). 2 Recommended Dose and Dosage Adjustment The dosage of LANVIS must be carefully adjusted for each patient to obtain optimum benefit without toxic effects. The usual initial dose is approximately 2 mg/kg body weight/day, orally. If after four weeks on this dosage there is no clinical improvement and no leukocyte depression, the dosage may be cautiously increased to 3 mg/kg/day.
The total daily dose may be given at one time. It is usually calculated to the closest multiple of 20 mg. Although the effect usually occurs slowly over a period of two to four weeks, occasionally there may be a rapid fall in leukocyte count within one or two weeks.
This may occur in some adults with acute leukemia and high total leukocyte counts. For this reason it is important to observe such patients closely. Geriatrics (≥ 65 years) There are insufficient data to recommend a specific dose in geriatric patients with leukemia.
In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy.
Pediatrics (≤ 18 years) For children, similar dosages to those used in adults, with appropriate correction for body surface area, have been used. Thiopurine S-methyltransferase-deficient Patients Genotypic or phenotypic tests of thiopurine S-methyltransferase (TPMT) are recommended prior to initiating LANVIS to identify high risk patients (see Hematologic and Monitoring and Laboratory Tests).
, severe myelosuppression) from conventional doses of LANVIS and generally require substantial dose reduction (see Table 1). LANVIS® (thioguanine) Page 6 of 28 Table 1 Recommended Starting Doses of LANVIS by TPMT Genotype and Phenotype TPMT Genotype and Phenotype Dosing Recommendations for LANVIS Homozygous wild-type or normal, high activity (two functional *1 alleles) Start with normal starting dose.
Adjust doses of LANVIS and of other myelosuppressive therapy without any special emphasis on LANVIS. Allow 2 weeks to reach steady state after each dose adjustment. Heterozygote or intermediate activity (one functional allele - *1, plus one of the nonfunctional alleles - *2, *3A, *3B, *3C, or *4) Reduce the starting dose by 30-50% and adjust doses of LANVIS based on degree of myelosuppression.
Allow 2-4 weeks to reach steady state after each dose adjustment. In setting of myelosuppression, and depending on other therapy, emphasis should be on reducing LANVIS over other agents Homozygous variant, mutant, or low/ deficient activity (two nonfunctional alleles - *2, *3A, *3B, *3C, or *4) Reduce the starting dose of LANVIS by 10-fold and dose thrice weekly instead of daily and adjust doses of LANVIS based on degree of myelosuppression.
Allow 4-6 weeks to reach steady state after each dose adjustment. In setting of myelosuppression, emphasis should be on reducing LANVIS over other agents.
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TPMT = thiopurine S-methyltransferase. NUDT15 Variant Patients Genotypic and phenotypic testing of NUDT15 variants should be considered before initiating thiopurine therapy in all patients (including pediatric patients) to reduce the risk of thiopurine-related severe leukocytopenia and alopecia, especially in Asian populations patients (see Hematologic and Monitoring and Laboratory Tests).
Patients with inherited mutated NUDT15 gene are at increased risk for severe thiopurine toxicity, such as early leukopenia and alopecia, from conventional doses of thiopurine therapy and require substantial dose reduction. Patients of Asian ethnicity are particularly at risk, due to the increased frequency of the mutation in this population.
The optimal starting dose for heterozygous or homozygous deficient patients has not been established. Therefore, hematological parameters should be monitored during treatment with LANVIS. The prescribing physician is advised to establish whether dose reduction is required based on patient response to treatment as well as their genetic profile.
Patients with variants in both the NUDT15 and TPMT enzymes are significantly less tolerant of thiopurines than those with risk alleles in only one of these two genes (see 10 CLINICAL PHARMACOLOGY). Hepatic Impairment There are no data on the effects of hepatic impairment on thioguanine exposure.
Hepatic impairment may increase exposure of thioguanine since it is primarily metabolized in the liver. Consideration should be given to reducing the starting dose of LANVIS in patients with impaired hepatic function (see Special Populations and Conditions).
Renal Impairment No information is available about thioguanine in patients with renal impairment. Consideration should be given to reducing the starting dose of LANVIS in patients with impaired renal function (see Special Populations and Conditions).
4 Administration LANVIS is for oral use. 5 Missed Dose If a scheduled dose is missed, the dose should be taken as soon as the patient remembers, unless it is almost time for the patient’s next dose. Two doses should not be taken together.
If more than two doses are missed, the patient should consult with their doctor. 5 OVERDOSAGE Signs and symptoms of overdosage may be immediate, such as nausea, vomiting, malaise, hypertension, and diaphoresis; or delayed, such as myelosuppression and azotemia.
It is not known whether thioguanine is dialyzable. Hemodialysis is thought to be of marginal use due to the rapid metabolism of thioguanine into active intracellular derivatives with longer persistence than the parent drug. There is no known pharmacologic antagonist of thioguanine.
The drug should be discontinued immediately if unintended toxicity occurs during treatment. Severe hematologic toxicity may require supportive therapy with platelet transfusions for bleeding, […]