Brand name: Desoxyn
Drug class: Amphetamines
VA class: CN801
CAS number: 537-46-2

Medically reviewed by Drugs.com on May 18, 2023. Written by ASHP.

Introduction

Dextrorotatory isomer of phenylmethylamine; sympathomimetic amine with CNS-stimulating activity.

Uses for Methamphetamine

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).

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.

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.

Use should depend on age and the clinician’s assessment of the severity and duration of symptoms and should not depend solely on one or more behavioral characteristics.

Not recommended for ADHD symptoms associated with acute stress reactions.

Exogenous Obesity

Has been used as an adjunct to caloric restriction in the short-term (i.e., a few weeks) treatment of exogenous obesity. However, because of limited efficacy (short-lived), such use no longer is recommended.

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

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

Misuse and Abuse

Misuse and abuse have experienced a resurgence, in large part, due to the relative ease with which methamphetamine can be synthesized clandestinely from readily available chemicals such as ephedrine, phenylpropanolamine (no longer commercially available in the US), or pseudoephedrine. Recent restrictions (including enactment of the Comprehensive Methamphetamine Control Act of 1996, the Methamphetamine Anti-Proliferation Act [MAPA] of 2000, and the Combat Methamphetamine Epidemic Act [CMEA] of 2005) on the availability of these compounds are hoped to reverse this resurgence in misuse and abuse.

Methamphetamine Dosage and Administration

Administration

Oral Administration

Administer orally.

When used as an anorexigenic agent, administer 30 minutes before each meal.

Because of potential for insomnia, avoid administering doses in the late evening.

Dosage

Available as methamphetamine hydrochloride; dosage expressed in terms of the salt.

Adjust dosage according to individual response and tolerance; the smallest dose required to produce the desired response should always be used.

When possible, therapy should be interrupted occasionally to determine if there is a recurrence of behavioral symptoms sufficient to require continued treatment.

If tolerance to anorectic effect occurs, manufacturer suggests not to exceed recommended dosage (in an attempt to increase effect), but rather to discontinue therapy.

Pediatric Patients

Exogenous Obesity

Oral

Children ≥12 years of age: 5 mg given 30 minutes before each meal recommended by manufacturer. Treatment should not exceed a few weeks.

Attention Deficit Hyperactivity Disorder

Oral

Children ≥6 years of age: Initially, 5 mg once or twice daily; daily dosage is increased in 5-mg increments at weekly intervals until the optimum response is attained.

Usual dosage is 20–25 mg daily, given in 2 divided doses.

Adults

Exogenous Obesity

Oral

5 mg given 30 minutes before each meal recommended by manufacturer. Treatment should not exceed a few weeks.

Prescribing Limits

Pediatric Patients

Exogenous Obesity

Oral

Children ≥12 years of age: Treatment should not exceed a few weeks.

Adults

Exogenous Obesity

Oral

Treatment should not exceed a few weeks.

Special Populations

Hepatic Impairment

No specific hepatic dosage recommendations.

Renal Impairment

No specific renal dosage recommendations.

Geriatric Patients

Select dosage with caution, usually starting at the low end of the dosage range, because of age-related decreases in hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy.

Cautions for Methamphetamine

Contraindications

• Contraindicated in patients with hypersensitivity or idiosyncrasy to sympathomimetic amines; in patients with symptomatic cardiovascular disease, hyperthyroidism, moderate to severe hypertension, glaucoma, or advanced arteriosclerosis; within 14 days of MAO inhibitor therapy; and in agitated patients.

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

Warnings/Precautions

Warnings

Sudden Death and Serious Cardiovascular Events

Sudden unexplained death, stroke, or MI reported in patients with or without structural cardiac abnormalities or other serious cardiac conditions receiving usual dosages of stimulants.

Epidemiologic data suggest a possible association between use of stimulants and sudden unexplained death in healthy children and adolescents. FDA unable to conclude that these data affect evaluation of overall risk and benefit of stimulants used to treat ADHD in children and adolescents. 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. Pediatric patients with ADHD and their parents should avoid discontinuing the child’s use of such stimulants before consulting a clinician.

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).

In general, avoid use of CNS stimulants in adults or children with known serious structural cardiac abnormalities, cardiomyopathy, serious heart rhythm abnormalities, CAD, or other serious cardiac conditions. (See Contraindications under Cautions.)

Patients who develop exertional chest pain, unexplained syncope, or other symptoms suggestive of cardiac disease during stimulant treatment should undergo a prompt cardiac evaluation.

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. Modest increases not expected to have short-term sequelae; however, monitor all patients for larger changes in BP and heart rate.

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).

Exacerbation or Precipitation of Psychotic Symptoms

May exacerbate symptoms of behavior disturbance and thought disorder in patients with preexisting psychotic disorder.

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

Precipitation of Manic Symptoms

May precipitate mixed or manic episodes in ADHD patients with comorbid bipolar disorder; use with caution in these patients. 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).

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

Aggression

Aggressive behavior and hostility (frequently observed in children and adolescents with ADHD) reported in patients receiving drug therapy for ADHD. 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.

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.

Manufacturer recommends monitoring growth during treatment; patients not growing or gaining weight as expected may require temporary discontinuance of treatment. 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 EEG abnormalities. If seizures occur, discontinue therapy.

Visual Effects

Visual disturbances (difficulty with accommodation, blurred vision) reported with stimulants.

General Precautions

Least amount of methamphetamine feasible should be prescribed or dispensed at one time in order to minimize possible overdosage.

Do not use to combat fatigue/exhaustion or to replace rest/sleep in normal persons.

Hypertension

Use with caution in patients with mild hypertension. Contraindicated in those with moderate or severe hypertension. (See Contraindications under Cautions.)

Nervous System Effects

Use with caution, if at all, in patients with hyperexcitability states or in those receiving drugs that may produce this effect. Also use with caution in asthenic patients or in those with psychopathic personalities or history of suicidal or homicidal tendencies.

Tics

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

Fetal/Neonatal Morbidity and Mortality

Teratogenicity and embryolethality demonstrated in animals receiving high multiples of the human dose.

Specific Populations

Pregnancy

Category C. (See Fetal/Neonatal Morbidity and Mortality under Cautions.)

Risk of prematurity, low birth weight, and withdrawal symptoms (e.g., dysphoria, lassitude, agitation) in infants born to dependent women.

Lactation

Amphetamines are distributed into milk. Discontinue nursing or the drug.

Pediatric Use

Not recommended for treatment of ADHD in pediatric patients <6 years of age.

Not recommended for management of exogenous obesity in pediatric patients <12 years of age.

Aggressive behavior, hostility, and psychotic (e.g., hallucinations, delusional thinking) or manic symptoms reported in children and adolescents receiving stimulants for management of ADHD. (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. Epidemiologic data also suggest a possible association between use of stimulants and sudden death in healthy children and adolescents. (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. (See Growth Suppression under Cautions.)

Geriatric Use

Insufficient experience in patients ≥65 years of age to determine whether geriatric patients respond differently than younger adults. Other clinical experience has not identified differences in responses between geriatric and younger patients.

Use with caution in geriatric or debilitated patients. Select dosage with caution. (See Geriatric Patients under Dosage and Administration.)

Common Adverse Effects

Elevation of BP, tachycardia, palpitations, dizziness, dysphoria, overstimulation, insomnia, tremor, restlessness, headache, diarrhea, constipation, dry mouth, unpleasant taste, urticaria, impotence, changes in libido.

Drug Interactions

Specific Drugs and Laboratory Tests

Methamphetamine Pharmacokinetics

Absorption

Bioavailability

Readily and rapidly absorbed from the GI tract.

Duration

Therapeutic effects persist for 6–12 hours; effects may continue up to 24 hours following administration of large doses.

Distribution

Extent

Amphetamines apparently cross the placenta since withdrawal manifestations have occurred in neonates. (See Pregnancy under Cautions.)

Amphetamines are distributed into milk.

Elimination

Metabolism

Metabolized in the liver by aromatic hydroxylation, N-dealkylation, and deamination.

Elimination Route

Excreted principally in urine. With normal urinary pH, approximately 62% of the dose is excreted in urine within the first 24 hours as unchanged drug (about (1/3)) and metabolites (about (2/3)).

Excretion is enhanced in acidic urine.

Half-life

4–5 hours. Alkaline urine substantially increases half-life.

Stability

Storage

Oral

Tablets

Tight, light-resistant containers at <30°C.

Actions

• Pharmacologic actions of methamphetamine are qualitatively similar to those of amphetamine and ephedrine and include CNS and respiratory stimulation and sympathomimetic activity including pressor response, mydriasis, bronchodilation, and contraction of the urinary bladder sphincter.

• CNS stimulating effect is approximately equal to or greater than that of amphetamine but less than that of dextroamphetamine; pressor effect is less than that of amphetamine but greater than that of ephedrine.

• Theories of dysfunction in ADHD focus on the prefrontal cortex, which controls many executive functions (e.g., planning, impulse control). Stimulants have putative effects on central dopamine and norepinephrine pathways that are crucial in frontal lobe function.

• Produces an anorexigenic effect, leading to loss of weight. No primary effect on appetite has been demonstrated and it has been postulated that anorexigenic effects are secondary to increased sympathetic activity resulting from release of norepinephrine and dopamine.

• Depresses motility of GI tract.

Advice to Patients

• Provide patient or caregiver with a copy of the manufacturer’s patient information (medication guide); discuss and answer questions about its contents as needed. Instruct patient or caregiver to read and understand contents of medication guide before initiating therapy and each time the prescription is refilled.

• Advise parents with concerns about long-term effects (e.g., effects on weight) and the need for continued therapy that drug holidays can be considered in consultation with the patient’s clinician. However, the benefits versus risks of such interruptions in therapy have not been established.

• Advise not to increase or decrease dosage unless instructed by their clinician.

• Advise that abrupt discontinuance following prolonged administration of high dosages may result in extreme fatigue and mental depression.

• Question about possible substance abuse, including in family members (since they may abuse the patient’s medication supply).

• Advise patients to inform clinician immediately if adverse cardiovascular (e.g., chest pain, shortness of breath, fainting) or psychiatric effects (e.g., hallucinations, delusional thinking, mania) occur.

• Instruct about the potential for methamphetamine to impair patient’s ability to perform potentially hazardous activities, such as driving a vehicle or operating heavy machinery.

• Importance of informing clinicians of existing or contemplated concomitant therapy, including prescription and OTC drugs, dietary supplements, and herbal products, as well as any concomitant illnesses/conditions (e.g., cardiac/cardiovascular disease, thyroid disease, glaucoma, suicidal ideation or behaviors, mental/psychiatric disorder).

• Importance of women informing clinicians if they are or plan to become pregnant or plan to breast-feed.

• Importance of informing patients of other important precautionary information. (See Cautions.)

Preparations

Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.

Please refer to the ASHP Drug Shortages Resource Center for information on shortages of one or more of these preparations.

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Frequently asked questions

• What medications can cause a false positive for methamphetamines?

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