Development of an UPLC-MS/MS micromethod for quantitation of cinitapride in plasma and its application in a pharmacokinetic interaction trial.

AIM: Cinitapride (CIN) is a benzamide-derived molecule used for the treatment of gastroesophageal reflux and dyspepsia. Its pharmacokinetics are controversial due to the use of supratherapeutic doses and the lack of sensitive methodology. Therefore, a sensitive and accurate micromethod was developed for its quantitation in human plasma. RESULTS: CIN was extracted from 300 µl of heparinized plasma by liquid-liquid extraction using cisapride as internal standard, and analyzed with an ultra performance liquid chromatograph employing positive multiple-reaction monitoring-MS. CONCLUSION: The method proved to be rapid, accurate and stable within a range between 50 and 2000 pg/ml and was successfully validated and applied in a pharmacokinetic interaction trial, where it was demonstrated that oral co-administration of simethicone does not modify the bioavailability of CIN.

Pharmacologic antagonism of dopamine receptor D3 attenuates neurodegeneration and motor impairment in a mouse model of Parkinson's disease.

Neuroinflammation involves the activation of glial cells, which is associated to the progression of neurodegeneration in Parkinson's disease. Recently, we and other researchers demonstrated that dopamine receptor D3 (D3R)-deficient mice are completely refractory to neuroinflammation and consequent neurodegeneration associated to the acute intoxication with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). In this study we examined the therapeutic potential and underlying mechanism of a D3R-selective antagonist, PG01037, in mice intoxicated with a chronic regime of administration of MPTP and probenecid (MPTPp). Biodistribution analysis indicated that intraperitoneally administered PG01037 crosses the blood-brain barrier and reaches the highest concentration in the brain 40 min after the injection. Furthermore, the drug was preferentially distributed to the brain in comparison to the plasma. Treatment of MPTPp-intoxicated mice with PG01037 (30 mg/kg, administrated twice a week for five weeks) attenuated the loss of dopaminergic neurons in the substantia nigra pars compacta, as evaluated by stereological analysis, and the loss of striatal dopaminergic terminals, as determined by densitometric analyses of tyrosine hydroxylase and dopamine transporter immunoreactivities. Accordingly, the treatment resulted in significant improvement of motor performance of injured animals. Interestingly, the therapeutic dose of PG01037 exacerbated astrogliosis and resulted in increased ramification density of microglial cells in the striatum of MPTPp-intoxicated mice. Further analyses suggested that D3R expressed in astrocytes favours a beneficial astrogliosis with anti-inflammatory consequences on microglia. Our findings indicate that D3R-antagonism exerts a therapeutic effect in parkinsonian animals by reducing the loss of dopaminergic neurons in the nigrostriatal pathway, alleviating motor impairments and modifying the pro-inflammatory phenotype of glial cells.

Quantification of imatinib in human serum: validation of a high-performance liquid chromatography-mass spectrometry method for therapeutic drug monitoring and pharmacokinetic assays.

BACKGROUND: Imatinib mesylate has been a breakthrough treatment for chronic myeloid leukemia. It has become the ideal tyrosine kinase inhibitor and the standard treatment for chronic-phase leukemia. Striking results have recently been reported, but intolerance to imatinib and noncompliance with treatment remain to be solved. Molecular monitoring by quantitative real-time polymerase chain reaction is the gold standard for monitoring patients, and imatinib blood levels have also become an important tool for monitoring. METHODS: A fast and cheap method was developed and validated using high-performance liquid chromatography-mass spectrometry for quantification of imatinib in human serum and tamsulosin as the internal standard. Remarkable advantages of the method includes use of serum instead of plasma, less time spent on processing and analysis, simpler procedures, and requiring reduced amounts of biological material, solvents, and reagents. Stability of the analyte was also studied. This research also intended to drive the validation scheme in clinical centers. The method was validated according to the requirements of the US Food and Drug Administration and Brazilian National Health Surveillance Agency within the range of 0.500-10.0 µg/mL with a limit of detection of 0.155 µg/mL. Stability data for the analyte are also presented. CONCLUSION: Given that the validated method has proved to be linear, accurate, precise, and robust, it is suitable for pharmacokinetic assays, such as bioavailability and bioequivalence, and is being successfully applied in routine therapeutic drug monitoring in the hospital service.

Blood matrix effects for male and female Wistar rats, in simultaneous HPLC-UV determination of riparin I and III from Aniba riparia (Nees) Mez. (Lauraceae).

Aniba riparia (Nees) Mez. (Lauraceae) is popularly known as "louro", and is found in Amazonia and in the Guianas, its distribution extends to the Andes. Alkamide alkaloids were isolated from its green fruit; they were denominated riparin I (methyl ether of N-benzoyl tyramine), riparin II (methyl ether of N-2-hydroxy-benzoyl tyramine) and riparin III (methyl ether of N-2,6-dihydroxy-benzoyl tyramine) in tribute to the plant. When administered orally and intraperitoneally to mice, riparin I and III are anxiolytic, yet without any sedative or muscle relaxing effects. The present study shows that variables such as extraction solvent, centrifugation force, and centrifugation time, are important in the simultaneous liquid-liquid extraction of riparin I and III from male and female Wistar rat blood in HPLC-UV studies. The study confirms matrix influence on simultaneous recovery and detection of riparin I and III. The effect of rat blood matrix for riparin I was -13.86%, while for riparin III it was -10.94%. The recovery for riparin I was 82.14%, while for riparin III it was 87.42%. The efficiency of the process was 73.25% for riparin I and 77.81% for riparin III, demonstrating an optimal method for simultaneous recovery of riparins I and III from the blood of rats. The matrix effect for rat blood showed values of 10.25% for riparin I and -83.01% for riparin III. Recovery for riparin I was 113.11%, whereas for riparin III it was 13.65%. The process efficiency of this method for female rat blood was 125.88% for riparin I and 2.58% for riparin III. Simultaneous recovery of riparin I and III from the blood of male and female rats using acetonitrile as the precipitating solvent, while centrifuged at 10,000 × g for 10 min demonstrated the importance of the parameters chosen for the extraction/recovery process of different analytes.

Relative bioavailability of a 5 mg mosapride/10 mg rabeprazole fixed dose combination tablet versus separate single tablets in healthy volunteers: a single-dose randomized open-label crossover study.

OBJECTIVE: To evaluate the relative bioavailability of a new formulation containing 5 mg mosapride and 10 mg rabeprazole (T) and compare it with the branded formulations of both drugs co-administered in separate tablets (R) to meet the regulatory requirements of bioequivalence in Argentina. METHODS: A randomized-sequence, open-label, two-period crossover study was conducted on 24 healthy Caucasian volunteers in a fasting state. A single oral dose of either T or R formulations was followed by a 7-day washout period. Blood samples for mosapride were collected before administration (baseline) and at 0.5, 1, 1.5, 2, 2.5, 3, 4, 6, 8, 12, 18, and 24 h after administration. Samples for rabeprazole were taken baseline and at 1, 2, 2.5, 3, 3.5, 4, 4.5, 5, 6, 7, 8 and 10 h after dosing. Mosapride and rabeprazole concentrations were determined using a validated LC-MS/MS method. Adverse events were monitored based on clinical parameters and volunteer reports. RESULTS: The geometric means (90% CI) C(max) for mosapride in T and R were 23.13 (20.05-39.45) and 23.09 (21.69-32.37) ng/mL, the AUC(0-)(t) were 70.80 (66.23-102.37) and 70.81 (66.35-93.26) ng h/mL and the AUC(0-∞) were 74.05 (69.29-106.11) and 74.98 (70.43-97.77) ng h/mL. For rabeprazole T and R the C(max) were 197.42 (186.12-239.91) and 195.50 (186.08-250.07) ng/mL, the AUC(0-)(t) were 294.90 (275.13-374.15) and 296.96 (280.11-387.89) ng h/mL and the AUC(0-∞) were 301.12 (280.78-380.82) and 304.07 (286.60-394.21), respectively. No differences were detected between the formulations. The T/R ratios (90% CI) for C(max), AUC(0-)(t) and AUC(0-∞) were 100.17% (82.35-121.84), 99.99% (87.58-114.16) and 98.77% (87.02-112.11) for mosapride, and 100.99% (85.14-119.77), 99.31% (84.74-116.38) and 99.03% (85.07-115.28) for rabeprazole. No subject complained of adverse events. CONCLUSIONS: In this single-dose study, the mosapride/rabeprazole tablets (test formulation) met the criterion for bioequivalence with the reference formulations. Study limitations include single-dose, open-label design, and a small sample of healthy volunteers.