Drug Facts
Composition & Profile
Identifiers & Packaging
HOW SUPPLIED Store between 20° to 25°C (68° to 77°F). (See USP Controlled Room Temperature.) Methohexital Sodium for Injection is a white, freeze-dried plug/lyophilized cake, filled in Vials*: The 500 mg vials (with 30 mg anhydrous sodium carbonate) are available as follows: • NDC 83270-003-01– Multi-Dose Vial – Pack of 1 *In crystalline form.; PRINCIPAL DISPLAY PANEL NDC:83270- 003 -01 Rx Only Methohexital sodium for injection, USP 500mg/Vial CIV ANESTHETIC BARBITURATE Preservative free - Discard Unused Portion After 24 hours 500 mg Multiple Dose Vial NDC:83270- 003 -01 Rx Only Methohexital sodium for injection, USP 500mg/Vial CIV ANESTHETIC BARBITURATE Preservative free - Discard Unused Portion After 24 hours Do not administer without reading directions in full prescribing information. 500 mg Multiple Dose Vial label-vial carton-label
- HOW SUPPLIED Store between 20° to 25°C (68° to 77°F). (See USP Controlled Room Temperature.) Methohexital Sodium for Injection is a white, freeze-dried plug/lyophilized cake, filled in Vials*: The 500 mg vials (with 30 mg anhydrous sodium carbonate) are available as follows: • NDC 83270-003-01– Multi-Dose Vial – Pack of 1 *In crystalline form.
- PRINCIPAL DISPLAY PANEL NDC:83270- 003 -01 Rx Only Methohexital sodium for injection, USP 500mg/Vial CIV ANESTHETIC BARBITURATE Preservative free - Discard Unused Portion After 24 hours 500 mg Multiple Dose Vial NDC:83270- 003 -01 Rx Only Methohexital sodium for injection, USP 500mg/Vial CIV ANESTHETIC BARBITURATE Preservative free - Discard Unused Portion After 24 hours Do not administer without reading directions in full prescribing information. 500 mg Multiple Dose Vial label-vial carton-label
Overview
Methohexital Sodium for injection, is 2,4,6 (1H, 3H, 5H)-Pyrimidinetrione, 1- methyl-5-(1-methyl-2-pentynyl)-5-(2-propenyl)-,(±)-,monosodium salt and has the empirical formula C 14 H 17 N 2 NaO 3 . Its molecular weight is 284.29. The structural formula is as follows: Methohexital sodium is a rapid, ultrashort-acting barbiturate anesthetic. Methohexital Sodium for Injection is a freeze-dried, sterile, nonpyrogenic mixture of methohexital sodium with 6% anhydrous sodium carbonate added as a buffer. It contains not less than 90% and not more than 110% of the labeled amount of methohexital sodium. It occurs as a white, freeze-dried plug that is freely soluble in water. This product is oxygen sensitive. The pH of the 1% solution is between 10 and 11; the pH of the 0.2% solution in 5% dextrose is between 9.5 and 10.5. Methohexital sodium may be administered by direct intravenous injection or continuous intravenous drip, intramuscular or rectal routes (see PRECAUTIONS/Pediatric Use ). Reconstituting instructions vary depending on the route of administration (see DOSAGE AND ADMINISTRATION ). structure
Indications & Usage
Methohexital Sodium for Injection can be used in adults as follows: 1.For intravenous induction of anesthesia prior to the use of other general anesthetic agents. 2.For intravenous induction of anesthesia and as an adjunct to subpotent inhalational anesthetic agents (such as nitrous oxide in oxygen) for short surgical procedures; Methohexital Sodium for Injection may be given by infusion or intermittent injection. 3.For use along with other parenteral agents, usually narcotic analgesics, to supplement subpotent inhalational anesthetic agents (such as nitrous oxide in oxygen) for longer surgical procedures. 4.As intravenous anesthesia for short surgical, diagnostic, or therapeutic procedures associated with minimal painful stimuli (see WARNINGS). 5.As an agent for inducing a hypnotic state. Methohexital Sodium for Injection can be used in pediatric patients older than 1 month as follows: 1.For rectal or intramuscular induction of anesthesia prior to the use of other general anesthetic agents. 2.For rectal or intramuscular induction of anesthesia and as an adjunct to subpotent inhalational anesthetic agents for short surgical procedures. 3.As rectal or intramuscular anesthesia for short surgical, diagnostic, or therapeutic procedures associated with minimal painful stimuli.
Dosage & Administration
Facilities for assisting ventilation and administering oxygen are necessary adjuncts for all routes of administration of anesthesia. Since cardiorespiratory arrest may occur, patients should be observed carefully during and after use of Methohexital Sodium for Injection. Age- and size- appropriate resuscitative equipment (i.e., intubation and cardioversion equipment, oxygen, suction, and a secure intravenous line) and personnel qualified in its use must be immediately available. Preanesthetic medication is generally advisable. Methohexital Sodium for Injection may be used with any of the recognized preanesthetic medications. Preparation of Solution FOLLOW DILUTION INSTRUCTIONS EXACTLY. Freshly prepare solutions of Methohexital Sodium for Injection and use promptly. Reconstituted solutions of Methohexital Sodium for Injection are chemically stable at room temperature for 24 hours. Diluents ONLY USE BACTERIOSTATIC-FREE DILUENT - Recommended diluents are based on route of administration (see Dilution Instructions ). Incompatible diluents: Lactated Ringer's Injection Dilution Instructions 1% solutions (10 mg/mL) should be prepared for intermittent intravenous and rectal administration; 0.2% solutions (2 mg/mL) should be prepared for continuous intravenous drug administration; 5% solutions (50 mg/mL) should be prepared for intramuscular administration. Contents of vials should be diluted as follows: FOR INTERMITTENT INTRAVENOUS and RECTAL ADMINISTRATION The preferred diluent for intermittent intravenous and rectal administration is Sterile Water for Injection. 5% Dextrose Injection, or 0.9% Sodium Chloride Injection are also acceptable diluents. Strength Amount of Diluent to Be Added to the Contents of the Methohexital Sodium for Injection Vial For 1% methohexital solution (10 mg/mL) 500 mg 50 mL no further dilution needed FOR CONTINUOUS INTRAVENOUS ADMINISTRATION For continuous drip anesthesia, prepare a 0.2% solution by adding 500 mg of Methohexital Sodium for Injection to 250 mL of diluent. For this dilution, either 5% glucose solution or isotonic (0.9%) sodium chloride solution ONLY is recommended as the diluent instead of sterile water for injection in order to avoid extreme hypotonicity. Strength Amount of Diluent to Be Added to the Contents of the Methohexital Sodium for Injection Vial For 0.2% methohexital solution (2 mg/mL) 500 mg 15 mL add to 235 mL diluent for 250 mL total volume FOR INTRAMUSCULAR ADMINISTRATION The preferred diluent for intramuscular administration is Sterile Water for Injection. 0.9% Sodium Chloride Injection is also an acceptable diluent. Strength Amount of Diluent to Be Added to the Contents of the Methohexital Sodium for Injection Vial For 5% methohexital solution (50 mg/mL) 500 mg 10 mL no further dilution needed Administration Dosage is highly individualized; the drug should be administered only by those completely familiar with its quantitative differences from other barbiturate anesthetics. Adults Methohexital Sodium for Injection is administered intravenously in a concentration of no higher than 1%. Higher concentrations markedly increase the incidence of muscular movements and irregularities in respiration and blood pressure. Induction of anesthesia For induction of anesthesia, a 1% solution is administered at a rate of about 1 mL/5 seconds. Gaseous anesthetics and/or skeletal muscle relaxants may be administered concomitantly. The dose required for induction may range from 50 to 120 mg or more but averages about 70 mg. The usual dosage in adults ranges from 1 to 1.5 mg/kg. The induction dose usually provides anesthesia for 5 to 7 minutes. Maintenance of anesthesia Maintenance of anesthesia may be accomplished by intermittent injections of the 1% solution or, more easily, by continuous intravenous drip of a 0.2% solution. Intermittent injections of about 20 to 40 mg (2 to 4 mL of a 1% solution) may be given as required, usually every 4 to 7 minutes. For continuous drip, the average rate of administration is about 3 mL of a 0.2% solution/minute (1 drop/second). The rate of flow must be individualized for each patient. For longer surgical procedures, gradual reduction in the rate of administration is recommended (see discussion of prolonged administration in WARNINGS ). Other parenteral agents, usually narcotic analgesics, are ordinarily employed along with Methohexital Sodium for Injection during longer procedures. Pediatric Patients Methohexital Sodium for Injection is administered intramuscularly in a 5% concentration and administered rectally as a 1% solution. Induction of anesthesia For the induction of anesthesia by the intramuscular route of administration, the usual dose ranges from 6.6 to 10 mg/kg of the 5% concentration. For rectal administration, the usual dose for induction is 25 mg/kg using the 1% solution. Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit. Compatibility Information Solutions of Methohexital Sodium for Injection should not be mixed in the same syringe or administered simultaneously during intravenous infusion through the same needle with acid solutions, such as atropine sulfate, metocurine iodide, and succinylcholine chloride. Alteration of pH may cause free barbituric acid to be precipitated. Solubility of the soluble sodium salts of barbiturates, including Methohexital Sodium, is maintained only at a relatively high (basic) pH. Because of numerous requests from anesthesiologists for information regarding the chemical compatibility of these mixtures, the following chart contains information obtained from compatibility studies in which a 1% solution of Methohexital Sodium for Injection was mixed with therapeutic amounts of agents whose solutions have a low (acid) pH. Active Ingredient Potency per mL Volume Used Immediate 15 min Physical Change 30 min 1 h Methohexital Sodium for Injection 10 mg 10 mL CONTROL Atropine Sulfate 1/150 gr 1 mL None Haze Atropine Sulfate 1/100 gr 1 mL None Ppt Ppt Succinylcholine chloride 0.5 mg 4 mL None None Haze Succinylcholine chloride 1 mg 4 mL None None Haze Metocurine Iodide 0.5 mg 4 mL None None Ppt Metocurine Iodide 1 mg 4 mL None None Ppt Scopolamine hydrobromide 1/120 gr 1mL None None None Haze Tubocurarine chloride 3 mg 4 mL None Haze
Warnings & Precautions
WARNINGS As with all potent anesthetic agents and adjuncts, Methohexital Sodium for Injection should be used only in hospital or ambulatory care settings that provide for continuous monitoring of respiratory (e.g. pulse oximetry) and cardiac function. Immediate availability of 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 assured. For deeply sedated patients, a designated individual other than the practitioner performing the procedure should be present to continuously monitor the patient. Maintenance of a patent airway and adequacy of ventilation must be ensured during induction and maintenance of anesthesia with methohexital sodium solution. Laryngospasm is common during induction with all barbiturates and may be due to a combination of secretions and accentuated reflexes following induction or may result from painful stimuli during light anesthesia. Apnea/hypoventilation may be noted during induction, which may impair pulmonary ventilation; the duration of apnea may be longer than that produced by other barbiturate anesthetics. Cardiorespiratory arrest may occur. This prescribing information describes intravenous use of methohexital sodium in adults. It also discusses intramuscular and rectal administration in pediatric patients older than one month. Although the published literature discusses intravenous administration in pediatric patients, the safety and effectiveness of intravenous administration of methohexital sodium in pediatric patients have not been established in well-controlled, prospective studies. (See PRECAUTIONS/Pediatric Use .) Seizures may be elicited in subjects with a previous history of convulsive activity, especially partial seizure disorders. Because the liver is involved in demethylation and oxidation of methohexital and because barbiturates may enhance preexisting circulatory depression, severe hepatic dysfunction, severe cardiovascular instability, or a shock-like condition may be reason for selecting another induction agent. Prolonged administration may result in cumulative effects, including extended somnolence, protracted unconsciousness, and respiratory and cardiovascular depression. Respiratory depression in the presence of an impaired airway may lead to hypoxia, cardiac arrest, and death. The CNS-depressant effect of Methohexital Sodium for Injection may be additive with that of other CNS depressants, including ethyl alcohol and propylene glycol. DANGER OF INTRA-ARTERIAL INJECTION—Unintended intra-arterial injection of barbiturate solutions may be followed by the production of platelet aggregates and thrombosis, starting in arterioles distal to the site of injection. The resulting necrosis may lead to gangrene, which may require amputation. The first sign in conscious patients may be a complaint of fiery burning that roughly follows the distribution path of the injected artery; if noted, the injection should be stopped immediately and the situation reevaluated. Transient blanching may or may not be noted very early; blotchy cyanosis and dark discoloration may then be the first sign in anesthetized patients. There is no established treatment other than prevention. The following should be considered prior to injection: 1. The extent of injury is related to concentration. Concentrations of 1% methohexital will usually suffice; higher concentrations should ordinarily be avoided. 2. Check the infusion to ensure that the catheter is in the lumen of a vein before injection. Injection through a running intravenous infusion may enhance the possibility of detecting arterial placement; however, it should be remembered that the characteristic bright-red color of arterial blood is often altered by contact with drugs. The possibility of aberrant arteries should always be considered. Post injury arterial injection of vasodilators and/or arterial infusion of parenteral fluids are generally regarded to be of no value in altering outcome. Animal experiments and published individual case reports concerned with a variety of arteriolar irritants, including barbiturates, suggest that 1 or more of the following may be of benefit in reducing the area of necrosis: 1. Arterial injection of heparin at the site of injury, followed by systemic anticoagulation. 2. Sympathetic blockade (or brachial plexus blockade in the arm). 3. Intra-arterial glucocorticoid injection at the site of injury, followed by systemic steroids. 4. A case report (nonbarbiturate injury) suggests that intra-arterial urokinase may promote fibrinolysis, even if administered late in treatment. If extravasation is noted during injection of methohexital, the injection should be discontinued until the situation is remedied. Local irritation may result from extravasation; subcutaneous swelling may also serve as a sign of arterial or periarterial placement of the catheter. Pediatric Neurotoxicity Published animal studies demonstrate that the administration of anesthetic and sedation drugs that block NMDA receptors and/or potentiate GABA activity increase neuronal apoptosis in the developing brain and result in long-term cognitive deficits when used for longer than 3 hours. The clinical significance of these findings is not clear. However, based on the available data, the window of vulnerability to these changes is believed to correlate with exposures in the third trimester of gestation through the first several months of life, but may extend out to approximately three years of age in humans. (See PRECAUTIONS/ Pregnancy, Pediatric Use, and ANIMAL TOXICOLOGY AND/OR PHARMACOLOGY. ) Some published studies in children suggest that similar deficits may occur after repeated or prolonged exposures to anesthetic agents early in life and may result in adverse cognitive or behavioral effects. These studies have substantial limitations, and it is not clear if the observed effects are due to the anesthetic/sedation drug administration or other factors such as the surgery or underlying illness. Anesthetic and sedation drugs are a necessary part of the care of children needing surgery, other procedures, or tests that cannot be delayed, and no specific medications have been shown to be safer than any other. Decisions regarding the timing of any elective procedures requiring anesthesia should take into consideration the benefits of the procedure weighed against the potential risks.
Boxed Warning
Methohexital Sodium for Injection should be used only in hospital or ambulatory care settings that provide for continuous monitoring of respiratory (e.g. pulse oximetry) and cardiac function. Immediate availability of 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 assured. For deeply sedated patients, a designated individual other than the practitioner performing the procedure should be present to continuously monitor the patient. (See WARNINGS.)
Contraindications
Methohexital Sodium for Injection is contraindicated in patients in whom general anesthesia is contraindicated, in those with latent or manifest porphyria, or in patients with a known hypersensitivity to barbiturates.
Adverse Reactions
Side effects associated with Methohexital Sodium for Injection are extensions of pharmacologic effects and include: Cardiovascular Circulatory depression, thrombophlebitis, hypotension, tachycardia, peripheral vascular collapse, and convulsions in association with cardiorespiratory arrest. Respiratory Respiratory depression (including apnea), cardiorespiratory arrest, laryngospasm, bronchospasm, hiccups, and dyspnea Neurologic Skeletal muscle hyperactivity (twitching), injury to nerves adjacent to injection site, and seizures Psychiatric Emergence delirium, restlessness, and anxiety may occur, especially in the presence of postoperative pain Gastrointestinal Nausea, emesis, abdominal pain, and liver function tests abnormal Allergic Erythema, pruritus, urticaria, and cases of anaphylaxis have been reported rarely Other Other adverse reactions include pain at injection site, salivation, headache, and rhinitis For medical advice about adverse reactions contact your medical professional. To report SUSPECTED ADVERSE REACTIONS, contact Onesource at 1-888-217-8103 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.
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