A rapid LC-ESI-MS/MS method for the quantitation of choline, an active metabolite of citicoline: Application to in vivo pharmacokinetic and bioequivalence study in Indian healthy male volunteers

Dysregulation of choline metabolism and therapeutic potential of citicoline in Huntington's disease

Huntington's disease (HD) is associated with dysregulated choline metabolism, but the underlying mechanisms remain unclear. This study investigated the expression of key enzymes in this pathway in R6/2 HD mice and human HD postmortem brain tissues. We further explored the therapeutic potential of modulating choline metabolism for HD. Both R6/2 mice and HD patients exhibited reduced expression of glycerophosphocholine phosphodiesterase 1 (GPCPD1), a key enzyme in choline metabolism, in the striatum and cortex. The striatum of R6/2 mice also showed decreased choline and phosphorylcholine, and increased glycerophosphocholine, suggesting disruption in choline metabolism due to GPCPD1 deficiency. Treatment with citicoline significantly improved motor performance, upregulated anti-apoptotic Bcl2 expression, and reduced oxidative stress marker malondialdehyde in both brain regions. Metabolomic analysis revealed partial restoration of disrupted metabolic patterns in the striatum and cortex following citicoline treatment. These findings strongly suggest the role of GPCPD1 deficiency in choline metabolism dysregulation in HD. The therapeutic potential of citicoline in R6/2 mice highlights the choline metabolic pathway as a promising target for future HD therapies.

Circulating choline and phosphocholine measurement by a hydrophilic interaction liquid chromatography-tandem mass spectrometry

Background

Given the growing interest in studying the role of choline and phosphocholine in the development and progression of tumor pathology, in this study we describe the development and validation of a fast and robust method for the simultaneous analysis of choline and phosphocholine in human plasma.

Methods

Choline and phosphocholine quantification in human plasma was obtained using a hydrophilic interaction liquid chromatography-tandem mass spectrometry technique. Assay performance parameters were evaluated using EMA guidelines.

Results

Calibration curve ranged from 0.60 to 38.40 μmol/L (R2 = 0.999) and 0.08-5.43 μmol/L (R2 = 0.998) for choline and phosphocholine, respectively. The Limit Of Detection of the method was 0.06 μmol/L for choline and 0.04 μmol/L for phosphocholine. The coefficient of variation range for intra-assay precision is 2.2-4.1 % (choline) and 3.2-15 % (phosphocholine), and the inter-assay precision range is < 1-6.5 % (choline) and 6.2-20 % (phosphocholine). The accuracy of the method was below the ±20 % benchmarks at all the metabolites concentration levels. In-house plasma pool of apparently healthy adults was tested, and a mean concentration of 15.97 μmol/L for Choline and 0.34 μmol/L for Phosphocholine was quantified.

Conclusions

The developed method shows good reliability in quantifying Choline and Phosphocholine in human plasma for clinical purposes.

Regenerative Effects of CDP-Choline: A Dose-Dependent Study in the Toxic Cuprizone Model of De- and Remyelination

Inflammatory attacks and demyelination in the central nervous system (CNS) are the key factors responsible for the damage of neurons in multiple sclerosis (MS). Remyelination is the natural regenerating process after demyelination that also provides neuroprotection but is often incomplete or fails in MS. Currently available therapeutics are affecting the immune system, but there is no substance that might enhance remyelination. Cytidine-S-diphosphate choline (CDP-choline), a precursor of the biomembrane component phospholipid phosphatidylcholine was shown to improve remyelination in two animal models of demyelination. However, the doses used in previous animal studies were high (500 mg/kg), and it is not clear if lower doses, which could be applied in human trials, might exert the same beneficial effect on remyelination. The aim of this study was to confirm previous results and to determine the potential regenerative effects of lower doses of CDP-choline (100 and 50 mg/kg). The effects of CDP-choline were investigated in the toxic cuprizone-induced mouse model of de- and remyelination. We found that even low doses of CDP-choline effectively enhanced early remyelination. The beneficial effects on myelin regeneration were accompanied by higher numbers of oligodendrocytes. In conclusion, CDP-choline could become a promising regenerative substance for patients with multiple sclerosis and should be tested in a clinical trial.

Quantitative quadrupolar NMR (qQNMR) using nitrogen-14 for the determination of choline in complex matrixes

NMR offers the unique potential to selectively excite the chosen nuclei avoiding in an extraordinary way the matrix effect. Quantitative Nitrogen-14 NMR (¹⁴N qNMR) spectroscopy has been introduced for the first time as a robust and validated method to determine choline in a variety of matrixes including quinoa grains, instant coffee and food supplements. A study about the ion pairing of choline bitartrate in aqueous solution by means of diffusion PGSE, NOESY and HOESY NMR have been also provided. Validation of the method within eight concentrations levels (from 1.58 to 79.0 mM) afforded a limit of detection of 400 μg/mL (1.58 mM), a quantification limit of 1000 μg/mL (3.95 mM), excellent linearity (R² higher than 0.999), intra-/inter-day precisions lower than 1.24% (CV), recoveries of 93.5%-102.5%, and complete absence of matrix effect. The fast and reliable quantification of choline together with the accuracy and simplicity of this new approach make it useful in the development of analytical procedures that could dramatically affect traditional analysis.

CDP-choline and galantamine, a personalized α7 nicotinic acetylcholine receptor targeted treatment for the modulation of speech MMN indexed deviance detection in healthy volunteers: a pilot study

RATIONALE

The combination of CDP-choline, an α7 nicotinic acetylcholine receptor (α7 nAChR) agonist, with galantamine, a positive allosteric modulator of nAChRs, is believed to counter the fast desensitization rate of the α7 nAChRs and may be of interest for schizophrenia (SCZ) patients. Beyond the positive and negative clinical symptoms, deficits in early auditory prediction-error processes are also observed in SCZ. Regularity violations activate these mechanisms that are indexed by electroencephalography-derived mismatch negativity (MMN) event-related potentials (ERPs) in response to auditory deviance.

OBJECTIVES/METHODS

This pilot study in thirty-three healthy humans assessed the effects of an optimized α7 nAChR strategy combining CDP-choline (500 mg) with galantamine (16 mg) on speech-elicited MMN amplitude and latency measures. The randomized, double-blinded, placebo-controlled, and counterbalanced design with a baseline stratification method allowed for assessment of individual response differences.

RESULTS

Increases in MMN generation mediated by the acute CDP-choline/galantamine treatment in individuals with low baseline MMN amplitude for frequency, intensity, duration, and vowel deviants were revealed.

CONCLUSIONS

These results, observed primarily at temporal recording sites overlying the auditory cortex, implicate α7 nAChRs in the enhancement of speech deviance detection and warrant further examination with respect to dysfunctional auditory deviance processing in individuals with SCZ.

LC-MS/MS determination of 4-hydroxynimesulide, an active metabolite of nimesulide and application to bioequivalence study in Indian subjects

A simple and highly sensitive bioanalytical method was developed and validated for simultaneous quantification of nimesulide (NSD) and its active metabolite 4-hydroxy-nimesulide (M1) in human plasma by liquid chromatography-tandem mass spectrometer (LC-MS/MS) and applied in a bioequivalence study performed on Indian subjects. The bioanalytical method was carried out by LC-MS/MS with celecoxib (CXB) as an internal standard (IS) using liquid-liquid extraction technique. The chromatographic separation was performed on a reversed-phase Agilent eclipse plus C18 (75 mm × 4.6 mm, particle size 3.5 µm) column with a mobile phase of acetronitrile and water containing 5 mM ammonium formate (9:1, v/v). Method validation and clinical sample were analysed as per USFDA and EMA guidelines and results met the acceptance criteria. The lower limit of quantitation of NSD and M1 was found 10 ng/mL with a large linearity range from 10 to 6000 ng/mL for both NSD and M1 using only 100 µL of plasma and reported no matrix effect. The multiple reaction monitoring transitions of m/z 307.20 → 229.20, m/z 323.00 → 245.00 and m/z 380.20 → 316.20 were used to measure NSD, M1 and CXB (IS), respectively. The assay method was successfully applied for the simultaneous quantification of both NSD and M1 in plasma samples after oral administration of nimesulide 100 mg tablet in healthy human subjects.

Citicoline: A Superior Form of Choline?

Medicines containing citicoline (cytidine-diphosphocholine) as an active principle have been marketed since the 1970s as nootropic and psychostimulant drugs available on prescription. Recently, the inner salt variant of this substance was pronounced a food ingredient in the major world markets. However, in the EU no nutrition or health claim has been authorized for use in commercial communications concerning its properties. Citicoline is considered a dietetic source of choline and cytidine. Cytidine does not have any health claim authorized either, but there are claims authorized for choline, concerning its contribution to normal lipid metabolism, maintenance of normal liver function, and normal homocysteine metabolism. The applicability of these claims to citicoline is discussed, leading to the conclusion that the issue is not a trivial one. Intriguing data, showing that on a molar mass basis citicoline is significantly less toxic than choline, are also analyzed. It is hypothesized that, compared to choline moiety in other dietary sources such as phosphatidylcholine, choline in citicoline is less prone to conversion to trimethylamine (TMA) and its putative atherogenic N-oxide (TMAO). Epidemiological studies have suggested that choline supplementation may improve cognitive performance, and for this application citicoline may be safer and more efficacious.

Combining CDP-choline and galantamine, an optimized α7 nicotinic strategy, to ameliorate sensory gating to speech stimuli in schizophrenia

Neural α7 nicotinic acetylcholine receptor (nAChR) expression and functioning deficits have been extensively associated with cognitive and early sensory gating (SG) impairments in schizophrenia (SCZ) patients and their relatives. SG, the suppression of irrelevant and redundant stimuli, is measured in a conditioning-testing (S₁-S₂) paradigm eliciting electroencephalography-derived P50 event-related potentials (ERPs), the S₂ amplitudes of which are typically suppressed relative to S₁. Despite extensive reports of nicotine-related improvements and several decades of research, an efficient nicotinic treatment has yet to be approved for SCZ. Following reports of SG improvements in low P50 suppressing SCZ patients and healthy participants with the α7 agonist, CDP-choline, this pilot study examined the combined modulatory effect of CDP-choline (500 mg) and galantamine (16 mg), a nAChR positive allosteric modulator and acetylcholinesterase inhibitor, on SG to speech stimuli in twenty-four SCZ patients in a randomized, double-blind and placebo-controlled design. As expected, in low P50 suppressors CDP-choline/galantamine (vs. Placebo) improved rP50 and dP50 scores by increasing inhibitory mechanisms as reflected by S₂P50 amplitude reductions. Results also suggest a moderating role for auditory verbal hallucinations in treatment response. These preliminary findings provide supportive evidence for the involvement of α7 nAChR activity in speech gating in SCZ and support additional trials, examining different dose combinations and repeated doses of this optimized and personalized targeted α7 cholinergic treatment for SG dysfunction in subgroups of SCZ patients.

LC-MS/MS assay for quantitation of enalapril and enalaprilat in plasma for bioequivalence study in Indian subjects

Background:

Enalapril (EPL) is an angiotensin-converting enzyme inhibitor for the treatment of hypertension and chronic heart failure. Enalaprilat (EPLT) is an active metabolite that contributes to the overall activity of EPL.

Aim:

To quantitate EPL along with its metabolite EPLT using LC–MS/MS, a bioanalytical method was developed and validated with tolbutamide in human plasma using a protein precipitation technique.

Results:

The sensitive and selective method has an LLOQ of 1 ng/ml with a linearity range of 1–500 ng/ml for both EPL and EPLT using 300 µl of plasma without any matrix effect.

Conclusion:

Linearity, specificity, accuracy, precision and stability, as well as its application to the analysis of plasma samples after oral administration of 20 mg of EPL maleate in healthy volunteers demonstrate applicability to bioavailability/bioequivalence studies.

The present study describes a sensitive, selective, simple, accurate and reproducible LC–MS/MS method for the simultaneous determination of both enalapril (EPL) and enalaprilat (EPLT) in human plasma. The results obtained indicate the high sensitivity of the described method for analysis of EPL and EPLT, which render this method particularly useful for pharmacokinetic or bioequivalence studies. The proposed method has been applied for the analysis of EPL and EPLT in the plasma of healthy volunteers in a single-dose pharmacokinetic study.

Neuroprotective properties of citicoline: facts, doubts and unresolved issues

Citicoline is the generic name of the pharmaceutical substance that chemically is cytidine-5'-diphosphocholine (CDP-choline), which is identical to the natural intracellular precursor of phospholipid phosphatidylcholine. Following injection or ingestion, citicoline is believed to undergo quick hydrolysis and dephosphorylation to yield cytidine and choline, which then enter the brain separately and are used to resynthesize CDP-choline inside brain cells. Neuroprotective activity of citicoline has been repeatedly shown in preclinical models of brain ischaemia and trauma, but two recent, large, pivotal clinical trials have revealed no benefits in ischaemic stroke and traumatic brain injury. However, the substance seems to be beneficial in some slowly advancing neurodegenerative disorders such as glaucoma and mild vascular cognitive impairment. This paper critically discusses issues related to the clinical pharmacology of citicoline, including its pharmacokinetics/biotransformation and pharmacodynamics/mode of action. It is concluded that at present, there is no adequate description of the mechanism(s) of the pharmacological actions of this substance. The possibility should be considered and tested that, in spite of apparently fast catabolism, the intact citicoline molecule or the phosphorylated intermediate products of its hydrolysis, cytidine monophosphate and phosphocholine, are pharmacologically active.

Development and validation of spectrophotometric methods for simultaneous estimation of citicoline and piracetam in tablet dosage form

Context:

Citicoline (CN) and piracetam (PM) combination in tablet formulation is newly introduced in market. It is necessary to develop suitable quality control methods for rapid and accurate determination of these drugs. Aim: The study aimed to develop the methods for simultaneous determination of CN and PM in combined dosage form.

Materials and Methods:

The first method was developed by formation and solving simultaneous equations using 280.3 and 264.1 nm as two analytical wavelengths. Second method was absorbance ratio in which wavelengths selected were 256.6 nm as its absorptive point and 280.3 nm as λmax of CN. According to International Conference on Harmonization (ICH) norm, the parameters – linearity, precision, and accuracy were studied. The methods were validated statistically and by recovery studies.

Results:

Both the drugs obeyed Beer-Lambert's law at the selected wavelengths in concentration range of 5-13 μg/ml for CN and 10-22 μg/ml for PM. The percentage of CN and PM in marketed tablet formulation was found to be 99.006 ± 0.173 and 99.257 ± 0.613, respectively; by simultaneous equation method. For Q-Absorption ratio method the percentage of CN and PM was found to be 99.078 ± 0.158 and 99.708 ± 0.838, respectively.

Conclusions:

The proposed methods were simple, reproducible, precise and robust. The methods can be successfully applied for routine analysis of tablets.