LONSURF Dose Calculator

LONSURF Dose Calculator: A Comprehensive Guide for Healthcare Professionals

LONSURF (trifluridine/tipiracil) is an oral chemotherapy drug used to treat metastatic colorectal cancer and gastric cancer. Proper dosing is crucial to maximize efficacy while minimizing toxicity. This LONSURF dose calculator helps healthcare providers determine the optimal dosage based on patient-specific factors such as body surface area (BSA), renal function, and hepatic status.

In this article, we’ll explain:

• Key terms used in the calculator

• Why these parameters matter in dosing

• How to interpret the calculator’s results

• How the calculator works

Key Terms & Their Importance in LONSURF Dosing

1. Body Surface Area (BSA)

• Definition: A calculated value (in m²) based on height and weight, used to standardize drug dosing.

• Why it matters: LONSURF dosing is based on BSA (35 mg/m² of trifluridine per dose). An accurate BSA ensures proper drug exposure.

2. Renal Function (eGFR/Creatinine Clearance)

• Definition: Measures how well kidneys filter waste; classified as normal, mild, moderate, or severe impairment.

• Why it matters: LONSURF is excreted renally. Impaired kidney function may require dose reductions to avoid toxicity.

3. Hepatic Function (Liver Status)

• Definition: Assessed via bilirubin levels and Child-Pugh classification (A, B, or C).

• Why it matters: Liver dysfunction affects drug metabolism. Severe impairment may necessitate dose adjustments.

4. Previous Treatment Toxicity

• Definition: Patient’s history of side effects (e.g., neutropenia, diarrhea) from prior chemotherapy.

• Why it matters: Patients with prior severe toxicity may need lower doses to prevent recurrence.

How to Interpret the Calculator’s Results

After entering patient data, the LONSURF dose calculator provides:

1. Recommended Dose (Trifluridine/Tipiracil)

• The calculator outputs the trifluridine dose (mg) and the corresponding tipiracil dose (which is fixed at a 1:0.1 ratio).

• Example: "Trifluridine: 50 mg per dose (twice daily), Tipiracil: 5 mg per dose."

2. Tablet Count

• Since LONSURF comes in 15 mg/6.14 mg tablets, the calculator suggests how many tablets per dose are needed.

• Example: "Tablets per dose: 4 × 15 mg/6.14 mg tablets."

3. Dose Adjustments & Warnings

• If renal/hepatic impairment is detected, the calculator automatically reduces the dose and explains why.

• Example: "Dose reduced by 25% for moderate renal impairment."

• If bilirubin or creatinine clearance is critically abnormal, a warning appears.

4. Administration Schedule

• Reminds users that LONSURF is taken twice daily on days 1-5 and 8-12 of a 28-day cycle.

How the LONSURF Dose Calculator Works

1. Input Patient Data

   • Gender, age, weight (kg/lbs), height (cm/in/ft).

   • Optional: Direct BSA input (if pre-calculated).

   • Renal/hepatic function, prior toxicity history.

2. Automatic Calculations

   • Converts weight/height to metric units (kg/cm).

   • Calculates BSA using the Mosteller formula:

     BSA(m2)=height(cm)×weight(kg)3600BSA(m2)=3600height(cm)×weight(kg)​​

   • Adjusts dose based on:

     • Renal impairment → 25-50% reduction

     • Hepatic impairment → 25-50% reduction

     • Prior toxicity → Further reductions if needed

3. Outputs Final Dose

   • Caps dose at 80 mg (trifluridine) per administration.

   • Provides tablet breakdown and safety notes.

Conclusion

This LONSURF dose calculator simplifies complex dosing adjustments, ensuring patients receive the right amount of medication while minimizing side effects. By considering BSA, kidney/liver function, and prior treatment history, healthcare providers can optimize therapy for better outcomes.

Try the calculator now to get personalized dosing recommendations!

Final Notes

• Always verify calculations with clinical judgment.

• Monitor patients for myelosuppression, GI toxicity, and liver/kidney function during treatment.

• Consult prescribing guidelines for further details.

This tool is for educational purposes only—always confirm dosing with a pharmacist or oncologist.

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