Search Medications (Drugs):
Medications (Drugs) from A to Z:
Home > Medications (Drugs) > Methamphetamine > Interactions with Methamphetamine

Interactions with Methamphetamine

If you are currently being treated with any of the following medications, you should not use Methamphetamine without reading these interactions.

Phenelzine, Tranylcypromine, Selegiline (oral), Isocarboxazid, Selegiline (transdermal), Linezolid, Rasagiline

CONTRAINDICATED: Centrally-acting sympathomimetic agents (i.e., CNS stimulants), particularly the amphetamines and amphetamine derivatives, may precipitate severe hypertensive reactions and hyperpyrexia in patients treated with monoamine oxidase inhibitors (MAOIs). Death has occurred in some reported cases. The mechanism involves a synergistic sympathomimetic effect due to enhanced norepinephrine storage in adrenergic neurons (MAOI activity) and increased liberation or decreased reuptake of catecholamines (central sympathomimetic activity). MAOIs also slow amphetamine metabolism, which may potentiate amphetamine effect on the release of norepinephrine and other monoamines from adrenergic nerve endings.

MANAGEMENT: In general, CNS stimulants should not be used concurrently with MAOIs or other agents that possess MAOI activity (e.g., furazolidone, linezolid, procarbazine). At least 14 days should elapse between discontinuation of MAOI therapy and initiation of treatment with CNS stimulants.

Potassium citrate

GENERALLY AVOID: Alkalinization of the urine can decrease the renal elimination of amphetamines. Amphetamine effects may be prolonged, and the risk of toxicity may be increased.

MANAGEMENT: Urinary alkalinizers should generally not be used with amphetamines, particularly in an amphetamine overdose situation.

Aluminum hydroxide, Aluminum carbonate, Magnesium hydroxide, Magnesium oxide

GENERALLY AVOID: Gastrointestinal alkalinizing agents can increase the absorption of amphetamines by increasing the concentration of the non-ionized species of the amphetamine molecule.

MANAGEMENT: Concomitant administration of amphetamines and gastrointestinal alkalinizing agents such as antacids or other medications that contain antacids (e.g., didanosine buffered tablets or pediatric oral solution) should generally be avoided.

Iopamidol

GENERALLY AVOID: Intrathecal administration of iodinated contrast media may induce seizures. Although clinical data are generally lacking, there may be a theoretical risk of increased seizure potential when used with selective serotonin reuptake inhibitors (SSRI antidepressants or anorectics), monoamine oxidase inhibitors, neuroleptic agents, central nervous system stimulants, opioids, tricyclic antidepressants, other tricyclic compounds (e.g., cyclobenzaprine, phenothiazines), and/or any substance that can reduce the seizure threshold (e.g., carbapenems, cholinergic agents, fluoroquinolones, interferons, chloroquine, mefloquine, lindane, theophylline). These agents are often individually epileptogenic and may have additive effects when combined.

MANAGEMENT: Drugs that can lower the seizure threshold should preferably be withheld for at least 48 hours prior to and 24 hours following intrathecal administration of iodinated contrast media, provided that temporary interruption of therapy does not pose an undue risk to the patient. Otherwise, close monitoring is advised during and after contrast administration. The manufacturers typically recommend avoiding concomitant administration of phenothiazines (including those used for their antihistamine properties), monoamine oxidase inhibitors, tricyclic antidepressants, central nervous system stimulants, and psychoactive drugs.

Perphenazine, Thiethylperazine, Mesoridazine, Trifluoperazine

GENERALLY AVOID: Phenothiazines may antagonize the pharmacologic effects of amphetamine, amphetamine derivatives, and other centrally-acting sympathomimetic agents (i.e., CNS stimulants). Conversely, these agents may diminish the neuroleptic efficacy of phenothiazines. The exact mechanism of interaction is unknown but may involve opposing effects on dopaminergic activity. Several clinical studies have demonstrated the reduction or lack of effect of amphetamines on weight loss in obese psychiatric patients treated with chlorpromazine and other neuroleptic agents. In one of these studies, dextroamphetamine also had no effect on sleep patterns. As for the reverse interaction, it is uncertain whether CNS stimulants actually antagonize the neuroleptic effect of phenothiazines, since CNS stimulants alone have been reported to cause or aggravate preexisting psychotic symptoms. Finally, it is conceivable that, because of their sympathomimetic effects, CNS stimulants may also potentiate the arrhythmogenicity of phenothiazines. A case of fatal ventricular arrhythmia was reported in a patient treated chronically with thioridazine who ingested a single capsule containing phenylpropanolamine 50 mg and chlorpheniramine 4 mg. However, a causal relationship was not established.

MANAGEMENT: Amphetamine, amphetamine derivatives, and other CNS stimulants should generally not be used, particularly for weight reduction, in patients treated with phenothiazines.

Sertraline, Paroxetine, Venlafaxine (oral), Fluvoxamine, Citalopram (oral), Escitalopram, Duloxetine

GENERALLY AVOID: Several case reports suggest that patients treated with serotonin reuptake inhibitors (SRIs) may exhibit an increased sensitivity to sympathomimetic agents. The mechanism of interaction is unclear. The reaction has been reported when fluoxetine was used concomitantly with phentermine, amphetamine, or phenylpropanolamine. Additionally, some sympathomimetic agents (e.g., amphetamines) may possess serotonergic activity and should generally not be administered with SRIs because of the additive risk of serotonin syndrome, which is a rare but serious and potentially fatal condition thought to result from hyperstimulation of brainstem 5-HT1A receptors. The interaction occurred in a patient treated with dexamphetamine approximately 2 weeks after the addition of venlafaxine. The medications were discontinued and the patient was given cyproheptadine for suspected serotonin syndrome, whereupon symptoms promptly resolved. A second episode occurred when dexamphetamine was subsequently resumed and citalopram added. The patient improved following cessation of citalopram on his own, and residual symptoms were successfully treated with cyproheptadine.

MANAGEMENT: In general, amphetamines and other sympathomimetic appetite suppressants should not be combined with serotonin reuptake inhibitors. Close monitoring for enhanced sympathomimetic effects is recommended if these agents must be used together. Patients should also be monitored for signs and symptoms of excessive serotonergic activity such as CNS irritability, altered consciousness, confusion, myoclonus, ataxia, abdominal cramping, hyperpyrexia, shivering, pupillary dilation, diaphoresis, hypertension, and tachycardia.

Delavirdine

MONITOR: According to the product labeling for delavirdine, coadministration of the drug may increase the plasma concentrations of amphetamines. The proposed mechanism is delavirdine inhibition of the CYP450 2D6 metabolism of amphetamines.

MANAGEMENT: Caution is advised if amphetamines are prescribed in combination with delavirdine. Patients should be monitored for excessive anorectic and central nervous system stimulant effects of amphetamines.

Tramadol

MONITOR CLOSELY: The risk of seizures may be increased during coadministration of tramadol with selective serotonin reuptake inhibitors (SSRI antidepressants or anorectics), monoamine oxidase inhibitors, neuroleptic agents, central nervous system stimulants, opioids, tricyclic antidepressants, other tricyclic compounds (e.g., cyclobenzaprine, phenothiazines), and/or any substance that can reduce the seizure threshold (e.g., carbapenems, cholinergic agents, fluoroquinolones, interferons, chloroquine, mefloquine, lindane, theophylline). These agents are often individually epileptogenic and may have additive effects when combined. Many of these agents also exhibit CNS- and/or respiratory-depressant effects, which may be enhanced during their concomitant use with tramadol.

MANAGEMENT: Caution is advised if tramadol is administered with any substance that can reduce the seizure threshold, particularly in the elderly and in patients with epilepsy, a history of seizures, or other risk factors for seizures (e.g., head trauma, brain tumor, metabolic disorders, alcohol and drug withdrawal, CNS infections).

Celecoxib (oral)

MONITOR: Coadministration with celecoxib may increase the plasma concentrations of drugs that are substrates of the CYP450 2D6 isoenzyme. The mechanism is decreased clearance due to inhibition of CYP450 2D6 activity by celecoxib.

MANAGEMENT: Caution is advised if celecoxib must be used concurrently with medications that undergo metabolism by CYP450 2D6, particularly those with a narrow therapeutic range. Dosage adjustments as well as clinical and laboratory monitoring may be appropriate for some drugs whenever celecoxib is added to or withdrawn from therapy.

Cinacalcet

MONITOR: Coadministration with cinacalcet may increase the plasma concentrations of drugs that are substrates of the CYP450 2D6 isoenzyme. The mechanism is decreased clearance due to inhibition of CYP450 2D6 activity by cinacalcet, which is expected to occur in patients who are CYP450 2D6 extensive metabolizers (approximately 93% of Caucasians and more than 98% of Asians and individuals of African descent). Concurrent administration of cinacalcet (25 or 100 mg) increased the systemic exposure of amitriptyline (50 mg) and its active metabolite, nortriptyline, by approximately 20% in CYP450 2D6 extensive metabolizers. However, because amitriptyline is metabolized by multiple CYP450 isoenzymes in addition to 2D6, the degree of interaction with cinacalcet may be less than that expected for other drugs that are primarily metabolized by 2D6.

MANAGEMENT: Caution is advised if cinacalcet must be used concurrently with medications that undergo metabolism by CYP450 2D6, particularly those with a narrow therapeutic range (e.g., class IC antiarrhythmic agents, phenothiazines, certain beta blockers, and most tricyclic antidepressants). Dosage adjustments as well as clinical and laboratory monitoring may be appropriate for some drugs whenever cinacalcet is added to or withdrawn from therapy.

Darifenacin

MONITOR: Coadministration with darifenacin may increase the plasma concentrations of drugs that are metabolized by CYP450 2D6. The mechanism is decreased clearance due to inhibition of the isoenzyme by darifenacin. According to the product labeling, darifenacin (30 mg once daily) increased the mean peak plasma concentration (Cmax) and area under the concentration-time curve (AUC) of imipramine (a CYP450 2D6 substrate) by 57% and 70%, respectively. These changes were accompanied by a 3.6-fold increase in the mean Cmax and AUC of desipramine, the active metabolite of imipramine. Conversely, some CYP450 2D6 substrates may also increase the plasma concentrations of darifenacin, which is itself metabolized by CYP450 2D6 and may participate in enzymatic competitive inhibition with other substrates.

MANAGEMENT: Caution is advised if darifenacin must be used concomitantly with medications that undergo metabolism by CYP450 2D6, particularly those with a narrow therapeutic range. Dosage adjustments as well as clinical and laboratory monitoring may be appropriate for some drugs whenever darifenacin is added to or withdrawn from therapy. Pharmacologic response to darifenacin should also be monitored more closely whenever a CYP450 2D6 inhibitor is added to or withdrawn from therapy, and the darifenacin dosage adjusted if necessary. Patients should be advised to contact their doctor if they experience undue adverse effects of darifenacin such as severe abdominal pain or constipation for 3 or more days.

Imatinib (oral)

MONITOR: Coadministration with imatinib may increase the plasma concentrations of drugs that are substrates of CYP450 2C9, 2D6 and/or 3A4. The mechanism is decreased clearance due to inhibition of these isoenzymes by imatinib. According to the manufacturer, imatinib increased the mean peak plasma concentration and area under the concentration-time curve of simvastatin (a CYP450 3A4 substrate) by 2- and 3.5-fold, respectively. Data for other substrates are not currently available, although human liver microsome studies indicate that imatinib is a potent competitive inhibitor of all three isoenzymes.

MANAGEMENT: Caution is advised if imatinib must be used concomitantly with medications that undergo metabolism by CYP450 2C9, 2D6 and/or 3A4, particularly those with a narrow therapeutic range. Dosage adjustments as well as clinical and laboratory monitoring may be appropriate for some drugs whenever imatinib is added to or withdrawn from therapy.

Ranolazine

MONITOR: Coadministration with ranolazine may increase the plasma concentrations of drugs that are substrates of the CYP450 2D6 isoenzyme. Ranolazine has been shown in vitro to be an inhibitor of CYP450 2D6. However, concomitant use of ranolazine with other drugs that are metabolized by CYP450 2D6 such as tricyclic antidepressants and antipsychotics has not been studied.

MANAGEMENT: Caution is advised if ranolazine must be used concurrently with medications that undergo metabolism by CYP450 2D6, particularly those with a narrow therapeutic range. Dosage adjustments as well as clinical and laboratory monitoring may be appropriate for some drugs whenever ranolazine is added to or withdrawn from therapy.

Ritonavir

MONITOR: Coadministration with ritonavir may increase the plasma concentrations of drugs that are substrates of the CYP450 2D6 isoenzyme. The mechanism is decreased clearance due to competitive inhibition of CYP450 2D6 activity by ritonavir. The systemic exposure (AUC) of some coadministered drugs has been reported to increase by up to twofold.

MANAGEMENT: Caution is advised if ritonavir must be used concurrently with medications that undergo metabolism by CYP450 2D6, particularly those with a narrow therapeutic range. Dosage adjustments as well as clinical and laboratory monitoring may be appropriate for some drugs whenever ritonavir is added to or withdrawn from therapy.

Terbinafine

MONITOR: Coadministration with terbinafine may increase the plasma concentrations of drugs that are substrates of the CYP450 2D6 isoenzyme. The mechanism is decreased clearance due to inhibition of CYP450 2D6 activity by terbinafine, which is expected to occur in patients who are CYP450 2D6 extensive metabolizers (approximately 93% of Caucasians and more than 98% of Asians and individuals of African descent). A case of nortriptyline (a CYP450 2D6 substrate) intoxication corresponding to significantly increased serum drug concentrations was reported in a patient shortly after the addition of terbinafine. Rechallenge in the patient produced similar results.

MANAGEMENT: Caution is advised if terbinafine must be used concurrently with medications that undergo metabolism by CYP450 2D6, particularly those with a narrow therapeutic range. Dosage adjustments as well as clinical and laboratory monitoring may be appropriate for some drugs whenever terbinafine is added to or withdrawn from therapy. Due to the long elimination half-life of terbinafine, especially following prolonged use, such interactions may be observed for several months after discontinuation of terbinafine therapy.

Lindane topical

MONITOR: Lindane penetrates human skin and has the potential to cause central nervous system toxicity. Seizures have been reported after excessive use or oral ingestion of lindane. There may be a theoretical risk of increased seizure potential when lindane is used with selective serotonin reuptake inhibitors (SSRI antidepressants or anorectics), monoamine oxidase inhibitors, neuroleptic agents, central nervous system stimulants, opioids, tricyclic antidepressants, other tricyclic compounds (e.g., cyclobenzaprine, phenothiazines), and/or any substance that can reduce the seizure threshold (e.g., carbapenems, cholinergic agents, fluoroquinolones, interferons, chloroquine, mefloquine, theophylline). These agents are often individually epileptogenic and may have additive effects when combined.

MANAGEMENT: Caution is advised if lindane is used with any substance that can reduce the seizure threshold, particularly in the very young or the elderly and in patients with epilepsy, a history of seizures, or other risk factors for seizures (e.g., head trauma, brain tumor, metabolic disorders, alcohol and drug withdrawal, CNS infections). Lindane should be used according to recommended dosage and directions for application.

Advertisement