Analysis of epinine and its metabolites in man after oral administration of its pro-drug ibopamine using high-performance liquid chromatography with electrochemical detection

Presence of N-methyldopamine in parkinsonian and normal human brains

N-Methyldopamine (epinine) has been identified for the first time in parkinsonian and normal human brains by gas chromatography-mass spectrometry. N-Methylsalsolinol and N-methylnorsalsolinol, which are analogues of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, which produces parkinsonism in humans, may be synthesized from N-methyldopamine by the Pictet-Spengler condensation reaction as an alternative metabolic pathway.

Simultaneous determination of free catecholamines and epinine and estimation of total epinine and dopamine in plasma and urine by high-performance liquid chromatography with fluorimetric detection

Epinine (N-methyldopamine) is the pharmacologically active hydrolysis product of the prodrug ibopamine, which is currently being widely studied for the treatment of congestive heart failure. This paper reports a sensitive and reliable method for the simultaneous determination of free catecholamines and epinine in plasma and urine. The compounds are isolated from plasma or urine by a specific liquid-liquid extraction, derivatized with the selective fluorogenic agent 1,2-diphenylethylenediamine, and quantitated by high-performance liquid chromatography with gradient elution and fluorimetric detection. The limits of detection for the derivatized catecholamines and epinine are 0.3-0.6 pg of injected compound. Intra- and inter-assay coefficients of variation of all four compounds are good (1-8%), as are the accuracy and linearity. A method is also reported for the determination of total dopamine and epinine in plasma and urine based on the same principle. This method, in which deconjugation is accomplished by acid hydrolysis at 95 degrees C, also shows good sensitivity and reproducibility.

Pharmacokinetics and pharmacodynamics of single oral doses of ibopamine, quinidine and their combination in normal man

The pharmacokinetics and haemodynamics (phono- and impedance cardiography) of single oral doses of 200 mg ibopamine (SK&F 100168), 400 mg quinidine sulphate, and their combination, have been assessed in 6 healthy male volunteers. No significant differences in the mean pharmacokinetic parameters of either drug were seen between the single and combined doses. Ibopamine caused an increase in mean estimated stroke volume (SV +29% for the maximum change from baseline and +15% cumulatively over the first h) with no change in mean heart rate (HR) or QTc. Quinidine administered concomitantly blunted the response of SV. A tendency to a lower mean concentration of epinine early after administration of the combination may have contributed to the difference. Quinidine alone hardly affected SV (-3% from baseline over the first h), but it did increase mean HR (+6 beats.min-1) and mean QTc (+30 ms). These changes were sustained up to 8 h after dosing, and were not affected by concurrent ibopamine.