Methohexital
Methohexital Uses, Dosage, Side Effects, Mechanism of Action, How Long Does it Take to Work? Methohexital is a brand name. Its generic name is Methohexital.
Methohexital Introduction
Methohexital, also known as Brevital, is a fast-acting barbiturate that has sedative-hypnotic and general anaesthetic effects. It is used for general anaesthesia in cosmetic and dental surgery, and to induce deep sedation for short duration medical procedures. Methohexital can also be used to prevent epileptic seizures.
Uses for Methohexital
Methohexital is used to induce general anaesthesia and deep sedation. It is used in cosmetic and dental surgery, and for short duration medical procedures such as bronchoscopy, endoscopy, and transrectal ultrasonography (TRUS). It is also used to prevent epileptic seizures.
Mechanism of Action
Methohexital works by increasing the activity of the inhibitory neurotransmitter GABA (gamma-Aminobutyric acid). GABA is a neurotransmitter that reduces the activity of the nerve cells in the brain and spinal cord, and this leads to a decrease in neuronal activity. This results in a calming and sedative effect.
How long does it take to work?
Methohexital has a rapid onset of action, usually within 30-60 seconds, and its effects last for 5-15 minutes or more depending on the dose.
Absorption
Methohexital is rapidly absorbed after intravenous or intramuscular injection. It is also absorbed after oral administration.
Route of Elimination
Methohexital is metabolized in the liver and eliminated primarily by the kidneys.
Dosage
The dose of Methohexital for adults is 0.5 mg/kg IV or IM. Inject slowly over 10-15 seconds or slow IV infusion, up to 1mg/kg. The dose for children is 0.5-1 mg/kg IV. Methohexital injection should not be given as a bolus injection.
Administration
Methohexital can be administered via intravenous injection or infusion, intramuscular injection, and oral tablets.
Side Effects
Common side effects of Methohexital include drowsiness, nausea and vomiting, dizziness, headache, restlessness, miosis (constriction of the pupils), and hypotension (low blood pressure). Rare or serious side effects may include respiratory depression, cardiac arrhythmia, and seizures.
Toxicity
High doses of Methohexital may lead to respiratory depression, hypotension, coma and death. If Methohexital is used in excessive doses, patients may experience central nervous system depression, respiratory depression, and cardiovascular collapse.
Precaution
Methohexital should be used with caution in patients with a history of drug abuse, respiratory or cardiovascular diseases, and other relevant medical conditions. It should not be used in patients who have taken other sedative drugs in the past such as benzodiazepines or opioids as they may cause additive effects.
Interaction
Methohexital may interact with other drugs, including narcotics, barbiturates, alcohol, antihistamines, and other central nervous system depressants. It should not be used in combination with these drugs as it can lead to additive effects.
Disease Interactions
Methohexital should not be used in patients with a history of porphyria or aneurysm or in patients with severe pulmonary disease. It should also not be used in patients with severe hepatic impairment, as the drug is partly metabolized in the liver.
Drug Interactions
Methohexital may interact with other drugs, including narcotics, barbiturates, alcohol, antihistamines, and other central nervous system depressants. It should not be used in combination with these drugs as it can lead to additive effects.
Food Interactions
Methohexital should not be taken with alcohol or with other drugs that have sedative effects such as barbiturates, narcotics, or antihistamines.
Pregnancy Use
Methohexital is not recommended for use in pregnant women as it can cause harm to the unborn baby. Animal studies have shown that Methohexital can cause fetal harm and other risks. It should be used only if the potential benefit justifies the potential risk to the fetus.
Lactation Use
Methohexital use is not recommended in nursing mothers as it may pass into the breast milk and cause harm to the infant. Nursing mothers should consult their doctor before using Methohexital.
Acute Overdose
An acute overdose of Methohexital can lead to respiratory depression, hypotension, cardiac arrhythmias, coma, and death. Treatment of overdose typically involves supportive care, such as intravenous fluids and oxygen, and administration of a benzodiazepine or narcotic antagonist.
Contraindication
Methohexital is contraindicated in patients with porphyria, severe pulmonary disease, severe hepatic impairment, aneurysm, or an allergy to barbiturates.
Use Direction
Methohexital should be used as directed by the doctor or healthcare professional who prescribed it. Follow all instructions carefully and do not use more than prescribed. Do not give Methohexital to a child without a doctor’s prescription.
Storage Condition
Methohexital should be stored at controlled room temperature, away from light and heat. Do not store in refrigerator or freezer. Keep the medication out of reach of children and pets.
Volume of Distribution
Methohexital is widely distributed throughout the body, with an estimated volume of distribution of 0.4 – 0.6 L/kg.
Half Life
The half-life of Methohexital is 15-30 minutes.
Clearance
Methohexital is mainly metabolized in the liver, with an estimated clearance of 1.08 mL/min/kg.
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