Determination of the enantiomeric purity of N-propionyl-6,7-dimethoxy-2-aminotetralin by cyclodextrin-modified micellar electrokinetic chromatography.

N-Propionyl-6,7-dimethoxy-2-aminotetralin (Z12231A), a useful intermediate in the synthesis of dopaminergic agonists, was resolved into its enantiomers by high-performance capillary electrophoresis. Cyclodextrin-modified micellar electrokinetic chromatography was employed with a combination of chiral selectors both in the aqueous phase (a hydroxyalkyl-beta-cyclodextrin) and in the micellar phase (sodium taurodeoxycholate). The absolute amount of the two chiral selectors as well as their ratio were found to be the most critical parameters in order to optimize separation. A resolution factor >3.5 was obtained, allowing a high amount of solute to be loaded in order to improve the detection limit. The reproducibility of the assay was also evaluated.

Determination of the dihydropyridine aryloxypropanolamine Z6568 and its acidic metabolites in plasma, urine and tissues by solid phase extraction and liquid chromatography/negative-ion mass spectrometry.

A sensitive and selective liquid chromatographic/mass spectrometric assay for the determination of the dihydropyridine aryloxypropanolamine compound Z6568 and its monoacidic metabolites in plasma, urine and tissues has been developed and validated. Z6568 and the acidic metabolites were isolated from the biological matrices by solid-phase extraction, separated by reversed-phase high-performance liquid chromatography and detected by mass spectrometry using a thermospray interface. Filament ionization and negative-ion detection were used, monitoring the molecular ion of Z6568 and a major fragment of the acidic metabolites. The analysis of spike plasma, urine and tissues demonstrated good accuracy and precision of the assay with a detection limit of 0.5 ng ml-1 for Z6568 and 2 ng ml-1 for the metabolites. Data relative to the optimization of the extraction procedure, mass spectrometric conditions and the validation protocol are reported. The method was used to investigate the metabolic fate and tissue distribution in laboratory animals.

Determination of the calcium antagonist SIM6080 and its N- and O-demethylated metabolites in plasma, urine and tissues by high-performance liquid chromatography.

A sensitive and versatile high-performance liquid chromatographic assay for the determination of the calcium antagonist SIM6080 and its four N- and O-demethylated metabolites in plasma, urine and tissues has been developed and validated. A two-step extraction procedure is employed followed by reversed-phase liquid chromatographic analysis using ultraviolet detection. An isomer of SIM6080 was used as the internal standard. The analysis of spiked plasma, urine and tissues demonstrated the accuracy and precision of the assay with quantitation limits of 5 ng/ml (plasma and urine) or 100 ng/g (tissues). This assay has been used for urinary recovery and tissue distribution studies, as well as for toxicokinetic protocols.

Determination of the dihydropyridine aryloxypropanolamine compound Z6568 and four metabolites in plasma by liquid chromatography/negative-ion mass spectrometry.

A sensitive and selective liquid chromatographic/mass spectrometric assay for the determination of the dihydropyridine aryloxypropanolamine compound Z6568 and four metabolites in plasma was developed and validated. Z6568 and the metabolites were isolated from plasma by a simple solvent extraction procedure and separated by reversed-phase high-speed liquid chromatography combined with thermospray mass spectrometry. Filament ionization was used and the molecular negative ions were monitored. The analysis of spiked plasma demonstrated the good accuracy and precision of the assay with a detection limit of 0.5 ng ml-1 for Z6568. Data relative to the optimization of the mass spectrometric conditions and the validation protocol are reported. the method has been used for pharmacokinetic studies in laboratory animals.

Determination of the calcium antagonist SIM6080 in plasma by high-resolution gas chromatography.

A sensitive and selective gas chromatographic method for the determination of the calcium antagonist SIM6080 in plasma has been developed and validated. A three-step extraction procedure is employed followed by capillary gas chromatographic analysis using nitrogen-selective detection and the programmed temperature vaporizer injection technique. The defluorinated analogue was used as the internal standard. The analysis of spiked plasma demonstrated the good accuracy and precision of the method with limit of detection of 1 ng/ml. The method has been used for pharmacokinetic studies in laboratory animals.

Ibopamine kinetics after a single oral dose in patients with congestive heart failure.

The kinetics of ibopamine, the 3,4-diisobutyryl ester of N-methyldopamine (epinine), was assessed in 27 patients with congestive heart failure (CHF) and 8 healthy normal subjects (NS). Nine patients were in functional class IV according to the NYHA definition, 9 in class III and 9 in class II. Ibopamine was administered at a single oral dose of 100 mg. Epinine, both free and total (mainly conjugated), plasma concentrations and urinary recoveries of total epinine, HVA and DOPAC were studied. The results showed that ibopamine kinetics is not substantially different in CHF patients and in NS. In both groups the absorption of the drug was equally prompt and elevated. Mean Cmax, tmax and AUC infinity values of total epinine in CHF patients did not differ significantly from those in NS. In CHF patients t 1/2 of total epinine was significantly higher than in NS (4.1 +/- 0.2 h vs 3.1 +/- 0.2 h, mean +/- SE). Mean Cmax, tmax, AUCt and MRT values of free epinine in CHF patients were not significantly different from those in NS. The urinary recovery of the 3 metabolites considered together was comparable in CHF patients and in NS. The mean +/- SE total urinary recoveries in the 24 h after dosing, expressed as percentages of the administered dose, were 60 +/- 3 in CHF patients and 69 +/- 4 in NS. Conjugated epinine in urine was found to be constituted by 3-O-sulfate (84%) and 4-O-sulfate (16%).

Ibopamine, an orally active dopamine-like drug: metabolism and pharmacokinetics in rats.

Ibopamine (SB-7505), the 3,4-diisobutyrylester of N-methyldopamine (epinine), was rapidly hydrolyzed to epinine by plasma esterases of rat as well as of other animal species and man. Ibopamine was rapidly and extensively metabolized after oral administration to rat. Plasma levels of free epinine peaked at 30-60 min from the administration; conjugated epinine was present in larger amount, with a maximum at 3 h. Both free and conjugated epinine were still detectable at 6 h, but not at 24 h. Epinine 4-O-glucuronide, 4-hydroxy-3-methoxyphenylacetic acid and 3,4-dihydroxyphenylacetic acid appeared as main urinary metabolites; epinine 3-O-sulphate, epinine 3-O-methylether and its glucuronide, and trace amounts of epinine 4-O-sulphate were also detected.

Ibopamine, an orally active dopamine-like drug: metabolism and pharmacokinetics in dogs.

Ibopamine (SB-7505), the 3,4-diisobutyryl ester of N-methyldopamine (epinine), exerts, on oral administration, cardiovascular effects similar to those of intravenously infused dopamine. Plasma levels and urinary excretion of metabolites were investigated in dogs after oral administration of 4 mg/kg of ibopamine hydrochloride. Epinine, which was readily formed from ibopamine by esterases hydrolysis, was present in plasma in free and sulphate-conjugated form. The urinary metabolites after 6 h from the administration amounted to 62% of the dose, as a sum of 37% of epinine 3-O-sulphate, and 15 and 10% of 4-hydroxy-3-methoxyphenylacetic acid and 3,4-dihydroxyphenylacetic acid, respectively, both in free and conjugated form. When the main metabolite, epinine 3-O-sulphate, was administered intravenously it appeared to be excreted in urine without being deconjugated to any detectable extent, while it appeared to be partially deconjugated on oral administration.

Male pseudohermaphroditism with hypertension due to a 17alpha-hydroxylation deficiency.

A case of male pseudohermaphroditism aged 48 years with systemic hypertension and hypokalaemic alkalosis is described. Results of metabolic studies point to a 17alpha-hydroxylase deficiency demonstrated by low cortisol (0-56 mg/24 h), high corticosterone (270 mg/24 h) and 11-deoxycorticosterone (5 mg/24 h) secretion rates. Adrenocorticotrophin and gonadotrophin levels were markedly raised but plasma androstenedione (3 ng/dl), testosterone (17 ng/dl), oestrone (3 ng/dl) and oestradiol(1-8 ng/dl) were all low. Plasma aldosterone levels and secretion rates in urine were low and were surprisingly unaffected by dexamethasone therapy although low renin levels rose with a marked return of the erect posture effect. Therapeutic levels of dexamethasone were, however, followed by incipient renal failure.