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Mechanism of Action

Amphetamines belong to the group of medicines called central nervous system (CNS) stimulants. They are used to treat attention-deficit hyperactivity disorder (ADHD). Amphetamines increase attention and decrease restlessness in patients who are overactive, unable to concentrate for very long or are easily distracted, and have unstable emotions. These medicines are used as part of a total treatment program that also includes social, educational, and psychological treatment.

Therapeutic Use

Activates Serotonin (5-HT1A) receptors in brain.

Absorption

Well absorbed after oral administration but low bioavailability . Peak blood levels reached in 60-90 min. after administration. Metabolism: Liver; oxidation.

Metabolism

Liver; oxidation

Half-life

Average 2.5 hour

Average Daily Dose (adult)

20-30 mg

Adverse Effects

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.

Check with your doctor as soon as possible if any of the following side effects occur:

• More common
  • Irregular heartbeat 
  
   Rare
  • Chest pain;  fever, unusually high;  skin rash or hives;  uncontrolled movements of head, neck, arms, and legs 

• With long-term use or high doses
  • Difficulty in breathing;  dizziness or feeling faint;  increased blood pressure;  mood or mental changes;  pounding heartbeat;  unusual tiredness or weakness 
  
  Other side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. However, check with your doctor if any of the following side effects continue or are bothersome:

• More common
  • False sense of well-being;  irritability;  nervousness;  restlessness;  trouble in sleeping 
  
  After these stimulant effects have worn off, drowsiness, trembling, unusual tiredness or weakness, or mental depression may occur.

• Less common
  • Blurred vision;  changes in sexual desire or decreased sexual ability;  constipation;  diarrhea;  dizziness or lightheadedness ;  dryness of mouth or unpleasant taste;  fast or pounding heartbeat;  headache ;  increased sweating;  loss of appetite;  nausea or vomiting;  stomach cramps or pain;  weight loss 

Drug Interaction

Monoamine oxidase inhibitors (increases blood pressure). Increases blood level of haloperidol if co-administered.

Contraindication

Although certain medicines should not be used together at all, in many cases two different medicines may be used together even if an interaction might occur. In these cases, changes in dose or other precautions may be necessary. When you are taking amphetamines, it is especially important that your health care professional know if you are taking any of the following:

• Amantadine (e.g., Symmetrel) or
• Caffeine (e.g., NoDoz) or
• Chlophedianol (e.g., Ulone) or
• Methylphenidate (e.g., Ritalin) or
• Nabilone (e.g., Cesamet) or
• Pemoline (e.g., Cylert)—Use of these medicines may increase the CNS stimulation effects of amphetamines and cause unwanted effects such as nervousness, irritability, trouble in sleeping, and possibly convulsions (seizures)
• Appetite suppressants (diet pills) or
• Medicine for asthma or other breathing problems or
• Medicine for colds, sinus problems, or hay fever or other allergies (including nose drops or sprays)—Use of these medicines may increase the CNS stimulation effects of amphetamines and cause unwanted effects such as nervousness, irritability, trouble in sleeping, or convulsions (seizures), as well as unwanted effects on the heart and blood vessels
• Beta-adrenergic blocking agents (acebutolol [e.g., Sectral], atenolol [e.g., Tenormin], betaxolol [e.g., Kerlone], carteolol [e.g., Cartrol], labetalol [e.g., Normodyne], metoprolol [e.g., Lopressor], nadolol [e.g., Corgard], oxprenolol [e.g., Trasicor], penbutolol [e.g., Levatol], pindolol [e.g., Visken], propranolol [e.g., Inderal], sotalol [e.g., Sotacor], timolol [e.g., Blocadren])—Use of amphetamines with beta-blocking agents may increase the chance of high blood pressure and heart problems
• Digitalis glycosides (heart medicine)—Amphetamines may cause additive effects, resulting in irregular heartbeat
• Meperidine—Use of meperidine by persons taking amphetamines is not recommended because the chance of serious side effects (such as high fever, convulsions, or coma) may be increased
• Monoamine oxidase (MAO) inhibitor activity—(isocarboxazid [e.g., Marplan], phenelzine [e.g., Nardil], procarbazine [e.g., Matulane], selegiline [e.g., Eldepryl], tranylcypromine [e.g., Parnate])—Taking amphetamines while you are taking or within 2 weeks of taking monoamine oxidase (MAO) inhibitors may increase the chance of serious side effects such as sudden and severe high blood pressure or fever
• Thyroid hormones—The effects of either these medicines or amphetamines may be increased; unwanted effects may occur in patients with heart or blood vessel disease
• Tricyclic antidepressants (amitriptyline [e.g., Elavil], amoxapine [e.g., Asendin], clomipramine [e.g., Anafranil], desipramine [e.g., Pertofrane], doxepin [e.g., Sinequan], imipramine [e.g., Tofranil], nortriptyline [e.g., Aventyl], protriptyline [e.g., Vivactil], trimipramine [e.g., Surmontil])—Although tricyclic antidepressants may be used with amphetamines to help make them work better, using the two medicines together may increase the chance of fast or irregular heartbeat, severe high blood pressure, or high fever

For patients taking the short-acting form of this medicine:

• Take the last dose for each day at least 6 hours before bedtime to help prevent trouble in sleeping.

For patients taking the long-acting form of this medicine:

• Take the daily dose about 10 to 14 hours before bedtime to help prevent trouble in sleeping.
• These capsules or tablets should be swallowed whole. Do not break, crush, or chew them before swallowing.

Amphetamines may be taken with or without food or on a full or empty stomach. However, if your doctor tells you to take the medicine a certain way, take it exactly as directed.

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

Mechanism of Action

Although it s mechanism of action is not known Pemoline is believed to be an amphetamine-like mild CNS stimulant. However, it has less peripheral sympathetic nervous system stimulating effects, therefore it produces fewer effects on the heart and blood pressure than does methylphenidate or amphetamine.

Therapeutic Use

Treatment of Attention Deficit Hyperactivity disorders (ADHD).

Absorption

Well absorbed in the GI tract. Peak effect 2-4 hours.

Metabolism

Metabolized in the liver and 50% is excreted unchanged by the kidneys.

Half-life

12 Hours.

Average Daily Dose (adult)

50 to 75 mg.

Adverse Effects

Insomnia (disturbed sleep), dyskenisia (impairment of normal movement) of the face and extremities, depression, headache, nystagmus (involuntary rapid eye movement), dizziness and irritability. There have been reports of liver dysfunction ranging from mild hepatitis to complete liver failure.

Drug Interaction

The interaction of Cylert (Pemoline) with other drugs has not been studied in humans. Contraindication: Use with caution in impaired renal or liver function. Should not be used in patients with Tourette s Syndrome.

Contraindication

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

Mechanism of Action

Methylphenidate is an amphetamine-like CNS stimulant that is believed to act by releasing dopamine and norepinephrine from CNS neurons.

Therapeutic Use

Treatment of attention deficit disorders (ADD).

Absorption

Well absorbed.

Metabolism

Metabolized in the liver and the metabolites are eliminated in the urine.

Half-life

2 1/2 Hours.

Average Daily Dose (adult)

20-30 mg daily. In children, Ritalin should be initiated in small doses, with gradual weekly increments. Daily dosage above 60 mg is not recommended.

Adverse Effects

Nervousness, insomnia (disturbed sleep), loss of appetite, nausea, palpitations, dizziness and increase in blood pressure. Can trigger cardiac arrhythmias.

Drug Interaction

Use cautiously with drugs that increase blood pressure and MAO inhibitors. It may inhibit the metabolism of other drugs metabolized by the P-450 enzymes such as; coumadin, phenytoin and antidepressants. This would require a reduction in dose of the latter drugs.

Contraindication

Contraindicated for marked anxiety, tension, agitation, glaucoma (eye disease) and Tourette s syndrome. Safety in children under 6 years of age has not been established. Use with caution in patients with hypertension or seizure history.

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