Determination and pharmacokinetic study of 1-p-(3.3-dimethyl-1-triazeno) benzoic acid in cancer patients by capillary gas chromatography.

A capillary gas chromatographic method was developed for determining 1-p-(3.3-dimethyl-1-triazeno) benzoic acid in the plasma and urine of cancer patients under pharmacokinetic study. The drug was extracted with ethyl acetate and methylated with diazomethane. Octadelane (10 microg/ml) was added as internal standard. The separation was carried out on an OV-1 quartz capillary column, 15 m x 0.32 mm (0.52 microm), with high-purity nitrogen as carrier gas and flame ionization detector (FID) as detector. The column temperature was held at 130 degrees C for 9 min and then programmed to 240 degrees C, at a rate of 35 degrees C/min. The temperature of both injector and detector was 260 degrees C. The standard curve was linear from 0.4 to 40 microg/mL in plasma, and from 0.8 to 20 microg/mL in urine, with correlation coefficients of 0.9979 and 0.9932. The relative standard deviations (RSD) were less than 9.7%. The minimum recovery of this method was 81.8%. This method was applied to the pharmacokinetic studies of 1-p-(3.3-dimethyl-1-triazeno) benzoic acid in cancer patients after a single dose (i.v.) of 160, 420 or 760 mg/m(2) was administered. They all conformed to the two-compartment open model and showed linear pharmacokinetics. The excretion of this drug in the urine was minimal.

Metabolism of 1,3-di-(4-[N-(4,6-dimethyl-2-pyrimidinyl)sulphamoyl] phenyl)triazene (DDPSPT) in the rat.

1. Six hours after rats were orally dosed with 1,3-di-(4-[N-(4,6-dimethyl-2-pyrimidinyl)sulphamoyl][U-14C]phenyl) triazene (14C-DDPSPT), approx. 81% of the 14C remained in the gastrointestinal tract (gut) and less than 3% was excreted in the urine. 2. Six hours after dosing, more than half of the 14C in the gut was present as DDPSPT. 14C-Labelled metabolites in the gut included 4-amino-N-(4,6-dimethyl-2-pyrimidinyl)-benzenesulphonamide (Sulmet), N4-glucosyl-N-(4,6-dimethyl-2-pyrimidinyl)benzenesulphonamide (N4-gluc-Sulmet), 4-acetamido-N-(4,6-dimethyl-2-pyrimidinyl)benzenesulphonamide (N4-acetyl-Sulmet), and [N-4,6-dimethyl-2-pyrimidinyl) benzenesulphonamide] (desamino-Sulmet). 3. 14C-Labelled compounds in the blood, liver and skeletal muscle included DDPSPT, Sulmet, N4-gluc-Sulmet, N4-acetyl-Sulmet and desamino-Sulmet. 4. There was little or no reaction of DDPSPT with cysteine, bovine serum albumin, AMP, GMP, or calf thymus deoxyribonucleic acid in vitro (pH 3, 5, 7 or 8).

Urinary metabolite of 1-(2,4,6-trichlorophenyl)-3,3-dimethyltriazene with an intact diazoamino structure.

The tumour-inhibiting substance 1-(2,4,6-trichlorophenyl)-3,3-dimethyltriazene is metabolised in rats to the corresponding substituted 1-O-(triazenyl-methyl) glucuronic acid. The urinary metabolite was purified by ion exchange chromatography and gel filtration, and isolated from the enriched fractions by freeze-drying. Cold acid cleavage into the 2,4,6-trichlorobenzene-diazonium cation and hydrolysis to glucuronic acid and formaldehyde indicated the presence of an O-glycosidic bond through an enzymically-introduced hydroxymethyl oxygen. This novel type of glucuronoside structure was established by chemical evidence, and confirmed by NMR and field-desorption mass spectrometry. It is conceivable that this metabolite represents a stabilised carrier form of the biologically-active triazene that transports the methylating agent from its site of formation to its ultimate target.

Urinary metabolites of 3,3-dimethyl-1-phenyltriazene.

Urinary metabolites excreted after a subcutaneous injection of 3,3-dimethyl-1[14C] phenyltriazene (DM[1-14C]PT) to rats accounted for 82% of the applied radioactivity. We have isolated aniline (1-2%), 2-hydroxyaniline (5-7%), 3-hydroxyaniline (about 1%) and 4-hydroxyaniline (31-37%) from ethyl acetate extracts of acid-hydrolysed urine, UV spectrometric determination of 4-hydroxyaniline, using the indophenol reaction, showed that the most abundant metabolite accounted for 56 to 61% of the applied dose. We have also demonstrated the excretion of metabolites containing the intact triazene structure (0.9-1.1%) by cold acid cleavage of these compounds, followed by coupling of the released arenediazonium cations with N-ethyl-1-naphthylamine (EN). The coloured derivatives of these metabolites, 4-benzeneazo-N-ethyl-1-naphthylamine (BAEN) (0.6-0.7%), 4-(2-hydroxybenzeneazo)-N-ethyl-1-napthylamine (2-HO-BAEN) (0.02%) and 4-(4-hydroxybenzeneazo)-N-ethyl-1-naphthylamine (4-HO-BAEN) (0.3-0.4%) were isolated. The identification of BAEN as the principal azo derivative of the excreted triazene metabolites is in full agreement with the proposed in vivo activation of 3,3-dimethyl-1-phenyltriazene (DMPT) to a carcinogenic methylating agent. The hydroxylation of the methyl group at N-3 yields the corresponding aminol, some of which is covalently bonded to a water-soluble compound.