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Drug Interactions between acetaminophen / caffeine / phenyltoloxamine and Rifamate

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

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Interactions between your drugs

Major

rifAMPin isoniazid

Applies to: Rifamate (isoniazid / rifampin) and Rifamate (isoniazid / rifampin)

Using isoniazid together with rifAMPin can cause serious side effects that may affect your liver. Call your doctor immediately if you experience a fever, chills, joint pain or swelling, excessive tiredness or weakness, unusual bleeding or bruising, skin rash or itching, loss of appetite, nausea, vomiting, or yellowing of the skin or the whites of your eyes. If your doctor does prescribe these medications together, you may need a dose adjustment or special tests to safely take 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

acetaminophen isoniazid

Applies to: acetaminophen / caffeine / phenyltoloxamine and Rifamate (isoniazid / rifampin)

Using acetaminophen together with isoniazid may alter the effects of acetaminophen and cause serious side effects that may affect your liver. Call your doctor immediately if you experience a fever, chills, joint pain or swelling, excessive tiredness or weakness, unusual bleeding or bruising, skin rash or itching, loss of appetite, nausea, vomiting, or yellowing of the skin or the whites of your eyes. If your doctor does prescribe these medications together, you may need a dose adjustment or special tests to safely take 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

isoniazid phenyltoloxamine

Applies to: Rifamate (isoniazid / rifampin) and acetaminophen / caffeine / phenyltoloxamine

Consumer information for this interaction is not currently available.

GENERALLY AVOID: Coadministration of monoamine oxidase inhibitors (MAOIs) and antihistamines may result in additive central nervous system depressant effects. In addition, limited data suggest that MAOIs may potentiate and prolong the anticholinergic effects of antihistamines due to inhibition of catecholamine degradation, which may lead to overstimulation of the sympathetic nervous system. In one published report, a woman who had been on phenelzine 30 mg/day for six months developed irritability and visual hallucinations two months following the addition of cyproheptadine 2 mg at bedtime to treat phenelzine-induced anorgasmia. The hallucinations cleared over 48 hours following the discontinuation of her medications. In another published report, a patient developed delirium with symptoms of aggression, paranoia, and vivid auditory as well as visual hallucinations after two days of receiving diphenhydramine 300 mg/day and linezolid 600 mg every 12 hours. The patient also had tachycardia, very warm skin, and possibly blurred vision (as evidenced by constant squinting). Central anticholinergic intoxication and dopaminergic hyperactivity were suspected. Symptoms subsided over four days following the discontinuation of diphenhydramine, while linezolid was continued with no subsequent sequelae. In a third report, a patient developed visual hallucinations associated with confusion and disorientation after nine days of linezolid and antihistamine therapy, including dexchlorpheniramine and cetirizine for the first four days and hydroxyzine for the next five. Physical examination did not reveal any focal neurological signs, myoclonus or ataxia, and cerebral CT scan and EEG were within normal limits. Symptoms resolved two days after linezolid was discontinued.

MANAGEMENT: Prescribing antihistamines in combination with MAOIs or other agents that possess MAOI activity (e.g., furazolidone, linezolid, procarbazine) should generally be avoided. If concomitant treatment is unavoidable, 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. It may be appropriate to monitor some patients for increased anticholinergic effects (e.g., constipation, urinary retention, fever, heat intolerance, blurred vision, confusion, hallucinations, dizziness, palpitations, arrhythmias, syncope), since certain populations such as the elderly and those with underlying organic brain disease tend to be more sensitive to these effects and may be susceptible to anticholinergic intoxication. It should be noted that the manufacturers of many of the sedating antihistamines (e.g., chlorpheniramine, dexchlorpheniramine, diphenhydramine, pheniramine, promethazine) consider their use within 14 days of MAOIs to be contraindicated.

References

  1. Kahn DA "Possible toxic interaction between cyproheptadine and phenelzine." Am J Psychiatry 144 (1987): 1242-3
  2. "Product Information. Periactin (cyproheptadine)." Merck & Co., Inc PROD (2002):
  3. "Product Information. Benadryl (diphenhydramine)." Parke-Davis PROD (2002):
  4. "Product Information. Matulane (procarbazine)." Roche Laboratories PROD (2001):
  5. Serio RN "Acute delirium associated with combined diphenhydramine and linezolid use." Ann Pharmacother 38 (2004): 62-5
  6. Ferry T, Ponceau B, Simon M, et al. "Possibly linezolid-induced peripheral and central neurotoxicity: report of four cases." Infection 33 (2005): 151-4
  7. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0
  8. Canadian Pharmacists Association "e-CPS. http://www.pharmacists.ca/function/Subscriptions/ecps.cfm?link=eCPS_quikLink" (2006):
  9. Cerner Multum, Inc. "Australian Product Information." O 0
View all 9 references
Minor

rifAMPin acetaminophen

Applies to: Rifamate (isoniazid / rifampin) and acetaminophen / caffeine / phenyltoloxamine

Information for this minor interaction is available on the professional version.

Drug and food interactions

Major

acetaminophen food

Applies to: acetaminophen / caffeine / phenyltoloxamine

Ask your doctor before using acetaminophen together with ethanol. This can cause serious side effects that affect your liver. Call your doctor immediately if you experience a fever, chills, joint pain or swelling, excessive tiredness or weakness, unusual bleeding or bruising, skin rash or itching, loss of appetite, nausea, vomiting, or yellowing of the skin or the whites of your eyes. If your doctor does prescribe these medications together, you may need a dose adjustment or special tests to safely take 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

rifAMPin food

Applies to: Rifamate (isoniazid / rifampin)

Consumer information for this interaction is not currently available.

GENERALLY AVOID: Concurrent use of rifampin in patients who ingest alcohol daily may result in an increased incidence of hepatotoxicity. The increase in hepatotoxicity may be due to an additive risk as both alcohol and rifampin are individually associated with this adverse reaction. However, the exact mechanism has not been established.

ADJUST DOSING INTERVAL: Administration with food may reduce oral rifampin absorption, increasing the risk of therapeutic failure or resistance. In a randomized, four-period crossover phase I study of 14 healthy male and female volunteers, the pharmacokinetics of single dose rifampin 600 mg were evaluated under fasting conditions and with a high-fat meal. Researchers observed that administration of rifampin with a high-fat meal reduced rifampin peak plasma concentration (Cmax) by 36%, nearly doubled the time to reach peak plasma concentration (Tmax) but reduced overall exposure (AUC) by only 6%.

MANAGEMENT: The manufacturer of oral forms of rifampin recommends administration on an empty stomach, 30 minutes before or 2 hours after meals. Patients should be encouraged to avoid alcohol or strictly limit their intake. Patients who use alcohol and rifampin concurrently or have a history of alcohol use disorder may require additional monitoring of their liver function during treatment with rifampin.

References

  1. "Product Information. Rifampin (rifAMPin)." Akorn Inc (2022):
  2. "Product Information. Rifampicin (rifampicin)." Mylan Pharmaceuticals Inc (2022):
  3. "Product Information. Rifadin (rifampicin)." Sanofi (2023):
  4. "Product Information. Rifadin (rifaMPICin)." Sanofi-Aventis Australia Pty Ltd (2024):
  5. Peloquin CA, Namdar R, Singleton MD, Nix DE "Pharmacokinetics of rifampin under fasting conditions, with food, and with antacids https://pubmed.ncbi.nlm.nih.gov/9925057/" (2024):
  6. "Product Information. Rofact (rifampin)." Bausch Health, Canada Inc. (2019):
View all 6 references
Moderate

isoniazid food

Applies to: Rifamate (isoniazid / rifampin)

Food decreases the levels of isoniazid in your body. Take isoniazid on an empty stomach at least 1 hour before or 2 hours after a meal. This will make it easier for your body to absorb the medication. If nausea occurs, ask your doctor if you can take isoniazid with food. Avoid alcohol while taking isoniazid. Alcohol may increase the risk of damage to the liver during isoniazid treatment. Alcohol can also cause isoniazid side effects to get worse. Contact your doctor if you experience flushing, chills, headache, nausea, vomiting, and diarrhea.

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Moderate

phenyltoloxamine food

Applies to: acetaminophen / caffeine / phenyltoloxamine

Alcohol can increase the nervous system side effects of phenyltoloxamine such as dizziness, drowsiness, and difficulty concentrating. Some people may also experience impairment in thinking and judgment. You should avoid or limit the use of alcohol while being treated with phenyltoloxamine. Do not use more than the recommended dose of phenyltoloxamine, and avoid activities requiring mental alertness such as driving or operating hazardous machinery until you know how the medication affects you. Talk to your doctor or pharmacist if you have any questions or concerns.

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Minor

caffeine food

Applies to: acetaminophen / caffeine / phenyltoloxamine

Information for this minor interaction is available on the professional version.

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.