Methohexital

Indications

Methohexital is used for: Anesthesia

Adult Dose

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

Child Dose

>1 Month Old 6.6-10 mg/kg IM administered as a 5% (50 mg/mL) solution OR 25 mg/kg PR administered as a 1% (10 mg/mL) solution

Renal Dose

Administration

Contra Indications

Porphyria Known hypersensitivity to barbiturates Relative: cardiovascular disease, hypotension, respiratory disease

Precautions

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

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

Interactions

Adverse Effects

Side effects of Methohexital : 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

Mechanism of Action

Ultra short-acting anesthetic barbiturate; no muscle relaxant activity