Fludarabine Phosphate (Page 4 of 5)

12.3 Pharmacokinetics

Studies with the intravenous product have demonstrated that fludarabine phosphate is converted to the active metabolite, 2F-ara-A. Clinical pharmacology studies have focused on 2F-ara-A pharmacokinetics.

Following administration of the intravenous product, systemic plasma clearance of 2F-ara-A is approximately 117 mL/min to 145 mL/min. After five daily 30 minute intravenous infusions of 25 mg 2F-ara- AMP/m2 to cancer patients, trough concentrations of 2F-ara-A increased by a factor of about 2. The terminal half-life of 2F-ara-A was approximately 20 hours. Plasma protein binding of 2F-ara-A was approximately 19% to 29%. A correlation was noted between the degree of absolute granulocyte count nadir and increased area under the concentration x time curve (AUC).

2F-ara-A exhibits dose proportional increases in AUC and Cmax after single oral doses of 50 mg, 70 mg or 90 mg of 2F-ara-AMP. Cmax of 2F-ara-A occurs 1 hour to 2 hours after single or multiple oral doses and is approximately 20 % to 30 % of the maximum plasma concentrations produced at the end of a 30 minute intravenous infusion of the same dose. The absolute oral bioavailability of 2F-ara-A is 50 — 65% following single and repeated doses of the immediate release tablet formulation. Similar systemic exposure (AUC) was observed after a single 40 mg/m2 fludarabine phosphate oral dose and a single 25 mg/m2 fludarabine phosphate intravenous dose. The terminal half-life of 2F-ara-A was similar to that following intravenous administration; approximately 20 hours. The Cmax , AUC and terminal half-life of 2F-ara-A are unaffected when administered with a high fat meal, although Tmax is slightly delayed from 1.3 hours to 2.2 hours.

Following intravenous administration, renal clearance of 2F-ara-A represents approximately 40% of the total body clearance of fludarabine phosphate, and total body clearance is inversely correlated with serum creatinine and creatinine clearance. In two patients with median creatinine clearance of 22 mL/min/1.73 m2 , 2F-ara-A clearance was reduced by 56%. Dosage adjustment based on creatinine clearance is recommended as follows:

Reduce dose by 20% in patients with mild to moderate renal impairment (creatinine clearance 30 to 70 mL/min/1.73 m2). [See Warnings and Precautions (5.7)]

Reduce dose by 50% in patients with severe renal impairment (creatinine clearance < 30 mL/min/1.73 m2). [See Warnings and Precautions (5.7)]

13 NONCLINICAL TOXICOLOGY

13.1 Carcinogenesis, Mutagenesis, Impairment of Fertility

No animal carcinogenicity studies with fludarabine phosphate have been conducted.

Fludarabine phosphate is a clastogen.

Fludarabine phosphate was clastogenic in vitro to Chinese hamster ovary cells (chromosome aberration assay) in the presence of metabolic activation and induced sister chromatid exchanges both in the presence and absence of metabolic activation. In addition, fludarabine phosphate was clastogenic in vivo (mouse micronucleus assay) but was not mutagenic to germ cells (dominant lethal test in male mice). Fludarabine phosphate was not mutagenic to bacteria (Ames test) or mammalian cells either in the presence or absence of metabolic activation.

Studies in mice, rats and dogs have demonstrated dose-related adverse effects on the male reproductive system. Observations consisted of a decrease in mean testicular weights in mice and rats with a trend toward decreased testicular weights in dogs and degeneration and necrosis of spermatogenic epithelium of the testes in mice, rats and dogs.

14 CLINICAL STUDIES

Study 1, a single-arm, open-label study of fludarabine phosphate film-coated tablets was conducted in 78 adult patients with CLL refractory to at least one prior standard alkylating-agent containing regimen. In this multicenter study patients were treated with oral fludarabine phosphate at a dose of 40 mg/m2 daily for 5 days every 28 days. The patient population median age was 64.5 years and consisted of 72% males and 28% females. Ninety-nine percent of the patients were Caucasian. The Rai stage for patients entering the study was: Stage 0 (3.9%), Stage I (20.5%), Stage II (32.1%), Stage III (11.5%), and Stage IV (32.1%). The mean number of treatment cycles was 5.1 with a mean daily dose of fludarabine phosphate of 38 mg/m2. The overall objective response, according to standardized response criteria developed by the National Cancer Institute CLL Working Group (NCI criteria), was 51 %, including 18% complete responses and 33% partial responses. The overall response rate, according to standardized criteria developed by the International Workshop on CLL (IWCLL criteria), was 46%, including 21% complete responses and 26% partial responses. Data on duration of response was not collected.

In Study 2, a supportive single-arm, open-label study, fludarabine phosphate tablets were administered to 81 previously untreated patients with B-CLL. In this multicenter study each patient was treated with oral fludarabine phosphate at a dose of 40 mg/m2 daily for 5 days every 28 days. The patient population median age was 64.0 years and consisted of 63% males and 37% females. Ninety-nine percent of the patients were Caucasian. The Rai stage for patients entering the study was: Stage 0 (3.7%), Stage I (37.0%), Stage II (37.0%), Stage III (9.9%), and Stage IV (12.3%). The mean number of treatment cycles was 5.9 with a mean daily dose per patient of 71 mg to 74 mg. The overall responses rate, according to NCI criteria, was 80%, including 12% complete responses and 68% partial responses. The overall response rate, according to IWCLL criteria, was 72%, including 37% complete responses and 35% partial responses. The median duration of response was 22.9 months.

Study 3 was a supportive randomized controlled open label study in patients with previously untreated B-CLL that included fludarabine phosphate monotherapy and fludarabine phosphate combination therapy arms. In this study 107 evaluable patients received fludarabine phosphate 40mg/m2 orally daily for 5 days every 28 days. The overall response rate according to modified NCI criteria was 74% and the CR plus nodular PR rate was 41%.

15 REFERENCES

  1. Preventing Occupational Exposures to Antineoplastic and Other Hazardous Drugs in Health Care Settings. NIOSH Alert 2004-165.

  2. OSHA Technical Manual, TED 1-0.15A, Section VI: Chapter 2. Controlling Occupational Exposure to Hazardous Drugs. OSHA, 1999.
    http://www.osha.gov/dts/osta/otm/otm_vi/otm_vi_2.html

  3. American Society of Health-System Pharmacists. ASHP guidelines on handling hazardous drugs. Am J Health-Syst Pharm. 2006;63:1172-1193.

  4. Polovich, M., White, J. M., & Kelleher, L.O. (eds.) 2005. Chemotherapy and biotherapy guidelines and recommendations for practice (2nd. ed.) Pittsburgh, PA: Oncology Nursing Society.

16 HOW SUPPLIED/STORAGE AND HANDLING

HOW SUPPLIED

Fludarabine phosphate is supplied in 10 milligram tablets that are film-coated, capsule shaped, salmon pink in color, and marked on one side with ‘LN’ in a regular hexagon. Each film-coated tablet contains 10 mg fludarabine phosphate. The tablets are supplied in blisters, each blister strip containing 5 tablets. Packages of 15 and 20 tablets are available in child-resistant containers.

NDC 45414-311-15: 15 — 10 milligram film-coated tablets per container. Each film-coated tablet is packaged in an individual blister package; 5 tablets per blister strip; 3 blister strips packaged in a plastic bottle with a child-resistant container closure; each bottle is packaged in an individual chip-board carton.

NDC 45414-311-20: 20 — 10 milligram film-coated tablets per container. Each film-coated tablet is packaged in an individual blister package; 5 tablets per blister strip; 4 blister strips packaged in a plastic bottle with a child-resistant container closure; each bottle is packaged in an individual chip-board carton.

STORAGE

Store under normal lighting conditions at 25°C (77°F); excursions permitted to 15-30°C (59-86°F) [see USP controlled room temperature].

HANDLING AND DISPOSAL

Procedures for proper handling and disposal should be considered. Consideration should be given to handling and disposal according to guidelines issued for cytotoxic drugs. Several guidelines on this subject have been published.1-4 Caution should be exercised in the handling of fludarabine phosphate. Do not crush tablets. Avoid exposure by direct contact of the skin or mucous membranes or by inhalation. If contact occurs, wash thoroughly with soap and water or wash the eyes immediately with gently flowing water for at least 15 minutes. Consult healthcare provider in case of a skin reaction or if the drug gets in the eyes.

17 PATIENT COUNSELING INFORMATION

17.1 Bone Marrow Suppression

Inform patients that fludarabine phosphate decreases blood cell counts such as white blood cells, platelets, and red blood cells. Thus, it is important that periodic assessment of their blood count be performed to detect the development of neutropenia, thrombocytopenia and anemia. [See Warnings and Precautions (5.2)]

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