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Interactions between Aldex-CT and Levodopa

2 drug interactions and 39 additional warnings found for the following 2 drugs:

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Drug interactions

Moderate drug interactions

Moderate:

diphenhydrAMINE levodopa

Applies to: Aldex-CT (diphenhydramine / phenylephrine) and levodopa
Monitor

Central nervous system- and/or respiratory-depressant effects may be additively or synergistically increased in patients taking multiple drugs that cause these effects, especially in elderly or debilitated patients. Sedation and impairment of attention, judgment, thinking, and psychomotor skills may increase.

Management

During concomitant use of these drugs, patients should be monitored for potentially excessive or prolonged CNS and respiratory depression. Cautious dosage titration may be required, particularly at treatment initiation. Ambulatory patients should be counseled to avoid hazardous activities requiring 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 (36)
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  2. Stambaugh JE, Lane C (1983) "Analgesic efficacy and pharmacokinetic evaluation of meperidine and hydroxyzine, alone and in combination." Cancer Invest, 1, p. 111-7
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  7. Divoll M, Greenblatt DJ, Lacasse Y, Shader RI (1981) "Benzodiazepine overdosage: plasma concentrations and clinical outcome." Psychopharmacology (Berl), 73, p. 381-3
  8. Naylor GJ, McHarg A (1977) "Profound hypothermia on combined lithium carbonate and diazepam treatment." Br Med J, 2, p. 22
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  11. Feldman SA, Crawley BE (1970) "Interaction of diazepam with the muscle-relaxant drugs." Br Med J, 1, p. 336-8
  12. Ochs HR, Greenblatt DJ, Verburg-Ochs B (1984) "Propranolol interactions with diazepam, lorazepam and alprazolam." Clin Pharmacol Ther, 36, p. 451-5
  13. Desager JP, Hulhoven R, Harvengt C, Hermann P, Guillet P, Thiercelin JF (1988) "Possible interactions between zolpidem, a new sleep inducer and chlorpromazine, a phenothiazine neuroleptic." Psychopharmacology (Berl), 96, p. 63-6
  14. Tverskoy M, Fleyshman G, Ezry J, Bradley EL, Jr Kissin I (1989) "Midazolam-morphine sedative interaction in patients." Anesth Analg, 68, p. 282-5
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  18. Markowitz JS, Wells BG, Carson WH (1995) "Interactions between antipsychotic and antihypertensive drugs." Ann Pharmacother, 29, p. 603-9
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  33. Cerner Multum, Inc. "Australian Product Information."
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  36. (2015) "Product Information. Rexulti (brexpiprazole)." Otsuka America Pharmaceutical, Inc.
Moderate:

levodopa phenylephrine

Applies to: levodopa and Aldex-CT (diphenhydramine / phenylephrine)
Generally avoid

Coadministration with levodopa may potentiate the cardiovascular effects of sympathomimetic agents (e.g., epinephrine, norepinephrine, isoproterenol, amphetamine). Additive increases in blood pressure and heart rate may occur due to enhanced sympathetic activity. However, data evaluating the interaction are not available.

Management

The use of levodopa with sympathomimetic agents should generally be avoided. If concomitant use is required, close monitoring of the cardiovascular system is recommended and the dose of the sympathomimetic agent may need to be reduced.

References (2)
  1. Cerner Multum, Inc. "UK Summary of Product Characteristics."
  2. Cerner Multum, Inc. "Australian Product Information."

Food/lifestyle interactions

Moderate food/lifestyle interactions

Moderate:

levodopa Food/Lifestyle

Applies to: levodopa
Generally avoid

Alcohol may potentiate some of the pharmacologic effects of levodopa. Use in combination may result in additive central nervous system depression and/or impairment of judgment, thinking, and psychomotor skills.

Monitor

Limited clinical data suggest that high protein content in the diet may reduce or cause fluctuations in the clinical response to oral and enteral formulations of levodopa in patients with Parkinson's disease. Proposed mechanisms include delayed gastric emptying, decreased levodopa absorption when taken with a protein rich diet, and competition with certain amino acids for transport across the gut wall and/or the blood brain barrier. Data have been conflicting. Clinical studies have variously reported no effect, reduced levodopa absorption with low-protein meals, reduced effects of oral and enteral formulations of levodopa with high daily protein intake, and no differences compared to fasting with high-protein meals. Neuroleptic malignant-like symptoms were reported in a patient with Parkinson's disease who was receiving pramipexole, entacapone, and immediate-release levodopa/carbidopa, after the protein content of his enteral feedings via nasogastric tube was increased from 0.88 g/kg/day to 1.8 g/kg/day; symptoms improved after the protein was reduced to 1 g/kg/day and bromocriptine was administered. Another patient receiving immediate-release carbidopa/levodopa, pramipexole, and entacapone experienced severe rigidity after initiation of continuous enteral nutrition via oral gastric tube containing 1.4 g/kg/day of protein; his Parkinsonian symptoms improved after the protein content was reduced to 0.9 g/kg/day, the feeding was changed to bolus feedings, and the levodopa was administered between boluses.

Management

In general, alcohol consumption should be avoided or limited during treatment with CNS-depressant agents. Until more data are available, it is advisable to avoid large fluctuations in daily protein intake and to monitor patients for altered effects of oral and enteral levodopa formulations if the protein content of the diet is increased.

References (7)
  1. Cerner Multum, Inc. "UK Summary of Product Characteristics."
  2. Wohlt PD, Zheng L, Gunderson S, Balzar SA, Johnson BD, Fish JT (2009) "Recommendations for the use of medications with continuous enteral nutrition." Am J Health Syst Pharm, 66, p. 1438-67
  3. (2022) "Product Information. Duopa (carbidopa-levodopa)." AbbVie US LLC
  4. (2021) "Product Information. Duodopa (carbidopa-levodopa)." AbbVie Pty Ltd, 18
  5. (2023) "Product Information. Vyalev (foscarbidopa-foslevodopa)." AbbVie Corporation
  6. (2022) "Product Information. Dhivy (carbidopa-levodopa)." Avion Pharmaceuticals
  7. (2024) "Product Information. Vyalev (foscarbidopa-foslevodopa)." AbbVie US LLC
Moderate:

diphenhydrAMINE Alcohol (Ethanol)

Applies to: Aldex-CT (diphenhydramine / phenylephrine)
Generally avoid

Use of anticholinergic agents with alcohol may result in sufficient impairment of attention so as to render driving and operating machinery more hazardous. In addition, the potential for abuse may be increased with the combination. The mechanism of interaction is not established but may involve additive depressant effects on the central nervous system. No effect of oral propantheline or atropine on blood alcohol levels was observed in healthy volunteers when administered before ingestion of a standard ethanol load. However, one study found impairment of attention in subjects given atropine 0.5 mg or glycopyrrolate 1 mg in combination with alcohol.

Management

Alcohol should generally be avoided during therapy with anticholinergic agents. Patients should be counseled to avoid activities requiring mental alertness until they know how these agents affect them.

References (1)
  1. Linnoila M (1973) "Drug effects on psychomotor skills related to driving: interaction of atropine, glycopyrrhonium and alcohol." Eur J Clin Pharmacol, 6, p. 107-12
Moderate:

levodopa multivitamins with minerals

Applies to: levodopa
Adjust dosing interval

The oral bioavailability and pharmacologic effects of levodopa and carbidopa may be decreased during concurrent administration with iron-containing products. The proposed mechanism is chelation of levodopa and carbidopa by the iron cation, forming an insoluble complex that is poorly absorbed from the gastrointestinal tract. In nine patients with Parkinson's disease, administration of levodopa-carbidopa 100 mg-25 mg with ferrous sulfate 325 mg decreased levodopa peak plasma concentration (Cmax) and systemic exposure (AUC) by 47% and 30%, respectively, and carbidopa Cmax and AUC by 77% and 82%, respectively, compared to administration with placebo. There was also evidence of reduced efficacy of levodopa in some patients. In another study consisting of eight healthy subjects, coadministration of levodopa 250 mg with ferrous sulfate 325 mg resulted in greater than 50% reductions in the Cmax and AUC of levodopa compared to administration of levodopa alone. The magnitude of the interaction was the greatest in patients whose plasma levels of levodopa were the highest following administration of levodopa alone.

Management

Until more information is available, patients receiving levodopa and/or carbidopa in combination with iron-containing products should be advised to separate the times of administration by as much as possible. Patients should be monitored for reduced efficacy of levodopa, and the dosage adjusted as necessary.

References (4)
  1. Campbell NR, Hasinoff B (1989) "Ferrous sulfate reduces levodopa bioavailability: chelation as a possible mechanism." Clin Pharmacol Ther, 45, p. 220-5
  2. Campbell NR, Hasinoff BB (1991) "Iron supplements: a common cause of drug interactions." Br J Clin Pharmacol, 31, p. 251-5
  3. Campbell NR, Rankine D, Goodridge AE, Hasinoff BB, Kara M (1990) "Sinemet-ferrous sulphate interaction in patients with Parkinson's disease." Br J Clin Pharmacol, 30, p. 599-605
  4. Greene RJ, Hall AD, Hider RC (1990) "The interaction of orally administered iron with levodopa and methyldopa therapy." J Pharm Pharmacol, 42, p. 502-4
Moderate:

phenylephrine Caffeine

Applies to: Aldex-CT (diphenhydramine / 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)
  1. 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
  2. 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
  3. (2001) "Product Information. Adderall (amphetamine-dextroamphetamine)." Shire Richwood Pharmaceutical Company Inc
  4. (2001) "Product Information. Tenuate (diethylpropion)." Aventis Pharmaceuticals
  5. (2001) "Product Information. Sanorex (mazindol)." Novartis Pharmaceuticals
  6. (2001) "Product Information. Focalin (dexmethylphenidate)." Mikart Inc
  7. (2024) "Product Information. Ephedrine (ephedrine)." Hameln Pharma Ltd
  8. (2023) "Product Information. Ephedrine Hydrochloride (ephedrine)." Wockhardt UK Ltd
  9. (2026) "Product Information. Strattera (atomoxetine)." Lilly, Eli and Company
  10. (2025) "Product Information. Atomoxetine (atomoxetine)." Zentiva Pharma UK Ltd
  11. (2026) "Product Information. Atomoxetine (Apo) (atomoxetine)." Arrotex Pharmaceuticals Pty Ltd
  12. Angita Pharma, Inc (2026) AG-ATOMOXETINE Product Monograph (Health Canada) https://pdf.hres.ca/dpd_pm/00059014.PDF
  13. (2026) "Product Information. Boots Decongestant (Pseudoephedrine) (pseudoephedrine)." The Boots Company Plc
  14. (2023) "Product Information. Sinus and Nasal Decongestant (Trust) (pseudoephedrine)." Noumed Pharmaceuticals Pty Ltd
  15. (2019) "Product Information. Ephedrine (ephedrine)." Pfizer Australia Pty Ltd
  16. (2024) "Product Information. EPHEDrine Sulfate (ePHEDrine)." Amneal Pharmaceuticals LLC
  17. (2024) "Product Information. Lemsip Cough Max for Mucus Cough and Cold (guaifenesin/paracetamol/phenylephrine)." Reckitt Benckiser Healthcare (UK) Ltd
  18. 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
  19. (2023) "Product Information. EPHEDrine Sulfate (ePHEDrine)." Baxter Corporation
  20. 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

35 potential interactions Applies to: 20 conditions, including Depression, Asthma, Benign Prostatic Hyperplasia, COPD, and Hypotension.

Asthma

Major:

levodopa

Levodopa has a major potential interaction with Asthma.

Because of the risk of bronchospasm, use of levodopa in patients with asthma, COPD, or other chronic underlying lung disease is not recommended.

Moderate:

Aldex-CT

The diphenhydrAMINE in Aldex-CT has a moderate potential interaction with Asthma.

Oral anxiolytic, sedative, and hypnotic agents may cause respiratory depression and apnea when given in high dosages or following acute overdose. However, some patients may be susceptible at commonly used dosages, including the elderly, debilitated or severely ill patients, those receiving other CNS depressants, and those with limited ventilatory reserve, chronic pulmonary insufficiency or other respiratory disorders. Therapy with anxiolytic, sedative, and hypnotic agents should be administered cautiously in these patients. Appropriate monitoring and individualization of dosage are recommended.

Moderate:

Aldex-CT

The diphenhydrAMINE in Aldex-CT has a moderate potential interaction with Asthma.

It has been suggested that the anticholinergic effect of antihistamines may reduce the volume and cause thickening of bronchial secretions, resulting in obstruction of respiratory tract. Some manufacturers and clinicians recommend that therapy with antihistamines be administered cautiously in patients with asthma or chronic obstructive pulmonary disease.

Benign Prostatic Hyperplasia

Moderate:

Aldex-CT

The phenylephrine in Aldex-CT 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:

Aldex-CT

The phenylephrine in Aldex-CT 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.

Major:

levodopa

Levodopa has a major potential interaction with Cardiovascular Conditions and Disorders.

Cardiac irregularities occur infrequently in patients on dopamine agonists. The initial administration and titration is recommended to occur under close cardiac monitoring in a facility equipped for intensive cardiac care. Adverse cardiac affects may include palpitation, sinus tachycardia, ventricular tachycardia, extrasystole, atrial flutter or fibrillation, or block of AV conduction.

Moderate:

Aldex-CT

The diphenhydrAMINE in Aldex-CT has a moderate potential interaction with Cardiovascular Conditions and Disorders.

Antihistamines may infrequently cause cardiovascular adverse effects related to their anticholinergic and local anesthetic (quinidine-like) activities. Tachycardia, palpitation, ECG changes, arrhythmias, hypotension, and hypertension have been reported. Although these effects are uncommon and usually limited to overdosage situations, the manufacturers and some clinicians recommend that therapy with antihistamines be administered cautiously in patients with cardiovascular disease, hypertension, and/or hyperthyroidism.

Cerebrovascular Insufficiency

Major:

Aldex-CT

The phenylephrine in Aldex-CT 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.

COPD

Major:

levodopa

Levodopa has a major potential interaction with COPD.

Because of the risk of bronchospasm, use of levodopa in patients with asthma, COPD, or other chronic underlying lung disease is not recommended.

Moderate:

Aldex-CT

The diphenhydrAMINE in Aldex-CT has a moderate potential interaction with COPD.

It has been suggested that the anticholinergic effect of antihistamines may reduce the volume and cause thickening of bronchial secretions, resulting in obstruction of respiratory tract. Some manufacturers and clinicians recommend that therapy with antihistamines be administered cautiously in patients with asthma or chronic obstructive pulmonary disease.

Depression

Major:

Aldex-CT

The diphenhydrAMINE in Aldex-CT has a major potential interaction with Depression.

A variety of abnormal thinking and behavior changes have been reported to occur in association with the use of most anxiolytics, sedatives and hypnotics. Some of these changes include decreased inhibition, aggressiveness, agitation, and hallucinations. These drugs can cause or exacerbate mental depression and cause suicidal behavior and ideation. Therapy with these drugs should be administered cautiously in patients with a history of depression or other psychiatric disorders. Patients should be monitored for any changes in mood or behavior. It may be prudent to refrain from dispensing large quantities of medication to these patients.

Diabetes Mellitus

Moderate:

Aldex-CT

The phenylephrine in Aldex-CT 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.

Gastrointestinal Hemorrhage

Moderate:

levodopa

Levodopa has a moderate potential interaction with Gastrointestinal Hemorrhage.

The use of levodopa, especially in combinations with carbidopa, has been associated with an increase in the frequency of gastrointestinal hemorrhage. Therapy with levodopa should be administered cautiously in patients with a history of peptic ulcer disease or gastrointestinal hemorrhage.

Gastrointestinal Obstruction

Moderate:

Aldex-CT

The diphenhydrAMINE in Aldex-CT has a moderate potential interaction with Gastrointestinal Obstruction.

Antihistamines often have anticholinergic activity, to which elderly patients are particularly sensitive. Therapy with antihistamines should be administered cautiously, if at all, in patients with preexisting conditions that are likely to be exacerbated by anticholinergic activity, such as urinary retention or obstruction; angle-closure glaucoma, untreated intraocular hypertension, or uncontrolled primary open-angle glaucoma; and gastrointestinal obstructive disorders. Conventional, first-generation antihistamines such as the ethanolamines (bromodiphenhydramine, carbinoxamine, clemastine, dimenhydrinate, diphenhydramine, doxylamine, phenyltoloxamine) tend to exhibit substantial anticholinergic effects. In contrast, the newer, relatively nonsedating antihistamines (e.g., cetirizine, fexofenadine, loratadine) reportedly have low to minimal anticholinergic activity at normally recommended dosages and may be appropriate alternatives.

Glaucoma/Intraocular Hypertension

Major:

levodopa

Levodopa has a major potential interaction with Glaucoma/Intraocular Hypertension.

The use of levodopa is contraindicated in patients with acute closed-angle glaucoma. Levodopa (with or without carbidopa) may be used in patients with open-angle glaucoma who are receiving appropriate therapy.

Moderate:

Aldex-CT

The diphenhydrAMINE in Aldex-CT has a moderate potential interaction with Glaucoma/Intraocular Hypertension.

Some hypnotic drugs can have an anticholinergic effect and should be used with caution in patients with glaucoma, and trouble urinating due to retention or enlarged prostate.

Moderate:

Aldex-CT

The phenylephrine in Aldex-CT 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.

Moderate:

Aldex-CT

The diphenhydrAMINE in Aldex-CT has a moderate potential interaction with Glaucoma/Intraocular Hypertension.

Antihistamines often have anticholinergic activity, to which elderly patients are particularly sensitive. Therapy with antihistamines should be administered cautiously, if at all, in patients with preexisting conditions that are likely to be exacerbated by anticholinergic activity, such as urinary retention or obstruction; angle-closure glaucoma, untreated intraocular hypertension, or uncontrolled primary open-angle glaucoma; and gastrointestinal obstructive disorders. Conventional, first-generation antihistamines such as the ethanolamines (bromodiphenhydramine, carbinoxamine, clemastine, dimenhydrinate, diphenhydramine, doxylamine, phenyltoloxamine) tend to exhibit substantial anticholinergic effects. In contrast, the newer, relatively nonsedating antihistamines (e.g., cetirizine, fexofenadine, loratadine) reportedly have low to minimal anticholinergic activity at normally recommended dosages and may be appropriate alternatives.

Hyperthyroidism

Major:

Aldex-CT

The phenylephrine in Aldex-CT 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.

Moderate:

Aldex-CT

The diphenhydrAMINE in Aldex-CT has a moderate potential interaction with Hyperthyroidism.

Antihistamines may infrequently cause cardiovascular adverse effects related to their anticholinergic and local anesthetic (quinidine-like) activities. Tachycardia, palpitation, ECG changes, arrhythmias, hypotension, and hypertension have been reported. Although these effects are uncommon and usually limited to overdosage situations, the manufacturers and some clinicians recommend that therapy with antihistamines be administered cautiously in patients with cardiovascular disease, hypertension, and/or hyperthyroidism.

Hypotension

Moderate:

Aldex-CT

The diphenhydrAMINE in Aldex-CT has a moderate potential interaction with Hypotension.

Antihistamines may infrequently cause cardiovascular adverse effects related to their anticholinergic and local anesthetic (quinidine-like) activities. Tachycardia, palpitation, ECG changes, arrhythmias, hypotension, and hypertension have been reported. Although these effects are uncommon and usually limited to overdosage situations, the manufacturers and some clinicians recommend that therapy with antihistamines be administered cautiously in patients with cardiovascular disease, hypertension, and/or hyperthyroidism.

Moderate:

levodopa

Levodopa has a moderate potential interaction with Hypotension.

Dopamine agonists may impair the systemic regulation of blood pressure, with resultant orthostatic hypotension at any time, but especially during dose escalation. Additionally, patients with Parkinson's disease may have an impaired capacity to respond to an orthostatic challenge. For these reasons, patients with Parkinson's disease (or restless legs syndrome) who are being treated with dopaminergic agonists typically require careful monitoring for signs/symptoms of orthostatic hypotension, especially during dose escalation, and should be advised of this risk.

Liver Disease

Major:

levodopa

Levodopa has a major potential interaction with Liver Disease.

The pharmacokinetics of levodopa have not been studied in patients with hepatic or renal impairment. Therapy with levodopa should be administered cautiously in patients with liver or disease. Periodic monitoring of hepatic and renal function is recommended during extended therapy.

Moderate:

Aldex-CT

The diphenhydrAMINE in Aldex-CT has a moderate potential interaction with Liver Disease.

Limited pharmacokinetic data are available for the older, first-generation antihistamines. Many appear to be primarily metabolized by the liver, and both parent drugs and metabolites are excreted in the urine. Patients with renal and/or liver disease may be at greater risk for adverse effects from antihistamines due to drug and metabolite accumulation. Therapy with antihistamines should be administered cautiously in such patients. Lower initial dosages may be appropriate.

Moderate:

Aldex-CT

The diphenhydrAMINE in Aldex-CT has a moderate potential interaction with Liver Disease.

In general, anxiolytics, sedatives and hypnotics 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 these drugs should be administered cautiously in patients with liver disease (some are not recommended in severe liver impairment), and the dosage should be adjusted accordingly. Laboratory testing is recommended prior and during treatment.

Pheochromocytoma

Major:

Aldex-CT

The phenylephrine in Aldex-CT 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:

Aldex-CT

The phenylephrine in Aldex-CT 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:

levodopa

Levodopa has a major potential interaction with Psychosis.

The use of dopamine agonists has been associated with psychiatric effects such as hallucinations, psychosis, confusion, anxiety, mania, hypomania, depression, rapid mood cycling, nightmares, and hypersexuality. Therapy with dopamine agonists should be administered cautiously in psychotic patients and all patients should be carefully observed for development of depression and suicidal tendencies.

Moderate:

levodopa

Levodopa has a moderate potential interaction with Psychosis.

Ordinarily, patients with major psychotic disorder should not be treated with dopaminergic antiparkinsonian agents, because of the risk of exacerbating psychosis. Hallucinations and psychotic-like behavior have been reported with dopaminergic medications. In addition, certain medications used to treat psychosis may exacerbate the symptoms of Parkinson's disease and may decrease the effectiveness of these drugs. The use of bromocriptine in patients with severe psychotic disorders is not recommended.

Renal Dysfunction

Major:

levodopa

Levodopa has a major potential interaction with Renal Dysfunction.

The pharmacokinetics of levodopa have not been studied in patients with hepatic or renal impairment. Therapy with levodopa should be administered cautiously in patients with liver or disease. Periodic monitoring of hepatic and renal function is recommended during extended therapy.

Moderate:

Aldex-CT

The diphenhydrAMINE in Aldex-CT has a moderate potential interaction with Renal Dysfunction.

Limited pharmacokinetic data are available for the older, first-generation antihistamines. Many appear to be primarily metabolized by the liver, and both parent drugs and metabolites are excreted in the urine. Patients with renal and/or liver disease may be at greater risk for adverse effects from antihistamines due to drug and metabolite accumulation. Therapy with antihistamines should be administered cautiously in such patients. Lower initial dosages may be appropriate.

Skin Cancer

Major:

levodopa

Levodopa has a major potential interaction with Skin Cancer.

The use of levodopa is considered by manufacturers to be contraindicated in patients with a history of melanoma or in patients with suspicious, undiagnosed skin lesions. Levodopa reportedly may activate malignant melanoma, although some investigators have found a causal relationship to be tenuous.

Sleep Disorders

Moderate:

levodopa

Levodopa has a moderate potential interaction with Sleep Disorders.

Patients treated with products containing carbidopa and levodopa report excessive somnolence and falling asleep while engaged in daily activities, sometimes with no warning sign of drowsiness. Advise patients about the risks, especially those suffering from sleep disorders or using concomitant sedating medications.

Urinary Retention

Moderate:

Aldex-CT

The diphenhydrAMINE in Aldex-CT has a moderate potential interaction with Urinary Retention.

Antihistamines often have anticholinergic activity, to which elderly patients are particularly sensitive. Therapy with antihistamines should be administered cautiously, if at all, in patients with preexisting conditions that are likely to be exacerbated by anticholinergic activity, such as urinary retention or obstruction; angle-closure glaucoma, untreated intraocular hypertension, or uncontrolled primary open-angle glaucoma; and gastrointestinal obstructive disorders. Conventional, first-generation antihistamines such as the ethanolamines (bromodiphenhydramine, carbinoxamine, clemastine, dimenhydrinate, diphenhydramine, doxylamine, phenyltoloxamine) tend to exhibit substantial anticholinergic effects. In contrast, the newer, relatively nonsedating antihistamines (e.g., cetirizine, fexofenadine, loratadine) reportedly have low to minimal anticholinergic activity at normally recommended dosages and may be appropriate alternatives.

Moderate:

Aldex-CT

The diphenhydrAMINE in Aldex-CT has a moderate potential interaction with Urinary Retention.

Some hypnotic drugs can have an anticholinergic effect and should be used with caution in patients with glaucoma, and trouble urinating due to retention or enlarged prostate.

More resources

Aldex-CT

A total of 629 drugs are known to interact with Aldex-CT.

levodopa

A total of 532 drugs are known to interact with levodopa.

Drug Interaction Classification

These classifications are only a guideline. The relevance of a particular drug interaction to a specific individual is difficult to determine. Always consult your healthcare provider before starting or stopping any medication.
Major Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit.
Moderate Moderately clinically significant. Usually avoid combinations; use it only under special circumstances.
Minor 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.
Unknown No interaction information available.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.