tubocurarine (Tubarine)
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Introduction
An alkaloid present in curare derived from Chondodendron species. Tradename: Tubarine.
Indications
- skeletal muscle relaxation during surgery & electroshock therapy
- has been used as a diagnostic agent for myasthenia gravis
- must ALWAYS be used with sedative (i.e. lorazepam) anesthetics & analgesics as needed
Dosage
- adjunct to anesthesia: 6-9 mg IV/IM followed by 3-4 mg every 3-5 min PRN
- electroshock therapy: 0.165 mg/kg (administer 3 mg less than the calculated dose)
- myasthenia gravis: 0.004-0.033 mg/kg
Pharmacokinetics
- rapid onset of action
- duration of action: 20-40 minutes after IV administration
- 30-80% is eliminated unchanged in the urine
- metabolized in the liver
elimination via kidney
1/2life = 2-3 hours
protein binding = 48-54 %
Adverse effects
- not common (1-10%)
- uncommon (< 1%)
- other
- muscle weakness
- redness at the site of injection
- increased adverse effects with hyperkalemia or hypokalemia Toxicity (reversal of effects):
- neostigmine, pyridostigmine, edrophonium (cholinesterase inhibitor) used with atropine (muscarinic inhibition) to reverse muscular blockade
Drug interactions
- aminoglycosides, tetracyclines, clindamycin, corticosteroids: in combination cause prolonged muscle weakness
- K+ depleting agents (thiazides, loop diuretics, amphotericin B, corticosteroids) can increase & prolong muscle paralysis
- neostigmine, pyridostigmine, edrophonium, & other cholinesterase inhibitors are used with atropine to reverse muscular blockade
- quinidine
- magnesium sulfate
- verapamil
- ketamine
Laboratory
Mechanism of action
- non-depolarizing neuromuscular junction blocker
- skeletal muscle relaxation produced by blocking response to acetylcholine at the myoneural junction
- blocks access of acetylcholine to the motor end-plate
- also inhibits ganglionic transmission & induces release of histamine
More general terms
References
- ↑ Clinical Guide to Laboratory Tests, 3rd edition, NW Tietz ed, WB Saunders, Philadelphia, 1995
- ↑ Drug Information & Medication Formulary, Veterans Affairs, Central California Health Care System, 1st ed., Ravnan et al eds, 1998 - not on National VA formulary
- ↑ Kaiser Permanente Northern California Regional Drug Formulary, 1998
- ↑ Clinical Guide to Laboratory Tests, NW Tietz (ed) 3rd ed, WB Saunders, Philadelpha 1995
- ↑ Stedman's Medical Dictionary 27th ed, Williams & Wilkins, Baltimore, 1999
- ↑ The Pharmacological Basis of Therapeutics, 9th ed. Gilman et al, eds. Permagon Press/McGraw Hill, 1996 pg 178
Database
- PubChem: http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=6000
- PubChem: http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=64645
- PubChem: http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=626970
- PubChem: http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=1211
- PubChem: http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=23422
- PubChem: http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=14955
- PubChem: http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=15947
- PubChem: http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=1210
- PubChem: http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=411885