Drug Interactions for Dexedrine Spansule
Acidifying Agents
Lower blood levels and efficacy of amphetamines. Increase dose based on clinical response. Examples of acidifying agents include gastrointestinal acidifying agents (e.g., guanethidine, reserpine, glutamic acid HCl, ascorbic acid) and urinary acidifying agents (e.g., ammonium chloride, sodium acid phosphate, methenamine salts).
Adrenergic Blockers
Adrenergic blockers are inhibited by amphetamines.
Alkalinizing Agents
Increase blood levels and potentiate the action of amphetamine. Co-administration of DEXEDRINE and gastrointestinal alkalinizing agents should be avoided. Examples of alkalinizing agents include gastrointestinal alkalinizing agents (e.g., sodium bicarbonate) and urinary alkalinizing agents (e.g. acetazolamide, some thiazides).
Tricyclic Antidepressants
May enhance the activity of tricyclic or sympathomimetic agents causing striking and sustained increases in the concentration of d-amphetamine in the brain; cardiovascular effects can be potentiated. Monitor frequently and adjust or use alternative therapy based on clinical response. Examples of tricyclic antidepressants include desipramine, Protriptyline.
CYP2D6 Inhibitors
The concomitant use of DEXEDRINE and CYP2D6 inhibitors may increase the exposure of DEXEDRINE 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 DEXEDRINE initiation and after a dosage increase. If serotonin syndrome occurs, discontinue DEXEDRINE and the CYP2D6 inhibitor [see WARNINGS and OVERDOSE]. Examples of CYP2D6 Inhibitors include paroxetine and fluoxetine (also serotonergic drugs), quinidine, ritonavir.
Serotonergic Drugs
The concomitant use of DEXEDRINE 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 DEXEDRINE initiation or dosage increase. If serotonin syndrome occurs, discontinue DEXEDRINE and the concomitant serotonergic drug(s) [see WARNINGS 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
Concomitant use of MAOIs and CNS stimulants can cause hypertensive crisis. Potential outcomes include death, stroke, myocardial infarction, aortic dissection, ophthalmological complications, eclampsia, pulmonary edema, and renal failure. Do not administer DEXEDRINE concomitantly or within 14 days after discontinuing MAOI [see CONTRAINDICATIONS and WARNINGS]. Examples of MAOIs include selegiline, tranylcypromine, isocarboxazid, phenelzine, linezolid, methylene blue.
Proton Pump Inhibitors
Time to maximum concentration (Tmax) of amphetamine is decreased compared to when administered alone.
Monitor patients for changes in clinical effect and adjust therapy based on clinical response. An example of a proton pump inhibitor is omeprazole.
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 amphetamines, 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 effects of amphetamines.
Lithium Carbonate
The 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 Abuse And Dependence
Controlled Substance
DEXEDRINE contains dextroamphetamine, a Schedule II controlled substance.
Abuse
DEXEDRINE has a high potential for abuse and misuse which can lead to the development of a substance use disorder, including addiction [see WARNINGS]. DEXEDRINE can be diverted for non-medical use into illicit channels or distribution.
Abuse is the intentional non-therapeutic use of a drug, even once, to achieve a desired psychological or physiological effect. Misuse is the intentional use, for therapeutic purposes, of a drug by an individual in a way other than prescribed by a health care provider or for whom it was not prescribed. Drug addiction is a cluster of behavioral, cognitive, and physiological phenomena that may include a strong desire to take the drug, difficulties in controlling drug use (e.g., continuing drug use despite harmful consequences, giving a higher priority to drug use than other activities and obligations), and possible tolerance or physical dependence.
Misuse and abuse of amphetamine may cause increased heart rate, respiratory rate, or blood pressure; sweating; dilated pupils; hyperactivity; restlessness; insomnia; decreased appetite; loss of coordination; tremors; flushed skin; vomiting; and/or abdominal pain. Anxiety, psychosis, hostility, aggression, and suicidal or homicidal ideation have also been observed with CNS stimulants abuse and/or misuse. Misuse and abuse of CNS stimulants, including DEXEDRINE, can result in overdose and death [see OVERDOSE], and this risk is increased with higher doses or unapproved methods of administration, such as snorting or injection.
Dependence
Physical Dependence
DEXEDRINE may produce physical dependence. Physical dependence is a state that develops as a result of physiological adaptation in response to repeated drug use, manifested by withdrawal signs and symptoms after abrupt discontinuation or a significant dose reduction of a drug.
Withdrawal signs and symptoms after abrupt discontinuation or dose reduction following prolonged use of CNS stimulants including DEXEDRINE include dysphoric mood; depression; fatigue; vivid, unpleasant dreams; insomnia or hypersomnia; increased appetite; and psychomotor retardation or agitation.
Tolerance
DEXEDRINE may produce tolerance. Tolerance is a physiological state characterized by a reduced response to a drug after repeated administration (i.e., a higher dose of a drug is required to produce the same effect that was once obtained at a lower dose).