Drug information of Methohexital

Methohexital


An intravenous anesthetic with a short duration of action that may be used for induction of anesthesia.

Mechanism of effect

Methohexital binds at a distinct binding site associated with a Cl- ionopore at the GABAA receptor, increasing the duration of time for which the Cl- ionopore is open. The post-synaptic inhibitory effect of GABA in the thalamus is, therefore, prolonged.

Pharmacodynamic

Methohexital, a barbiturate, is used for the induction of anesthesia prior to the use of other general anesthetic agents and for induction of anesthesia for short surgical, diagnostic, or therapeutic procedures associated with minimal painful stimuli. Little analgesia is conferred by barbiturates; their use in the presence of pain may result in excitation.

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

Dosage

Adult

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

Pediatric

>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

Drug contraindications

cardiovascular conditions

Alerts

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

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

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

Points of recommendation

Avoid driving and doing other tasks or actions that call for you to be alert until the effects of methohexital wear off and you feel fully awake.

Talk with your doctor before you drink alcohol or use other drugs and natural products that slow your actions.

This medicine may raise the chance of seizures in some people, including people who have had seizures in the past. Talk to your doctor to see if you have a greater chance of seizures while taking methohexital.

This medicine may affect certain lab tests. Tell all of your health care providers and lab workers that you take methohexital.

Studies in young animals and children have shown that frequent or long-term use of anesthesia drugs or drugs used for sleep in children younger than 3 years of age may lead to long-term brain problems. This may also happen in unborn babies if the mother uses methohexital during the third trimester of pregnancy. Talk with the doctor.

Tell your doctor if you are pregnant or plan on getting pregnant. You will need to talk about the benefits and risks of using methohexital while you are pregnant.

Tell your doctor if you are breast-feeding. You will need to talk about any risks to your baby.

Pregnancy level

Not assigned


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