LONSURF Dose Calculator: Trifluridine/Tipiracil Dose by BSA

Medically reviewed by Dr. Taimoor Asghar, physician.

In short: Calculate the LONSURF (trifluridine/tipiracil) dose from body surface area using the FDA label Table 1: 35 mg/m2 twice daily with the exact 15 mg and 20 mg tablet combinations, the 30, 25 and 20 mg/m2 dose reduction levels, and the Table 2 doses for severe renal impairment. Use the calculator above, then read the guide below to interpret your result and its limitations.

Enter the body surface area (or height and weight) and the dose level, and this calculator returns the LONSURF dose exactly as the FDA label gives it: the starting dose from Table 1 at 35 mg/m2 with the precise combination of 15 mg and 20 mg tablets, the reduced dose levels of 30, 25 and 20 mg/m2, and the Table 2 doses for severe renal impairment. LONSURF is dosed twice daily with food on Days 1 through 5 and Days 8 through 12 of each 28-day cycle, with a maximum of 80 mg per dose.

Body surface area entry

Body surface area (m2)

Dosing situation Dose level (mg/m2 per dose) The starting dose is read from the label's Table 1. Reduced levels are calculated at the chosen mg/m2 and rounded to the nearest 5 mg, as the label directs. In severe renal impairment the dose comes from the label's Table 2.

What LONSURF is and who it is for

LONSURF is an oral cytotoxic combination of trifluridine, a nucleoside metabolic inhibitor, and tipiracil, a thymidine phosphorylase inhibitor that protects trifluridine from breakdown. Section 1 of the FDA-approved label gives two indications. As a single agent or in combination with bevacizumab, LONSURF is indicated for adult patients with metastatic colorectal cancer previously treated with fluoropyrimidine-, oxaliplatin- and irinotecan-based chemotherapy, an anti-VEGF biological therapy, and, if RAS wild-type, an anti-EGFR therapy. As a single agent it is also indicated for adult patients with metastatic gastric or gastroesophageal junction adenocarcinoma previously treated with at least two prior lines of chemotherapy that included a fluoropyrimidine, a platinum, either a taxane or irinotecan, and if appropriate HER2/neu-targeted therapy. In both settings the dose is set by body surface area, which is what this calculator works from. All doses on this page are stated on the basis of the trifluridine component, as the label states them.

The recommended dosage, exactly as the label gives it

Section 2.1 of the label: the recommended dosage of LONSURF, as a single agent or in combination with bevacizumab, is 35 mg/m2 up to a maximum of 80 mg per dose, taken orally twice daily with food on Days 1 through 5 and Days 8 through 12 of each 28-day cycle, until disease progression or unacceptable toxicity. The dose is rounded to the nearest 5 mg increment. Patients are instructed to swallow the tablets whole, not to retake doses that are vomited or missed, and to continue with the next scheduled dose. LONSURF is a cytotoxic drug, and the label directs that applicable special handling and disposal procedures be followed. The maximum is 80 mg per dose, so the highest total daily dose is 160 mg, a distinction that matters when checking a prescription.

Table 1: the label's starting dose table, reproduced in full

The label does not leave the prescriber to multiply 35 by the BSA and round. It prints the answer as Table 1, the calculated initial dose for each BSA band, including the number of 15 mg and 20 mg tablets that make up each dose. LONSURF is supplied in exactly those two strengths: 15 mg trifluridine/6.14 mg tipiracil tablets and 20 mg trifluridine/8.19 mg tipiracil tablets (section 3). This calculator looks the starting dose up in this table, and so should any manual check.

BSA (m2)	Total daily dose (mg)	Dose per administration (mg, twice daily)	15 mg tablets per dose	20 mg tablets per dose
Below 1.07	70	35	1	1
1.07 to 1.22	80	40	0	2
1.23 to 1.37	90	45	3	0
1.38 to 1.52	100	50	2	1
1.53 to 1.68	110	55	1	2
1.69 to 1.83	120	60	0	3
1.84 to 1.98	130	65	3	1
1.99 to 2.14	140	70	2	2
2.15 to 2.29	150	75	1	3
2.30 and above	160	80	0	4

Two things are worth noticing in the table. First, the tablet combinations follow a fewest-tablets pattern, and they are not always the combination intuition suggests: 45 mg is three 15 mg tablets, not a 20 mg tablet plus smaller change that does not exist, and 60 mg is three 20 mg tablets. Second, at the band edges the table and the raw arithmetic can disagree by one 5 mg step. At a BSA of 1.22 m2 the product 35 x 1.22 is 42.7 mg, which rounds to 45 mg, yet the table gives 40 mg for the whole band ending at 1.22. At a BSA of 1.07 m2 the product is 37.45 mg, which rounds to 35 mg, yet the table gives 40 mg from 1.07 upward. These are not errors in the table; the table is the prescribing instruction, constructed so that the delivered dose stays within an accepted tolerance of 35 mg/m2 across each band. Where the two disagree, follow the table.

Worked examples

Example 1. A patient is 170 cm tall and weighs 70 kg. The Mosteller formula gives a BSA of the square root of (170 x 70 / 3600) = 1.82 m2. That sits in the Table 1 band 1.69 to 1.83, so the starting dose is 60 mg twice daily, taken as three 20 mg tablets per dose, a total daily dose of 120 mg on each of Days 1 to 5 and 8 to 12.

Example 2. A patient with a BSA of 1.45 m2 falls in the band 1.38 to 1.52: starting dose 50 mg twice daily, two 15 mg tablets plus one 20 mg tablet per dose, 100 mg per day. After a first dose reduction to 30 mg/m2, the calculated dose is 30 x 1.45 = 43.5 mg, which rounds to 45 mg, three 15 mg tablets per dose. After a second reduction to 25 mg/m2 it is 36.25 mg, rounding to 35 mg, one 15 mg plus one 20 mg tablet. At the third reduction, 20 mg/m2 gives 29 mg, rounding to 30 mg, two 15 mg tablets per dose.

Example 3. A tall patient with a BSA of 2.35 m2 is in the open-ended top band: 80 mg twice daily, four 20 mg tablets per dose, 160 mg per day. Note that 35 x 2.35 = 82.25 mg, so the label's 80 mg per-dose maximum is what sets this dose, not the multiplication.

Dose reductions for adverse reactions (section 2.2)

LONSURF's dose-limiting toxicity is myelosuppression, and the label builds the modification rules around blood counts. Complete blood cell counts are obtained prior to and on Day 15 of each cycle. A cycle is not initiated until the absolute neutrophil count (ANC) is at least 1,500/mm3 or febrile neutropenia has resolved, platelets are at least 75,000/mm3, and Grade 3 or 4 non-hematologic adverse reactions have resolved to Grade 0 or 1. Within a cycle, LONSURF is withheld for an ANC below 500/mm3 or febrile neutropenia, platelets below 50,000/mm3, or a Grade 3 or 4 non-hematologic adverse reaction. After recovery, treatment is resumed at a dose reduced by 5 mg/m2 per dose when any of the following occurred: febrile neutropenia; uncomplicated Grade 4 neutropenia (recovered to at least 1,500/mm3) or thrombocytopenia (recovered to at least 75,000/mm3) that resulted in more than a 1-week delay in starting the next cycle; or a non-hematologic Grade 3 or 4 adverse reaction, except Grade 3 nausea and/or vomiting controlled by antiemetic therapy or Grade 3 diarrhea responsive to antidiarrheal medication.

Dose level	Dose (mg/m2 per dose)	How this calculator obtains it
Starting dose	35	Label Table 1 lookup by BSA band
First reduction	30	30 x BSA, rounded to the nearest 5 mg
Second reduction	25	25 x BSA, rounded to the nearest 5 mg
Third reduction	20	20 x BSA, rounded to the nearest 5 mg

A maximum of 3 dose reductions are permitted. The dose is never escalated after it has been reduced, and LONSURF is permanently discontinued in patients who are unable to tolerate 20 mg/m2 twice daily. One practical wrinkle: a reduced dose can work out to 25 mg per administration, which cannot be assembled from 15 mg and 20 mg tablets. The label's own solution, printed in Table 2, is to split the day unevenly: one 20 mg tablet in the morning and two 15 mg tablets (30 mg) in the evening, giving the correct 50 mg total daily dose. This calculator flags that method whenever a calculated dose is 25 mg.

Severe renal impairment (section 2.3)

In patients with severe renal impairment, defined in the label as a creatinine clearance of 15 to 29 mL/min by the Cockcroft-Gault formula, the recommended dosage is 20 mg/m2 twice daily on the same Days 1 to 5 and 8 to 12 schedule, read from Table 2 rather than Table 1. Patients who cannot tolerate 20 mg/m2 twice daily are reduced to 15 mg/m2 twice daily, and LONSURF is permanently discontinued in patients who cannot tolerate 15 mg/m2 twice daily. Table 2 gives both levels by BSA band:

Table 2 at the 20 mg/m2 level (severe renal impairment, starting level):

BSA (m2)	Total daily dose (mg)	Dose per administration (mg, twice daily)	15 mg tablets per dose	20 mg tablets per dose
Below 1.14	40	20	0	1
1.14 to 1.34	50	25	Split day: 1 x 20 mg tablet in the morning, 2 x 15 mg tablets in the evening
1.35 to 1.59	60	30	2	0
1.60 to 1.94	70	35	1	1
1.95 to 2.09	80	40	0	2
2.10 to 2.34	90	45	3	0
2.35 and above	100	50	2	1

Table 2 at the 15 mg/m2 level (severe renal impairment, reduced level):

BSA (m2)	Total daily dose (mg)	Dose per administration (mg, twice daily)	15 mg tablets per dose	20 mg tablets per dose
Below 1.15	30	15	1	0
1.15 to 1.49	40	20	0	1
1.50 to 1.84	50	25	Split day: 1 x 20 mg tablet in the morning, 2 x 15 mg tablets in the evening
1.85 to 2.09	60	30	2	0
2.10 to 2.34	70	35	1	1
2.35 and above	80	40	0	2

The bands differ slightly between the two levels (the 20 mg/m2 bands break at 1.14, 1.35, 1.60, 1.95, 2.10 and 2.35; the 15 mg/m2 bands at 1.15, 1.50, 1.85, 2.10 and 2.35), so the calculator keeps two separate tables rather than scaling one. The tablet combinations follow the same fewest-tablets pattern as Table 1: 30 mg is two 15 mg tablets, 35 mg is one of each, 50 mg is two 15 mg plus one 20 mg, and each table has exactly one 25 mg band, which uses the morning and evening split described above.

Checks before any LONSURF dose is dispensed. (1) LONSURF is cytotoxic: follow special handling and disposal procedures, and swallow tablets whole. (2) The 80 mg maximum is per dose, not per day. (3) Confirm which table applies: Table 1 for standard dosing, Table 2 only when creatinine clearance is 15 to 29 mL/min. (4) A dose that has been reduced is never re-escalated, and treatment stops if 20 mg/m2 (or 15 mg/m2 in severe renal impairment) cannot be tolerated. (5) Blood counts gate every cycle: no new cycle until the ANC, platelet and non-hematologic recovery criteria in section 2.2 are met.

Sources

LONSURF (trifluridine and tipiracil) tablets, for oral use. FDA-approved prescribing information, Taiho Oncology (DailyMed setid f5beed22-d71d-4c0d-8dca-2c7317d65d85, SPL version 15, published 18 November 2025): section 1.1 (metastatic colorectal cancer indication) and 1.2 (metastatic gastric cancer indication); section 2.1 (recommended dosage 35 mg/m2 up to a maximum of 80 mg per dose, twice daily with food on Days 1 through 5 and Days 8 through 12 of each 28-day cycle, dose rounded to the nearest 5 mg increment, and Table 1, reproduced in full on this page); section 2.2 (blood count requirements before and on Day 15 of each cycle, withholding criteria, resumption after a 5 mg/m2 per-dose reduction for the listed events, maximum of 3 dose reductions, no re-escalation, permanent discontinuation below 20 mg/m2 twice daily); section 2.3 (severe renal impairment, creatinine clearance 15 to 29 mL/min: 20 mg/m2 twice daily per Table 2, reduction to 15 mg/m2 twice daily, discontinuation below 15 mg/m2, Table 2 reproduced on this page including the 25 mg morning and evening split); section 3 (tablets of 15 mg trifluridine/6.14 mg tipiracil and 20 mg trifluridine/8.19 mg tipiracil). BSA from height and weight uses the Mosteller formula, BSA (m2) = square root of (height in cm x weight in kg / 3600).

Key takeaways

The FDA label's recommended dosage is 35 mg/m2 per dose, up to a maximum of 80 mg per dose (based on the trifluridine component), taken orally twice daily with food on Days 1 through 5 and Days 8 through 12 of each 28-day cycle, until disease progression or unacceptable toxicity.
Three 20 mg tablets.
A 25 mg dose cannot be assembled from 15 mg and 20 mg tablets.
Per section 2.2 of the label, after recovery from febrile neutropenia, uncomplicated Grade 4 neutropenia or thrombocytopenia that delays the next cycle by more than 1 week, or a Grade 3 or 4 non-hematologic adverse reaction (with stated exceptions), LONSURF is resumed after reducing the dose by 5 mg/m2 per dose from the previous dose.

Frequently asked questions

What is the starting dose of LONSURF?

The FDA label's recommended dosage is 35 mg/m2 per dose, up to a maximum of 80 mg per dose (based on the trifluridine component), taken orally twice daily with food on Days 1 through 5 and Days 8 through 12 of each 28-day cycle, until disease progression or unacceptable toxicity. The exact starting dose for a given body surface area is read from Table 1 of the label, which also gives the combination of 15 mg and 20 mg tablets for each dose.

How many tablets make up a 60 mg LONSURF dose?

Three 20 mg tablets. A 60 mg dose is the Table 1 starting dose for a body surface area of 1.69 to 1.83 m2, given twice daily, so the total daily dose is 120 mg. Other Table 1 combinations include 35 mg as one 15 mg plus one 20 mg tablet, 45 mg as three 15 mg tablets, 50 mg as two 15 mg plus one 20 mg, and the maximum 80 mg dose as four 20 mg tablets.

What happens when the LONSURF dose works out to 25 mg?

A 25 mg dose cannot be assembled from 15 mg and 20 mg tablets. The label solves this in its Table 2 for renal impairment: for a total daily dose of 50 mg, patients take one 20 mg tablet in the morning and two 15 mg tablets (30 mg) in the evening, alternating 20 mg and 30 mg doses that average 25 mg per dose. This calculator applies the same label method whenever a calculated dose is 25 mg.

How is the LONSURF dose reduced for adverse reactions?

Per section 2.2 of the label, after recovery from febrile neutropenia, uncomplicated Grade 4 neutropenia or thrombocytopenia that delays the next cycle by more than 1 week, or a Grade 3 or 4 non-hematologic adverse reaction (with stated exceptions), LONSURF is resumed after reducing the dose by 5 mg/m2 per dose from the previous dose. The ladder is 35, then 30, then 25, then 20 mg/m2. A maximum of 3 dose reductions are permitted, the dose is never re-escalated after a reduction, and LONSURF is permanently discontinued in patients who cannot tolerate 20 mg/m2 twice daily.

What is the LONSURF dose in severe renal impairment?

For patients with severe renal impairment (creatinine clearance 15 to 29 mL/min by the Cockcroft-Gault formula), section 2.3 of the label sets the dose at 20 mg/m2 twice daily using Table 2, for example 35 mg per dose at a body surface area of 1.60 to 1.94 m2. Patients who cannot tolerate 20 mg/m2 are reduced to 15 mg/m2 twice daily, and LONSURF is permanently discontinued in patients who cannot tolerate 15 mg/m2 twice daily.

Why does this calculator use the label table instead of just multiplying 35 by my BSA?

Because Table 1 of the label is the prescribing instruction, and at its band edges it differs slightly from the raw multiplication. At a BSA of 1.22 m2, 35 x 1.22 = 42.7 mg, which rounds to 45 mg, but the label table gives 40 mg for the whole band 1.07 to 1.22 m2. At a BSA of 1.07 m2 the raw product is 37.45 mg, which rounds to 35 mg, but the table gives 40 mg. Where the table and the arithmetic disagree, the table governs, so this calculator looks the starting dose up in Table 1 exactly as printed.

Medical disclaimer: This calculator reproduces the dosing tables and dose modification rules of the FDA-approved LONSURF prescribing information for educational and checking purposes. It does not prescribe: LONSURF is a cytotoxic drug for previously treated metastatic colorectal and gastric cancer, the dose level, cycle timing and any dose modification are decisions for the treating oncology team based on blood counts and toxicity, and the bevacizumab prescribing information governs when the drugs are combined. Verify every dose against the current label and the prescription before dispensing or administering.