ANESTHETICS, GENERAL (Systemic)

Some commonly used brand names are:

In the U.S.—

  • Amidate 2
  • Brevital 6
  • Diprivan 9
  • Ethrane 1
  • Fluothane 3
  • Forane 4
  • Ketalar 5
  • Penthrane 7
  • Pentothal 10

In Canada—

  • Brietal 6
  • Diprivan 9
  • Ethrane 1
  • Fluothane 3
  • Forane 4
  • Ketalar 5
  • Pentothal 10

Other commonly used names are: Methohexitone and Thiopentone

Note:

For quick reference, the following general anesthetics are numbered to match the corresponding brand names.

This information applies to the following medicines:
1. Enflurane (EN-floo-rane)
2. Etomidate (e-TOM-i-date)
3. Halothane (HA-loe-thane)
4. Isoflurane (eye-soe-FLURE-ane)
5. Ketamine (KEET-a-meen)
6. Methohexital (meth-oh-HEX-i-tal)
7. Methoxyflurane (meth-ox-ee-FLOO-rane)
8. Nitrous Oxide (NYE-trus)§
9. Propofol (PROE-po-fole)
10. Thiopental (thye-oh-PEN-tal)
† Not commercially available in Canada
‡ Generic name product may be available in the U.S.
§ Generic name product may be available in Canada

Category

  • Anesthetic, general

Description

General anesthetics (an-ess-THET-iks) normally are used to produce loss of consciousness before and during surgery. However, for obstetrics (labor and delivery) or certain minor procedures, an anesthetic may be given in small amounts to relieve anxiety or pain without causing unconsciousness. Some of the anesthetics may be used for certain procedures in a medical doctor's or dentist's office.

Propofol is used sometimes in patients in intensive care units in hospitals to cause unconsciousness. This may allow the patients to withstand the stress of being in the intensive care unit and help the patients cooperate when a machine must be used to assist with breathing. However, propofol should not be used in children in intensive care units.

Thiopental also is sometimes used to control convulsions (seizures) caused by certain medicines or seizure disorders. Thiopental may be used to reduce pressure on the brain in certain conditions. Thiopental also is used to help treat some mental disorders. Thiopental may also be used for other conditions as determined by your doctor.

General anesthetics are usually given by inhalation or by injection into a vein. However, certain anesthetics may be given rectally to help produce sleep before surgery or certain other procedures. Although most general anesthetics can be used by themselves in producing loss of consciousness, some are often used together. This allows for more effective anesthesia in certain patients.

General anesthetics are given only by or under the immediate supervision of a medical doctor or dentist trained to use them . If you will be receiving a general anesthetic during surgery, your doctor or anesthesiologist will give you the medicine and closely follow your progress.

General anesthetics are available in the following dosage forms:

  • Inhalation
  • Enflurane
    • Inhalation (U.S. and Canada)
  • Halothane
    • Inhalation (U.S. and Canada)
  • Isoflurane
    • Inhalation (U.S. and Canada)
  • Methoxyflurane
    • Inhalation (U.S.)
  • Nitrous oxide
    • Inhalation (U.S. and Canada)
  • Parenteral
  • Etomidate
    • Injection (U.S.)
  • Ketamine
    • Injection (U.S. and Canada)
  • Methohexital
    • Injection (U.S. and Canada)
  • Propofol
    • Injectable emulsion (U.S. and Canada)
  • Thiopental
    • Injection (U.S. and Canada)
  • Rectal
  • Methohexital
    • Rectal solution (U.S. and Canada)
  • Thiopental
    • Rectal solution (U.S. and Canada)
    • Rectal suspension (U.S.)

Before Receiving This Medicine

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For general anesthetics, the following should be considered:

Allergies—Tell your doctor if you have ever had any unusual or allergic reaction to barbiturates or general anesthetics. Also tell your health care professional if you are allergic to any other substances, such as foods, preservatives, or dyes.

Pregnancy—

  • For barbiturate anesthetics (methohexital and thiopental) —Methohexital has not been studied in pregnant women. However, it has not been shown to cause birth defects or other problems in animal studies. Studies on effects in pregnancy with thiopental have not been done in either humans or animals. However, use of barbiturate anesthetics during pregnancy may affect the nervous system in the fetus.
  • For etomidate —Etomidate has not been studied in pregnant women. Although studies in animals have not shown etomidate to cause birth defects, it has been shown to cause other unwanted effects in the animal fetus when given in doses usually many times the human dose.
  • For inhalation anesthetics (enflurane, halothane, isoflurane, methoxyflurane, and nitrous oxide) —Enflurane, halothane, isoflurane, methoxyflurane, and nitrous oxide have not been studied in pregnant women. However, studies in animals have shown that inhalation anesthetics may cause birth defects or other harm to the fetus.
    When used as an anesthetic for an abortion, enflurane, halothane, or isoflurane may cause increased bleeding.
    When used in small doses to relieve pain during labor and delivery, halothane may slow delivery and increase bleeding in the mother after the baby is born. These effects do not occur with small doses of enflurane, isoflurane, or methoxyflurane. However, they may occur with large doses of these anesthetics.
  • For ketamine —Ketamine has not been studied in pregnant women. Studies in animals have not shown that ketamine causes birth defects, but it has caused damage to certain tissues when given in large amounts for a long period of time.
  • For propofol —Propofol has not been studied in pregnant women. Although studies in animals have not shown propofol to cause birth defects, it has been shown to cause deaths in nursing mothers and their offspring when given in doses usually many times the human dose.

General anesthetics may cause unwanted effects, such as drowsiness, in the newborn baby if large amounts are given to the mother during labor and delivery.

Breast-feeding—Barbiturate anesthetics (methohexital and thiopental), halothane, and propofol pass into the breast milk. However, general anesthetics have not been reported to cause problems in nursing babies.

Children—Anesthetics given by inhalation and ketamine have been tested in children and have not been shown to cause different side effects or problems in children than they do in adults.

Although there is no specific information comparing use of etomidate in children with use in other age groups, this medicine is not expected to cause different side effects or problems in children than it does in adults.

Although there is no specific information comparing use of thiopental administered intravenously in children with use in other age groups, using thiopental intravenously in children is not expected to cause different side effects or problems in children than it does in adults.

Propofol has been tested in children to produce loss of consciousness before and during surgery. It has not been shown to cause different side effects or problems in children than it does in adults. Propofol should not be used in critically ill children to help the children withstand the stress of being in the intensive care unit. Some critically ill children have developed problems with their body chemistries after receiving propofol, and a few children have died as a result of this. It is not known if propofol or the severe illnesses of the children caused this problem.

Older adults—Elderly people are especially sensitive to the effects of the barbiturate anesthetics (methohexital and thiopental), etomidate, propofol, and anesthetics given by inhalation. This may increase the chance of side effects.

Ketamine has not been shown to cause different side effects or problems in older people than it does in younger adults.

Other medicines—Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are receiving general anesthetics, it is especially important that your health care professional know if you are taking any other medicine , including any of the following:

  • “Street” drugs, such as amphetamines (“uppers”), barbiturates (“downers”), cocaine, marijuana, phencyclidine (PCP or “angel dust”), and heroin or other narcotics—Serious, possibly fatal, side effects may occur if your medical doctor or dentist gives you an anesthetic without knowing that you have taken another medicine

Other medical problems—The presence of other medical problems may affect the use of general anesthetics. Make sure you tell your doctor if you have any other medical problems, especially:

  • Malignant hyperthermia, during or shortly after receiving an anesthetic (history of, or family history of). Signs of malignant hyperthermia include very high fever, fast and irregular heartbeat, muscle spasms or tightness, and breathing problems—This side effect may occur again

Proper Use of This Medicine

Dosing—The dose of a general anesthetic will be different for different patients. Your doctor will decide on the right amount for you. The dose will depend on:

  • Your age;
  • Your general physical condition;
  • The kind of surgery or other procedure you are having; and
  • Other medicines you are taking or will receive before and during surgery.

Precautions After Receiving This Medicine

For patients going home within 24 hours after receiving a general anesthetic:

  • General anesthetics may cause you to feel drowsy, tired, or weak for up to a few days after they have been given. They may also cause problems with coordination and your ability to think. Therefore, for at least 24 hours (or longer if necessary) after receiving a general anesthetic, do not drive, use machines, or do anything else that could be dangerous if you are not alert .
  • Unless otherwise directed by your medical doctor or dentist, do not drink alcoholic beverages or take other CNS depressants (medicines that slow down the nervous system, possibly causing drowsiness) for about 24 hours after you have received a general anesthetic . To do so may add to the effects of the anesthetic. Some examples of CNS depressants are antihistamines or medicine for hay fever, other allergies, or colds; other sedatives, tranquilizers, or sleeping medicine; prescription pain medicine or narcotics; other barbiturates; medicine for seizures; and muscle relaxants.

Side Effects of This Medicine

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention. While you are receiving a general anesthetic, your doctor will closely follow its effects. However, some effects may not be noticed until later.

Check with your doctor as soon as possible if any of the following side effects occur within 2 weeks after you have received an anesthetic:

Rare

Abdominal or stomach pain; back or leg pain; black or bloody vomit; fever; headache (severe); increase or decrease in amount of urine; loss of appetite; nausea (severe); pale skin; unusual tiredness or weakness; weakness of wrist and fingers; weight loss (unusual); yellow eyes or skin

Other side effects may occur that usually do not need medical attention. The following side effects should go away as the effects of the anesthetic wear off. However, check with your doctor if any of the following side effects continue or are bothersome:

More common

Shivering or trembling

Less common

Blurred or double vision or other vision problems; dizziness, lightheadedness, or feeling faint; drowsiness; headache; mood or mental changes; nausea (mild) or vomiting; nightmares or unusual dreams

Other side effects not listed above may also occur in some patients. If you notice any other effects, check with your doctor.

Additional Information

Once a medicine has been approved for marketing for a certain use, experience may show that it is also useful for other medical problems. Although these uses are not included in product labeling, ketamine and thiopental are used in certain patients with the following medical conditions:

  • Anesthesia in children (ketamine)
  • Hypoxia, cerebral (shortage of oxygen supplied to the brain) (thiopental)
  • Ischemia, cerebral (shortage of blood supplied to the brain) (thiopental)
  • Sedation in children (ketamine)

Other than the above information, there is no additional information relating to proper use, precautions, or side effects for these uses.

Revised: 12/04/2001

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