Interactions between Formulation R and Halothane
1 drug interaction and 12 additional warnings found for the following 2 drugs:
- Formulation R (phenylephrine topical)
- halothane
Drug interactions
Major drug interactions
Major:
halothane phenylephrine topical
Applies to: halothane and Formulation R (phenylephrine topical)
Generally avoid
The combination of phenylephrine and halothane may increase the risk of ventricular irritability and cardiac arrhythmias. Adverse events have been reported in anesthetized patients after administration of phenylephrine ophthalmic drops.
Management
This combination should be avoided or used very cautiously and the patient's hemodynamic status should be closely monitored.
References (5)
- (2002) "Product Information. Neo-Synephrine (phenylephrine)." Abbott Pharmaceutical
- Agencia Española de Medicamentos y Productos Sanitarios Healthcare (2008) Centro de información online de medicamentos de la AEMPS - CIMA. https://cima.aemps.es/cima/publico/home.html
- Richards, E, Lopez, MJ, Maani CV (2026) Phenyleprhine https://www.ncbi.nlm.nih.gov/books/NBK534801/
- (2017) "Product Information. Lidocaine-Phenylephrine (lidocaine-phenylephrine nasal)." Martindale Pharmaceuticals Ltd
- (2021) "Product Information. Minims Phenylephrine Hydrochloride (phenylephrine ophthalmic)." Bausch & Lomb (Australia) Pty Ltd
Food/lifestyle interactions
No alcohol/food interactions were found. However, this does not necessarily mean no interactions exist. Always consult your healthcare provider.
Disease interactions
12 potential interactions Applies to: 12 conditions, including Benign Prostatic Hyperplasia, Arrhythmia, Hypotension, Hyperthyroidism, and Pseudotumor Cerebri.
Arrhythmia
Moderate:
halothane
Halothane has a moderate potential interaction with Arrhythmia.
Inhalation anesthetics causes hypotension, frequently decreases pulse rate and induces supraventricular arrhythmias, and increase cerebral spinal fluid. Ventricular arrhythmia has occurred during administration of halothane due to sensitization of myocardial conduction tissue to epinephrine and norepinephrine. Therapy with inhalation anesthetics should be administered cautiously in patients with cardiovascular disorders including hemodynamic impairment or conduction disorders, significantly increased intracranial pressure, or impaired cerebral circulation.
Benign Prostatic Hyperplasia
Moderate:
Formulation R
The phenylephrine topical in Formulation R has a moderate potential interaction with Benign Prostatic Hyperplasia.
Topically applied sympathomimetic agents are systemically absorbed, with the potential for producing clinically significant systemic effects, particularly during prolonged or indiscriminate use. In patients with prostate enlargement, urinary difficulty may develop or worsen due to smooth muscle contraction in the bladder neck via stimulation of alpha-1 adrenergic receptors. Therapy with topical sympathomimetic agents should be administered cautiously in patients with hypertrophy or neoplasm of the prostate. It is important that the recommended dosages of the individual products not be exceeded.
Cardiovascular Conditions and Disorders
Moderate:
Formulation R
The phenylephrine topical in Formulation R has a moderate potential interaction with Cardiovascular Conditions and Disorders.
Topically applied sympathomimetic agents are systemically absorbed, with the potential for producing clinically significant systemic effects, particularly during prolonged or indiscriminate use. 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. The use of topical sympathomimetic agents has rarely been associated with palpitations, tachycardia, arrhythmia, hypertension, reflex bradycardia, and coronary occlusion. Therapy with topical sympathomimetic agents should be administered cautiously in patients with sensitivity to sympathomimetic amines, hyperthyroidism, or underlying cardiovascular or cerebrovascular disorders, especially coronary insufficiency, cardiac arrhythmia, or hypertension.
Cerebral Vascular Disorder
Moderate:
halothane
Halothane has a moderate potential interaction with Cerebral Vascular Disorder.
Inhalation anesthetics causes hypotension, frequently decreases pulse rate and induces supraventricular arrhythmias, and increase cerebral spinal fluid. Ventricular arrhythmia has occurred during administration of halothane due to sensitization of myocardial conduction tissue to epinephrine and norepinephrine. Therapy with inhalation anesthetics should be administered cautiously in patients with cardiovascular disorders including hemodynamic impairment or conduction disorders, significantly increased intracranial pressure, or impaired cerebral circulation.
Cerebrovascular Insufficiency
Moderate:
Formulation R
The phenylephrine topical in Formulation R has a moderate potential interaction with Cerebrovascular Insufficiency.
Topically applied sympathomimetic agents are systemically absorbed, with the potential for producing clinically significant systemic effects, particularly during prolonged or indiscriminate use. 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. The use of topical sympathomimetic agents has rarely been associated with palpitations, tachycardia, arrhythmia, hypertension, reflex bradycardia, and coronary occlusion. Therapy with topical sympathomimetic agents should be administered cautiously in patients with sensitivity to sympathomimetic amines, hyperthyroidism, or underlying cardiovascular or cerebrovascular disorders, especially coronary insufficiency, cardiac arrhythmia, or hypertension.
Diabetes Mellitus
Moderate:
Formulation R
The phenylephrine topical in Formulation R has a moderate potential interaction with Diabetes Mellitus.
Topically applied sympathomimetic agents are systemically absorbed, particularly during prolonged or indiscriminate use. Slight increases in blood glucose concentrations may occur with the use of these drugs. Therapy with topical sympathomimetic agents should be administered cautiously in patients with diabetes mellitus. Closer monitoring of blood glucose concentrations may be appropriate. It is important that the recommended dosages of the individual products not be exceeded.
Heart Block
Moderate:
halothane
Halothane has a moderate potential interaction with Heart Block.
Inhalation anesthetics causes hypotension, frequently decreases pulse rate and induces supraventricular arrhythmias, and increase cerebral spinal fluid. Ventricular arrhythmia has occurred during administration of halothane due to sensitization of myocardial conduction tissue to epinephrine and norepinephrine. Therapy with inhalation anesthetics should be administered cautiously in patients with cardiovascular disorders including hemodynamic impairment or conduction disorders, significantly increased intracranial pressure, or impaired cerebral circulation.
Hyperthyroidism
Moderate:
Formulation R
The phenylephrine topical in Formulation R has a moderate potential interaction with Hyperthyroidism.
Topically applied sympathomimetic agents are systemically absorbed, with the potential for producing clinically significant systemic effects, particularly during prolonged or indiscriminate use. 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. The use of topical sympathomimetic agents has rarely been associated with palpitations, tachycardia, arrhythmia, hypertension, reflex bradycardia, and coronary occlusion. Therapy with topical sympathomimetic agents should be administered cautiously in patients with sensitivity to sympathomimetic amines, hyperthyroidism, or underlying cardiovascular or cerebrovascular disorders, especially coronary insufficiency, cardiac arrhythmia, or hypertension.
Hypotension
Moderate:
halothane
Halothane has a moderate potential interaction with Hypotension.
Inhalation anesthetics causes hypotension, frequently decreases pulse rate and induces supraventricular arrhythmias, and increase cerebral spinal fluid. Ventricular arrhythmia has occurred during administration of halothane due to sensitization of myocardial conduction tissue to epinephrine and norepinephrine. Therapy with inhalation anesthetics should be administered cautiously in patients with cardiovascular disorders including hemodynamic impairment or conduction disorders, significantly increased intracranial pressure, or impaired cerebral circulation.
Ischemic Heart Disease
Moderate:
halothane
Halothane has a moderate potential interaction with Ischemic Heart Disease.
Inhalation anesthetics causes hypotension, frequently decreases pulse rate and induces supraventricular arrhythmias, and increase cerebral spinal fluid. Ventricular arrhythmia has occurred during administration of halothane due to sensitization of myocardial conduction tissue to epinephrine and norepinephrine. Therapy with inhalation anesthetics should be administered cautiously in patients with cardiovascular disorders including hemodynamic impairment or conduction disorders, significantly increased intracranial pressure, or impaired cerebral circulation.
Prostate Tumor, Benign
Moderate:
Formulation R
The phenylephrine topical in Formulation R has a moderate potential interaction with Prostate Tumor, Benign.
Topically applied sympathomimetic agents are systemically absorbed, with the potential for producing clinically significant systemic effects, particularly during prolonged or indiscriminate use. In patients with prostate enlargement, urinary difficulty may develop or worsen due to smooth muscle contraction in the bladder neck via stimulation of alpha-1 adrenergic receptors. Therapy with topical sympathomimetic agents should be administered cautiously in patients with hypertrophy or neoplasm of the prostate. It is important that the recommended dosages of the individual products not be exceeded.
Pseudotumor Cerebri
Moderate:
halothane
Halothane has a moderate potential interaction with Pseudotumor Cerebri.
Inhalation anesthetics causes hypotension, frequently decreases pulse rate and induces supraventricular arrhythmias, and increase cerebral spinal fluid. Ventricular arrhythmia has occurred during administration of halothane due to sensitization of myocardial conduction tissue to epinephrine and norepinephrine. Therapy with inhalation anesthetics should be administered cautiously in patients with cardiovascular disorders including hemodynamic impairment or conduction disorders, significantly increased intracranial pressure, or impaired cerebral circulation.
More resources
Formulation R
A total of 197 drugs are known to interact with Formulation R.
- Formulation r is in the drug class anorectal preparations.
- Formulation r is used to treat the following conditions:
halothane
A total of 420 drugs are known to interact with halothane.
- Halothane is in the drug class general anesthetics.
- Halothane is used to treat Anesthesia.
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
Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.