Stimulant drugs are drugs that excite the central nervous system.
There are several drugs used as stimulants. Although in large part they share the same properties, their use is determined by how well they are absorbed from the gastrointestinal tract. These drugs are related to the body's normal stimulant hormones epinephrine and norepinephrine.
- Injectable stimulants are used to stimulate the heart or breathing. Epinephrine (adrenalin) is the most common.
- Topical stimulants are used as decongestants, since they cause blood vessels to contract. They are also used to stop superficial bleeding by contracting the capillaries and for relief of conjunctivitis. They may be applied to the skin, inhaled, or applied in the form of drops as nose drops or eye drops.
- Oral stimulants, including the two drugs in this class (methylphenidate [Ritalin] and amphetamine) are used to treat extreme daytime sleepiness also known as narcolepsy and for their calming effect in attention-deficit hyperactivity disorder (ADHD).
- Caffeine, a stimulant found in foods and drinks, is used to promote wakefulness and alertness.
The orally active stimulants were formerly used as an aid to dieting but were of little value for this purpose. They may still be used in the most extreme cases of obesity but are no longer routinely prescribed for this purpose. Some were widely used as decongestants for colds and allergies. They are subject to abuse, and amphetamines and methylphenidate are controlled substances in the United States.
Pemoline (Cylert) is also a member of this class but is rarely used because of its potential for causing severe liver problems. This drug should be reserved for treatment of children whose ADHD cannot be controlled with either first or second line drug therapy and whose condition is so severe that the potential benefits justify the risk.
Stimulant drugs, in addition to their proper medicinal use, are subject to abuse. The drugs commonly abused are methylphenidate, amphetamine, and methamphetamine. A related drug, 3,4-methylenedioxymethamphetamine (better known as ecstasy or MDMA), is also widely abused. Unlike methylphenidate and amphetamine, MDMA has no legitimate therapeutic use.
Cocaine is chemically different from the traditional stimulants but provides similar effects. It is used medicinally as a local anesthetic but is not available for self-administration. Cocaine has become a major drug abuse problem.
The most common use of methylphenidate and amphetamine in children is for control of attention-deficit/hyperactivity disorder. This is a condition marked by general restlessness, excessive activity, and inability to concentrate on a topic. Children who have this problem are unable to concentrate on schoolwork and fall behind their classmates. They are frequently disruptive. For this condition, the stimulants have a reverse activity and have a calming, rather than a stimulating effect.
When used to treat young children, there is some evidence that stimulant drugs reduce the rate of growth. This may be made up for by a growth spurt when the drugs are discontinued.
Stimulant drugs increase blood pressure.
The side effects for stimulant drugs are different when they are used as stimulants and when they are used for their calming effect in ADHD. The effects listed below are those seen when amphetamines and/or methylphenidate are used to treat attention-deficit hyperactivity disorder:
- reduction in rate of growth
- exacerbation of related problems such as Tourette's disorder
- appetite suppression
There are many additional side effects seen when amphetamines or methylphenidate are used or abused for their stimulant properties, but these effects are not normally seen when the stimulants are used for a proper diagnosis of ADHD and dosed appropriately.
Some of the adverse effects that may result from stimulant abuse are increased wakefulness, increased physical activity, decreased appetite, increased respiration, high fever, euphoria, irritability, insomnia, confusion, tremors, convulsions, anxiety, paranoia, and aggressiveness. The high fever and convulsions may be fatal. Long term abuse of stimulants may result in permanent brain damage that causes involuntary, Parkinson-like movements.
Methamphetamine causes increased heart rate and blood pressure and can cause irreversible damage to blood vessels in the brain, producing strokes. Other effects of methamphetamine include respiratory problems, irregular heartbeat, and extreme anorexia. Its use can result in cardiovascular collapse and death.
The reports of growth suppression associated with amphetamines and methylphenidate are not definitive but appear to be valid. This growth suppression is balanced by a growth spurt when the drugs are discontinued. For this reason, stimulants should only be administered during school hours and discontinued during summer and holiday periods.
Stimulant drugs have no interactions with drugs that are normally prescribed for children.
Because of the potential for abuse, methylphenidate and amphetamines must be kept out of reach of children, particularly visitors and older siblings of a child being treated for ADHD.
Because of the risk of growth suppression, stimulant drugs should only be administered during school periods. They should not be used to calm an active child for the convenience of parents or babysitters.
Children who fail a trial of one stimulant may respond to another drug in the same class. A child who does poorly on methylphenidate may respond to amphetamines and vice versa.
Approximately 15 to 30 percent of children with ADHD have underlying Tourette's disorder, a condition marked by vocal and motor tics. Starting treatment with methylphenidate or amphetamines may unmask the condition, and the tics will become apparent. This is not an effect of the drug, but rather a consideration of the underlying problem.
There is some dispute over the lowest age at which stimulant therapy may be appropriately started, but it seems agreed that these drugs should not be used to treat children under the age of three years.
Sometimes, drugs which are properly prescribed for ADHD are diverted and used by other children as recreational drugs. If a child who has been well stabilized on stimulants for ADHD begins to get worse, consider the possibility that the drugs are being sold to others, rather than being used therapeutically. Stimulant drugs should be administered by a parent, guardian, school nurse, or other responsible person. This will both guard against diversion and assure that children are not forgetting to take their medication.
The effects of cocaine are generally similar to those of amphetamines.
Signs of possible stimulant abuse, regarding amphetamines and cocaine, include dilated pupils, frequent lip licking and dry mouth, excessive activity, and lack of sleep. The drug abuser becomes talkative, but the discussion lacks continuity or coherence, and the subject changes frequently.
See also Caffeine.
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Samuel Uretsky, PharmD
Attention deficit hyperactivity disorder (ADHD)—A condition in which a person (usually a child) has an unusually high activity level and a short attention span. People with the disorder may act impulsively and may have learning and behavioral problems.
Tic—A brief and intermittent involuntary movement or sound.
Tourette syndrome—A neurological disorder characterized by multiple involuntary movements and uncontrollable vocalizations called tics that come and go over years, usually beginning in childhood and becoming chronic. Sometimes the tics include inappropriate or obscene language (coprolalia).