Dextroamphetamineinteractions

MAO Inhibitors MAOI antidepressants, as well as a metabolite of furazolidone, slow amphetamine metabolism. This slowing potentiates amphetamines, increasing their effect 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. Serotonergic Drugs The concomitant use of dextroamphetamine sulfate tablets 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 dextroamphetamine sulfate tablets initiation or dosage increase. If serotonin syndrome occurs, discontinue dextroamphetamine sulfate tablets 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. CYP2D6 Inhibitors The concomitant use of dextroamphetamine sulfate tablets and CYP2D6 inhibitors may increase the exposure of dextroamphetamine sulfate tablets 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 dextroamphetamine sulfate tablets initiation and after a dosage increase. If serotonin syndrome occurs, discontinue dextroamphetamine sulfate tablets and the CYP2D6 inhibitor (see WARNINGS, OVERDOSAGE ). 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 the 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 Agent 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 actions 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. 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.