PENTOSTATIN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for PENTOSTATIN (PENTOSTATIN).
Pentostatin is a potent inhibitor of adenosine deaminase (ADA), an enzyme involved in purine metabolism. Inhibition of ADA leads to accumulation of deoxyadenosine and deoxyadenosine triphosphate (dATP), which inhibits ribonucleotide reductase and DNA synthesis, resulting in cytotoxicity, particularly in lymphocytes.
| Metabolism | Pentostatin is primarily excreted unchanged in the urine. Minimal hepatic metabolism occurs, but specific metabolic pathways are not well characterized. |
| Excretion | Renal: 90% as unchanged drug; fecal: <1% |
| Half-life | Terminal half-life: 5-15 hours (mean 10 hours); prolonged to 20-50 hours in renal impairment |
| Protein binding | ~5% (primarily to albumin) |
| Volume of Distribution | 20 L/kg (approximate); large Vd indicates extensive tissue distribution |
| Bioavailability | Oral: <10% (not administered orally); IV: 100% |
| Onset of Action | IV: Clinical effects (antileukemic response) observed within 1-2 weeks |
| Duration of Action | Duration of effect: variable; drug-induced lymphopenia persists for 2-4 weeks post-treatment |
4 mg/m2 intravenously every 2 weeks.
| Dosage form | INJECTABLE |
| Renal impairment | CrCl >60 mL/min: no adjustment. CrCl 30-60 mL/min: reduce dose to 2 mg/m2. CrCl <30 mL/min: not recommended. |
| Liver impairment | Child-Pugh A: no adjustment. Child-Pugh B: reduce dose to 2 mg/m2. Child-Pugh C: not recommended. |
| Pediatric use | 2-4 mg/m2 intravenously every 2 weeks, maximum 4 mg/m2. |
| Geriatric use | No specific dose adjustment, but monitor renal function closely due to age-related decline; consider renal adjustment as per adult guidelines. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for PENTOSTATIN (PENTOSTATIN).
| Breastfeeding | No human data on excretion in breast milk; M/P ratio unknown. Pentostatin and its metabolites may be present in milk. Because of potential for serious adverse reactions in breastfed infants (e.g., myelosuppression, immunosuppression), breastfeeding is not recommended during therapy and for at least 4 weeks after last dose. |
| Teratogenic Risk | Pregnancy category D. First trimester: Associated with teratogenicity based on animal studies and limited human data; risk of fetal malformations (e.g., skeletal, CNS) cannot be excluded. Second and third trimesters: May cause fetal harm, including growth restriction and oligohydramnios; potential for neonatal bone marrow suppression, immunosuppression, and infection. Use only if benefit outweighs risk; effective contraception advised. |
■ FDA Black Box Warning
Pentostatin should be administered under the supervision of a physician experienced in the use of antineoplastic therapy. Severe renal, hepatic, pulmonary, and neurologic toxicities have been reported. Myelosuppression is severe and may require dose adjustment.
| Serious Effects |
Hypersensitivity to pentostatin; severe renal impairment (creatinine clearance < 60 mL/min); severe hepatic impairment; recent or concurrent use of fludarabine (increased risk of pulmonary toxicity).
| Precautions | Renal toxicity (elevated creatinine, acute renal failure), hepatic toxicity (elevated liver enzymes, hepatic failure), pulmonary toxicity (interstitial pneumonitis, pulmonary fibrosis), neurologic toxicity (seizures, peripheral neuropathy), myelosuppression (neutropenia, thrombocytopenia, anemia), increased risk of infection, and immunosuppression. Dose reduction is required in renal impairment. Monitor renal function, liver function, blood counts, and neurologic status. |
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| Fetal Monitoring | Maternal: Complete blood count with differential, renal function (serum creatinine, BUN), hepatic function (LFTs), and electrolytes before each dose; monitor for signs of infection, bleeding, and acute kidney injury. Fetal: Serial ultrasound for fetal growth and amniotic fluid volume assessment; consider Doppler studies if placental insufficiency suspected. Close multidisciplinary collaboration between oncology and maternal-fetal medicine specialists. |
| Fertility Effects | Pentostatin may impair fertility in both males and females. In males, may cause oligospermia, azoospermia, and testicular atrophy. In females, may induce amenorrhea, ovarian failure, and premature menopause. Effects may be irreversible. Advise counseling on fertility preservation options before treatment. |