Fluorouracil, also known by its brand name Adrucil, works by interfering with the synthesis of DNA and RNA in cancer cells. It is classified as an antimetabolite drug. When cancer cells divide and multiply rapidly, they require thymidine to produce the building blocks of DNA. Fluorouracil acts as a false building block that gets incorporated into DNA and RNA during their synthesis. However, having fluorouracil in the place of thymidine causes the DNA and RNA strands to break apart, which prevents the cancer cells from dividing and growing out of control. In this way, 5FU is able to stop the progression of cancer by selectively killing cells undergoing DNA synthesis.

Approved Uses

5FU has been approved by the FDA for treatment of several types of cancers either as a single agent or in combination with other drugs. Some of its common uses include:

– Colorectal cancer: As first-line or adjuvant treatment following surgery to decrease risk of recurrence. It is often given with leucovorin (folinic acid) to improve efficacy.

– Breast cancer: In combination with doxorubicin and cyclophosphamide as adjuvant chemotherapy after breast surgery.

– Gastric cancer: Used along with other drugs like cisplatin and irinotecan for advanced or metastatic gastric cancer.

– Pancreatic cancer: Together with leucovorin for advanced or metastatic pancreatic cancer.

– Head and neck cancers: Combined with cisplatin for locally advanced squamous cell carcinomas of the head and neck.

Administration and Dosing

Fluorouracil (5FU) is administered either as an intravenous push or intravenous infusion, depending on the treatment regimen. For example, in FOLFOX regimen for colorectal cancer, 5FU is given as a continuous intravenous infusion for 46 hours along with leucovorin and oxaliplatin injections.

The dosage of 5FU needs to be calculated based on the person’s body surface area and kidney function. The typical dosage ranges from 350 mg/m2 to 600 mg/m2 per day. The duration of treatment depends on the cancer type but usually lasts for 4-6 months with cycles repeating every 2-3 weeks. Due to its toxic effects, 5FU requires careful monitoring by oncologists during the treatment period.

Side Effects

The common side effects of 5FU chemotherapy include:

– Mucositis – Inflammation and ulcers in the mouth, throat, esophagus and intestines resulting in pain and difficulty swallowing.

– Diarrhea – Loose or watery stools, needing to pass stool frequently.

– Hand-foot syndrome – Redness, swelling, pain and peeling of skin on palms and soles.

– Fatigue – General lack of energy and feeling weak.

– Nausea and vomiting.

– Suppression of bone marrow – Increases risk of infection and bleeding due to low white and red blood cell counts.

– Hair thinning – Hair may thin or fall out during treatment.

– Headaches.

– Dry skin.

Long term side effects are rare but can include nerve damage (neuropathy) and heart damage. Patients undergoing 5FU chemotherapy require close medical supervision and supportive care for managing all potential side effects.

Drug Interactions

Some drugs that can interact with 5FU when taken together include:

– Warfarin (Coumadin)- 5FU may increase anticoagulant effect leading to risk of bleeding.

– Phenytoin (Dilantin)- Use of anticonvulsant may decrease effectiveness of 5FU.

– Levodopa- May increase dopamine effect causing side effects like nausea and vomiting.

– Alcohol- Should be avoided as it may enhance 5FU toxicity risk.

– Vitamin supplements containing Folic acid or levoleucovorin- Interferes with 5FU action and may reduce efficacy.

Hence it is crucial to inform all prescription drugs, supplements and herbs being taken to the oncologist before starting 5FU chemotherapy to prevent unfavorable interactions.

Monitoring and Management

During 5FU therapy, close monitoring of blood counts and other parameters like liver and kidney function tests is necessary. Immediate medical attention should be sought if signs of excessive toxicity like severe diarrhea, mouth sores or fever develop.

Some tips for managing common side effects include:

– UsingPain relievers and mouthwashes for mucositis

– Drinking oral rehydration solutions for diarrhea

– Applying moisture barriers and wearing gloves/socks for hand-foot syndrome

– Taking antiemetics for nausea

– Practicing skin care and taking breaks from chemo for hair loss

– Following a healthy diet and staying hydrated

Overall, 5FU remains an important part of many chemotherapy regimens for treating various cancers due to its favorable efficacy and toxicity profile when administered properly. Future research is evaluating new formulations and targeted drug combinations to improve therapeutic outcomes.

*Note:
1.  Source: Coherent Market Insights, Public sources, Desk research
2. We have leveraged AI tools to mine information and compile it