Ceredase Pharmacology, Pharmacokinetics, Studies, Metabolism - Alglucerase

Ceredase Pharmacology, Pharmacokinetics, Studies, Metabolism - Alglucerase

CLINICAL PHARMACOLOGY

Ceredase(alglucerase injection) catalyzes the hydrolysis of the glycolipid, glucocerebroside, to glucose and ceramide as part of the normal degradation pathway for membrane lipids. Glucocerebroside is primarily derived from hematologic cell turnover. Gaucher disease is characterized by a functional deficiency in Beta-glucocerebrosidase enzymatic activity and the resultant accumulation of lipid glucocerebroside in tissue macrophages which become engorged and are termed Gaucher cells. Gaucher cells are typically found in liver, spleen and bone marrow and occasionally, as well, in lung, kidney and intestine. Secondary hematologic sequelae include severe anemia and thrombocytopenia in addition to the characteristic progressive hepatosplenomegaly. Skeletal complications, including osteonecrosis and osteopenia with secondary pathological fractures, are a common feature of Gaucher disease.

Pharmacokinetics

Following an intravenous infusion of different doses (between 0.6 and 234 units/kg) of Ceredase (alglucerase injection) over a 4-hour period, steady-state enzymatic activity was achieved by 60 minutes. Individual steady-state enzymatic activity and area under the curve of the activity increased linearly with the infused dose (0.6 to 121 units/ kg). Following infusion termination, plasma enzymatic activity declined rapidly with elimination half-life ranging between 3.6 and 10.4 minutes. Plasma clearance of Ceredase, calculated from its plasma enzymatic activity, was variable and ranged between 6.34 and 25.39 mL/mini/kg, whereas the volume of distribution ranged from 49.4 to 282.1 mL/kg. Within the dosage range of 0.6 and 121 units/kg, elimination half-life, plasma clearance, and volume of distribution values appear to be independent of the infused dose.

Pharmacologic Actions

Chronic administration of Ceredase (alglucerase injection) in 13 patients with Type I Gaucher disease from initial studies induced the following effects:

1. Splenomegaly and hepatomegaly were significantly reduced, presumably by disruption of the lysosomal storage sites and metabolism of glucocerebroside in Gaucher cells. This effect was demonstrated within 6 months of initiation of therapy.
2. Hematologic deficiencies in hemoglobin, hematocrit, erythrocyte and platelet counts were significantly improved. In most patients a change in hemoglobin was the first observable effect. In some patients hemoglobin levels were normalized after 6 months of therapy.
3. Improved mineralization of bone, as revealed by plain radiographs of long bones, occurred in three patients after prolonged treatment as a result of a reduction in the osteolytic actions of lipid-laden Gaucher cells in the marrow.
4. Cachexia and wasting in children were reduced.