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Drug Interactions between Cozaar and porfimer

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

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Interactions between your drugs

Moderate

losartan porfimer

Applies to: Cozaar (losartan) and porfimer

GENERALLY AVOID: Patients exposed to photosensitizing agents at the same time as or in the 30 to 90 days following treatment with porfimer may be at an increased risk of a photosensitivity reaction (e.g., erythema, swelling, pruritus, burning sensations, feeling hot, and/or blisters). These agents have each been individually associated with photosensitivity reactions and may have additive effects if used together. Medicinal products with known phototoxic or photoallergic potential include, but are not limited to, hypericin-containing products (e.g., St. John's Wort), griseofulvin, thiazide diuretics, sulfonylureas, phenothiazines, sulfonamides, quinolones, and tetracyclines. Photosensitivity with porfimer is due to residual drug being present in the skin. Porfimer is cleared from a variety of tissues over 40 to 72 hours after treatment, but organs of the reticuloendothelial system (e.g., liver, spleen), skin and the tumor itself retain the drug for a longer period. Patients treated with porfimer will be photosensitive for at least 30 days and possibly up to 90 days or more for patients with hepatic or severe renal dysfunction. In clinical studies of porfimer, photosensitivity reactions occurred in approximately 20% of cancer patients and 69% of high-grade dysplasia in Barrett's esophagus patients.

MANAGEMENT: Use of photosensitizing agents should be avoided for at least 30 days and maybe up to 90 days or longer after porfimer treatment depending on the patient's hepatic function, renal function, and/or ability to tolerate exposure to sunlight. Following treatment with porfimer, patients should follow measures outlined in the product labeling for light and sun exposure. It is important to counsel patients to expose their skin to ambient indoor light as it is not only safe but will help eliminate porfimer through the skin by a process called "photobleaching." Before exposing skin or eyes to direct sunlight or bright indoor light (e.g., examination lamps, dental lamps, operating room lamps, floodlights, halogen lamps, unshaded light bulbs at close proximity, etc.), patients should test for residual photosensitivity as described in porfimer's product labeling.

References

  1. Hoffman GA, Gradl G, Schulz M, Haidinger G, Tanew A, Weber B (2020) "The frequency of photosensitizing drug dispensings in Austria and Germany: A correlation with their photosensitizing potential based on published literature." J Eur Acad Dermatol Venereol, 34, p. 589-600
  2. Blakely KM, Drucker AM, Rosen CF (2019) "Drug-induced photosensitivity—an update: Culprit drugs, prevention and management." Drug Saf, 42, p. 827-47
  3. (2023) "Product Information. Photofrin (porfimer)." Pinnacle Biologicals, Inc.
  4. Concordia Laboratories Inc. (2023) Photofrin sterile porfimer sodium for injection for intravenous use antineoplastic photosensitizing agent. https://pdf.hres.ca/dpd_pm/00028148.PDF
  5. Pinnacle Biologics B.V. (2023) Annex I summary of product characteristics https://www.ema.europa.eu/en/documents/product-information/photobarr-epar-product-information_en.pdf
View all 5 references

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Drug and food interactions

Moderate

losartan food

Applies to: Cozaar (losartan)

GENERALLY AVOID: Moderate-to-high dietary intake of potassium, especially salt substitutes, may increase the risk of hyperkalemia in some patients who are using angiotensin II receptor blockers (ARBs). ARBs can promote hyperkalemia through inhibition of angiotensin II-induced aldosterone secretion. Patients with diabetes, heart failure, dehydration, or renal insufficiency have a greater risk of developing hyperkalemia.

MANAGEMENT: Patients should receive dietary counseling and be advised to not use potassium-containing salt substitutes or over-the-counter potassium supplements without consulting their physician. If salt substitutes are used concurrently, regular monitoring of serum potassium levels is recommended. Patients should also be advised to seek medical attention if they experience symptoms of hyperkalemia such as weakness, irregular heartbeat, confusion, tingling of the extremities, or feelings of heaviness in the legs.

MONITOR: Grapefruit juice may modestly decrease and delay the conversion of losartan to its active metabolite, E3174. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruits. The clinical significance is unknown. Moreover, pharmacokinetic alterations associated with interactions involving grapefruit juice are often subject to a high degree of interpatient variability.

MANAGEMENT: Patients who regularly consume grapefruits and grapefruit juice should be monitored for altered efficacy of losartan. Grapefruits and grapefruit juice should be avoided if an interaction is suspected. Orange juice is not expected to interact.

References

  1. (2001) "Product Information. Cozaar (losartan)." Merck & Co., Inc
  2. Zaidenstein R, Soback S, Gips M, Avni B, Dishi V, Weissgarten Y, Golik A, Scapa E (2001) "Effect of grapefruit juice on the pharmacokinetics of losartan and its active metabolite E3174 in healthy volunteers." Ther Drug Monit, 23, p. 369-73
  3. Ray K, Dorman S, Watson R (1999) "Severe hyperkalaemia due to the concomitant use of salt substitutes and ACE inhibitors in hypertension: a potentially life threatening interaction." J Hum Hypertens, 13, p. 717-20

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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

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