Dextroamphetamine Sulfate

Class: Amphetamines
VA Class: CN801
CAS Number: 51-63-8
Brands: Adderall, Dexedrine, DextroStat

• Abuse Potential


• 
  

  Amphetamines have a high potential for abuse.^{101 102 103}

  
  


• 
  

  Administration of amphetamines for prolonged periods of time may lead to drug dependence.^{101 102 103 b}

  
  


• 
  

  Particular attention should be paid to the possibility of individuals obtaining amphetamines for nontherapeutic use or distribution to others, and the drugs should be prescribed or dispensed sparingly.^{101 102 103}

  
  


• 
  

  The possibility that family members may abuse the patient’s medication should be considered.^e

  
  

• Sudden Death and Serious Cardiovascular Events


• 
  

  Possible sudden death and serious cardiovascular events, particularly in individuals who abuse amphetamines.^{101 102 103 h} (See Sudden Death and Serious Cardiovascular Events under Cautions.)

  
  

Introduction

Dextrorotatory isomer of amphetamine; noncatechol, sympathomimetic amine with CNS-stimulating activity.^{102 b}

Uses for Dextroamphetamine Sulfate

Attention Deficit Hyperactivity Disorder

Used as an adjunct to psychological, educational, social, and other remedial measures in the treatment of attention deficit hyperactivity disorder (ADHD) (hyperkinetic disorder, hyperkinetic syndrome of childhood, minimal brain dysfunction).^{101 102 103 b e}

Can be used for ADHD in pediatric (children, adolescents) as well as adult patients.^{d e}

Almost all studies comparing behavioral therapy versus stimulants alone have shown a much stronger therapeutic effect from stimulants than from behavioral therapy, and stimulants (e.g., amphetamines, methylphenidate) remain the drugs of choice for the management of ADHD.^{d e}

Drug therapy is not indicated in all patients with ADHD, and such therapy should be considered only after a complete evaluation including medical history has been performed.^{b e}

Use should depend on age, adequate diagnosis (based on medical, special psychological, educational, and social resources), and the clinician’s assessment of the severity and duration of symptoms and should not depend solely on one or more behavioral characteristics.^{103 b e}

Not recommended for ADHD symptoms associated with acute stress reactions.^b

Narcolepsy

Used as a stimulant to reduce daytime sleepiness in the management of narcolepsy.^{101 102 b}

Amphetamines remain the mainstay of treatment for narcolepsy based on a long record of clinical experience.^f

Tolerance to the clinical effects may develop with long-term therapy, particularly at high dosages.^f

Exogenous Obesity

Has been used as an adjunct to caloric restriction and behavioral modification in the short-term treatment of exogenous obesity†.^d However, because of the limited efficacy (short-lived) and risk of abuse, such use no longer is included in the FDA-approved labeling^{101 102 103} and is discouraged.^d

The anorexigenic effect appears to be temporary, seldom lasting more than a few weeks, and tolerance may occur.^d

Obesity usually is a chronic disease, and short-term or intermittent therapy with anorexigenic drugs is unlikely to maintain a long-term benefit.

Dextroamphetamine Sulfate Dosage and Administration

Administration

Oral Administration

When used as an anorexigenic, the dose is given 30–60 minutes before meals.^d

Conventional Tablets (Adderall, Dexedrine, and Generic Equivalents)

Administer initial dose on awakening;^{101 102 b} when administered in divided doses, additional doses are given at intervals of 4–6 hours.^{101 102 b} Because of potential for insomnia, avoid administering in the late evening.^{101 102 b}

Extended-release Capsules (Dexedrine Spansules and Generic Equivalents)

Administer initial dose on awakening.^b Because of potential for insomnia, avoid administering in the late evening.¹⁰²

Fixed-combination Extended-release Capsules (Adderall XR)

Administer on awakening.¹⁰³ Because of potential for insomnia, avoid administering in the afternoon.¹⁰³

Administer capsules with or without food;¹⁰³ capsules may be swallowed intact or the entire contents of a capsule(s) may be sprinkled on a small amount of applesauce immediately prior to administration.¹⁰³ Do not subdivide the capsule contents.¹⁰³ Do not chew or crush the pellets contained in the capsules and do not store the sprinkle/food mixture for later use.¹⁰³

Dosage

Dosages of dextroamphetamine sulfate alone and of total amphetamine base equivalence are the same.^{101 103 e f}

Dextroamphetamine sulfate extended-release capsules or fixed-combination extended-release capsules containing various salts of dextroamphetamine and amphetamine can be substituted for their respective conventional short-acting preparations if less-frequent daily dosing is desirable.^{102 103 b}

Dosage of fixed-combination preparations containing various salts of dextroamphetamine and amphetamine is expressed as total amphetamine base equivalence.^{101 103 b}

Adjust dosage according to individual response and tolerance; the smallest dose required to produce the desired response should always be used.^{101 102 103 b}

When possible, therapy should be interrupted occasionally to determine if there is a recurrence of behavioral symptoms sufficient to require continued treatment.^{101 102 103 b}

Pediatric Patients

Attention Deficit Hyperactivity Disorder

Dosage titration usually requires 2–4 weeks.^e

Conventional Tablets (Adderall, Dexedrine, and Generic Equivalents)

Oral

Dosing in pediatric patients may begin with once-daily administration in the early morning, adding a noon dose if the effect does not last throughout the school day.^e Increasing the morning dose may extend its duration.^e A third dose may be added at around 4 p.m. if necessary.^e

Children 3–5 years of age: Initially, 2.5 mg daily; the daily dosage is increased in 2.5-mg increments at weekly intervals until the optimum response is attained.^{101 102 b e}

Children ≥6 years of age: Initially, 5 mg once or twice daily; the daily dosage is increased in 5-mg increments at weekly intervals until the optimum response is attained.^{101 102 b e} Total daily dosage rarely should exceed 40 mg.^{101 102 b e}

Extended-release Capsules (Dexedrine Spansules and Generic Equivalents)

Oral

Total daily dosage of dextroamphetamine sulfate is the same for extended-release capsules (Dexedrine Spansules) and conventional tablets (Dexedrine).¹⁰²

Although extended-release capsules usually are administered once daily,¹⁰² some patients may benefit from dividing the dosage into 2 doses daily.

Children 3–5 years of age: Dosage must be initiated and titrated with conventional tablets in this age group.¹⁰² Can substitute with once-daily dosing only when the total daily dose is divisible by 5 mg.¹⁰²

Children ≥6 years of age: Initially, 5 or 10 mg once daily; the daily dosage is increased in 5-mg increments at weekly intervals until the optimum response is attained.^{102 b} Total daily dosage rarely should exceed 40 mg.^{102 b}

Fixed-combination Extended-release Capsules (Adderall XR)

Oral

Children 6–12 years of age: Initially, 10 mg once daily; daily dosage may be increased in 5- or 10-mg increments at weekly intervals to a maximum dosage of 30 mg daily.^{103 b} Alternatively, initiate with 5 mg once daily when lower initial dosage is appropriate.^{103 b}

Adolescents 13–17 years of age: Initially, 10 mg once daily.¹⁰³ Increase to 20 mg once daily after 1 week if symptoms not adequately controlled.¹⁰³ No evidence that dosages >20 mg daily provide any additional benefit.¹⁰³

When switching from fixed-combination conventional tablets (Adderall) to fixed-combination extended-release capsules (Adderall XR), the total daily dosage may remain the same but may be given once daily.^{103 b}

Narcolepsy

When intolerable adverse effects occur (e.g., insomnia, anorexia), dosage should be reduced.^{101 102 b}

Conventional Tablets (Adderall, Dexedrine, and Generic Equivalents)

Oral

Children 6–12 years of age: Initially, 5 mg daily; daily dosage is increased in 5-mg increments at weekly intervals until the optimum response is attained.^{101 102 b}

Children ≥12 years of age: Initially, 10 mg daily; daily dosage is increased in 10-mg increments at weekly intervals until the optimum response is attained.^{101 102 b}

Maintenance: Usually, 5–60 mg daily, depending on patient age and response, given in divided doses.^{101 102 b}

Extended-release Capsules (Dexedrine Spansules and Generic Equivalents)

Oral

Total daily dosage of dextroamphetamine sulfate is the same for extended-release capsules (Dexedrine Spansules) and conventional tablets (Dexedrine).¹⁰²

Although extended-release capsules usually are administered once daily,¹⁰² some patients may benefit from dividing the dosage into 2 doses daily.

Children 6–12 years of age: Initially, 5 mg once daily; daily dosage is increased in 5-mg increments at weekly intervals until the optimum response is attained.^{102 b}

Children ≥12 years of age: Initially, 10 mg once daily; daily dosage is increased in 10-mg increments at weekly intervals until the optimum response is attained.^{102 b}

Maintenance: Usually, 5–60 mg once daily, depending on patient age and response, given in divided doses.^{102 b}

Adults

Attention Deficit Hyperactivity Disorder

Conventional Tablets (Adderall, Dexedrine, and Generic Equivalents)

Dosage titration usually requires 2–4 weeks.^e

Oral

Initially, 5 mg once or twice daily; the daily dosage is increased in 5- to 10-mg increments at weekly intervals until the optimum response is attained.^{101 102 b e} Total daily dosage rarely should exceed 40 mg.^{101 102 b e}

Extended-release Capsules (Dexedrine Spansules and Generic Equivalents)

Oral

Total daily dosage of dextroamphetamine sulfate is the same for extended-release capsules (Dexedrine Spansules) and conventional tablets (Dexedrine).¹⁰²

Although extended-release capsules usually are administered once daily,¹⁰² some patients may benefit from dividing the dosage into 2 doses daily.

Initially, 5 or 10 mg once daily; the daily dosage is increased in 5-mg increments at weekly intervals until the optimum response is attained.^{102 b e} Total daily dosage rarely should exceed 40 mg.^{102 b e}

Fixed-combination Extended-release Capsules (Adderall XR)

Oral

20 mg once daily as initial therapy or when switching from other drugs.¹⁰³ No evidence that dosages >20 mg daily provide any additional benefit.¹⁰³

When switching from fixed-combination conventional tablets (Adderall) to fixed-combination extended-release capsules (Adderall XR), the total daily dosage may remain the same but may be given once daily.^{103 b}

Narcolepsy

When intolerable adverse effects occur (e.g., insomnia, anorexia), dosage should be reduced.^{101 102 b}

Conventional Tablets (Adderall, Dexedrine, and Generic Equivalents)

Oral

Initially, 10 mg daily; daily dosage is increased in 10-mg increments at weekly intervals until the optimum response is attained.^{101 102 b}

Maintenance: Usually, 5–60 mg daily, depending on response, given in divided doses.^{101 102 b}

Prescribing Limits

Pediatric Patients

Attention Deficit Hyperactivity Disorder

Excessive dosage can cause pediatric patients to become overfocused on the medication or to appear dull or overly restricted. Rarely, psychotic reactions, mood disturbances, or hallucinations can occur.

Conventional Tablets (Adderall, Dexedrine, and Generic Equivalents)

Oral

Dosage rarely should exceed a total daily dosage of 40 mg.^{101 b e} Individual doses rarely should exceed 10 mg each in children <25 kg.^e

Extended-release Capsules (Dexedrine Spansules and Generic Equivalents)

Oral

Dosage rarely should exceed a total daily dosage of 40 mg.^{102 b e} Individual doses rarely should exceed 10 mg each in children <25 kg.^e

Fixed-combination Extended-release Capsules (Adderall XR)

Oral

Children 6–12 years of age: Dosages >30 mg daily have not been studied systematically.^{103 b}

Adolescents 13–17 years of age: Dosages up to 40 mg daily in individuals weighing ≤75 kg or 60 mg daily in those weighing >75 kg have been used in clinical studies; however, no evidence that dosages >20 mg daily provide any additional benefit.¹⁰³

Long-term use (>3 weeks in children or >4 weeks in adolescents) has not been studied systematically.¹⁰³ If used for long-term therapy, periodically reevaluate the usefulness of the drug.¹⁰³

Adults

Attention Deficit Hyperactivity Disorder

Conventional Tablets (Adderall, Dexedrine, and Generic Equivalents)

Oral

Dosages up to 0.9 mg/kg daily but rarely exceeding 40 mg daily.^{101 102 b e} Such higher doses may be more likely in adults than in school-aged children because of increased dosing frequency to cover a longer work day.^e

Tolerance is more likely with relatively high dosages.^e

Extended-release Capsules (Dexedrine Spansules and Generic Equivalents)

Oral

Dosages up to 0.9 mg/kg daily but rarely exceeding 40 mg daily.^{102 b e} Such higher doses may be more likely in adults than in school-aged children because of increased dosing frequency to cover a longer work day.^e

Tolerance is more likely with relatively high dosages.^e

Fixed-combination Extended-release Capsules (Adderall XR)

Oral

Dosages up to 60 mg daily have been evaluated in clinical studies; however, no evidence that dosages >20 mg daily provide any additional benefit.¹⁰³

Long-term use (>4 weeks) has not been studied systematically.¹⁰³ If used for long-term therapy, periodically reevaluate the usefulness of the drug.¹⁰³

Special Populations

Hepatic Impairment

No specific hepatic dosage recommendations.^{101 102 103}

Renal Impairment

No specific renal dosage recommendations.^{101 102 103}

Geriatric Patients

No specific geriatric dosage recommendations.^{101 103}

Cautions for Dextroamphetamine Sulfate

Contraindications

• 
  

  Contraindicated in patients with hypersensitivity or idiosyncrasy to the sympathomimetic amines,^{101 102 103 d} symptomatic cardiovascular disease,^{101 102 103 d} hyperthyroidism,^{101 102 103 d} moderate to severe hypertension,^{101 102 103 d} glaucoma,^{101 102 103 d e} or advanced arteriosclerosis;^{101 102 103 d} within 14 days of MAO inhibitor therapy;^{101 102 103 d e} and in agitated patients.^{101 102 103 d}

  
  


• 
  

  Although amphetamines generally should not be used in patients with a history of drug abuse,^{101 102 103 d e} some experts state that this is not an absolute contraindication, provided the patient can be monitored more carefully than would otherwise be indicated.^e

  
  

Warnings/Precautions

Warnings

Sudden Death and Serious Cardiovascular Events

Sudden unexplained death, stroke, and MI reported in adults with ADHD receiving usual dosages of stimulants; sudden death also reported in children and adolescents with structural cardiac abnormalities or other serious cardiac conditions receiving usual dosages of the drugs.^{102 103 h}

Epidemiologic data suggest a possible association between use of stimulants and sudden unexplained death in healthy children and adolescents.^{i j k} FDA unable to conclude that these data affect evaluation of overall risk and benefit of stimulants used to treat ADHD in children and adolescents.ⁱ FDA is conducting an ongoing safety review of amphetamines and other stimulants to evaluate possible link between use of these agents and sudden death in children.^{i j k} Pediatric patients with ADHD and their parents should avoid discontinuing the child’s use of such stimulants before consulting a clinician.ⁱ

Thoroughly review medical history (including evaluation for family history of sudden death or ventricular arrhythmia) and perform physical examination in all children, adolescents, and adults being considered for stimulant therapy; if initial findings suggest presence of cardiac disease, perform further cardiac evaluation (e.g., ECG, echocardiogram).^{102 103}

In general, avoid use of CNS stimulants in patients with known serious structural cardiac abnormalities, cardiomyopathy, serious heart rhythm abnormalities, CAD, or other serious cardiac conditions.^{102 103} (See Contraindications under Cautions.)

Patients who develop exertional chest pain, unexplained syncope, or other manifestations suggestive of cardiac disease during stimulant therapy should undergo prompt cardiac evaluation.^{102 103}

Effects on BP and Heart Rate

Possible modest increases in average BP (i.e., by about 2–4 mm Hg) and heart rate (i.e., by about 3–6 bpm); larger increases may occur.^{102 103} Modest increases not expected to have short-term sequelae; however, monitor all patients for larger changes in BP and heart rate.^{102 103}

Caution advised in patients with underlying medical conditions that might be affected by increases in BP or heart rate (e.g., hypertension, heart failure, recent MI, ventricular arrhythmia).^{102 103}

Exacerbation or Precipitation of Psychotic Symptoms

May exacerbate symptoms of behavior disturbance and thought disorder in patients with preexisting psychotic disorder.^{102 103}

Psychotic symptoms (e.g., hallucinations, delusional thinking) may occur with usual dosages in children and adolescents without prior history of psychotic illness.^{102 103} If psychotic symptoms occur, consider causal relationship to stimulants, and discontinue therapy as appropriate.^{102 103}

Precipitation of Manic Symptoms

May precipitate mixed or manic episodes in ADHD patients with comorbid bipolar disorder; use with caution in these patients.^{102 103} Prior to initiating therapy, carefully screen patients with ADHD and comorbid depressive symptoms to identify risk for bipolar disorder; screening should include a detailed psychiatric history (e.g., family history of suicide, bipolar disorder, or depression).^{102 103}

Manic symptoms may occur with usual dosages in children and adolescents without prior history of mania.^{102 103} If manic symptoms occur, consider causal relationship to stimulants, and discontinue therapy as appropriate.^{102 103}

Aggression

Aggressive behavior and hostility (frequently observed in children and adolescents with ADHD) reported in patients receiving drug therapy for ADHD.^{102 103} No systematic evidence that stimulants cause these adverse effects; however, monitor patients beginning treatment for ADHD for onset or worsening of aggressive behavior or hostility.^{102 103}

Growth Suppression

Long-term (i.e., >14 months) administration expected to cause at least a temporary suppression of normal weight and/or height patterns in some children and adolescents.^{102 103} Dose-related weight loss reported in adolescents during first 4 weeks of therapy with fixed-combination extended-release capsules.¹⁰³

Manufacturers recommend monitoring growth during treatment; patients not growing or gaining weight as expected may require temporary discontinuance of treatment.^{101 102 103} However, AAP states that studies of stimulants in children found little or no decrease in expected height, with any decrease in growth early in treatment being compensated for later on.

Seizures

Possible lowering of seizure threshold in patients with history of seizures, in those with prior EEG abnormalities but no history of seizures, and, very rarely, in those without history of seizures and with no prior evidence of EEG abnormalities.^{102 103} If seizures occur, discontinue therapy.^{102 103}

Visual Effects

Visual disturbances (difficulty with accommodation, blurred vision) reported with stimulants.^{102 103}

Sensitivity Reactions

Tartrazine Sensitivity

Some commercially available preparations of dextroamphetamine (e.g., DextroStat, Dexedrine tablets) contain the dye tartrazine (FD&C yellow No. 5), which may cause allergic reactions including bronchial asthma in susceptible individuals.^{102 b} Incidence of tartrazine sensitivity is low, but it frequently occurs in patients who are sensitive to aspirin.^b

General Precautions

Least amount of amphetamine feasible should be prescribed or dispensed at one time in order to minimize possible overdosage.^{101 102 103}

Tics

Amphetamines reported to exacerbate motor and phonic tics and Tourette’s syndrome.^{101 102 103} However, a history of tics or their development during therapy is not an absolute contraindication to continued use.^e Several controlled studies have not found stimulants to worsen or precipitate tics or Tourette’s syndrome.^e Nevertheless, evaluate for presence of tics and Tourette’s syndrome in children and their families prior to initiating stimulant therapy.^{102 103 d}

Specific Populations

Pregnancy

Category C.^{101 102 103 f}

Risk of prematurity, low birth weight, and withdrawal symptoms (e.g., dysphoria, lassitude, agitation) in infants born to dependent women.^{101 102 103 f}

Lactation

Distributed into milk.^{101 103 f} Discontinue nursing or the drug.^{101 103}

Pediatric Use

Not recommended for ADHD in children <3 years of age.^{101 102 103 e}

Aggressive behavior, hostility, and psychotic (e.g., hallucinations, delusional thinking) or manic symptoms reported in children and adolescents receiving stimulants for management of ADHD.^{102 103} (See Warnings under Cautions.)

Sudden death reported in children and adolescents with structural cardiac abnormalities or other serious cardiac conditions receiving usual dosages of stimulants.^{102 103} Epidemiologic data also suggest a possible association between use of stimulants and sudden death in healthy children and adolescents.^{i j k} (See Sudden Death and Serious Cardiovascular Events under Cautions.)

Long-term administration expected to cause at least a temporary suppression of normal weight and/or height patterns in some children and adolescents.^{102 103} (See Growth Suppression under Cautions.)

Hepatic Impairment

Possible inhibition of drug elimination, resulting in prolonged exposure.¹⁰³

Renal Impairment

Possible inhibition of drug elimination, resulting in prolonged exposure.¹⁰³

Common Adverse Effects

Most commonly abdominal pain (stomachache), loss of appetite, insomnia.¹⁰³

Also, palpitations,^{101 102 103} tachycardia,^{101 102 103} elevation of BP,^{101 102 103} overstimulation,^{101 102 103} restlessness,^{101 102 103} dizziness,^{101 102 103} euphoria,^{101 102 103} dyskinesia,^{101 102 103} dysphoria,^{101 102 103} tremor,^{101 102 103} headache,^{101 102 103} dryness of mouth,^{101 102 103} taste aberration,^{101 103} diarrhea,^{101 102 103} constipation,^{101 102 103} abdominal bloating,^{101 103} impotence,^{101 102 103} changes in libido.^{101 102 103}

Isolated reports of cardiomyopathy associated with chronic amphetamine use.^{101 102 103}

Anorexia and weight loss may occur as undesirable effects when amphetamines are used for other than the anorectic effect.^{101 102 103}

Interactions for Dextroamphetamine Sulfate

Inhibits MAO.¹⁰³

Amphetamine or metabolites modestly inhibit CYP2D6, 1A2, and 3A4 in vitro.¹⁰³ In vivo effects on metabolism of drugs metabolized by CYP isoenzymes not known.¹⁰³

Specific Drugs and Laboratory Tests

Drug or Test	Interaction	Comments
Acidifying agents, GI (ascorbic acid, glutamic acid hydrochloride, reserpine)	Decreases absorption, serum concentrations, and efficacy of amphetamines101 102 103
Acidifying agents, urinary (ammonium chloride, sodium acid phosphate)	Increases urinary excretion and decreases serum concentrations and efficacy of amphetamines101 102 103
Adrenergic blockers	Potential inhibition of adrenergic blockade101 102 103
Alkalinizing agents, GI (antacids, sodium bicarbonate)	Increases absorption and serum concentrations and potentiates the effects of amphetamines101 102 103	Avoid concomitant use103
Alkalinizing agents, urinary (acetazolamide and some thiazides)	Decreases urinary excretion and increases serum concentrations and potentiates the effects of amphetamines101 102 103
Antidepressants, tricyclic (desipramine, protriptyline)	Enhanced activity of tricyclic antidepressants; desipramine or protriptyline cause striking and sustained increases in the concentration of dextroamphetamine in the brain; cardiovascular effects can be potentiated101 102 103
Antihistamines	May counteract the sedative effects of antihistamines101 102 103
Antihypertensives	May antagonize the hypotensive effects of antihypertensives101 102 103
Chlorpromazine	Inhibits the central stimulant effects of amphetamines by blocking dopamine and norepinephrine receptors101 102 103	Can be used to treat amphetamine poisoning101 102 d
Ethosuximide	Intestinal absorption may be delayed by amphetamines101 102 103
Haloperidol	Inhibits the central stimulant effects of amphetamines by blocking dopamine receptors101 102 103
Lithium carbonate	May inhibit the anorectic and stimulatory effects of amphetamine101 102 103
MAO inhibitors	Slow the metabolism of amphetamines, increasing their effect on the release of norepinephrine and other monoamines leading to headaches and other signs of hypertensive crisis101 102 103 Toxic neurologic effects, hypertensive crisis, and malignant hyperpyrexia can occur, sometimes with fatal results101 102 103	Amphetamines contraindicated in patients currently or recently (within 14 days) receiving MAO inhibitor101 102 103
Meperidine	Amphetamines potentiate the analgesic effect of meperidine101 102 103
Methenamine	Acidifying agents used with methenamine increase urinary excretion and decrease efficacy of amphetamines101 102 103
Norepinephrine	Amphetamines enhance the adrenergic effects of norepinephrine101 102 103
Phenobarbital	Amphetamines may delay absorption of phenobarbital; concomitant use may produce a synergistic anticonvulsant action101 102 103
Phenytoin	Amphetamines may delay absorption of phenytoin; concomitant use may produce a synergistic anticonvulsant action101 102 103
Propoxyphene	In propoxyphene overdosage, amphetamine CNS stimulation is potentiated and fatal convulsions can occur101 102 103
Sympathomimetic agents	Enhanced activity of sympathomimetic agents102 103
Test, plasma corticosteroids	Can elevate plasma corticosteroid concentrations; this increase is greatest in the evening101 102 103
Test, urinary steroids	May interfere with urinary steroid determinations101 102 103
Veratrum alkaloids	Amphetamines inhibit the hypotensive effect of veratrum101 102 103

Dextroamphetamine Sulfate Pharmacokinetics

Absorption

Bioavailability

Similar for dextroamphetamine sulfate extended-release capsules versus immediate-release tablets.¹⁰²

Plasma concentration-time profiles for fixed combinations containing various salts of dextroamphetamine and amphetamine are similar for single 20-mg extended-release dose versus two 10-mg immediate-release doses given 4 hours apart.¹⁰³

Peak plasma concentration and AUC of amphetamines decrease with increasing body weight in individuals receiving fixed-combination extended-release capsules (Adderall XR).¹⁰³

Duration

Therapeutic effects persist for 4–24 hours.^PDH

Food

Food does not affect the rate or extent of absorption of dextroamphetamine sulfate from the extended-release capsules (e.g., Dexedrine Spansules).¹⁰²

Food does not affect the extent of absorption of the fixed-combination extended-release preparation (Adderall XR), but prolongs T_max by 2.5 hours (for d-amphetamine) and 2.1 hours (for l-amphetamine).¹⁰³ Opening the capsule and sprinkling the contents on applesauce results in comparable absorption to the intact capsule taken in the fasted state.¹⁰³

Plasma Concentrations

T_max, immediate-release dextroamphetamine sulfate: About 3 hours.^{101 102}

T_max, extended-release dextroamphetamine sulfate: About 8 hours.¹⁰²

T_max, immediate-release fixed combinations containing various salts of dextroamphetamine and amphetamine: About 3 hours.¹⁰³

T_max, extended-release fixed combinations containing various salts of dextroamphetamine and amphetamine: About 7 hours.¹⁰³

Therapeutic plasma concentrations are 5–10 mcg/dL.^PDH

Distribution

Extent

Distributed widely throughout body, with high levels in the brain.^PDH

Apparently crosses the placenta since withdrawal manifestations have occurred in neonates.^{101 102 103 f}

Distributed into milk in concentrations 3–7 times maternal blood concentrations.^f

Volume of distribution increases with increasing body weight in individuals receiving fixed-combination extended-release capsules.¹⁰³

Elimination

Metabolism

Metabolized to several active metabolites.¹⁰³

Enzymes involved in metabolism not clearly defined; however, CYP2D6 is involved with formation of at least one metabolite.¹⁰³ Because CYP2D6 is genetically polymorphic, potential variability in metabolism among patients exists.