Interactions between Phendimetrazine and Sitrex
1 drug interaction and 39 additional warnings found for the following 2 drugs:
- phendimetrazine
- Sitrex (guaifenesin/phenylephrine)
Drug interactions
Moderate drug interactions
Moderate:
phenylephrine phendimetrazine
Applies to: Sitrex (guaifenesin / phenylephrine) and phendimetrazine
Monitor
Coadministration of two or more sympathomimetic or noradrenergic agents may increase the risk of nervousness, irritability, tachycardia, and/or increased blood pressure. Central nervous system (CNS) stimulants, particularly amphetamines, can potentiate the adrenergic response to vasopressors and other sympathomimetic and/or noradrenergic agents, including norepinephrine transporter inhibitors. Additive increases in blood pressure and heart rate may occur due to enhanced peripheral sympathetic activity.
Management
Caution is advised if two or more sympathomimetic or noradrenergic agents are coadministered. Pulse and blood pressure should be closely monitored. Consultation with individual product labeling, as well as relevant institutional protocols, may be advisable for further guidance.
References (20)
- Rosenblatt JE, Lake CR, van Kammen DP, Ziegler MG, Bunney WE Jr (1979) "Interactions of amphetamine, pimozide, and lithium on plasma norepineophrine and dopamine-beta-hydroxylase in schizophrenic patients." Psychiatry Res, 1, p. 45-52
- Cavanaugh JH, Griffith JD, Oates JA (1970) "Effect of amphetamine on the pressor response to tyramine: formation of p-hydroxynorephedrine from amphetamine in man." Clin Pharmacol Ther, 11, p. 656
- (2001) "Product Information. Adderall (amphetamine-dextroamphetamine)." Shire Richwood Pharmaceutical Company Inc
- (2001) "Product Information. Tenuate (diethylpropion)." Aventis Pharmaceuticals
- (2001) "Product Information. Sanorex (mazindol)." Novartis Pharmaceuticals
- (2001) "Product Information. Focalin (dexmethylphenidate)." Mikart Inc
- (2024) "Product Information. Ephedrine (ephedrine)." Hameln Pharma Ltd
- (2023) "Product Information. Ephedrine Hydrochloride (ephedrine)." Wockhardt UK Ltd
- (2026) "Product Information. Strattera (atomoxetine)." Lilly, Eli and Company
- (2025) "Product Information. Atomoxetine (atomoxetine)." Zentiva Pharma UK Ltd
- (2026) "Product Information. Atomoxetine (Apo) (atomoxetine)." Arrotex Pharmaceuticals Pty Ltd
- Angita Pharma, Inc (2026) AG-ATOMOXETINE Product Monograph (Health Canada) https://pdf.hres.ca/dpd_pm/00059014.PDF
- (2026) "Product Information. Boots Decongestant (Pseudoephedrine) (pseudoephedrine)." The Boots Company Plc
- (2023) "Product Information. Sinus and Nasal Decongestant (Trust) (pseudoephedrine)." Noumed Pharmaceuticals Pty Ltd
- (2019) "Product Information. Ephedrine (ephedrine)." Pfizer Australia Pty Ltd
- (2024) "Product Information. EPHEDrine Sulfate (ePHEDrine)." Amneal Pharmaceuticals LLC
- (2024) "Product Information. Lemsip Cough Max for Mucus Cough and Cold (guaifenesin/paracetamol/phenylephrine)." Reckitt Benckiser Healthcare (UK) Ltd
- emc (2026) Product information: sudafed plus blocked nose 1mg/50mg/ml nasal spray. https://www.medicines.org.uk/emc/product/14256/smpc?utm_source=chatgpt.com
- (2023) "Product Information. EPHEDrine Sulfate (ePHEDrine)." Baxter Corporation
- Neo Health (OTC) Pty Ltd (2026) Product information: pseudoephedrine hydrochloride-paracetamol capsules. https://www.ebs.tga.gov.au/ebs/picmi/picmirepository.nsf/pdf?OpenAgent&id=CP-2024-PI-02603-1&d=20260804172310101&d=20260827172310101
Food/lifestyle interactions
Moderate food/lifestyle interactions
Moderate:
phendimetrazine Food/Lifestyle
Applies to: phendimetrazine
Generally avoid
Alcohol may potentiate the central nervous system and cardiovascular effects of centrally-acting appetite suppressants. In one study, concurrent administration of methamphetamine (30 mg intravenously) and ethanol (1 gm/kg orally over 30 minutes) increased heart rate by 24 beats/minute compared to methamphetamine alone. This increases cardiac work and myocardial oxygen consumption, which may lead to more adverse cardiovascular effects than either agent alone. Subjective effects of ethanol were diminished in the eight study subjects, but those of methamphetamine were not affected. The pharmacokinetics of methamphetamine were also unaffected except for a decrease in the apparent volume of distribution at steady state.
Management
Concomitant use of centrally-acting appetite suppressants and alcohol should be avoided if possible, especially in patients with a history of cardiovascular disease. Patients should be counselled to avoid hazardous activities requiring complete mental alertness and motor coordination until they know how these agents affect them, and to notify their physician if they experience excessive or prolonged CNS effects that interfere with their normal activities.
References (3)
- Mendelson J, Jones RT, Upton R, Jacob P 3rd (1995) "Methamphetamine and ethanol interactions in humans." Clin Pharmacol Ther, 57, p. 559-68
- (2001) "Product Information. Didrex (benzphetamine)." Pharmacia and Upjohn
- (2012) "Product Information. Suprenza (phentermine)." Akrimax Pharmaceuticals
Moderate:
phenylephrine Caffeine
Applies to: Sitrex (guaifenesin / phenylephrine)
Monitor
Coadministration of two or more sympathomimetic or noradrenergic agents may increase the risk of nervousness, irritability, tachycardia, and/or increased blood pressure. Central nervous system (CNS) stimulants, particularly amphetamines, can potentiate the adrenergic response to vasopressors and other sympathomimetic and/or noradrenergic agents, including norepinephrine transporter inhibitors. Additive increases in blood pressure and heart rate may occur due to enhanced peripheral sympathetic activity.
Management
Caution is advised if two or more sympathomimetic or noradrenergic agents are coadministered. Pulse and blood pressure should be closely monitored. Consultation with individual product labeling, as well as relevant institutional protocols, may be advisable for further guidance.
References (20)
- Rosenblatt JE, Lake CR, van Kammen DP, Ziegler MG, Bunney WE Jr (1979) "Interactions of amphetamine, pimozide, and lithium on plasma norepineophrine and dopamine-beta-hydroxylase in schizophrenic patients." Psychiatry Res, 1, p. 45-52
- Cavanaugh JH, Griffith JD, Oates JA (1970) "Effect of amphetamine on the pressor response to tyramine: formation of p-hydroxynorephedrine from amphetamine in man." Clin Pharmacol Ther, 11, p. 656
- (2001) "Product Information. Adderall (amphetamine-dextroamphetamine)." Shire Richwood Pharmaceutical Company Inc
- (2001) "Product Information. Tenuate (diethylpropion)." Aventis Pharmaceuticals
- (2001) "Product Information. Sanorex (mazindol)." Novartis Pharmaceuticals
- (2001) "Product Information. Focalin (dexmethylphenidate)." Mikart Inc
- (2024) "Product Information. Ephedrine (ephedrine)." Hameln Pharma Ltd
- (2023) "Product Information. Ephedrine Hydrochloride (ephedrine)." Wockhardt UK Ltd
- (2026) "Product Information. Strattera (atomoxetine)." Lilly, Eli and Company
- (2025) "Product Information. Atomoxetine (atomoxetine)." Zentiva Pharma UK Ltd
- (2026) "Product Information. Atomoxetine (Apo) (atomoxetine)." Arrotex Pharmaceuticals Pty Ltd
- Angita Pharma, Inc (2026) AG-ATOMOXETINE Product Monograph (Health Canada) https://pdf.hres.ca/dpd_pm/00059014.PDF
- (2026) "Product Information. Boots Decongestant (Pseudoephedrine) (pseudoephedrine)." The Boots Company Plc
- (2023) "Product Information. Sinus and Nasal Decongestant (Trust) (pseudoephedrine)." Noumed Pharmaceuticals Pty Ltd
- (2019) "Product Information. Ephedrine (ephedrine)." Pfizer Australia Pty Ltd
- (2024) "Product Information. EPHEDrine Sulfate (ePHEDrine)." Amneal Pharmaceuticals LLC
- (2024) "Product Information. Lemsip Cough Max for Mucus Cough and Cold (guaifenesin/paracetamol/phenylephrine)." Reckitt Benckiser Healthcare (UK) Ltd
- emc (2026) Product information: sudafed plus blocked nose 1mg/50mg/ml nasal spray. https://www.medicines.org.uk/emc/product/14256/smpc?utm_source=chatgpt.com
- (2023) "Product Information. EPHEDrine Sulfate (ePHEDrine)." Baxter Corporation
- Neo Health (OTC) Pty Ltd (2026) Product information: pseudoephedrine hydrochloride-paracetamol capsules. https://www.ebs.tga.gov.au/ebs/picmi/picmirepository.nsf/pdf?OpenAgent&id=CP-2024-PI-02603-1&d=20260804172310101&d=20260827172310101
Disease interactions
37 potential interactions Applies to: 27 conditions, including High Blood Pressure, Depression, Type 2 Diabetes, Anxiety and Stress, and Benign Prostatic Hyperplasia.
Alcoholism
Major:
phendimetrazine
Phendimetrazine has a major potential interaction with Alcoholism.
CNS stimulants (especially amphetamines) have a high potential for abuse and misuse, which can lead to development of a substance use disorder, including addiction. Misuse and abuse of CNS stimulants can result in overdose and death; this risk is increased with higher doses or unapproved methods of administration (e.g., snorting, injection). Before prescribing a CNS stimulant, each patient's risk for abuse, misuse, and addiction should be assessed. Throughout therapy, it is recommended to reassess each patient's risk and frequently monitor for signs/symptoms of abuse, misuse, and addiction. Therapy with CNS stimulants should be administered cautiously, if at all, in patients with a history of alcohol or substance abuse. The use of some agents is contraindicated in patients with a history of drug abuse.
Anxiety and Stress
Major:
phendimetrazine
Phendimetrazine has a major potential interaction with Anxiety and Stress.
Some CNS stimulants are contraindicated in patients with marked agitation and/or anxiety since these symptoms may be aggravated. CNS stimulants may also exacerbate symptoms of behavior disturbance and thought disorder in psychotic patients, particularly children. Therapy with CNS stimulants should be administered cautiously in patients with a history of psychosis or a predisposition to agitated states.
Benign Prostatic Hyperplasia
Moderate:
Sitrex
The phenylephrine in Sitrex has a moderate potential interaction with Benign Prostatic Hyperplasia.
Sympathomimetic agents may cause or worsen urinary difficulty in patients with prostate enlargement due to smooth muscle contraction in the bladder neck via stimulation of alpha-1 adrenergic receptors. Therapy with sympathomimetic agents should be administered cautiously in patients with hypertrophy or neoplasm of the prostate.
Cardiovascular Conditions and Disorders
Major:
phendimetrazine
Phendimetrazine has a major potential interaction with Cardiovascular Conditions and Disorders.
Many amphetamines and amphetamine-like drugs are contraindicated in patients with advanced arteriosclerosis, symptomatic or unstable cardiac or cerebrovascular disease, moderate to severe hypertension, or hyperthyroidism. Like other sympathomimetic amines, amphetamines may cause cardiovascular adverse effects such as palpitation, tachycardia, cardiac arrhythmias, and elevation of blood pressure. Rarely, cardiomyopathy manifested as ventricular hypertrophy and/or congestive heart failure has been reported during chronic amphetamine use. In addition, sudden death has been reported in association with amphetamine therapy at usual dosages in children with structural cardiac abnormalities. In general, amphetamines should not be used in patients with structural cardiac abnormalities. If not otherwise contraindicated, therapy with amphetamines should be administered cautiously in patients with a current or past history of cardiovascular or cerebrovascular disease.
Major:
Sitrex
The phenylephrine in Sitrex has a major potential interaction with Cardiovascular Conditions and Disorders.
Sympathomimetic agents may cause adverse cardiovascular effects, particularly when used in high dosages and/or in susceptible patients. In cardiac tissues, these agents may produce positive chronotropic and inotropic effects via stimulation of beta- 1 adrenergic receptors. Cardiac output, oxygen consumption, and the work of the heart may be increased. In the peripheral vasculature, vasoconstriction may occur via stimulation of alpha-1 adrenergic receptors. Palpitations, tachycardia, arrhythmia, hypertension, reflex bradycardia, coronary occlusion, cerebral vasculitis, myocardial infarction, cardiac arrest, and death have been reported. Some of these agents, particularly ephedra alkaloids (ephedrine, ma huang, phenylpropanolamine), may also predispose patients to hemorrhagic and ischemic stroke. Therapy with sympathomimetic agents should generally be avoided or administered cautiously in patients with sensitivity to sympathomimetic amines, hyperthyroidism, or underlying cardiovascular or cerebrovascular disorders. These agents should not be used in patients with severe coronary artery disease or severe/uncontrolled hypertension.
Cerebral Vascular Disorder
Major:
phendimetrazine
Phendimetrazine has a major potential interaction with Cerebral Vascular Disorder.
Many amphetamines and amphetamine-like drugs are contraindicated in patients with advanced arteriosclerosis, symptomatic or unstable cardiac or cerebrovascular disease, moderate to severe hypertension, or hyperthyroidism. Like other sympathomimetic amines, amphetamines may cause cardiovascular adverse effects such as palpitation, tachycardia, cardiac arrhythmias, and elevation of blood pressure. Rarely, cardiomyopathy manifested as ventricular hypertrophy and/or congestive heart failure has been reported during chronic amphetamine use. In addition, sudden death has been reported in association with amphetamine therapy at usual dosages in children with structural cardiac abnormalities. In general, amphetamines should not be used in patients with structural cardiac abnormalities. If not otherwise contraindicated, therapy with amphetamines should be administered cautiously in patients with a current or past history of cardiovascular or cerebrovascular disease.
Cerebrovascular Insufficiency
Major:
Sitrex
The phenylephrine in Sitrex has a major potential interaction with Cerebrovascular Insufficiency.
Sympathomimetic agents may cause adverse cardiovascular effects, particularly when used in high dosages and/or in susceptible patients. In cardiac tissues, these agents may produce positive chronotropic and inotropic effects via stimulation of beta- 1 adrenergic receptors. Cardiac output, oxygen consumption, and the work of the heart may be increased. In the peripheral vasculature, vasoconstriction may occur via stimulation of alpha-1 adrenergic receptors. Palpitations, tachycardia, arrhythmia, hypertension, reflex bradycardia, coronary occlusion, cerebral vasculitis, myocardial infarction, cardiac arrest, and death have been reported. Some of these agents, particularly ephedra alkaloids (ephedrine, ma huang, phenylpropanolamine), may also predispose patients to hemorrhagic and ischemic stroke. Therapy with sympathomimetic agents should generally be avoided or administered cautiously in patients with sensitivity to sympathomimetic amines, hyperthyroidism, or underlying cardiovascular or cerebrovascular disorders. These agents should not be used in patients with severe coronary artery disease or severe/uncontrolled hypertension.
Depression
Major:
phendimetrazine
Phendimetrazine has a major potential interaction with Depression.
The use of CNS stimulants can cause psychotic symptoms, suicidal ideation, and aggression, and can exacerbate symptoms of behavior disturbance and thought disorder; CNS stimulants may induce a manic or mixed episode in patients with bipolar disorder. Psychiatric symptoms have been reported in patients with and without history of psychiatric disorders. All patients (particularly those with psychotic or bipolar disorders) should be monitored closely, especially during treatment initiation and at times of dose changes. Extreme caution should be exercised when CNS stimulants are given to patients with a history of psychosis, depression, mania, or bipolar disorder. Prior to initiating therapy, all patients should be screened for risk factors for developing a manic episode (e.g., comorbid or history of depressive symptoms or family history of suicide, bipolar disease, or depression). If any psychiatric symptoms emerge or are exacerbated, treatment suspension should be considered. Some CNS stimulants are contraindicated in patients with marked agitation or anxiety.
Diabetes Mellitus
Moderate:
phendimetrazine
Phendimetrazine has a moderate potential interaction with Diabetes Mellitus.
Insulin requirements in patients with diabetes mellitus may be altered in association with the use of some centrally-acting anorexiants and concomitant dietary restrictions. Caution and monitoring is recommended in patients with diabetes.
Moderate:
Sitrex
The phenylephrine in Sitrex has a moderate potential interaction with Diabetes Mellitus.
Sympathomimetic agents may cause increases in blood glucose concentrations. These effects are usually transient and slight but may be significant with dosages higher than those normally recommended. Therapy with sympathomimetic agents should be administered cautiously in patients with diabetes mellitus. Closer monitoring of blood glucose concentrations may be appropriate.
Drug Dependence
Major:
phendimetrazine
Phendimetrazine has a major potential interaction with Drug Dependence.
CNS stimulants (especially amphetamines) have a high potential for abuse and misuse, which can lead to development of a substance use disorder, including addiction. Misuse and abuse of CNS stimulants can result in overdose and death; this risk is increased with higher doses or unapproved methods of administration (e.g., snorting, injection). Before prescribing a CNS stimulant, each patient's risk for abuse, misuse, and addiction should be assessed. Throughout therapy, it is recommended to reassess each patient's risk and frequently monitor for signs/symptoms of abuse, misuse, and addiction. Therapy with CNS stimulants should be administered cautiously, if at all, in patients with a history of alcohol or substance abuse. The use of some agents is contraindicated in patients with a history of drug abuse.
Glaucoma/Intraocular Hypertension
Major:
phendimetrazine
Phendimetrazine has a major potential interaction with Glaucoma/Intraocular Hypertension.
Some amphetamines and amphetamine-like drugs are contraindicated in patients with narrow-angle glaucoma or anatomically narrow angles. Like other sympathomimetic amines, amphetamines can induce transient mydriasis. In patients with narrow angles, pupillary dilation can provoke an acute attack of angle-closure glaucoma. If possible, these agents should also be avoided in patients with other forms of glaucoma since mydriasis may occasionally increase intraocular pressure.
Major:
phendimetrazine
Phendimetrazine has a major potential interaction with Glaucoma/Intraocular Hypertension.
The use of most CNS stimulants is contraindicated in patients with glaucoma, as these agents exhibit sympathomimetic activity and may induce mydriasis provoking an increase in intraocular pressure.
Moderate:
Sitrex
The phenylephrine in Sitrex has a moderate potential interaction with Glaucoma/Intraocular Hypertension.
Sympathomimetic agents can induce transient mydriasis via stimulation of alpha-1 adrenergic receptors. In patients with anatomically narrow angles or narrow-angle glaucoma, pupillary dilation can provoke an acute attack. In patients with other forms of glaucoma, mydriasis may occasionally increase intraocular pressure. Therapy with sympathomimetic agents should be administered cautiously in patients with or predisposed to glaucoma, particularly narrow-angle glaucoma.
Heart Disease
Major:
phendimetrazine
Phendimetrazine has a major potential interaction with Heart Disease.
Many CNS stimulants are contraindicated in patients with significant cardiovascular impairment such as uncompensated heart failure, severe coronary disease, severe hypertension (including that associated with hyperthyroidism or pheochromocytoma), cardiac structural abnormalities, serious arrhythmias, etc. Sudden death has been reported in patients with structural cardiac abnormalities or other serious cardiac disease who are treated with CNS stimulants at the recommended dosages for attention deficit hyperactivity disorder; use of these agents should be avoided in patients with known structural cardiac abnormalities, cardiomyopathy, serious cardiac arrhythmia, coronary artery disease, or other serious cardiac disease. Additionally, stroke, myocardial infarction, chest pain, syncope, arrhythmias, and other symptoms have been reported in adults under treatment. A careful assessment of the cardiovascular status should be done in patients being considered for treatment. This includes family history, physical exam, and further cardiac evaluation (EKG and echocardiogram). Patients who develop symptoms should have a detailed cardiac evaluation and if needed, treatment should be suspended.
Major:
phendimetrazine
Phendimetrazine has a major potential interaction with Heart Disease.
Many amphetamines and amphetamine-like drugs are contraindicated in patients with advanced arteriosclerosis, symptomatic or unstable cardiac or cerebrovascular disease, moderate to severe hypertension, or hyperthyroidism. Like other sympathomimetic amines, amphetamines may cause cardiovascular adverse effects such as palpitation, tachycardia, cardiac arrhythmias, and elevation of blood pressure. Rarely, cardiomyopathy manifested as ventricular hypertrophy and/or congestive heart failure has been reported during chronic amphetamine use. In addition, sudden death has been reported in association with amphetamine therapy at usual dosages in children with structural cardiac abnormalities. In general, amphetamines should not be used in patients with structural cardiac abnormalities. If not otherwise contraindicated, therapy with amphetamines should be administered cautiously in patients with a current or past history of cardiovascular or cerebrovascular disease.
High Blood Pressure
Major:
phendimetrazine
Phendimetrazine has a major potential interaction with High Blood Pressure.
Many CNS stimulants are contraindicated in patients with significant cardiovascular impairment such as uncompensated heart failure, severe coronary disease, severe hypertension (including that associated with hyperthyroidism or pheochromocytoma), cardiac structural abnormalities, serious arrhythmias, etc. Sudden death has been reported in patients with structural cardiac abnormalities or other serious cardiac disease who are treated with CNS stimulants at the recommended dosages for attention deficit hyperactivity disorder; use of these agents should be avoided in patients with known structural cardiac abnormalities, cardiomyopathy, serious cardiac arrhythmia, coronary artery disease, or other serious cardiac disease. Additionally, stroke, myocardial infarction, chest pain, syncope, arrhythmias, and other symptoms have been reported in adults under treatment. A careful assessment of the cardiovascular status should be done in patients being considered for treatment. This includes family history, physical exam, and further cardiac evaluation (EKG and echocardiogram). Patients who develop symptoms should have a detailed cardiac evaluation and if needed, treatment should be suspended.
Major:
phendimetrazine
Phendimetrazine has a major potential interaction with High Blood Pressure.
CNS stimulants increase blood pressure and heart rate; the use of some agents may be contraindicated in patients with severe/uncontrolled hypertension. Caution should be used when administering to patients with preexisting high blood pressure (even mild hypertension) and other cardiovascular conditions. All patients under treatment should be regularly monitored for potential tachycardia and hypertension.
History - Cerebrovascular Disease
Major:
phendimetrazine
Phendimetrazine has a major potential interaction with History - Cerebrovascular Disease.
Many amphetamines and amphetamine-like drugs are contraindicated in patients with advanced arteriosclerosis, symptomatic or unstable cardiac or cerebrovascular disease, moderate to severe hypertension, or hyperthyroidism. Like other sympathomimetic amines, amphetamines may cause cardiovascular adverse effects such as palpitation, tachycardia, cardiac arrhythmias, and elevation of blood pressure. Rarely, cardiomyopathy manifested as ventricular hypertrophy and/or congestive heart failure has been reported during chronic amphetamine use. In addition, sudden death has been reported in association with amphetamine therapy at usual dosages in children with structural cardiac abnormalities. In general, amphetamines should not be used in patients with structural cardiac abnormalities. If not otherwise contraindicated, therapy with amphetamines should be administered cautiously in patients with a current or past history of cardiovascular or cerebrovascular disease.
History - Myocardial Infarction
Major:
phendimetrazine
Phendimetrazine has a major potential interaction with History - Myocardial Infarction.
Many amphetamines and amphetamine-like drugs are contraindicated in patients with advanced arteriosclerosis, symptomatic or unstable cardiac or cerebrovascular disease, moderate to severe hypertension, or hyperthyroidism. Like other sympathomimetic amines, amphetamines may cause cardiovascular adverse effects such as palpitation, tachycardia, cardiac arrhythmias, and elevation of blood pressure. Rarely, cardiomyopathy manifested as ventricular hypertrophy and/or congestive heart failure has been reported during chronic amphetamine use. In addition, sudden death has been reported in association with amphetamine therapy at usual dosages in children with structural cardiac abnormalities. In general, amphetamines should not be used in patients with structural cardiac abnormalities. If not otherwise contraindicated, therapy with amphetamines should be administered cautiously in patients with a current or past history of cardiovascular or cerebrovascular disease.
Hyperthyroidism
Major:
phendimetrazine
Phendimetrazine has a major potential interaction with Hyperthyroidism.
Many CNS stimulants are contraindicated in patients with significant cardiovascular impairment such as uncompensated heart failure, severe coronary disease, severe hypertension (including that associated with hyperthyroidism or pheochromocytoma), cardiac structural abnormalities, serious arrhythmias, etc. Sudden death has been reported in patients with structural cardiac abnormalities or other serious cardiac disease who are treated with CNS stimulants at the recommended dosages for attention deficit hyperactivity disorder; use of these agents should be avoided in patients with known structural cardiac abnormalities, cardiomyopathy, serious cardiac arrhythmia, coronary artery disease, or other serious cardiac disease. Additionally, stroke, myocardial infarction, chest pain, syncope, arrhythmias, and other symptoms have been reported in adults under treatment. A careful assessment of the cardiovascular status should be done in patients being considered for treatment. This includes family history, physical exam, and further cardiac evaluation (EKG and echocardiogram). Patients who develop symptoms should have a detailed cardiac evaluation and if needed, treatment should be suspended.
Major:
phendimetrazine
Phendimetrazine has a major potential interaction with Hyperthyroidism.
Many amphetamines and amphetamine-like drugs are contraindicated in patients with advanced arteriosclerosis, symptomatic or unstable cardiac or cerebrovascular disease, moderate to severe hypertension, or hyperthyroidism. Like other sympathomimetic amines, amphetamines may cause cardiovascular adverse effects such as palpitation, tachycardia, cardiac arrhythmias, and elevation of blood pressure. Rarely, cardiomyopathy manifested as ventricular hypertrophy and/or congestive heart failure has been reported during chronic amphetamine use. In addition, sudden death has been reported in association with amphetamine therapy at usual dosages in children with structural cardiac abnormalities. In general, amphetamines should not be used in patients with structural cardiac abnormalities. If not otherwise contraindicated, therapy with amphetamines should be administered cautiously in patients with a current or past history of cardiovascular or cerebrovascular disease.
Major:
Sitrex
The phenylephrine in Sitrex has a major potential interaction with Hyperthyroidism.
Sympathomimetic agents may cause adverse cardiovascular effects, particularly when used in high dosages and/or in susceptible patients. In cardiac tissues, these agents may produce positive chronotropic and inotropic effects via stimulation of beta- 1 adrenergic receptors. Cardiac output, oxygen consumption, and the work of the heart may be increased. In the peripheral vasculature, vasoconstriction may occur via stimulation of alpha-1 adrenergic receptors. Palpitations, tachycardia, arrhythmia, hypertension, reflex bradycardia, coronary occlusion, cerebral vasculitis, myocardial infarction, cardiac arrest, and death have been reported. Some of these agents, particularly ephedra alkaloids (ephedrine, ma huang, phenylpropanolamine), may also predispose patients to hemorrhagic and ischemic stroke. Therapy with sympathomimetic agents should generally be avoided or administered cautiously in patients with sensitivity to sympathomimetic amines, hyperthyroidism, or underlying cardiovascular or cerebrovascular disorders. These agents should not be used in patients with severe coronary artery disease or severe/uncontrolled hypertension.
Liver Disease
Moderate:
phendimetrazine
Phendimetrazine has a moderate potential interaction with Liver Disease.
In general, CNS stimulants are extensively metabolized by the liver. Their plasma clearance may be decreased and their half-life prolonged in patients with impaired hepatic function. Therapy with CNS stimulants should be administered cautiously in patients with moderate to severe liver disease, and the dosage should be adjusted accordingly in certain agents. Additionally, postmarketing reports have shown that atomoxetine can cause severe liver injury; laboratory testing should be done at the first sign/symptom of liver dysfunction (jaundice, dark urine, upper quadrant tenderness) and treatment should be discontinued in patients with evidence of liver injury.
Neurosis
Major:
phendimetrazine
Phendimetrazine has a major potential interaction with Neurosis.
Some CNS stimulants are contraindicated in patients with marked agitation and/or anxiety since these symptoms may be aggravated. CNS stimulants may also exacerbate symptoms of behavior disturbance and thought disorder in psychotic patients, particularly children. Therapy with CNS stimulants should be administered cautiously in patients with a history of psychosis or a predisposition to agitated states.
Peripheral Arterial Disease
Major:
phendimetrazine
Phendimetrazine has a major potential interaction with Peripheral Arterial Disease.
Many CNS stimulants are contraindicated in patients with significant cardiovascular impairment such as uncompensated heart failure, severe coronary disease, severe hypertension (including that associated with hyperthyroidism or pheochromocytoma), cardiac structural abnormalities, serious arrhythmias, etc. Sudden death has been reported in patients with structural cardiac abnormalities or other serious cardiac disease who are treated with CNS stimulants at the recommended dosages for attention deficit hyperactivity disorder; use of these agents should be avoided in patients with known structural cardiac abnormalities, cardiomyopathy, serious cardiac arrhythmia, coronary artery disease, or other serious cardiac disease. Additionally, stroke, myocardial infarction, chest pain, syncope, arrhythmias, and other symptoms have been reported in adults under treatment. A careful assessment of the cardiovascular status should be done in patients being considered for treatment. This includes family history, physical exam, and further cardiac evaluation (EKG and echocardiogram). Patients who develop symptoms should have a detailed cardiac evaluation and if needed, treatment should be suspended.
Pheochromocytoma
Major:
phendimetrazine
Phendimetrazine has a major potential interaction with Pheochromocytoma.
Many CNS stimulants are contraindicated in patients with significant cardiovascular impairment such as uncompensated heart failure, severe coronary disease, severe hypertension (including that associated with hyperthyroidism or pheochromocytoma), cardiac structural abnormalities, serious arrhythmias, etc. Sudden death has been reported in patients with structural cardiac abnormalities or other serious cardiac disease who are treated with CNS stimulants at the recommended dosages for attention deficit hyperactivity disorder; use of these agents should be avoided in patients with known structural cardiac abnormalities, cardiomyopathy, serious cardiac arrhythmia, coronary artery disease, or other serious cardiac disease. Additionally, stroke, myocardial infarction, chest pain, syncope, arrhythmias, and other symptoms have been reported in adults under treatment. A careful assessment of the cardiovascular status should be done in patients being considered for treatment. This includes family history, physical exam, and further cardiac evaluation (EKG and echocardiogram). Patients who develop symptoms should have a detailed cardiac evaluation and if needed, treatment should be suspended.
Major:
Sitrex
The phenylephrine in Sitrex has a major potential interaction with Pheochromocytoma.
Sympathomimetic agents may cause adverse cardiovascular effects, particularly when used in high dosages and/or in susceptible patients. In cardiac tissues, these agents may produce positive chronotropic and inotropic effects via stimulation of beta- 1 adrenergic receptors. Cardiac output, oxygen consumption, and the work of the heart may be increased. In the peripheral vasculature, vasoconstriction may occur via stimulation of alpha-1 adrenergic receptors. Palpitations, tachycardia, arrhythmia, hypertension, reflex bradycardia, coronary occlusion, cerebral vasculitis, myocardial infarction, cardiac arrest, and death have been reported. Some of these agents, particularly ephedra alkaloids (ephedrine, ma huang, phenylpropanolamine), may also predispose patients to hemorrhagic and ischemic stroke. Therapy with sympathomimetic agents should generally be avoided or administered cautiously in patients with sensitivity to sympathomimetic amines, hyperthyroidism, or underlying cardiovascular or cerebrovascular disorders. These agents should not be used in patients with severe coronary artery disease or severe/uncontrolled hypertension.
Prostate Tumor, Benign
Moderate:
Sitrex
The phenylephrine in Sitrex has a moderate potential interaction with Prostate Tumor, Benign.
Sympathomimetic agents may cause or worsen urinary difficulty in patients with prostate enlargement due to smooth muscle contraction in the bladder neck via stimulation of alpha-1 adrenergic receptors. Therapy with sympathomimetic agents should be administered cautiously in patients with hypertrophy or neoplasm of the prostate.
Psychosis
Major:
phendimetrazine
Phendimetrazine has a major potential interaction with Psychosis.
The use of CNS stimulants can cause psychotic symptoms, suicidal ideation, and aggression, and can exacerbate symptoms of behavior disturbance and thought disorder; CNS stimulants may induce a manic or mixed episode in patients with bipolar disorder. Psychiatric symptoms have been reported in patients with and without history of psychiatric disorders. All patients (particularly those with psychotic or bipolar disorders) should be monitored closely, especially during treatment initiation and at times of dose changes. Extreme caution should be exercised when CNS stimulants are given to patients with a history of psychosis, depression, mania, or bipolar disorder. Prior to initiating therapy, all patients should be screened for risk factors for developing a manic episode (e.g., comorbid or history of depressive symptoms or family history of suicide, bipolar disease, or depression). If any psychiatric symptoms emerge or are exacerbated, treatment suspension should be considered. Some CNS stimulants are contraindicated in patients with marked agitation or anxiety.
Major:
phendimetrazine
Phendimetrazine has a major potential interaction with Psychosis.
Some CNS stimulants are contraindicated in patients with marked agitation and/or anxiety since these symptoms may be aggravated. CNS stimulants may also exacerbate symptoms of behavior disturbance and thought disorder in psychotic patients, particularly children. Therapy with CNS stimulants should be administered cautiously in patients with a history of psychosis or a predisposition to agitated states.
Renal Dysfunction
Moderate:
phendimetrazine
Phendimetrazine has a moderate potential interaction with Renal Dysfunction.
Overall CNS stimulants should be administered with caution in patients with significantly impaired renal function as the reduction in the rate of elimination may alter the therapeutic response. The dosage should be adjusted accordingly in certain agents.
Seizures
Moderate:
phendimetrazine
Phendimetrazine has a moderate potential interaction with Seizures.
Due to general central nervous system stimulation, therapy with CNS stimulant drugs may cause seizures. These drugs may lower the convulsive threshold in patients with history of seizures, with prior electroencephalogram (EEG) abnormalities without seizures, and very rarely, without history of seizures and no prior EEG evidence of seizures. Therapy with CNS stimulants should be used with caution in patients with or predisposed to seizures. If seizures occur, therapy should be discontinued.
Syncope
Major:
phendimetrazine
Phendimetrazine has a major potential interaction with Syncope.
The use of some CNS stimulants has been associated with an increased risk of developing pulmonary hypertension, a rare but fatal disorder. The onset or aggravation of exertional dyspnea, or unexplained symptoms of angina pectoris, syncope, or lower extremity edema suggest the possibility of occurrence of pulmonary hypertension. Under these circumstances, treatment must be immediately discontinued, and the patient should be evaluated to confirm diagnosis. Caution should be exercised in patients with preexisting valvular heart disease or history of pulmonary hypertension. These drugs are not recommended in patients with known heart murmur or valvular heart disease.
Tic Disorder
Major:
phendimetrazine
Phendimetrazine has a major potential interaction with Tic Disorder.
CNS stimulants have been reported to worsen Tourette's syndrome and exacerbate motor and verbal tics. Before initiating therapy, it is recommended to assess family history and clinically evaluate patients for tics or Tourette's syndrome. Therapy with CNS stimulants, if necessary, should be administered cautiously in patients with tic disorders or family history of Tourette's syndrome. The manufacturers of the CNS stimulants, methylphenidate (racemic) and dexmethylphenidate (the more pharmacologically active d-enantiomer), consider their use to be contraindicated in such patients.
Type 2 Diabetes
Moderate:
phendimetrazine
Phendimetrazine has a moderate potential interaction with Type 2 Diabetes.
Obese, type 2 diabetic patients who achieve weight loss may demonstrate improved metabolic control of their disease as a result of their reduced weight. Therefore, patients with type 2 diabetes mellitus should be monitored during weight-reduction therapy (or therapy that may be expected to induce significant weight loss as a secondary effect) for hypoglycemia and reduced need for oral hypoglycemic medication or insulin, and the dosages of these agents adjusted accordingly. Patients should be apprised of the risk of hypoglycemia and be alert to potential signs and symptoms such as headache, dizziness, drowsiness, nervousness, confusion, tremor, hunger, weakness, perspiration, and palpitation.
Valvular Heart Disease
Major:
phendimetrazine
Phendimetrazine has a major potential interaction with Valvular Heart Disease.
The use of some CNS stimulants has been associated with an increased risk of developing pulmonary hypertension, a rare but fatal disorder. The onset or aggravation of exertional dyspnea, or unexplained symptoms of angina pectoris, syncope, or lower extremity edema suggest the possibility of occurrence of pulmonary hypertension. Under these circumstances, treatment must be immediately discontinued, and the patient should be evaluated to confirm diagnosis. Caution should be exercised in patients with preexisting valvular heart disease or history of pulmonary hypertension. These drugs are not recommended in patients with known heart murmur or valvular heart disease.
More resources
phendimetrazine
A total of 189 drugs are known to interact with phendimetrazine.
- Phendimetrazine is in the following drug classes: anorexiants, CNS stimulants.
- Phendimetrazine is used to treat Weight Loss.
Sitrex
A total of 228 drugs are known to interact with Sitrex.
- Sitrex is in the drug class upper respiratory combinations.
- Sitrex is used to treat the following conditions:
Drug Interaction Classification
| Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit. | |
| Moderately clinically significant. Usually avoid combinations; use it only under special circumstances. | |
| Minimally clinically significant. Minimize risk; assess risk and consider an alternative drug, take steps to circumvent the interaction risk and/or institute a monitoring plan. | |
| No interaction information available. |
Further information
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