Pharmacokinetics and tolerability of NSC23925b, a novel P-glycoprotein inhibitor: preclinical study in mice and rats.

Overexpression of P-glycoprotein (Pgp) increases multidrug resistance (MDR) in cancer, which greatly impedes satisfactory clinical treatment and outcomes of cancer patients. Due to unknown pharmacokinetics, the use of Pgp inhibitors to overcome MDR in the clinical setting remains elusive despite promising in vitro results. The purpose of our current preclinical study is to investigate the pharmacokinetics and tolerability of NSC23925b, a novel and potent P-glycoprotein inhibitor, in rodents. Plasma pharmacokinetic studies of single-dose NSC23925b alone or in combination with paclitaxel or doxorubicin were conducted in male BALB/c mice and Sprague-Dawley rats. Additionally, inhibition of human cytochrome P450 (CYP450) by NSC23925b was examined in vitro. Finally, the maximum tolerated dose (MTD) of NSC23925b was determined. NSC23925b displayed favorable pharmacokinetic profiles after intraperitoneal/intravenous (I.P./I.V.) injection alone or combined with chemotherapeutic drugs. The plasma pharmacokinetic characteristics of the chemotherapy drugs were not affected when co-administered with NSC23925b. All the animals tolerated the I.P./I.V. administration of NSC23925b. Moreover, the enzymatic activity of human CYP450 was not inhibited by NSC23925b. Our results demonstrated that Pgp inhibitor NSC23925b exhibits encouraging preclinical pharmacokinetic characteristics and limited toxicity in vivo. NSC23925b has the potential to treat cancer patients with MDR in the future.

Guidance on the use of miglustat for treating patients with type 1 Gaucher disease.

Type 1 Gaucher disease (GD) is a progressive lysosomal storage disorder due to an autosomal recessive deficiency of glucocerebrosidase. Clinical manifestations include anemia, thrombocytopenia, hepatosplenomegaly, and bone and pulmonary disease. Intravenous enzyme replacement (ERT) with imiglucerase is the accepted standard for treatment of symptomatic patients. More than 3,500 patients worldwide have received ERT with well-documented beneficial effects on the hematological, visceral, skeletal, and pulmonary manifestations, and with resultant improvement in health-related quality of life. Miglustat, an imino sugar that reversibly inhibits glucosylceramide synthase and reduces intracellular substrate burden, is an oral treatment for patients with type 1 GD that was recently approved in the United States for symptomatic patients with mild to moderate clinical manifestations for whom ERT is not an option. Because responses to miglustat are slower and less robust than those observed with ERT, and because miglustat is associated with significant side effects, clinicians who care for patients with GD should become familiar with the limited indications for miglustat use and the circumstances when it may be prescribed appropriately. This review article and position statement represents the current opinion of American physicians with extensive expertise in GD regarding patient management in the context of the availability of standard imiglucerase treatment and the recent introduction of miglustat.