter motor block
*Liu BG et al, AnesAnalg.2000May.
Simpsons D et al,2005
Ropivacaine-Pharmacology
•Ropivacaine is less lipid soluble.
•A smaller volume of distribution.
•Greater clearance.
•Shorter elimination half-life than
bupivacaine.
-Shorter duration of action esp
motor blockade – early recovery.
Ropivacaine-Pharmacology
•Ropivacaine undergoes
hepatic biotransformation
and renal excretion
•Excreted 86% as metobolites
•Safe in CESLD & CESRD
*Jokinen MJ et al, Anesthesiology,2007Jan.
Jokinen MJ et al,Clinical Anesthesiology,2005
Ropivacaine-Pharmacology
• The specific gravity of
Ropivacaine Injection
-from 1.002 to 1.005 at
25°C.
-Isobaric
Ropivacine-Safe Dose
• 3-5mg /kg.
• Pediatric-1-2mg/kg
Ropivacaine-Epidural dose
Drug
Conc%
Volume
Dose mg
15-30
40-225 15-20 180-350
LEVO 0.25-0.75 15-30
40-250 15-20 180-350
ROPI 0.25-0.75 15-30
40-250 15-20 180-350
BUPI 0.25-0.5
Onset
Duration
*Miller’s anesthesia,7th edition
Ropivacaine-Spinal dose
Drug
(%)
Bupi
0.5
0.75
Levo
Ropi
0.5
0.75
0.5
0.75
Total
Volume
Dose
(mL)
(mg)
15-20
3-4
2-3
15-20
3-4
15-20
2-3
15-20
3-4
15-20
2-3
15-20
Duration
Baricity
(min)
Iso
Hyper
Iso
Hyper
Iso
Hyper
90-200
90-200
90-200
90-200
90-200
90-200
*Miller’s anesthesia,7th edition
Ropivacaine – clinical efficacy
• When used for spinal
anesthesia, 0.75% ropivacaine
produces less intense sensory
and motor block than 0.5%
bupivacaine.
• Equipotent to bupivacaine
when used for lumbar
epidural labor analgesia and
C-section.
Ropivacaine – clinical efficacy
• In epidural and other
blocks bupivacaine and
ropivacaine demonstrate
similar intensity of sensory
anesthesia.
Ropivacaine – clinical efficacy
• Ropivacaine motor block
-delayed in onset.
-less intense.
-shorter in duration.
Toxicity
• Ropivacaine < Levobupivacaine
< Bupivacaine
• Even at 50% higher dosage!!!
*Dony et al. Anesth Analg, 2000
Toxicity
• Tolerated blood conc. level
[ROP] >> [BUP] = [LBUP]
• Mortality:
BUP (50%) > LBUP (30%) > ROP (10%)
•
•
•
* Groban et al. Anesth Analg, 2001.
Ohmura et al. Anesth Analg, 2001.
Santos et al. Anesthesiology, 2001.
Ropivacine-Why Safer Than
Bupivacaine?
• Bupivacaine is a 50:50 racemic
mixture of the S- and Renantiomers.
• The R isomer has greater affinity
and binding time for voltagegated sodium channels, and so
cardiotoxicity.
Ropivacine-Why Safer Than
Bupivacaine?
• R-bupivacaine is also more
arrhythmogenic.
• Slows ventricular conduction
4.6 times as much as Sbupivacaine.
Ropivacine-Why Safer Than
Bupivacaine?
• The Ropivacaine is the
pure S-enantiomer so
decreased cardiotoxicity .
Ropivacine-Why Safer Than
Bupivacaine?
• Cumulative doses up to 770 mg
over 24 hours (intraoperative
block plus postoperative infusion)
• Continuous epidural infusion at
rates up to 28 mg per hour for 72
hours have been well tolerated in
adults, ie, 2016 mg plus surgical
dose of approximately 100-150
mg as top-up.
*www.fda druginformation.com
Ropivacine-Why Safer Than
Bupivacaine?
• Ropivacaine has a larger
therapeutic index
• 70% less likely to cause
severe cardiac dysarrhythmias
• Greater CNS tolerance
• The improved safety profile is
due to a lower lipid solubility
Ropivacaine
HYPE?
HOPE?
LA toxicity more in
• Heart block, HT, structural
heart disease.
• >65yr,<12yr.
• Pregnancy.
• Acidosis.
• Liver dysfunction.
• Acutely ill and debilitated.
Role of Ropivacaine
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•
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SAFE PRACTICE
Pediatric patients.
Geriatric patients.
Continuous infusions.
For labour analgesia.
Rescue spinal anesthesia.
Ropivacaine
LA toxicity treatment
• Supportive care: intubation,
vasopressors, appropriate
defibrillation, fluids, stop
injection of LA.
• Intralipid…Bolus 1cc/kg of 20%
intralipid, 0.25cc/kg/min of
20% intralipid for 10 minutes
• Bolus can be repeated every 5
minutes up to a maximum of
8cc/kg of 20% intralipid
LA toxicity treatment
• Cardiac support should be
continued as ACLS dictates
• Adrenaline and vasopressin
are usefull.
Ropivacaine