Galamustine Hydrochloride

A high-performance liquid chromatography (HPLC) method is described for the determination of reactive nitrogen mustard anticancer drugs in plasma after derivatization with diethyl-dithiocarbamic acid (DDTC). Three compounds were studied: two reactive species (mechlorethamine (HN2) and galactose 6-mustard (G-6-M] and a less reactive species (melphalan (L-PAM] included for validation experiments. Mass and NMR spectrometry confirmed that one molecule of DDTC reacts with each arm of the mustard, displacing a chlorine atom to form a stable disubstituted adduct. With the reactive mustards a 30-min incubation at 37 degrees C is recommended for greater than 90% derivatization efficiency. Gradient elution was employed to analyze all three compounds using the same conditions with a microBondapak C18 10-microns particle size column (30 cm by 3.8 mm i.d.). The retention time (tR) of HN2-DDTC2 was 13.1 min +/- 1.5% within day CV; tR of L-PAM was 7.6 min and L-PAM-DDTC2 was 14.6 min +/- 0.8% CV. G-6-M-DDTC2 yielded a double peak, tR = 10.7 min and 10.9 min +/- 2.9% CV. The limit of detection on column was 0.5 ng for HN2, 1 ng for L-PAM, and 5 ng for G-6-M. A solid-phase sample preparation technique using "Bond Elut" phenyl is described that extracts from plasma G-6-M-DDTC2 with greater than 74% efficiency and HN2-DDTC2 with greater than 90% efficiency. When the drugs were derivatized in plasma, recovery remained high for G-6-M (greater than 84%) but dropped to 50% for HN2.(ABSTRACT TRUNCATED AT 250 WORDS)

We have previously reported that chloroethyl nitrosourea and nitrogen mustard bone marrow toxicity can be selectively reduced by placement of the cytotoxic group on specific positions of a glucose molecule. We have now synthesized and evaluated a new drug in which the mustard cytotoxic group is attached to the carbon-6 position of galactose (C6-GLM). C6-GLM, administered i.p. as a single 10% lethal dose of 15.5 mg/kg, produced a 121% increase in life span (ILS) in mice bearing the ascitic P388 leukemia, compared to a 60% ILS with a 10% lethal dose of nitrogen mustard (P less than 0.01). A single p.o. dose of C6-GLM, 16 mg/kg, produced an ILS of 58%. Against i.p.-implanted B-16 melanoma, i.p. C6-GLM produced a 56% ILS compared to 30% with an equitoxic dose of nitrogen mustard (P less than 0.01). The activity of the two drugs for Ehrlich ascites was comparable, with 60% survivors with the galactose mustard. A single 10% lethal dose of C6-GLM reduced the white blood cells to 74% of control; circulating granulocytes remained at 91% of initial values. With nitrogen mustard, the nadir white blood cell count was 57% of control with an absolute granulocyte count of 70% of initial values (P less than 0.01). The toxicity of melphalan was considerably greater, with a lower and more protracted while blood cell nadir and an absolute neutrophil count nadir of 49% of control. These findings paralleled the relative decrements in bone marrow DNA synthesis produced by the three drugs. Measurement of human bone marrow granulocyte-macrophage colony-forming units, following in vitro exposure to graded concentrations of the three mustards, confirmed the bone marrow sparing properties of C6-GLM. At the highest concentration, 1 X 10(-2) mM, the latter drug produced only a 33% reduction in colonies compared to a 75% reduction with nitrogen mustard and a virtual elimination of activity of colony-forming units with melphalan. The demonstration of antitumor activity, at least equivalent to nitrogen mustard, without the necessity of significant bone marrow toxicity supports the development of C6-GLM for clinical trials in humans.