Liquid chromatographic determination of 1-adamantanamine and 2-adamantanamine in human plasma after pre-column derivatization with o-phthalaldehyde and 1-thio-β-d-glucose

Electrochemiluminescence of an iridium complex doped with SiO2 nanoparticles to detect 2-adamantanamine based on the host-guest interaction of cucurbit[7]uril

The poor solubility of iridium complexes severely hampers its application in the electrochemiluminescence (ECL) sensing field. The doping of an iridium complex with silica (SiO2) nanospheres provides feasible solution for this problem. Herein, one kind of water insoluble iridium complex ([Ir(dFppy)2(d(CF3)bpy)](PF6)) was doped with SiO2 nanoparticles to obtain a luminescent nanocomposite (SiO2@Ir) which could generate strong ECL signals to act as a beacon molecule. An "off-on-off" mode ECL sensor was proposed based on the competitive host-guest interactions between 2-adamantanamine (2-ADA), ferrocene (Fc) and cucurbit[7]uril (Q[7]). Fc could be used as an inhibitor to decrease the ECL signal, while Q[7] could wrap Fc to recover the ECL signal. Q[7] has a stronger binding ability with 2-ADA than Fc. As a result, 2-ADA could replace Fc from the cavity of Q[7], and the ECL signal was inhibited again. Under the optimal conditions, the ECL intensity varied linearly with 2-ADA concentration in the range of 1.0 × 10-8 to 1.0 × 10-6 mol L-1 with a detection limit of 2.5 × 10-10 mol L-1. The results not only provided a new avenue for the application of water insoluble iridium complexes in ECL sensing, but also revealed the attractive potential of host-guest interactions in the fabrication of biosensors.

Simultaneous liquid chromatographic assay of amantadine and its four related compounds in phosphate-buffered saline using 4-fluoro-7-nitro-2,1,3-benzoxadiazole as a fluorescent derivatization reagent

Simultaneous HPLC assay of 1-adamantanamine hydrochloride (amantadine) and its four related compounds [2-adamantanamine hydrochloride (2-ADA), 1-adamantanmethylamine (ADAMA), 1-(1-adamantyl)ethylamine hydrochloride (rimantadine) and 3,5-dimethyl-1-adamantanamine hydrochloride (memantine)] in phosphate-buffered saline (pH 7.4) after pre-column derivatization with 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F) was developed. Phosphate-buffered saline samples were mixed with borate buffer and NBD-F solution in acetonitrile at 60 degrees C for 5 min and injected into HPLC. Five derivatives were well separated from each other. The lower limits of detection of amantadine, 2-ADA, ADAMA, rimantadine and memantine were 0.008, 0.001, 0.0008, 0.0015 and 0.01 microg/mL, respectively. The coefficients of variation for intra- and inter-day assay were less than 6.4 and 8.2%, respectively. The method presented was applied to a binding study of these compounds to human alpha(1)-acid glycoprotein. While affinity constants and capacities for ADAMA, rimantadine and memantine were calculated by means of Scatchard plots, those for the others were not determined. ADAMA, rimantadine and memantine were bound with different affinities and capacities. These results indicate that NBD-F is a good candidate as a fluorescent reagent to simultaneously determine amantadine and its four related compounds by HPLC after pre-column derivatization. Our method can be applied to binding studies for protein.

Simultaneous determination of amantadine and rimantadine by HPLC in rat plasma with pre-column derivatization and fluorescence detection for pharmacokinetic studies

We investigated simultaneous high-performance liquid chromatographic (HPLC) determination of amantadine hydrochloride (AMA) and rimantadine hydrochloride (RIM) levels in rat plasma after fluorescent derivatization with o-phthalaldehyde and 2-mercaptoethanol. Afterwards, the method was applied to determine their pharmacokinetics. The retention times of AMA and RIM derivatives were 12.6 and 22.2 min and the lower limits of detection were 0.025 and 0.016 microg/mL, respectively. The coefficients of variation for intra- and inter-day assay of AMA and RIM were less than 5.1 and 7.6%, respectively. After i.v. administration of AMA or RIM to rats, the total body clearance and distribution volume at the steady-state of RIM were higher than those of AMA. Bioavailability of AMA and RIM was 34.9 and 37.2%, respectively. When AMA and RIM were p.o. co-administered, the area under the plasma concentration--time curve of RIM was significantly lower than that after RIM alone. On the other hand, pharmacokinetic parameters of AMA did not significantly change. These results indicate that our HPLC assay is simple, rapid, sensitive and reproducible for simultaneously determining AMA and RIM concentrations in rat plasma and is applicable to their pharmacokinetic studies. Also, co-administration of AMA and RIM may result in the lack of pharmacological effects of RIM.