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Barbiturates

Barbiturates

Definition

Barbiturates are medicines that act on the central nervous system. They cause drowsiness and can control seizures.

Purpose

Barbiturates are in the group of medicines known as central nervous system depressants (CNS). Also known as sedative-hypnotic drugs, barbiturates make people very relaxed, calm, and sleepy. These drugs are sometimes used to help patients relax before surgery. Some may also be used to control seizures (convulsions). Although barbiturates have been used to treat nervousness and sleep problems, they have generally been replaced by other medicines for these purposes.

Although barbiturates have largely been replaced by other classes of drugs, some are still used in anesthesiology to induce anesthsia and lower the dose of inhaled anesthetics required for surgical procedures.

Pentobarbital (Nembutal) has been used in neurosurgery to reduce blood flow to the brain. This reduces swelling and pressure in the brain, making brain surgery safer.

Secobarbital (Seconal) may be given by mouth or as a suppository to induce sleepiness and relaxation before local anesthesia or the insertion of a tube into the nose or throat.

These medicines may become habit-forming and should not be used to relieve everyday anxiety and tension or to treat sleeplessness over long periods.


Description

Barbiturates are available only with a physician's prescription and are sold in capsule, tablet, liquid, and injectable forms. Some commonly used barbiturates are phenobarbital (Barbita) and secobarbital (Seconal).


Recommended dosage

Recommended dosage depends on the type of barbiturate and other factors such as the patient's age and the condition for which the medicine is being taken. The patient should consult with the physician who prescribed the drug or the pharmacist who filled the prescription for the correct dosage.

The following recommendations do not apply when barbiturates are given as a single oral or intravenous dose prior to or during surgery. The recommendations should be considered if the drugs are used for treatment of anxiety or seizures.

Patients should always take barbiturates exactly as directed. Larger or more frequent doses should never be taken, and the drug should not be taken for longer than directed. If the medicine does not seem to be working, even after taking it for several weeks, the patient should not increase the dosage. Instead, the physician who prescribed the medicine should be consulted.

People taking barbiturates should not stop taking them suddenly without first checking with the physician who prescribed the medication. It may be necessary to taper the dose gradually to reduce the chance of withdrawal symptoms. If it is necessary to stop taking the drug, the patient should check with the physician for instructions on how to stop.


Precautions

People taking barbiturates must see a physician regularly. The physician will check to make sure the medicine is working as it should and will note unwanted side effects.

Because barbiturates work on the central nervous system, they may add to the effects of alcohol and other drugs that slow the central nervous system, such as antihistamines, cold medicine, allergy medicine, sleep aids, medicine for seizures, tranquilizers, some pain relievers, and muscle relaxants . They may also add to the effects of anesthetics, including those used for dental procedures. The combined effects of barbiturates and alcohol or other CNS depressants (drugs that slow the central nervous system) can be very dangerous, leading to unconsciousness or even death. Anyone taking barbiturates should not drink alcohol and should check with his or her physician before taking any medicines classified as CNS depressants.

Taking an overdose of barbiturates or combining barbiturates with alcohol or other central nervous system depressants can cause unconsciousness and even death. Anyone who shows signs of an overdose or a reaction to combining barbiturates with alcohol or other drugs should get emergency medical help immediately. Signs include:

  • severe drowsiness
  • breathing problems
  • slurred speech
  • staggering
  • slow heartbeat
  • severe confusion
  • severe weakness

Barbiturates may change the results of certain medical tests. Before having medical tests, anyone taking this medicine should alert the health care professional in charge.

People may feel drowsy, dizzy, lightheaded, or less alert when using these drugs. These effects may even occur the morning after taking a barbiturate at bedtime. Because of these possible effects, anyone who takes these drugs should not drive, use machines or do anything else that might be dangerous until they have found out how the drugs affect him or her.

Barbiturates may cause physical or mental dependence when taken over long periods. Anyone who shows these signs of dependence should check with his or her physician right away:

  • the need to take larger and larger doses of the medicine to get the same effect
  • a strong desire to keep taking the medicine
  • withdrawal symptoms, such as anxiety, nausea or vomiting, convulsions, trembling, or sleep problems, when the medicine is stopped

Children may be especially sensitive to barbiturates. This sensitivity may increase the chance of side effects such as unusual excitement.

Older people may also be more sensitive than others to the effects of this medicine. In older people, barbiturates may be more likely to cause confusion, depression, and unusual excitement. These effects are also more likely in people who are very ill.


Special conditions

People with certain medical conditions or who are taking certain other medicines can have problems if they take barbiturates. Before taking these drugs, be sure to let the physician know about any of these conditions:

allergies. Anyone who has had unusual reactions to barbiturates in the past should let his or her physician know before taking the drugs again. The physician should also be told about any allergies to foods, dyes, preservatives, or other substances.

pregnancy. Taking barbiturates during pregnancy increases the chance of birth defects and may cause other problems such as prolonged labor and withdrawal effects in the baby after birth. Pregnant women who must take barbiturates for serious or life-threatening conditions should thoroughly discuss with their physicians the benefits and risks of taking this medicine.

breastfeeding. Barbiturates pass into breast milk and may cause problems such as drowsiness, breathing problems, or slow heartbeat in nursing babies whose mothers take the medicine. Women who are breast-feeding should check with their physicians before using barbiturates.

other medical conditions. Before using barbiturates, people with any of these medical problems should make sure their physicians are aware of their conditions:


  • alcohol or drug abuse
  • depression
  • hyperactivity (in children)
  • pain
  • kidney disease
  • liver disease
  • diabetes
  • overactive thyroid
  • underactive adrenal gland
  • chronic lung diseases such as asthma or emphysema
  • severe anemia
  • porphyria

use of certain medicines. Taking barbiturates with certain other drugs may affect the way the drugs work or may increase the chance of side effects.


Side effects

The most common side effects are dizziness, lightheadedness, drowsiness, and clumsiness or unsteadiness. These problems usually go away as the body adjusts to the drug and do not require medical treatment unless they persist or interfere with normal activities.

More serious side effects are not common, but may occur. If any of the following side effects occur, the physician who prescribed the medicine should be contacted immediately:

  • fever
  • muscle or joint pain
  • sore throat
  • chest pain or tightness in the chest
  • wheezing
  • skin problems, such as rash, hives, or red, thickened, or scaly skin
  • bleeding sores on the lips
  • sores or painful white spots in the mouth
  • swollen eyelids, face, or lips

In addition, if confusion, depression, or unusual excitement occur after taking barbiturates, a physician should be contacted as soon as possible.

Patients who take barbiturates for a long time or at high doses may notice side effects for some time after they stop taking the drug. These effects usually appear within eight to 16 hours after the patient stops taking the medicine. If these or other troublesome symptoms occur after stopping treatment with barbiturates, a physician should be contacted:

  • dizziness, lightheadedness or faintness
  • anxiety or restlessness
  • hallucinations
  • vision problems
  • nausea and vomiting
  • seizures (convulsions)
  • muscle twitches or trembling hands
  • weakness
  • sleep problems, nightmares, or increased dreaming

Other side effects may occur. Anyone who has unusual symptoms during or after treatment with barbiturates should consult with his or her physician.


Interactions

Birth control pills may not work properly when taken while barbiturates are being taken. To prevent pregnancy, additional methods of birth control are advised while taking barbiturates.

Barbiturates may also interact with other medicines. When this happens, the effects of one or both of the drugs may change or the risk of side effects may be greater. Anyone who takes barbiturates should let the physician know all other medicines he or she is taking. Among the drugs that may interact with barbiturates are:

  • other central nervous system (CNS) depressants such as medicine for allergies, colds, hay fever, and asthma; sedatives; tranquilizers; prescription pain medicine; muscle relaxants; medicine for seizures; sleep aids; barbiturates; and anesthetics
  • blood thinners
  • adrenocorticoids (cortisone-like medicines)
  • antiseizure medicines such as valproic acid (Depakote and Depakene), and carbamazepine (Tegretol)

The list above does not include every drug that may interact with barbiturates. A physician or pharmacist should be consulted before combining barbiturates with any other prescription or nonprescription (over-thecounter) medicine.


Resources

books

AHFS: Drug Information. Washington, DC: American Society of Healthsystems Pharmaceuticals, 2003.

Brody, T. M., J. Larner, K. P. Minneman, and H. C. Neu. Human Pharmacology: Molecular to Clinical, 2nd edition. St. Louis: Mosby Year-Book, 1998.

Karch, A. M. Lippincott's Nursing Drug Guide. Springhouse, Penn: Lippincott Williams & Wilkins, 2003.

Reynolds, J. E. F., ed. Martindale The Extra Pharmacopoeia 31st Ed. London: The Pharmaceutical Press, 1993.

periodicals

Miller, Norman S. "Sedative-Hypnotics: Pharmacology and Use." Journal of Family Practice 29 (December 1989): 665.


Nancy Ross-Flanigan

Sam Uretsky

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"Barbiturates." Gale Encyclopedia of Surgery: A Guide for Patients and Caregivers. . Encyclopedia.com. 21 Aug. 2017 <http://www.encyclopedia.com>.

"Barbiturates." Gale Encyclopedia of Surgery: A Guide for Patients and Caregivers. . Encyclopedia.com. (August 21, 2017). http://www.encyclopedia.com/medicine/encyclopedias-almanacs-transcripts-and-maps/barbiturates-0

"Barbiturates." Gale Encyclopedia of Surgery: A Guide for Patients and Caregivers. . Retrieved August 21, 2017 from Encyclopedia.com: http://www.encyclopedia.com/medicine/encyclopedias-almanacs-transcripts-and-maps/barbiturates-0

Barbiturates

Barbiturates

Definition

Barbiturates are medicines that act on the central nervous system and cause drowsiness and can control seizures.

Purpose

Barbiturates are in the group of medicines known as central nervous system depressants (CNS). Also known as sedative-hypnotic drugs, barbiturates make people very relaxed, calm, and sleepy. These drugs are sometimes used to help patients relax before surgery. Some may also be used to control seizures (convulsions). Although barbiturates have been used to treat nervousness and sleep problems, they have generally been replaced by other medicines for these purposes.

These medicines may become habit forming and should not be used to relieve everyday anxiety and tension or to treat sleeplessness over long periods.

Description

Barbiturates are available only with a physician's prescription and are sold in capsule, tablet, liquid, and injectable forms. Some commonly used barbiturates are phenobarbital (Barbita) and secobarbital (Seconal).

Recommended dosage

Recommended dosage depends on the type of barbiturate and other factors such as the patient's age and the condition for which the medicine is being taken. Check with the physician who prescribed the drug or the pharmacist who filled the prescription for the correct dosage.

Always take barbiturates exactly as directed. Never take larger or more frequent doses, and do not take the drug for longer than directed. If the medicine does not seem to be working, even after taking it for several weeks, do not increase the dosage. Instead, check with the physician who prescribed the medicine.

Do not stop taking this medicine suddenly without first checking with the physician who prescribed it. It may be necessary to taper down gradually to reduce the chance of withdrawal symptoms. If it is necessary to stop taking the drug, check with the physician for instructions on how to stop.

Precautions

See a physician regularly while taking barbiturates. The physician will check to make sure the medicine is working as it should and will note unwanted side effects.

Because barbiturates work on the central nervous system, they may add to the effects of alcohol and other drugs that slow the central nervous system, such as antihistamines, cold medicine, allergy medicine, sleep aids, medicine for seizures, tranquilizers, some pain relievers, and muscle relaxants. They may also add to the effects of anesthetics, including those used for dental procedures. The combined effects of barbiturates and alcohol or other CNS depressants (drugs that slow the central nervous system) can be very dangerous, leading to unconsciousness or even death. Anyone taking barbiturates should not drink alcohol and should check with his or her physician before taking any medicines classified as CNS depressants.

KEY TERMS

Adrenal glands Two glands located next to the kidneys. The adrenal glands produce the hormones epinephrine and norepinephrine and the corticosteroid (cortisone-like) hormones.

Anemia A lack of hemoglobinthe compound in blood that carries oxygen from the lungs throughout the body and brings waste carbon dioxide from the cells to the lungs, where it is released.

Central nervous system The brain and spinal cord.

Hallucination A false or distorted perception of objects, sounds, or events that seems real. Hallucinations usually result from drugs or mental disorders.

Hypnotic A medicine that causes sleep.

Porphyria A disorder in which porphyrins build up in the blood and urine.

Porphyrin A type of pigment found in living things, such as chlorophyll, that makes plants green and hemoglobin which makes blood red.

Sedative Medicine that has a calming effect and may be used to treat nervousness or restlessness.

Seizure A sudden attack, spasm, or convulsion.

Withdrawal symptoms A group of physical or mental symptoms that may occur when a person suddenly stops using a drug to which he or she has become dependent.

Taking an overdose of barbiturates or combining barbiturates with alcohol or other central nervous system depressants can cause unconsciousness and even death. Anyone who shows signs of an overdose or a reaction to combining barbiturates with alcohol or other drugs should get emergency medical help immediately. Signs include:

  • severe drowsiness
  • breathing problems
  • slurred speech
  • staggering
  • slow heartbeat
  • severe confusion
  • severe weakness

Barbiturates may change the results of certain medical tests. Before having medical tests, anyone taking this medicine should alert the health care professional in charge.

People may feel drowsy, dizzy, lightheaded, or less alert when using these drugs. These effects may even occur the morning after taking a barbiturate at bedtime. Because of these possible effects, anyone who takes these drugs should not drive, use machines or do anything else that might be dangerous until they have found out how the drugs affect them.

Barbiturates may cause physical or mental dependence when taken over long periods. Anyone who shows these signs of dependence should check with his or her physician right away:

  • the need to take larger and larger doses of the medicine to get the same effect
  • a strong desire to keep taking the medicine
  • withdrawal symptoms, such as anxiety, nausea or vomiting, convulsions, trembling, or sleep problems, when the medicine is stopped

Children may be especially sensitive to barbiturates. This may increase the chance of side effects such as unusual excitement.

Older people may also be more sensitive that others to the effects of this medicine. In older people, barbiturates may be more likely to cause confusion, depression, and unusual excitement. These effects are also more likely in people who are very ill.

Special conditions

People with certain medical conditions or who are taking certain other medicines can have problems if they take barbiturates. Before taking these drugs, be sure to let the physician know about any of these conditions:

ALLERGIES. Anyone who has had unusual reactions to barbiturates in the past should let his or her physician know before taking the drugs again. The physician should also be told about any allergies to foods, dyes, preservatives, or other substances.

PREGNANCY. Taking barbiturates during pregnancy increases the chance of birth defects and may cause other problems such as prolonged labor and withdrawal effects in the baby after birth. Pregnant women who must take barbiturates for serious or life-threatening conditions should thoroughly discuss with their physicians the benefits and risks of taking this medicine.

BREASTFEEDING. Barbiturates pass into breast milk and may cause problems such as drowsiness, breathing problems, or slow heartbeat in nursing babies whose mothers take the medicine. Women who are breastfeeding should check with their physicians before using barbiturates.

OTHER MEDICAL CONDITIONS. Before using barbiturates, people with any of these medical problems should make sure their physicians are aware of their conditions:

  • alcohol or drug abuse
  • depression
  • hyperactivity (in children)
  • pain
  • kidney disease
  • liver disease
  • diabetes
  • overactive thyroid
  • underactive adrenal gland
  • chronic lung diseases such as asthma or emphysema
  • severe anemia
  • porphyria

USE OF CERTAIN MEDICINES. Taking barbiturates with certain other drugs may affect the way the drugs work or may increase the chance of side effects.

Side effects

The most common side effects are dizziness, light-headedness, drowsiness, and clumsiness or unsteadiness. These problems usually go away as the body adjusts to the drug and do not require medical treatment unless they persist or interfere with normal activities.

More serious side effects are not common, but may occur. If any of the following side effects occur, check with the physician who prescribed the medicine immediately:

  • fever
  • muscle or joint pain
  • sore throat
  • chest pain or tightness in the chest
  • wheezing
  • skin problems, such as rash, hives, or red, thickened, or scaly skin
  • bleeding sores on the lips
  • sores or painful white spots in the mouth
  • swollen eyelids, face, or lips

In addition, check with a physician as soon as possible if confusion, depression, or unusual excitement occur after taking barbiturates.

Patients who take barbiturates for a long time or at high doses may notice side effects for some time after they stop taking the drug. These effects usually appear within 8-16 hours after the patient stops taking the medicine. Check with a physician if these or other troublesome symptoms occur after stopping treatment with barbiturates:

  • dizziness, lightheadedness or faintness
  • anxiety or restlessness
  • hallucinations
  • vision problems
  • nausea and vomiting
  • seizures (convulsions)
  • muscle twitches or trembling hands
  • weakness
  • sleep problems, nightmares, or increased dreaming

Other side effects may occur. Anyone who has unusual symptoms during or after treatment with barbiturates should get in touch with his or her physician.

Interactions

Birth control pills may not work properly when taken while barbiturates are being taken. To prevent pregnancy, use additional or additional methods of birth control while taking barbiturates.

Barbiturates may also interact with other medicines. When this happens, the effects of one or both of the drugs may change or the risk of side effects may be greater. Anyone who takes barbiturates should let the physician know all other medicines he or she is taking. Among the drugs that may interact with barbiturates are:

  • Other central nervous system (CNS) depressants such as medicine for allergies, colds, hay fever, and asthma; sedatives; tranquilizers; prescription pain medicine; muscle relaxants; medicine for seizures; sleep aids; barbiturates; and anesthetics.
  • Blood thinners.
  • Adrenocorticoids (cortisone-like medicines).
  • Antiseizure medicines such as valproic acid (Depakote and Depakene), and carbamazepine (Tegretol).

The list above does not include every drug that may interact with barbiturates. Be sure to check with a physician or pharmacist before combining barbiturates with any other prescription or nonprescription (over-the-counter) medicine.

Resources

PERIODICALS

Miller, Norman S. "Sedative-Hypnotics: Pharmacology and Use." Journal of Family Practice 29 (December 1989): 665.

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"Barbiturates." Gale Encyclopedia of Medicine, 3rd ed.. . Retrieved August 21, 2017 from Encyclopedia.com: http://www.encyclopedia.com/medicine/encyclopedias-almanacs-transcripts-and-maps/barbiturates

Barbiturates

Barbiturates

Definition

Barbiturates are a large class of drugs, consisting of many different brand name products with generic equivalents, that are used primarily for mild sedation, general anesthesia, and as a treatment for some types of epilepsy. One barbiturate, butalbital, exists only as a component of several headache preparations. The most common members of the barbiturate family are phenobarbital (Luminal)), pentobarbital (Nembutal), amobarbital (Amytal), secobarbital (Seconal), thiopental (Pentothal), methohexital (Brevital), and butalbital (component of Fiorinal and Fioricet). They exist in numerous formulations and strengths.

Purpose

Barbiturates are used to sedate patients prior to surgery as well as to produce general anesthesia, to treat some forms of epilepsy, and to treat simple and migraine headache. These drugs are highly addictive and are often abused as recreational drugs. Although still commercially available, barbiturates such as secobarbital, pentobarbital, and amobarbital are no longer routinely recommended for the treatment of insomnia because of their ability to cause dependence, tolerance, and withdrawal. These drugs also have significant side effects when taken in large doses and can cause respiratory failure and death.

Description

The therapeutic effects of barbiturates as a class of drugs are all related to their ability to sedate and, at high enough doses and with certain preparations, to induce sleep. All barbiturates also have anticonvulsant properties although phenobarbital is the preferred barbiturate to treat epilepsy because it can produce anticonvulsant effects at levels low enough not to cause extreme sedation or sleep.

Recommended dosage

The typical dose of phenobarbital for use as an anticonvulsant in adults is 50100 mg given two to three times per day. When a series of serious seizures known as status epilepticus occurs, adults are usually first given 300800 mg intravenously (directly into the vein) followed by 120240 mg every 20 minutes up to a maximum of 10002000 mg. For sedation, adults are given 30120 mg per day divided into two or three doses. For sedation before surgery, 100200 mg are given in an intramuscular injection (a shot) about one hour before the surgery.

The typical dose for an anticonvulsant effect in newborns is 2 mg to 4 mg of phenobarbital per kilogram of body weight per day. In infants, this dose is 5 mg to 8 mg per kilogram of body weight per day. In children one to five years of age, the dose is 6 mg to 8 mg per kilogram of body weight per day. In children aged five to 12 years, the dose is 4 mg to 6 mg per kilogram of body weight per day. All of these doses are given in one to two divided doses per day.

In newborns with status epilepticus, phenobarbital 15 mg to 20 mg per kilogram of body weight is given in a single or divided dose. Infants and children are given 10 mg to 20 mg per kilogram of body weight in a single or divided dose. They may also receive 5 mg per kilogram of body weight every 15 to 30 minutes up to a maximum of 40 mg per kilogram body weight. For anesthesia before surgery, 1 mg to 3 mg per kilogram of body weight is given about one hour before the surgery.

The typical dose of butalbital, as a component of headache preparations such as Fiorinal or Fioricet, is 50-100 mg administered every four to six hours as needed.

Precautions

Children who are hyperactive should not receive phenobarbital or other barbiturates. Some children paradoxically become stimulated and hyperactive after receiving barbiturates.

The use of barbiturates in the elderly (over age 65) should be watched closely. Elderly patients must be carefully monitored for confusion, agitation, delirium , and excitement if they take barbiturates. Barbiturates should be avoided in elderly patients who are receiving drugs for other mental disorders such as schizophrenia or depression.

Women should not use barbiturates during pregnancy unless they are necessary to control seizures. In these cases, they should take the minimum amount to control the seizures. Barbiturate use by pregnant women has been associated with increased risk of fetal damage and bleeding during childbirth. Women who are breast-feeding should not take barbiturates because these drugs enter the breast milk and may cause serious side effects in the nursing baby.

Long-term barbiturate use should be avoided unless there is a strong medical need, as in the case of epilepsy, because of the potential for addiction , dependence, tolerance, and withdrawal. People should not drive, operate heavy equipment, or perform other hazardous activities requiring mental alertness while taking barbiturates.

Side effects

The most common side effect of barbiturate use is drowsiness. Less common side effects include agitation, confusion, breathing difficulties, abnormally low blood pressure, nausea, vomiting, constipation, lower body temperature, decreased heart rate, movement difficulty, nightmares, anxiety, nervousness, mental depression, and dizziness. Rare but reported side effects include fever, headache, anemia, allergic reactions, and liver damage.

Interactions

Patients should always tell their doctor and dentist when they are taking barbiturates. Barbiturates should generally not be taken with other drugs used to treat mental disorders.

There are a number of drugs that barbiturates should not be combined with because the barbiturates may increase the metabolism of these drugs and thus, reduce the amount of these drugs available to be of benefit. These drugs include oral corticosteroids such as predisolone, methylprednisolone, prednisone, or dexamethasone, estrogen and oral contraceptives, blood-thinning medications such as warfarin (Coumadin), the antibiotic doxycycline (Vibramycin), and anticonvulsants such as phenytoin (Dilantin).

Barbiturates should not be combined with alcohol because the combination produces additive depressant effects in the central nervous system.

Barbiturates may lower the amount of absorption of the vitamins D and K.

Resources

BOOKS

Consumer Reports Staff. Consumer Reports Complete Drug Reference. 2002 ed. Denver: Micromedex Thomson Healthcare, 2001.

Ellsworth, Allan J., and others. Mosby's Medical Drug Reference, 20012002. St. Louis: Mosby, 2001.

Hardman, Joel G. and Lee E. Limbird, eds. Goodman & Gilman's The Pharmacological Basis of Therapeutics. 10th ed. New York: McGraw-Hill, 2001.

Mosby's GenRx Staff. Mosby's GenRx. 9th ed. St. Louis: Mosby, 1999.

Venes, Donald, and Clayton L. Thomas. Taber's Cyclopedic Medical Dictionary. 19th ed. Philadelphia: F. A. Davis, 2001.

Mark Mitchell, M.D.

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"Barbiturates." Gale Encyclopedia of Mental Disorders. . Encyclopedia.com. 21 Aug. 2017 <http://www.encyclopedia.com>.

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"Barbiturates." Gale Encyclopedia of Mental Disorders. . Retrieved August 21, 2017 from Encyclopedia.com: http://www.encyclopedia.com/psychology/encyclopedias-almanacs-transcripts-and-maps/barbiturates

Barbiturates

Barbiturates

Barbiturate is the name given to a drug made from barbituric acid, a combination of urea (a compound found in urine and other body fluids) and malonic acid. Barbiturates work by depressing (slowing down) the activity of nerves, muscles, heart tissue, and the brain. They are part of a class of drugs called the sedative-hypnotics, which can alter a person's mood and are generally prescribed for relaxation and sleep. Barbiturates act on the central nervous system and can produce effects ranging from mild sedation to coma (prolonged unconsciousness), depending upon the dosage given. If used improperly, barbiturates can even cause death. Barbiturates are not used for medical purposes as often as they once were. In many cases they have been replaced by the more effective and safer sedative-hypnotics called benzodiazepines (such as Valium and Librium). These tranquilizers are also addictive, however, and in some cases have become subject to abuse.

Barbiturate Hazards

Barbiturates can impair a person's ability to think rationally and to reason. They are is highly physically addictive (habit-forming). A person abusing barbiturates may exhibit symptoms similar to drunkenness, including loss of inhibition, loud or violent behavior, lack of muscle coordination, and depression. Withdrawal from barbiturate addiction can produce severe side effects. The addicted person may shake, be unable to sleep, feel anxious, and sometimes experience convulsions and delirium (a state of extreme mental excitement). Death can occur if a person stops taking barbiturates suddenly instead of gradually. If combined with alcohol, barbiturates can be particularly deadly.

Developing Barbiturates

The first barbituric acid was prepared in 1864 by Adolf von Baeyer. His student, organic chemist Emil Fischer, worked with physiologist Joseph von Mering to introduce the first barbiturate derivative (something copied or adapted from existing material) for use as a sedative (a substance that reduces feelings of stress or excitement) in 1903. Fischer and von Mering produced 5.5 diethylbarbituric acid, a hypnotic (a substance that produces a sleep-like state) and sedative known by the trade names Barbital, Veronal, and Dorminal. By 1912 a phenylethyl derivative was developed and commercially introduced as Phenobarbital and Luminal. Since then, more than 2,500 barbiturates have been created. About 50 of these synthetic derivatives have been marketed.

Barbiturate Use

Doctors often prescribe barbiturates to help people relax during times of great stress or to help patients suffering from anxiety disorders. Because of possible side effects, barbiturates are usually given on a short-term basis, and the patient is closely monitored. Short-acting barbiturates such as thiopental are injected as general anesthesia before surgery. Pentobarbital and secobarbital are the barbiturates used most often to relax patients before surgery. A long-acting barbiturate, phenobarbital, is prescribed with other medicines to prevent epileptic seizures. Secobarbital was used as a medication to treat anxiety before tranquilizers were developed; it is still used for the short-term treatment of insomnia (the inability to sleep).

Barbiturates are not effective as painkillers until the dosage produces unconsciousness (they can even heighten a patient's sense of pain up to that point). Barbiturate-induced (caused) sleep is characterized by slow brain wave activity. It prevents a person from entering the deepest and most restful stage of sleep, known as REM (rapid-eye-movement). People are sternly warned not to drink alcohol while taking barbiturates, because mixing these two substances can prove fatal. Alcohol itself is a depressant (something that lowers the rate of body functions). Combining alcohol with a barbiturate can depress the nervous system to such an extent that it ceases functioning altogether.

[See also Tranquilizers ]

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Barbiturates

Barbiturates

The term barbiturate is a name given to a group of drugs that function by depressing the activity of the central nervous system. Their principal effect is to reduce stress and bring the user a feeling of calm. Often, this sedation can help someone fall asleep. This is why barbiturates are often termed sleeping pills.

Barbiturates were first made over a century ago by the Bayer laboratories in Germany. They take their name from barbital, which was the first barbiturate used medically, in the first decade of the twentieth century.

Aside from their stress relief, the nervous system alteration induced by barbiturates can also be beneficial in the management of diseases like epilepsy .

Of the dozen or so barbiturates still in common medical use, the speed at which the effects are produced and the length of time the effects persist are the distinguishing features between the drugs.

Some barbiturates produce an effect within seconds of being taken. Others require more time to act but last longer. Finally, those used for sedation before an operation can last for hours.

Barbiturates are important to forensic scientists when they are present in blood samples in excess amounts. This can occur accidentally, since the effective dose of many of the drugs is not too different from a dose that causes harm. One well-known victim of an accidental overdose of sleeping pills was the musician Jimi Hendrix. As well, a barbiturate overdose can be deliberately administered. When present in excessive amounts, the drugs can cause debilitating changes. Sedation can even be so severe that coma and death result.

Forensic investigators can be interested in determining if barbiturates were a factor in someone's illness or death. Recollections of the victim's behavior can be helpful in determining the involvement of barbiturates. For example, side effects of an overdose include slurred speech and unsteady balance. Admittedly, these are also symptoms of excessive alcohol consumption.

More definitive evidence of barbiturate use comes from the chemical demonstration of the drug in tissue samples. Because most barbiturates tend to accumulate in fat deposits in the body, to be released at varying rates depending on the specific drug, a barbiturate may be detectable in tissue specimens recovered even some time after death.

see also Amphetamines; Analytical instrumentation; Autopsy; Death, cause of; Narcotic; Psychotropic drugs.

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Barbiturates

BARBITURATES

Barbiturates refer to a class of general central nervous system depressants that are derived from barbituric acid, a chemical discovered in 1863 by the Nobel Prize winner in chemistry (1905) Adolf von Baeyer (1835-1917). Barbituric acid itself is devoid of central depressant activity; however, German scientists Emil Hermann Fischer and Joseph von Mering made some modifications to its structure and synthesized barbital, which was found to possess depressant properties. Scientists had been looking for a drug to treat anxiety and nervousness but without the dependence-producing effects of Opiate drugs such as Opium, Codeine, and Morphine. Other drugs such as bromide salts, Chloral Hydrate, and paraldehyde were useful sedatives, but they all had problems such as toxicity or they left such a bad taste in patients' mouths that they preferred not to take them. Fischer and von Mering noted that barbital produced sleep in both humans and animals. It was introduced into chemical medicine in 1903 and was soon in widespread use.

By 1913, the second barbiturate, Phenobarbi-Tal, was introduced into medical practice. Since that time, more than 2,000 similar chemicals have been synthesized but only about 50 of these have been marketed. Although the barbiturates were quickly used to treat a number of disorders effectively, their side effects were becoming apparent. The chief problem, an overdose, can result in respiratory depression, which can be fatal. By the mid-1950s, more than 70 percent of admissions to a poison-control center in Copenhagen, Denmark, involved barbiturates. Additionally, it became apparent that the barbiturates were subject to abuse, which could lead to dependence, and that a serious withdrawal syndrome could ensue when the drugs were abruptly discontinued. In the 1960s, the introduction of a safer class of hypnotic drugs, the Benzodiazepines reduced the need for barbiturates.

Barbiturates are dispensed in distinctly colored capsules making them very easy to identify by the lay public. In fact, users within the drug culture often refer to the various barbiturates by names associated with their physical appearance. Examples of these names include blue birds, blue clouds, yellow jackets, red devils, sleepers, pink ladies, and Christmas trees. The term goofball is often used to describe barbiturates in general. All barbiturates are chemically similar to barbital, the structure of which is shown in Figure 1.

All barbiturates are general central nervous system depressants. This means that sedation, sleep, and even anesthesia will develop as the dose is increased. Some barbiturates also are useful in reducing seizure activity and so have been used to treat some forms of epilepsy. The various barbiturates differ primarily in their onset and duration of action, ability to enter the brain, and the rate at which they are metabolized. These differences are achieved principally by adding or subtracting atoms to the two branches on position #5 in Figure 1. The barbiturates are classified on the basis of their duration of action, which ranges from ultrashort-acting to long-acting. The onset of action of the ultrashort-acting barbiturates occurs in seconds and lasts a few minutes. The short-acting compounds take effect within a few minutes and can last four to eight hours, while the intermediate- and long-acting barbiturates can take almost an hour to take effect but last six to twelve hours. Table 1 lists the common barbiturates, their trade names, typical route of administration, and plasma half-life. The plasma half-life is a measure of how long the drug remains in the blood, but not how long the effects last, although it does provide a general indication of when to expect the effects to wane (a half-life of five hours means that one-half of the drug will be removed from the system in five hours; one-half of the remaining drug will be removed during the next five hours, etc.).

EFFECTS ON THE BODY AND THERAPEUTIC USES

Barbiturates affect all excitable tissues in the body. However, Neurons are more sensitive to their effects than other tissues. The depth of central nervous system depression ranges from mild sedation to coma and depends on many factors including which drug is used, its dose, the route of administration, and the level of excitability present just before the barbiturate was taken. The most common uses for the barbiturates are still to promote sleep and to induce anesthesia. Barbiturate-induced sleep resembles normal sleep in many ways, but there are a few important differences. Barbiturates reduce the amount of time spent in rapid eye movement or REM sleepa very important phase of sleep. Prolonged use of barbiturates causes restlessness during the late stages of sleep. Since the barbiturates remain in our bodies for some time after we awaken, there can be residual drowsiness that can impair judgment and distort moods for some time after the obvious sedative effects have disappeared. Curiously, some people are actually excited by barbiturates, and the individual may even appear inebriated. This paradoxical reaction often occurs in the elderly and is more common after taking phenobarbital.

The general use of barbiturates as hypnotics (Sleeping Pills) has decreased significantly, since they have been replaced by the safer benzodiazepines. Phenobarbital and butabarbital are still available, however, as sedatives in a number of combination medications used to treat a variety of inflammatory disorders. These two drugs also are used occasionally to antagonize the unwanted overstimulation produced by ephedrine, Amphetamine, and theophylline.

Since epilepsy is a condition of abnormally increased neuronal excitation, any of the barbiturates can be used to treat convulsions when given in anesthetic doses; however, phenobarbital has a selective anticonvulsant effect that makes it particularly useful in treating grand mal seizures. This selective effect is shared with mephobarbital and metharbital. Thus, phenobarbital is often used in hospital emergency rooms to treat convulsions such as those that develop during tetanus, eclampsia, status epilepticus, cerebral hemorrhage, and poisoning by convulsant drugs. The benzodiazepines are, however, gradually replacing the barbiturates in this setting as well.

It is not completely understood how barbiturates work but, in general, they act to enhance the activity of GABA on GABA-sensitive neurons by acting at the same receptor on which GABA exerts its effects (see Figure 2). GABA is a Neurotransmit-Ter that normally acts to reduce the electrical activity of the brain; its action is like a brake. Thus, barbiturates enhance the braking effects of GABA to promote sedation. There is an area in the brain called the reticular activating system, which is responsible for maintaining wakefulness. Since this area has many interconnecting or polysynaptic neurons, it is the first to succumb to the barbiturates, and that is why an individual becomes tired and falls asleep after taking a barbiturate.

PHARMACOKINETICS AND DISTRIBUTION

The ultrashort-acting barbiturates differ from the other members of this class mainly by the means by which they are inactivated. Methohexital and its relatives are very soluble in lipids (i.e., fatty tissue). The brain is composed of a great deal of lipid; when the ultrashort-acting barbiturates are given intravenously, they proceed directly to the brain to produce anesthesia and unconsciousness. After only a few minutes, however, these drugs are redistributed to the fats in the rest of the body so their concentration is reduced in the brain. Thus, recovery from IV barbiturate anesthesia can be very fast. For this reason, drugs such as methohexital and thiopental are used primarily as intravenous anesthetic agents and not as sedatives.

The other longer-acting barbiturates must be metabolized by the liver into inactive compounds before the effects wane. Since these metabolites are more soluble in water, they are excreted through the kidneys and into the urine. As is the case with most drugs, metabolism and excretion is much quicker in young adults than in the elderly and infants. Plasma half-lives are also increased in pregnant women because the blood volume is expanded due to the development of the placenta and fetus.

TOLERANCE, DEPENDENCE, AND ABUSE

Repeated administration of any number of drugs results in eventual compensatory changes in the body. These changes are usually in the opposite direction of those initially produced by the drug such that more and more drug is needed to achieve the initial desired effect. This process is called Tolerance. There are two basic mechanisms for tolerance development: tissue tolerance and metabolic or pharmacokinetic tolerance. Tissue tolerance refers to the changes that occur on the tissue or cell that is affected by the drug. Metabolic tolerance refers to the increase in the processes that metabolize or break down the drug. This process generally occurs in the liver. Barbiturates are subject to both types of tolerance development.

Tolerance does not develop equally in all effects produced by barbiturates. Barbiturate-induced respiratory depression is one example. Barbiturates reduce the drive to breathe and the processes necessary for maintaining a normal breathing rhythm. Thus, while tolerance is quickly developing to the desired sedative effects, the toxic doses change to a lesser extent. As a result, when the dose is increased to achieve the desired effects (e.g., sleep), the margin of safety actually decreases as the dose comes closer to producing toxicity. A complete cessation of breathing is often the cause of death in barbiturate poisoning (Rall, 1990).

If tolerance develops and the amount of drug taken continues to increase, then Physical Dependence can develop. This means that if the drug is suddenly stopped, the tissues' compensatory effects become unbalanced and withdrawal signs appear. In the case of barbiturates, mild signs of withdrawal include apprehension, insomnia, excitability, mild tremors, and loss of appetite. If the dose was very high, more severe signs of withdrawal can occur, such as weakness, vomiting, decrease in blood pressure regulatory mechanisms (so that pressure drops when a person rises from a lying position, called orthostatic hypotension), increased pulse and respiratory rates, and grand mal (epileptic) seizures or convulsions. Delirium with fever, disorientation, and Hallucinations may also occur. Unlike withdrawal from the opioids, withdrawal from central nervous system depressants such as barbiturates can be life threatening. The proper treatment of a barbiturate-dependent individual always includes a slow reduction in the dose to avoid the dangers of rapid detoxification.

Few, if any, illegal laboratories manufacture barbiturates. Diversion of licit production from pharmaceutical companies is the primary source for the illicit market. Almost all barbiturate users take it by mouth. Some try to dissolve the capsules and inject the liquid under their skin (called skin-popping) but the toxic effects of the alcohols used to dissolve the drug and the strong alkaline nature of the solutions can cause lesions of the skin. Intravenous administration is a rare practice among barbiturate abusers.

Many barbiturate users become dependent to some degree during the course of treatment for insomnia. This type of problem is called iatrogenic, because it is initiated by a physician. In some instances the problem will be limited to continued use at gradually increasing doses at night, to prevent insomnia that is in turn due to withdrawal. However, some individuals who are susceptible to the euphoric effects of barbiturates may develop a pattern of taking increasingly larger doses to become intoxicated, rather than for the intended therapeutic effects (for example, to promote sleepiness). To achieve these aims, the person may obtain prescriptions from a number of physicians and take them to a number of pharmacistsor secure their needs from illicit distributors (dealers). If the supply is sufficient, the barbiturate abuser can rapidly increase the dose within a matter of weeks. The upper daily limit is about 1,500 to 3,000 milligrams; however, many can titrate their daily dose to the 800 to 1,000 milligram range such that the degree of impairment is not obvious to others. The pattern of abuse resembles that of ethyl (drinking) Alcohol, in that it can be daily or during binges that last from a day to many weeks at a time. This pattern of using barbiturates for intoxification is more typically seen in those who, from the beginning, obtain barbiturates from illicit sources rather than those who began by seeking help for insomnia.

Barbiturates are sometimes used along with other drugs. Often, the barbiturate is used to potentiate, or boost, the effects of another drug upon which a person is physically dependent. Alcohol and Heroin are commonly taken together in this way. Since barbiturates are "downers," they also are used to counteract the unwanted overstimulation associated with stimulant-induced intoxication. It is not uncommon for stimulant abusers (on Cocaine or amphetamines) to use barbiturates to combat the continued "high" and the associated motor disturbances associated with heavy and continued cocaine use. Also, barbiturates are used to ward off the early signs of withdrawal from alcohol.

Treatment for barbiturate dependence is often conducted under carefully controlled conditions, because of the potential for severe developments, such as seizures. Under all conditions, a program of supervised withdrawal is needed. Many years ago, pentobarbital was used for this purpose and the dose was gradually decreased until no drug was given. More recently, phenobarbital or the benzodiazepinesChlordiazepoxide and diazepamhave been used for their greater margin of safety. The reason that the benzodiazepines sometimes work is because the general central nervous system depressantsbarbiturates, alcohol, and benzodiazepinesdevelop cross-dependence to one another. Thus a patient's barbiturate or alcohol withdrawal signs are reduced or even eliminated by diazepam.

(See also: Addiction: Concepts and Definitions ; Withdrawal )

BIBLIOGRAPHY

CsÁky, T. Z. (1979). Cutting's handbook of pharmacology: The actions and uses of drugs, 6th ed. New York: Appleton-Century Crofts.

Henningfield, J. E., & Ator, N. A. (1986). Barbiturates: Sleeping potion or intoxicant? In The encyclopedia of psychoactive drugs. New York: Chelsea House.

Mendelson, J. H., & Mello, N. K. (1992). Medical diagnosis and treatment of alcoholism. New York: McGraw-Hill.

Rall, T. W. (1990). Hypnotics and sedatives: Ethanol. In A. G. Gilman et al. (Eds.), Goodman and Gilman's the pharmacological basis of therapeutics, 8th ed. New York: Pergamon.

Winger, G., Hoffman, F.G., & Woods, J. H. (1992). A handbook of drugs and alcohol abuse: the biomedical aspects, 3rd ed. New York: Oxford University Press.

Scott E. Lukas

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