Methamphetamineinteractions

Acidifying and Alkalinizing Agents: Agents that alter GI and urinary pH can alter blood levels of amphetamine. Acidifying agents can decrease amphetamine blood levels, while alkalinizing agents can increase amphetamine blood levels.

7.1 Drugs Having

Clinically Important Interactions with Methamphetamine Hydrochloride Tablets Table 1 presents clinically important drug interactions with methamphetamine hydrochloride tablets.

Table 1: Clinically Important Drug Interactions with Methamphetamine Hydrochloride Tablets Monoamine Oxidase Inhibitors (MAOI) Clinical Impact: MAOI antidepressants slow amphetamine metabolism, increasing amphetamines effect on the release of norepinephrine and other monoamines from adrenergic nerve endings causing headaches and other signs of hypertensive crisis. Toxic neurological effects and malignant hyperpyrexia can occur, sometimes with fatal results.

Intervention: Concomitant use of methamphetamine hydrochloride tablets with monoamine oxidase inhibitors (MAOIs) or within 14 days after discontinuing MAOI treatment is contraindicated.

Serotonergic Drugs Clinical Impact: The concomitant use of amphetamines, including methamphetamine, and serotonergic drugs increases the risk of serotonin syndrome.

Intervention: Initiate methamphetamine hydrochloride tablets with lower doses and monitor patients for signs and symptoms of serotonin syndrome, particularly during methamphetamine hydrochloride tablets initiation or dosage increase. If serotonin syndrome occurs, discontinue methamphetamine hydrochloride tablets and the concomitant serotonergic drug(s).

Alkalinizing Agents Clinical Impact: Alkalinizing agents may increase exposure to amphetamines and potentiate the action of amphetamine.

Intervention: Avoid co-administration of methamphetamine hydrochloride tablets and gastrointestinal and urinary alkalinizing agents.

Acidifying Agents Clinical Impact: Acidifying agents lower blood levels and efficacy of amphetamines.

Intervention: Increase dose of methamphetamine hydrochloride tablets based on clinical response.

Tricyclic Antidepressants Clinical Impact: May enhance the activity of tricyclic or sympathomimetic agents causing sustained increases in the concentration of d-amphetamine in the brain; cardiovascular effects can be potentiated.

Intervention: Monitor frequently and adjust methamphetamine hydrochloride tablets dose or use alternative therapy based on clinical response.

CYP2D6 Inhibitors Clinical Impact: Concomitant use of methamphetamine hydrochloride tablets and CYP2D6 inhibitors may increase the exposure of methamphetamine compared to the use of the drug alone, and increase the risk of serotonin syndrome.

Intervention: Start with lower doses and monitor patients for signs and symptoms of serotonin syndrome particularly during methamphetamine hydrochloride tablets initiation and after a dosage increase. If serotonin syndrome occurs, discontinue methamphetamine hydrochloride tablets and the CYP2D6 inhibitor. Gastric pH Modulators Clinical Impact: Time to maximum concentration (T max ) of amphetamine is decreased compared to when administered alone.

Intervention: Monitor patients for changes in clinical effect and use alternative therapy based on clinical response.

Guanethidine Clinical Impact: Methamphetamine may decrease the hypotensive effect of guanethidine.

Intervention: Monitor patients and adjust therapy based on clinical response. Insulin requirements in diabetes mellitus may be altered in association with the use of methamphetamine and the concomitant dietary regimen.

7.2 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.