AMPHETAMINE Drug Interactions: What You Need to Know

Drug Interactions Acidifying agents Gastrointestinal acidifying agents (guanethidine, reserpine, glutamic acid HCl, ascorbic acid, fruit juices, etc.) lower absorption of amphetamines. Urinary acidifying agents (ammonium chloride, sodium acid phosphate, etc.) increase concentration of the ionized species of the amphetamine molecule, thereby increasing urinary excretion. Both groups of agents lower blood levels and efficacy of amphetamines. Adrenergic blockers Adrenergic blockers are inhibited by amphetamines. Alkalinizing agents Gastrointestinal alkalinizing agents (sodium bicarbonate, etc.) increase absorption of amphetamines. Urinary alkalinizing agents (acetazolamide, some thiazides) increase the concentration of the non-ionized species of the amphetamine molecule, thereby decreasing urinary excretion. Both groups of agents increase blood levels and therefore potentiate the action of amphetamines. Antidepressants tricyclic Amphetamines may enhance the activity of tricyclic or sympathomimetic agents; d-amphetamine with desipramine or protriptyline and possibly other tricyclics cause striking and sustained increases in the concentration of d- amphetamine in the brain; cardiovascular effects can be potentiated. CYP2D6 Inhibitors The concomitant use of amphetamine sulfate and CYP2D6 inhibitors may increase the exposure of amphetamine sulfate compared to the use of the drug alone and increase the risk of serotonin syndrome. Initiate with lower doses and monitor patients for signs and symptoms of serotonin syndrome particularly during amphetamine sulfate initiation and after a dosage increase. If serotonin syndrome occurs, discontinue amphetamine sulfate and the CYP2D6 inhibitor (see WARNING , OVERDOSAGE ). Examples of CYP2D6 Inhibitors include paroxetine and fluoxetine (also serotonergic drugs), quinidine, ritonavir.

Serotonergic Drugs

The concomitant use of amphetamine sulfate and serotonergic drugs increases the risk of serotonin syndrome. Initiate with lower doses and monitor patients for signs and symptoms of serotonin syndrome, particularly during amphetamine sulfate initiation or dosage increase. If serotonin syndrome occurs, discontinue amphetamine sulfate and the concomitant serotonergic drug(s) (see WARNING and PRECAUTIONS ). Examples of serotonergic drugs include selective serotonin reuptake inhibitors (SSRI), serotonin norepinephrine reuptake inhibitors (SNRI), triptans, tricyclic antidepressants, fentanyl, lithium, tramadol, tryptophan, buspirone, St. John's Wort. MAO inhibitors MAOI antidepressants, as well as a metabolic of furazolidone, slow amphetamine metabolism. This slowing potentiates amphetamines, increasing their affect on the release of norepinephrine and other monoamines from adrenergic nerve endings; this can cause headaches and other signs of hypertensive crisis. A variety of neurological toxic effects and malignant hyperpyrexia can occur, sometimes with fatal results.

Antihistamines

Amphetamines may counteract the sedative effect of antihistamines.

Antihypertensives

Amphetamines may antagonize the hypotensive effects of antihypertensives.

Chlorpromazine

Chlorpromazine blocks dopamine and norepinephrine reuptake, thus inhibiting the central stimulant effects of amphetamine, and can be used to treat amphetamine poisoning.

Ethosuximide

Amphetamines may delay intestinal absorption of ethosuximide.

Haloperidol

Haloperidol blocks dopamine and norepinephrine reuptake, thus inhibiting the central stimulant affects of amphetamines. Lithium carbonate The antiobesity and stimulatory effects of amphetamines may be inhibited by lithium carbonate.

Meperidine

Amphetamines potentiate the analgesic effect of meperidine. Methenamine therapy Urinary excretion of amphetamines is increased, and efficacy is reduced by acidifying agents used in methenamine therapy.

Norepinephrine

Amphetamines enhance the adrenergic effect of norepinephrine.

Phenobarbital

Amphetamines may delay intestinal absorption of Phenobarbital. Co- administration of phenobarbital may produce a synergistic anticonvulsant action.

Phenytoin

Amphetamines may delay intestinal absorption of phenytoin; co- administration of phenytoin may produce a synergistic anticonvulsant action. Propoxyphene In cases of propoxyphene overdosage, amphetamine CNS stimulation is potentiated and fatal convulsions can occur. Veratrum alkaloids Amphetamines inhibit the hypotensive effect of veratrum alkaloids.

Drug/Laboratory

Test interactions Amphetamines can cause a significant elevation in plasma corticosteroid levels. This increase is greatest in the evening. Amphetamines may interfere with urinary steroid determinations.

Carcinogenesis/Mutagenesis

Mutagenicity studies and long term studies in animals to determine the carcinogenic potential of amphetamine sulfate have not been performed.

Pregnancy Teratogenic Effects

Dextroamphetamine sulfate has been shown to have embryotoxic and teratogenic effects when administered to A/Jax mice and C57BL mice in doses approximately 41 times the maximum human dose. Embryotoxic effects were not seen in New Zealand white rabbits given the drug in doses 7 times the human dose nor in rats given 12.5 times the maximum human dose. There are no adequate and well-controlled studies in pregnant women. Amphetamine sulfate should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

Nonteratogenic Effects

Infants born to mothers dependent on amphetamines have an increased risk of premature delivery and low birth weight. Also, these infants may experience symptoms of withdrawal as demonstrated by dysphoria, including agitation, and significant lassitude.

Nursing Mothers

Amphetamines are excreted in human milk. Mothers taking amphetamines should be advised to refrain from nursing.

Pediatric Use

Long-term effects of amphetamines in children have not been well established. Amphetamines are not recommended for use as anorectic agents in children under 12 years of age, or in children under 3 years of age with Attention Deficit Disorder with Hyperactivity described under INDICATIONS AND USAGE . Clinical experience suggests that in psychotic children, administration of amphetamines may exacerbate symptoms of behavior disturbance and thought disorder. Amphetamines have been reported to exacerbate motor and phonic tics and Tourette's syndrome. Therefore clinical evaluation for tics and Tourette's syndrome in children and their families should precede use of stimulant medications. Data is inadequate to determine whether chronic administration of amphetamines may be associated with growth inhibition; therefore growth should be monitored during treatment.

Drug

Treatment is not indicated in all cases of Attention Deficit Disorder with Hyperactivity and should be considered only in light of the complete history and evaluation of the child. The decision to prescribe amphetamines should depend on the physician's assessment of the chronicity and severity of the child's symptoms and their appropriateness for his/her age. Prescription should not depend solely on the presence of one or more of the behavioral characteristics. When these symptoms are associated with acute stress reactions, treatment with amphetamines is usually not indicated.

Amphetamine extended-release orally disintegrating tablets are contraindicated: In patients known to be hypersensitive to amphetamine, or other components of amphetamine extended-release orally disintegrating tablets. Hypersensitivity reactions such as angioedema and anaphylactic reactions have been reported in patients treated with other amphetamine products [see Adverse Reactions ( 6.2 )] . Patients taking monoamine oxidase inhibitors (MAOIs), or within 14 days of stopping MAOIs (including MAOIs such as linezolid or intravenous methylene blue), because of an increased risk of hypertensive crisis [see Warnings and Precautions ( 5.7 ), Drug Interactions ( 7.1 )] . Known hypersensitivity to amphetamine products or other ingredients in amphetamine extended-release orally disintegrating tablets. ( 4 ) Use of monoamine oxidase inhibitor (MAOI) or within 14 days of the last MAOI dose. ( 4 )

AND PRECAUTIONS . Risks to Patients with Serious Cardiac Disease: Avoid use in patients with known structural cardiac abnormalities, cardiomyopathy, serious heart arrhythmia, coronary artery disease, or other serious cardiac disease. ( 5.2 )

Increased Blood

Pressure and Heart Rate: Monitor blood pressure and pulse. ( 5.3 )

Psychiatric Adverse

Reactions: Prior to initiating amphetamine extended-release orally disintegrating tablets, screen patients for risk factors for developing a manic episode. If new psychotic or manic symptoms occur, consider discontinuing amphetamine extended-release orally disintegrating tablets. ( 5.4 ) Long-Term Suppression of Growth in Pediatric Patients: Closely monitor growth (height and weight) in pediatric patients. Pediatric patients not growing or gaining height or weight as expected may need to have their treatment interrupted. ( 5.5 )

Peripheral

Vasculopathy, including Raynaud’s phenomenon: Careful observation for digital changes is necessary during amphetamine extended-release orally disintegrating tablets treatment. Further clinical evaluation (e.g. rheumatology referral) may be appropriate for patients who develop signs or symptoms of peripheral vasculopathy. ( 5.6 )

Serotonin

Syndrome: Increased risk when co-administered with serotonergic agents (e.g. SSRIs, SNRIs, triptans), but also during overdosage situations. If it occurs, discontinue amphetamine extended-release orally disintegrating tablets and initiate supportive treatment. ( 5.7 , 17 ) Motor and Verbal Tics, and Worsening of Tourette’s Syndrome: Before initiating amphetamine extended-release orally disintegrating tablets, assess the family history and clinically evaluate patients for tics or Tourette’s syndrome. Regularly monitor patients for the emergence or worsening of tics or Tourette’s syndrome. Discontinue treatment if clinically appropriate. ( 5.8 )

5.1 Abuse, Misuse, and Addiction Amphetamine extended-release orally disintegrating tablets has a high potential for abuse and misuse. The use of amphetamine extended-release orally disintegrating tablets exposes individuals to the risks of abuse and misuse, which can lead to the development of a substance use disorder, including addiction. amphetamine extended-release orally disintegrating tablets can be diverted for non-medical use into illicit channels or distribution [ see Drug Abuse and Dependence ( 9.2 ) ]. Misuse and abuse of CNS stimulants, including amphetamine extended-release orally disintegrating tablets, can result in overdose and death [ see Overdosage ( 10 ) ], and this risk is increased with higher doses or unapproved methods of administration, such as snorting or injection. Before prescribing amphetamine extended-release orally disintegrating tablets, assess each patient’s risk for abuse, misuse, and addiction. Educate patients and their families about these risks and proper disposal of any unused drug. Advise patients to store amphetamine extended-release orally disintegrating tablets in a safe place, preferably locked, and instruct patients to not give amphetamine extended-release orally disintegrating tablets to anyone else. Throughout amphetamine extended-release orally disintegrating tablets treatment, reassess each patient’s risk of abuse, misuse, and addiction and frequently monitor for signs and symptoms of abuse, misuse, and addiction.

5.2 Risks to Patients with Serious Cardiac Disease Sudden death has been reported in patients with structural cardiac abnormalities or other serious cardiac disease who were treated with CNS stimulants at the recommended ADHD dosage. Avoid amphetamine extended-release orally disintegrating tablets use in patients with known structural cardiac abnormalities, cardiomyopathy, serious cardiac arrhythmia, coronary artery disease, or other serious cardiac disease.

5.3 Increased Blood Pressure and Heart Rate CNS stimulants cause an increase in blood pressure (mean increase about 2 to 4 mm Hg) and heart rate (mean increase about 3 to 6 bpm). Some patients may have larger increases. Monitor all amphetamine extended-release orally disintegrating tablets-treated patients for potential tachycardia and hypertension.

5.4 Psychiatric Adverse Reactions Exacerbation of Pre-existing Psychosis CNS stimulants may exacerbate symptoms of behavior disturbance and thought disorder in patients with a pre-existing psychotic disorder. Induction of a Manic Episode in Patients with Bipolar Disorder CNS stimulants may induce a manic or mixed episode in patients. Prior to initiating amphetamine extended-release orally disintegrating tablets treatment, screen patients for risk factors for developing a manic episode (e.g., comorbid or has a history of depressive symptoms or a family history of suicide, bipolar disorder, and depression).

New

Psychotic or Manic Symptoms CNS stimulants, at the recommended dosage, may cause psychotic or manic symptoms, e.g., hallucinations, delusional thinking, or mania in patients without prior history of psychotic illness or mania. In a pooled analysis of multiple short-term, placebo-controlled studies of CNS stimulants, psychotic or manic symptoms occurred in 0.1% of CNS stimulant-treated patients compared to 0% of placebo-treated patients. If such symptoms occur, consider discontinuing amphetamine extended-release orally disintegrating tablets.

5.5 Long-Term Suppression of Growth in Pediatric Patients Amphetamine extended-release orally disintegrating tablets is not approved for use and is not recommended in pediatric patients below 6 years of age <span class="opacity-50 text-xs">[see Use in Specific Population (8.4) ]</span>. CNS stimulants have been associated with weight loss and slowing of growth rate in pediatric patients. Closely monitor growth (weight and height) in amphetamine extended-release orally disintegrating tablets-treated pediatric patients treated with CNS stimulants. Pediatric patients not growing or gaining height or weight as expected may need to have their treatment interrupted.

5.6 Peripheral Vasculopathy, including Raynaud’s Phenomenon CNS stimulants, including amphetamine extended-release orally disintegrating tablets, used to treat ADHD are associated with peripheral vasculopathy, including Raynaud’s phenomenon. Signs and symptoms are usually intermittent and mild; however, sequelae have included digital ulceration and/or soft tissue breakdown. Effects of peripheral vasculopathy, including Raynaud’s phenomenon, were observed in post-marketing reports and at the therapeutic dosage of CNS stimulants in all age groups throughout the course of treatment. Signs and symptoms generally improved after dosage reduction or discontinuation of the CNS stimulant. Careful observation for digital changes is necessary during amphetamine extended-release orally disintegrating tablets-treatment. Further clinical evaluation (e.g., rheumatology referral) may be appropriate for amphetamine extended-release orally disintegrating tablets-treated patients who develop signs or symptoms of peripheral vasculopathy.

5.7 Serotonin Syndrome Serotonin syndrome, a potentially life-threatening reaction, may occur when amphetamines are used in combination with other drugs that affect the serotonergic neurotransmitter systems such as monoamine oxidase inhibitors (MAOIs), selective serotonin reuptake inhibitors (SSRIs), serotonin norepinephrine reuptake inhibitors (SNRIs), triptans, tricyclic antidepressants, fentanyl, lithium, tramadol, tryptophan, buspirone, and St. John’s Wort <span class="opacity-50 text-xs">[see Drug Interactions ( 7.1 )]</span>. The co-administration with cytochrome P450 2D6 (CYP2D6) inhibitors may also increase the risk with increased exposure to amphetamine extended-release orally disintegrating tablets. In these situations, consider an alternative non-serotonergic drug or an alternative drug that does not inhibit CYP2D6 <span class="opacity-50 text-xs">[see Drug Interactions ( 7.1 )]</span> . Serotonin syndrome symptoms may include mental status changes (e.g., agitation, hallucinations, delirium, and coma), autonomic instability (e.g., tachycardia, labile blood pressure, dizziness, diaphoresis, flushing, hyperthermia), neuromuscular symptoms (e.g., tremor, rigidity, myoclonus, hyperreflexia, incoordination), seizures, and/or gastrointestinal symptoms (e.g., nausea, vomiting, diarrhea). Concomitant use of amphetamine extended-release orally disintegrating tablets with MAOI drugs is contraindicated <span class="opacity-50 text-xs">[see Contraindications ( 4 )]</span>. Discontinue treatment with amphetamine extended-release orally disintegrating tablets and any concomitant serotonergic agents immediately if the above symptoms occur, and initiate supportive symptomatic treatment. If concomitant use of amphetamine extended-release orally disintegrating tablets with other serotonergic drugs or CYP2D6 inhibitors is clinically warranted, initiate amphetamine extended-release orally disintegrating tablets with lower doses, monitor patients for the emergence of serotonin syndrome during drug initiation or titration, and inform patients of the increased risk for serotonin syndrome.

5.8 Motor and Verbal Tics, and Worsening of Tourette’s Syndrome CNS stimulants, including amphetamine, have been associated with the onset or exacerbation of motor and verbal tics. Worsening of Tourette’s syndrome has also been reported <span class="opacity-50 text-xs">[see Adverse Reactions ( 6.2 )]</span> . Before initiating amphetamine extended-release orally disintegrating tablets, assess the family history and clinically evaluate patients for tics or Tourette’s syndrome. Regularly monitor amphetamine extended-release orally disintegrating tablets-treated patients for the emergence or worsening of tics or Tourette’s syndrome and discontinue treatment if clinically appropriate.

5.9 Potential for Overdose Due to Medication Errors Medication errors, including substitution and dispensing errors, between amphetamine extended-release orally disintegrating tablets and other amphetamine products could occur, leading to possible overdosage. To avoid substitution errors and overdosage, do not substitute for other amphetamine products on a milligram-per-milligram basis because of different amphetamine base compositions and differing pharmacokinetic profiles <span class="opacity-50 text-xs">[see Dosage and Administration ( 2.5 )]</span> .