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Drug Interactions between benzocaine / butamben / tetracaine topical and phenazopyridine / sulfamethoxazole

This report displays the potential drug interactions for the following 2 drugs:

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Interactions between your drugs

Moderate

sulfamethoxazole benzocaine topical

Applies to: phenazopyridine / sulfamethoxazole and benzocaine / butamben / tetracaine topical

Ask your doctor before using benzocaine topical together with sulfamethoxazole. Benzocaine topical may decrease the effects of sulfamethoxazole. Ask your doctor to consider an alternative to benzocaine topical. If your doctor prescribes these medications together, you may need a dose adjustment to safely use both medications. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

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Moderate

sulfamethoxazole tetracaine topical

Applies to: phenazopyridine / sulfamethoxazole and benzocaine / butamben / tetracaine topical

Consumer information for this interaction is not currently available.

GENERALLY AVOID: Ester-type local anesthetics are hydrolyzed to paraaminobenzoic acid, which can inhibit the action of sulfonamides.

MONITOR: Ester-type local anesthetics can cause methemoglobinemia, and coadministration with other oxidizing agents that can also induce methemoglobinemia such as sulfonamides may increase the risk. Topical formulations of ester-type local anesthetics may be absorbed systemically and may also have the potential to induce methemoglobinemia, particularly when applied to mucous membranes. Additional risk factors include very young age (e.g., infants less than 6 months); application to inflamed/abraded areas or broken skin; anemia; cardiac or pulmonary disease; peripheral vascular disease; liver cirrhosis; shock; sepsis; acidosis; and genetic predisposition (e.g., NADH cytochrome-b5 reductase deficiency; glucose-6-phosphate dehydrogenase (G6PD) deficiency; hemoglobin M). There have been rare reports of significant methemoglobinemia associated with administration of topical anesthetics, primarily following application to mucous membranes prior to dental procedures or via the oropharyngeal route prior to procedures such as intubation, laryngoscopy, bronchoscopy, and endoscopy. Very rarely, methemoglobinemia has also been reported with use of anesthetic throat lozenges.

MANAGEMENT: The administration of injectable ester-type local anesthetics to patients who are on sulfonamides should generally be avoided. Amide-type anesthetics are not expected to inhibit the action of sulfonamides and may be considered as alternatives (e.g., bupivacaine, levobupivacaine, lidocaine, mepivacaine). However, caution is advised due to the potential for development of methemoglobinemia. Likewise, caution should be exercised when topical formulations of ester-type local anesthetics are administered to patients receiving sulfonamides, particularly when applied to mucous membranes or given via the oropharyngeal route. Signs and symptoms of methemoglobinemia may be delayed some hours after drug exposure. Patients or their caregivers should be advised to seek medical attention if they notice signs and symptoms of methemoglobinemia such as slate-grey cyanosis in buccal mucous membranes, lips, and nail beds; nausea; headache; dizziness; lightheadedness; lethargy; fatigue; dyspnea; tachypnea; tachycardia; palpitation; anxiety; and confusion. In severe cases, patients may progress to central nervous system depression, stupor, seizures, acidosis, cardiac arrhythmias, syncope, shock, coma, and death. Methemoglobinemia should be considered if central cyanosis is unresponsive to oxygen. Calculated oxygen saturation and pulse oximetry are generally not accurate in the setting of methemoglobinemia. The diagnosis can be confirmed by an elevated methemoglobin level of at least 10% using co-oximetry. Methemoglobin concentrations greater than 10% of total hemoglobin will typically cause cyanosis, and levels over 70% are frequently fatal. However, symptom severity is not always related to methemoglobin levels. Mild cases often respond to withdrawal of offending agents and symptomatic support. If patient does not respond to administration of oxygen, clinically significant or symptomatic methemoglobinemia can be treated with methylene blue 1 to 2 mg/kg by slow intravenous injection over 5 to 10 minutes, which may be repeated within 30 to 60 minutes if necessary. Higher dosages of methylene blue (usually greater than 7 mg/kg) should be avoided, as it can paradoxically exacerbate methemoglobinemia. Additionally, methylene blue is ineffective and can cause hemolytic anemia in patients with G6PD deficiency. These patients may be treated with exchange transfusion, dialysis, and/or hyperbaric oxygenation in addition to symptomatic support.

Moderate

phenazopyridine benzocaine topical

Applies to: phenazopyridine / sulfamethoxazole and benzocaine / butamben / tetracaine topical

Some of the medication in benzocaine topical may be absorbed into the bloodstream following local application. When present in sufficient concentrations in the blood, local anesthetics such as benzocaine topical may cause methemoglobinemia, a rare condition that can lead to oxygen deprivation in tissues and vital organs due to reduced oxygen-carrying capacity of the blood. The risk is increased when combined with other medications that can also induce methemoglobinemia such as phenazopyridine. Individuals may be more susceptible to developing methemoglobinemia during treatment with these medications if they are very young (especially neonates and infants) or have anemia, diseases of the heart or lungs, blood circulation disorders, liver cirrhosis, shock, sepsis, and certain genetic predispositions such as NADH cytochrome-b5 reductase deficiency, glucose-6-phosphate dehydrogenase deficiency, and hemoglobin M. In addition, use of topical anesthetics on inflamed or abraded areas or broken skin, as well as excessive use such as application of large doses or on larger than recommended areas, can increase absorption and result in high blood levels of the medication. Topical anesthetics that are applied to mucous membranes such as inside the mouth, nose, or throat (e.G., for sore throat; for numbing prior to dental procedures or scoping of the lungs or gastrointestinal tract) may also be absorbed to a significant extent. Close medical supervision is necessary when medications that can cause methemoglobinemia are used together. Do not exceed the recommended dose or frequency and duration of use when treated with products that contain local anesthetics, including some over-the-counter preparations. Signs and symptoms of methemoglobinemia may be delayed by several hours after treatment with topical anesthetics. Patients (or their caregivers) should seek immediate medical attention if they develop a gray discoloration of the skin, mouth, or nail bed; nausea; headache; dizziness; lightheadedness; fatigue; shortness of breath; rapid or shallow breathing; a rapid heartbeat; palpitation; anxiety; or confusion. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

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Moderate

phenazopyridine tetracaine topical

Applies to: phenazopyridine / sulfamethoxazole and benzocaine / butamben / tetracaine topical

Some of the medication in tetracaine topical may be absorbed into the bloodstream following local application. When present in sufficient concentrations in the blood, local anesthetics such as tetracaine topical may cause methemoglobinemia, a rare condition that can lead to oxygen deprivation in tissues and vital organs due to reduced oxygen-carrying capacity of the blood. The risk is increased when combined with other medications that can also induce methemoglobinemia such as phenazopyridine. Individuals may be more susceptible to developing methemoglobinemia during treatment with these medications if they are very young (especially neonates and infants) or have anemia, diseases of the heart or lungs, blood circulation disorders, liver cirrhosis, shock, sepsis, and certain genetic predispositions such as NADH cytochrome-b5 reductase deficiency, glucose-6-phosphate dehydrogenase deficiency, and hemoglobin M. In addition, use of topical anesthetics on inflamed or abraded areas or broken skin, as well as excessive use such as application of large doses or on larger than recommended areas, can increase absorption and result in high blood levels of the medication. Topical anesthetics that are applied to mucous membranes such as inside the mouth, nose, or throat (e.G., for sore throat; for numbing prior to dental procedures or scoping of the lungs or gastrointestinal tract) may also be absorbed to a significant extent. Close medical supervision is necessary when medications that can cause methemoglobinemia are used together. Do not exceed the recommended dose or frequency and duration of use when treated with products that contain local anesthetics, including some over-the-counter preparations. Signs and symptoms of methemoglobinemia may be delayed by several hours after treatment with topical anesthetics. Patients (or their caregivers) should seek immediate medical attention if they develop a gray discoloration of the skin, mouth, or nail bed; nausea; headache; dizziness; lightheadedness; fatigue; shortness of breath; rapid or shallow breathing; a rapid heartbeat; palpitation; anxiety; or confusion. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

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Drug and food interactions

Moderate

sulfamethoxazole food

Applies to: phenazopyridine / sulfamethoxazole

Ask your doctor before using sulfamethoxazole together with ethanol. Contact your doctor if you experience unpleasant side effects such as fast heartbeats, warmth or redness under your skin, tingly feeling, nausea, or vomiting. If you experience these side effects, you may need to avoid ethanol while taking sulfamethoxazole. You should check your food and medicine labels to see if these products contain ethanol. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

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Therapeutic duplication warnings

No warnings were found for your selected drugs.

Therapeutic duplication warnings are only returned when drugs within the same group exceed the recommended therapeutic duplication maximum.


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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.