Dosing & Uses
Dosage Forms & Strengths
powder for injection: Schedule IV
- 500mg
- 2.5g
Anesthesia
Induction: 50-120 mg (70 mg average) IV push at 10 mg ( 1 mL of 1% solution) over 5 seconds, depending on patient response
Maintenance: 20-40 mg (2-4 mL of 1% soluiton) IV push q4-7min PRN, OR 4-6 mg/min IV drip
Interactions
Interaction Checker
No Results
Contraindicated
Serious - Use Alternative
Significant - Monitor Closely
Minor
Adverse Effects
Frequency Not Defined
Hiccups, coughing, muscle twitching & laryngospasm, which may impair pulmonary ventilation
Respiratory depression, apnea, dyspnea, cardiorespiratory arrest (which may occur in association with seizures), or hypotension may occur
Circulatory depression, peripheral vasculatory collapse, bronchospasm, postanesthetic shivering, salivation, skeletal muscle hyperactivity (twitching to convulsive-like movements), seizures, restlessness, anxiety (especially in the presence of postop pain), headache, nausea, vomiting, abd pain, & emergence delirium may also occur
Acute allergic reactions including erythema, pruritus, urticaria, rhinitis, hypotension, dyspnea, anxiety, restlessness, abdominal pain & peripheral vascular collapse have been reported
Thrombophlebitis, injection site pain, & injury to nerves adjacent to injection site
Extravasation may cause local irritation manifested as pain, swelling, ulceration, & necrosis
Warnings
Black Box Warnings
Methohexital should be used in hospital or ambulatory care settings that can provide continuous monitoring of respiratory (eg, pulse oximetry) and cardiac function
Resuscitative drugs and age- and size-appropriate equipment for bag valve mask ventilation and intubation and personnel trained in their use and skilled in airway management should be readily available
For deeply sedated patients, a designated individual other than the practitioner performing the procedure should be present to continuously monitor the patient
Contraindications
Porphyria
Known hypersensitivity to barbiturates
Relative: cardiovascular disease, hypotension, respiratory disease
Cautions
Severe anemia, extreme obesity, debilitated patients
Renal/hepatic/endocrine/circulatory dysfunction, obstructive pulmonary dz, severe HTN, status asthmaticus
Rapid bolus doses will increase cardiorespiratory effects including laryngospasm, apnea, hypotension, myocardial depression, cardiovascular collapse
Mild sedation may persist 8-12 hr
Patients should be instructed on discharge not to drive or operate heavy machinery
General anesthetics and sedation drugs in young children and pregnant women
Brain development
- Prolonged or repeated exposure may result in negative effects on fetal or young children’s brain development
- Caution with use during surgeries or procedures in children younger than 3 yr or in pregnant women during their third trimester
- Administration of anesthetic and sedation drugs that block NMDA receptors and/or potentiate GABA activity increase neuronal apoptosis in developing brain and result in long-term cognitive deficits when used for longer than 3 hours; assess the risk:benefit ratio in these populations, especially for prolonged procedures (ie, >3 hr) or multiple procedures
Pregnancy & Lactation
Pregnancy
There are no adequate and well-controlled studies in pregnant women; published studies in pregnant primates demonstrate that administration of anesthetic and sedation drugs that block NMDA receptors and/or potentiate GABA activity during the period of peak brain development increases neuronal apoptosis in the developing brain of the offspring when used for longer than 3 hours; clinical significance not clear; however, studies in juvenile animals suggest neuroapoptosis correlates with long-term cognitive deficits
Lactation
Excreted in breast milk; use by nursing mothers should be evaluated carefully
Pregnancy Categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk. C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done. D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk. X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist. NA: Information not available.Pharmacology
Mechanism of Action
Ultra short-acting anesthetic barbiturate; no muscle relaxant activity
Pharmacokinetics
Half-Life: 3-6 hr
Onset: Immediate (IV); 2-10 min (IM); 5-15 min (PR)
Duration: 10-20 min (IV); 45 min (PR)
Metabolism: Hepatically conjugated to inactive metabolites; slow
Excretion: Urine; trace amounts of drug &/or metabolites also excreted in feces & sweat
Administration
IV Compatibilities
Solution: D5/LR, D5W in NS, D5W, LR, NS
Additive: chlorpromazine, hydralazine, kanamycin, lidocaine, mechlorethamine, methyldopate, prochlorperazine, promazine, promethazine, streptomycin
Syringe: glycopyrrolate
IV Administration
Do not use diluents containing bacteriostats
Soln should be clear or colorless or it should not be used
Administer by injection or infusion, in concentration no higher than 1%
Avoid intraarterial injection & extravasation
Storage
Store at controlled room temp
Images
Patient Handout
Formulary
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