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Sota
Omoigui's
Anesthesia Drug Handbook
3rd Edition:
:
Thiopental Sodium
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SECTION
ONE:
Uses, Dosing,
Elimination
SECTION TWO:
Preparation, Pharmacology, Pharmacokinetics
SECTION THREE:
Interactions, Toxicity
Guidelines/Precautions
Principal Adverse Reactions
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Uses
induction agent, supplementation of regional anesthesia, anticonvulsant, reduction of elevated intracranial pressure, cerebral protection (barbiturate narcosis)
Dosing
Anesthesia Induction: IV 3-5 mg/kg (Children 5-6 mg/kg Infants 7-8 mg/kg)
Anesthesia Induction - Thiopental-Propofol (50:50 Mixture) - IV 0.15 mls/kg.
Anesthesia supplementation: IV 0.5-1 mg/kg Rectal induction: 25 mg/kg
Anticonvulsant IV 0.5-2 mg/kg. Repeat prn.
Reduction of ICP: IV 1-4 mg/kg
Barbiturate Narcosis IV bolus 8mg/kg p.r.n. to maintain EEG burst suppression (Mean total dose 40 mg/kg)
Infusion : 0.05-0.35 mg/kg/min
Inotropic and respiratory support are required at high doses.
Elimination
hepatic
How supplied
Injection: 250 mg, 400 mg and 500 mg syringes
Vials with diluent 500 mg and 1 g
Kits with 1, 2.5, 5 g
Rectal suspension: 400 mg per g of suspension
Storage
Powder: Room Temperature (15-30 degrees Celsius). Reconstituted solutions should be used promptly. Solutions are stable for 24 hours either refrigerated (2-8 degrees Celsius) or at room temperature. Thiopental -propofol mixture is stable for up to six hours at room temperature.
DILUTION FOR INFUSION: Barbiturate Narcosis: IV: 5000 mg in 250 mls Sterile Water or NS (20 mg/ml)
Pharmacology
This ultra short-acting thiobarbiturate depresses the central nervous system and induces hypnosis and anesthesia but not analgesia. Recovery after a short dose is rapid (due to redistribution from the brain to other body tissues), with some somnolence and anterograde amnesia. Because of the high lipid solubility and slow elimination, repeated intravenous doses lead to a cumulative drug effect. The drug produces respiratory depression and hemodynamic effects including a decrease in systemic vascular resistance, arterial pressure, cardiac output and a fall in coronary perfusion pressure. Uterine blood flow is decreased. Induction doses of thiopental may suppress the adrenal cortex and decrease plasma cortisol levels. However unlike etomidate, the adrenal suppression is rapidly reversible and responds to ACTH stimulation. Thiopental decreases cerebral blood flow, cerebral metabolic rate and intracranial pressure. Cerebral perfusion pressure is maintained. The nonspecific late latency waves of somatosensory, brainstem auditory and visual evoked potentials are uniformly depressed. EEG changes include an initial increase in the alpha amplitude followed by a progressive decrease in activity. High doses of thiopental that induce burst suppression to the isoelectric point may provide protection during profound controlled hypotension and reduce infarct size in patients with cerebral emboli and temporary focal ischemia. Thiopental narcosis does not affect outcome in patients with severe head injuries or after cardiac arrest. Histamine release can occur and allergic reactions most likely represent anaphylaxis.
Pharmacokinetics
ONSET OF ACTION: IV 10-20 seconds
Rectal 8-10 minutes (variable)
PEAK EFFECT: IV 30-40 seconds
DURATION OF ACTION: IV 5-15 minutes (awakening)
Interactions
potentiates CNS and circulatory depressant effects of narcotics, sedative hypnotics, alcohol, volatile anesthetics; decreases effects of oral anticoagulants, digoxin, beta blockers, corticosteroids, quinidine, theophylline; actions prolonged by MAO inhibitors, chloramphenicol; incompatible with solutions of succinylcholine, tubocurarine or other drugs with an acid pH; arterial or extravascular injection (especially with concentrations above 5%) produces necrosis, gangrene.
Guidelines
(1) Treat intraarterial or extravascular injection by local infiltration of phentolamine (5 to 10 mg in 10 mls NS), injection into the artery of a dilute solution of papaverine (40 to 80 mg) or 10 mls of 1% procaine to inhibit smooth muscle spasm. Urokinase 75,000 IU may be injected into the artery for lysis of clot emboli. If necessary perform sympathetic block of the brachial plexus or stellate ganglion.
(2) Shivering after pentothal anesthesia is a thermal reaction due to increased sensitivity to cold. Treatment consists of warming the patient with blankets, maintaining room temperature and administration of meperidine, chlorpromazine or methylphenidate.
(3) Contraindicated in patients with status asthmaticus, acute intermittent porphyria, variegate porphyria and hereditary coproporphyria.
(4) Use with caution in patients with hypertension, hypovolemia, ischemic heart disease, acute adrenocortical insufficiency, uremia, septicemia.
(5) Reduce doses in elderly, hypovolemic, high risk surgical patients and with concomitant use of narcotics and sedatives
(6) Most incidences of coughing and airway spasm during thiopental induction, are due to manipulation of the airway during light levels of anesthesia, rather than a direct drug effect. In patients with active bronchospasm, ketamine may be preferable to thiopental for intravenous induction.
Principal Adverse Reactions
CVS: circulatory depression, arrhythmias
PULM: respiratory depression, apnea, laryngospasm, bronchospasm
CNS: emergence delirium, prolonged somnolence and recovery, headache.
GI: nausea, emesis, salivation
DERM: thrombophlebitis, necrosis, gangrene
ALLERGIC: erythema, pruritus, urticaria, anaphylactic reactions
OTHER: skeletal muscle hyperactivity, shivering
Reactions
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Toll-Free: (800) 9-MEDIC-9, Phone: (310) 675-9121,
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NOTICE:
Every effort has been made to ensure that the drug dosage schedules
herein are accurate and in accord with the standards accepted
at the time of publication. As new research and experience broaden
our knowledge, changes in treatment and drug therapy occur. The
medications described do not necessarily have specific approval
by the Food and Drug Administration for use in the situations
and the dosages for which they are recommended. This information
is advisory only. The package insert should be consulted for use
and dosage as approved by the FDA, for any changes in indications
and dosages and for added warnings and precautions. The ultimate
responsibility lies with the prescribing physician.
No part of this information may be reproduced or transmitted electronically
in any information storage or retrieval system, or within any
monitoring system without prior permission in writing from S.O.T.A.
Technologies (Electronic Publishers).
The Universal Drug Infusion Slide Ruler (patent pending) is now
available. It incorporates an infusion data guide and enables
infusion calculations for any drug at any dose and at any concentration.
It may be obtained by calling S.O.T.A Technologies (800 9-MEDIC-9)
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COMPOUNDED
TOPICAL MEDICATIONS MAY BE ORDERED (BY PRESCRIPTION ONLY) FROM L.A.
PAIN CLINIC. CALL 310 675-9121 or 1 800 9-MEDIC-9. |
Copyright 2000. Sota Omoigui, M.D. All rights reserved.
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