REVERSED PHASE LIQUID CHROMATOGRAPHIC DETERMINATION OF VINPOCETINE IN HUMAN PLASMA AND ITS PHARMACOKINETIC APPLICATION

Effect of vinpocetine on embryonic heart rate in vitro

Vinpocetine is a readily available nutritional supplement claimed to improve memory and weight loss. However, it blocks the Ikr current essential for cardiac action potential repolarisation and Ikr inhibition can cause "torsade de pointes" arrhythmias and sudden death. Moreover, Ikr blockers have exhibited teratogenic effects in reproductive toxicology studies, leading to increased birth defects and embryonic mortality. The FDA advises against vinpocetine use in pregnant and prospective mothers based on animal studies showing dose-dependent fetal mortality in rats and rabbits, and cardiovascular malformations in surviving fetuses. However, the mechanisms responsible for vinpocetine's fetal toxicity remain unclear. The present study used rat embryo culture to evaluate vinpocetine and its major metabolite, apovincaminic acid, on embryonic heart rate, a possible causative factor behind its adverse effects. Both compounds induced embryonic bradycardia in a concentration-dependent manner, with vinpocetine proving more potent. The minimum vinpocentine concentration to induce bradycardia was 100 nM, a level unlikely to be reached in humans following typical doses. Embryonic arrhythmias were also observed at the highest concentrations. These results suggest that the FDA's cautionary statement may generate undue anxiety, although re-evaluation of teratogenicity risk associated with vinpocetine should be revisited if a link to cardiac arrhythmias in adults is established.

Vinpocetine (A comprehensive profile)

Vinpocetine (VIN) is a herbal supplement extracted from the periwinkle plant. It is a multi-action agent, which is used to treat various neurological disorders such as Alzheimer's and Parkinson's disease. Vinpocetine has also anti-inflammatory, analgesic, antioxidant property and treats various thinking and memory problems. Currently, vinpocetine is also available in the market as a dietary supplement to enhance cognition and memory. This profile explains the physicochemical properties, methods of preparation, content of related impurities and different spectroscopical behavior of vinpocetine. It also discusses the reported methods of analysis of the drug, which include Compendial Methods, Electrochemical Methods, Spectrophotometric Methods and Chromatographic Methods of analysis. Furthermore, this profile explains the stability of the drug subjected to stress conditions of acid, alkaline and photolytic degradation. In addition, the clinical applications of the drug, its uses, side effects, dosing information, pharmacokinetics and mechanism of action are also discussed.

Development of a Validated Stability-Indicating HPLC Method for Vinpocetine in the Presence of Potential İmpurities in Tablet Dosage Form by Multi-Response Optimization

BACKGROUND

Vinpocetine has been prescribed for the treatment of ischemic brain diseases for many years. The drug, which has side effects such as headache, flushing, and decreased blood pressure, is not found in nature, but it can be synthesized by several approaches.

OBJECTIVES

A simple, rapid, selective, stability-indicating high performance liquid chromatographic method was developed for the simultaneous estimation of vinpocetine and their potential impurities in a tablet formulation.

METHODS

Optimum HPLC conditions were tried to be determined by statistical experimental design method. The proposed method was validated as per the ICH guidelines. Stress study was used to demonstrate the stability-indicating ability of the developed method in the quantification of vinpocetine and potential impurities within the same run.

RESULTS

According to multi-response optimization using the Derringer's desirability function, the mobile phase consisted of acetonitrile: Phosphate Buffer (pH 6.0) in the ratio of 65:35 ʋ/ʋ at a flow rate of 1.7 mL/min. Significant degradations were observed for the drug product under acid hydrolysis and alkali hydrolysis. The new method showed reasonable detection and quantification limits with good selectivity, precision, linearity and recovery.

CONCLUSIONS

These validation results have shown that this method is suitable for quantitative determination of vinpocetine and its impurities in quality control laboratories.

HIGHLIGHTS

A reliable and rapid HPLC method which was optimized with response surface methodology and multi-response optimization based on Derringer's desirability function was developed for the simultaneous analysis of vinpocetine and its impurities in a tablet formulation.

Vinpocetine, cognition, and epilepsy

OBJECTIVE

Vinpocetine has been shown to enhance memory in animal models, with possible cognitive benefit in humans. The present study sought to demonstrate if vinpocetine can enhance cognition in healthy volunteers or patients with epilepsy. In addition, we compare blood levels of vinpocetine and its active metabolite (apovincaminic acid; AVA) in humans and animals to further characterize factors related to possible therapeutic benefit.

METHODS

The cognitive effects of vinpocetine were assessed in healthy adult volunteers (n = 8) using a double-blind, randomized, crossover design at single doses (placebo, 10, 20, and 60 mg oral). Cognitive effects of vinpocetine in patients with focal epilepsy (n = 8) were tested using a double-blind, randomized, crossover design at single doses (placebo, 20 mg oral) followed by one-month open label at 20 mg oral three times a day. The neuropsychological battery included both computerized and non-computerized tests. Levels of vinpocetine and AVA in the human studies were compared to levels in 45 mice across time dosed at 5-20 mg/kg intraperitoneal of vinpocetine.

RESULTS

No significant cognitive benefits were seen in healthy volunteers or patients with epilepsy. No appreciable side effects occurred. Vinpocetine and AVA levels were lower in humans than animals.

CONCLUSIONS

Vinpocetine was well tolerated, but was not associated with positive cognitive effects. However, blood levels obtained in humans were substantially less than levels in animals obtained from dosages known to be effective in one model. This suggests that higher dosages are needed in humans to assess vinpocetine's cognitive efficacy.

In Situ Hexosomal Gel as a Promising Tool to Ameliorate the Transnasal Brain Delivery of Vinpocetine: Central Composite Optimization and In Vivo Biodistribution

Vascular dementia is a condition characterized by a wretched cerebral circulation which can lead to memory loss. Vinpocetine showed ability to promote the cerebral circulation and depict neuroprotective impacts. However, it suffers from poor bioavailability and requires frequent daily dosing which is not suitable for dementia patients. In our study, these limitations were overcome by the prolonged direct delivery of vinpocetine to the brain utilizing an intranasal in situ hexosomal gel. A central composite design was utilized and the optimum dispersion (consisting of 15% w/w of oleic acid and 5% w/w of pluronic F127) was loaded in an in situ gel system using gellan gum with 1% w/v. The optimized Formulae achieved a controlled drug release over 24 h and the pharmacokinetic data revealed that the C_max and AUC_0-24 in the rats' brain after the intranasal application of the dispersion and in situ gel were significantly higher relative to the vinpocetine solution applied intravenously at the same dose. The potential of both formulae to deliver vinpocetine to the brain directly through the intranasal route was confirmed by the high BTE% of 370.97% and 480.70% and the high DTP% of 73.04% and 79.19% for the dispersion and in situ gel, respectively.

Neuroprotective effects of novel nanosystems simultaneously loaded with vinpocetine and piracetam after intranasal administration

AIMS

The study aim was to test the efficacy of a novel created hybrid nanosystem compared to other nanosystems in treatment of scopolamine induced memory impairment.

MAIN METHODS

The fabrication and characterization of nanoformulations (microemulsion, liposomes, ethosomes, transfersomes and transethosomes) coencapsulating two cognitive enhancers; piracetam and vinpocetine delivered intranasally, in addition to a novel nanocomposite microemulsion/vesicular nanoformulation was described.

KEY FINDINGS

Formulations delivered the drugs across sheep nasal mucosa, with cumulative percentage reaching 29.99% for vinpocetine and 57.78% for piracetam. While the solution form of the drugs was totally ineffective, the selected transethosomal, microemulsion and nanocomposite formulations reversed the scopolamine induced effect on the step through latency of passive avoidance test and the spontaneous alternation behavior in Y maze test, further confirmed by histopathlogical examination. All three nanoformulations significantly decreased the acetylcholinesterase activity and the extent of lipid peroxidation by 32-42%. The nanocomposite formulation was superior to the microemulsion and transethosomal formulations in its anti-inflammatory and antiapoptotic effects, delineated by higher extent of inhibition of COX-2 and caspase 3 expression respectively.

SIGNIFICANCE

Results support the hypothesis that the novel microemulsion/vesicular nanocomposite system is a promising neuroprotective modality for intranasal brain targeting which is worthy of exploitation in other brain diseases.

Embryo-fetal development studies with the dietary supplement vinpocetine in the rat and rabbit

Dietary supplement and natural product use is increasing within the United States, resulting in growing concern for exposure in vulnerable populations, including young adults and women of child-bearing potential. Vinpocetine is a semisynthetic derivative of the Vinca minor extract, vincamine. Human exposure to vinpocetine occurs through its use as a dietary supplement for its purported nootropic and neuroprotective effects. To investigate the effects of vinpocetine on embryo-fetal development, groups of 25 pregnant Sprague-Dawley rats and 8 pregnant New Zealand White rabbits were orally administered 0, 5, 20, or 60 mg vinpocetine/kg and 0, 25, 75, 150, or 300 mg/kg daily from gestational day (GD) 6-20 and GD 7-28, respectively. Pregnant rats dosed with vinpocetine demonstrated dose-dependent increases in postimplantation loss, higher frequency of early and total resorptions, lower fetal body weights, and fewer live fetuses following administration of 60 mg/kg, in the absence of maternal toxicity. Additionally, the rat fetuses displayed dose-dependent increases in the incidences of ventricular septum defects and full supernumerary thoracolumbar ribs. Similarly, albeit at higher doses than the rats, pregnant rabbits administered vinpocetine displayed an increase in postimplantation loss and fewer live fetuses (300 mg/kg), in addition to significantly lower fetal body weights (≥75 mg/kg). In conclusion, vinpocetine exposure resulted in similar effects on embryo-fetal development in the rat and rabbit. The species differences in sensitivity and magnitude of response is likely attributable to a species difference in metabolism. Taken together, these data suggest a potential hazard for pregnant women who may be taking vinpocetine.

Systemic exposure of vinpocetine in pregnant Sprague Dawley rats following repeated oral exposure: An investigation of fetal transfer

Vinpocetine is being used worldwide by people of all ages, including pregnant women, for its purported multiple health benefits. However, limited data is available addressing the safety/toxicity of vinpocetine. The National Toxicology Program conducted studies to examine potential effects of vinpocetine on the developing rat. Disposition data is helpful to put the fetal findings into context and provide information on the potential risk for humans. The current study reports the systemic exposure and toxicokinetic (TK) parameters of vinpocetine and metabolite, apovincaminic acid (AVA), in pregnant Harlan Sprague Dawley rats, fetuses and amniotic fluid following oral gavage exposure of dams to 5 and 20mg/kg vinpocetine from gestational day 6 to 18. Vinpocetine was absorbed rapidly in dams with a maximum plasma concentration (Cmax) reaching ≤1.37h. Predicted Cmax and area under the concentration versus time curve (AUC) increased less than proportionally to the dose. Vinpocetine was rapidly distributed to the peripheral compartment. More importantly, significant transfer of vinpocetine from dam to fetuses was observed with fetal Cmax and AUC≥55% of dams. Vinpocetine was cleared rapidly from dam plasma with an elimination half-life of ≤4.02h with no apparent dose-related effect. Vinpocetine was rapidly and highly metabolized to AVA with AVA plasma levels in dams ≥2.7-fold higher than vinpocetine, although in the fetuses, AVA levels were much lower than vinpocetine. Comparison of current rat data with literature human data demonstrates that systemic exposure to vinpocetine in rats following repeated exposure to 5mg/kg is similar to that following a single human relevant dose of 10mg suggesting that the findings from the toxicology study may be relevant to humans.

Development and evaluation of nanoparticles based on mPEG-PLA for controlled delivery of vinpocetine: in vitro and in vivo studies

The aim of present study was to develop VIN-loaded mPEG-PLA nanoparticle systems. The VIN mPEG-PLA nanoparticles were prepared using an emulsion solvent evaporation method, and studied their particle size, morphology, encapsulation efficiency and drug-loading coefficient. Moreover, the nanoparticles were evaluated on the drug release behaviors in vitro and bioavailability in vivo. The results show that the spherical nanoparticles obtained were negatively charged with a zeta potential of about -23.4 mV and characterized ∼110 nm with a narrow size distribution. The encapsulation efficiency and drug loading of prepared NPs were 76.4 ± 6.3 and 9.2 ± 2.2% (n=5), respectively. The in vitro release showed that the percent of accumulated dissolution of VIN NPs in phosphate-buffered saline 6.8 over 24 h was <80%, which was almost 100% of VIN in commercial injections. The in vivo study indicated that systemic absorption of VIN was significantly enhanced by incorporating into mPEG-PLA NPs compared with VIN injection (2.87-fold in AUC_0-t). The results suggested that the form of VIN in mPEG-PLA NPs could enter the body circulation to perform sustained release in vitro and in vivo.

Identification and quantification of vinpocetine and picamilon in dietary supplements sold in the United States

Vinpocetine and picamilon are drugs prescribed in many countries to treat a variety of cerebrovascular disorders. In the United States, vinpocetine and picamilon have never been approved by the US Food and Drug Administration, but they are both available for sale directly to consumers as dietary supplements. We designed our study to determine the accuracy of supplement labels with regard to the presence and quantity of vinpocetine and picamilon. A validated ultra-high performance liquid chromatography-photodiode-array method was developed for the quantification of vinpocetine and picamilon. The separation was achieved using a reversed phase (C-18) column, photodiode array detection, and water/acetonitrile as the mobile phase. Vinpocetine and picamilon were detected at concentrations as low as 10 and 50 ng/mL, respectively. The presence of vinpocetine and picamilon was confirmed using reference standards. Twenty-three supplements labelled as containing vinpocetine were available for sale at two large supplement retail chains; 17 contained vinpocetine with quantities ranging from 0.3 to 32 mg per recommended daily serving. No vinpocetine was detected in six of the sampled supplements. The supplement label implied that vinpocetine was a constituent of lesser periwinkle in three of the supplements. Of the 31 picamilon supplements available for sale from a variety of retailers: 30 contained picamilon in quantities ranging from 2.7 to 721.5 mg per recommended daily serving. We found that consumers cannot obtain accurate information from supplement labels regarding the presence or quantity of vinpocetine and picamilon. Copyright © 2015 John Wiley & Sons, Ltd.

A novel oral delivery system consisting in "drug-in cyclodextrin-in nanostructured lipid carriers" for poorly water-soluble drug: vinpocetine

The purpose of this study was to develop a new delivery system based on drug cyclodextrin (CD) complexation and loading into nanostructured lipid carriers (NLC) to improve the oral bioavailability of vinpocetine (VP). Three different CDs and three different methods to obtain solid vinpocetine-cyclodextrin-tartaric acid complexes (VP-CD-TA) were contrasted. The co-evaporation vinpocetine-β-cyclodextrin-tartaric acid loaded NLC (VP-β-CD-TA COE-loaded NLC) was obtained by emulsification ultrasonic dispersion method. VP-β-CD-TA COE-loaded NLC was suitably characterized for particle size, polydispersity index, zeta potential, entrapment efficiency and the morphology. The crystallization of drug in VP-CD-TA and NLC was investigated by differential scanning calorimetry (DSC). The in vitro release study was carried out at pH 1.2, pH 6.8 and pH 7.4 medium. New Zealand rabbits were applied to investigate the pharmacokinetic behavior in vivo. The VP-β-CD-TA COE-loaded NLC presented a superior physicochemical property and selected to further study. In the in vitro release study, VP-β-CD-TA COE-loaded NLC exhibited a higher dissolution rate in the pH 6.8 and pH 7.4 medium than VP suspension and VP-NLC. The relative bioavailability of VP-β-CD-TA COE-loaded NLC was 592% compared with VP suspension and 92% higher than VP-NLC. In conclusion, the new formulation significantly improved bioavailability of VP for oral delivery, demonstrated a perspective way for oral delivery of poorly water-soluble drugs.

Novel sugar esters proniosomes for transdermal delivery of vinpocetine: preclinical and clinical studies

Vinpocetine (Vin) existing oral formulations suffer poor bioavailability (∼7%) since Vin undergoes a marked first-pass effect (∼75%) and its absorption is dissolution rate-limited. In this study, a novel sustained release proniosomal system was designed using sugar esters (SEs) as non-ionic surfactants in which proniosomes were converted to niosomes upon skin water hydration following topical application under occlusive conditions. Different in vitro aspects (encapsulation efficiency, vesicle size and shape, effect of occlusion, in vitro release, skin permeation and stability) were studied leading to an optimized formula that was assessed clinically for transdermal pharmacokinetics and skin irritation. All formulae exhibited high entrapment efficiencies, regardless of the surfactant HLB. Vesicle size analysis showed that all vesicles were in the range from 0.63 μm to 2.52 μm which favored efficient transdermal delivery. The extent of drug permeation through the skin from the optimized formula--containing laurate SE with shorter fatty acid chain length and high HLB--was quite high (91%) after 48 h under occlusive conditions. The extent of absorption of Vin from proniosomes was larger when compared to the oral tablet with a relative bioavailability (F(rel)) of 206%. Histopathological evaluation revealed only moderate skin irritation when using SEs compared to skin inflammation when using Tween 80. Sugar esters proniosomes may be a promising carrier for vinpocetine, especially due to their simple scaling up and their ability to control drug release.

Preparation and characterization of vinpocetine loaded nanostructured lipid carriers (NLC) for improved oral bioavailability

The purpose of this study is to develop an optimized nanostructured lipid carriers (NLC) formulation for vinpocetine (VIN), and to estimate the potential of NLC as oral delivery system for poorly water-soluble drug. In this work, VIN-loaded NLC (VIN-NLC) was prepared by a high pressure homogenization method. The VIN-NLC showed spherical morphology with smooth surface under transmission electron microscope (TEM) and scanning electron microscopic (SEM) analysis. The average encapsulation efficiency was 94.9+/-0.4%. The crystallization of drug in NLC was investigated by powder X-ray diffraction and differential scanning calorimetry (DSC). The drug was in an amorphous state in the NLC matrix. In the in vitro release study, VIN-NLC showed a sustained release profile of VIN and no obviously burst release was observed. The oral bioavailability study of VIN was carried out using Wistar rats. The relative bioavailability of VIN-NLC was 322% compared with VIN suspension. In conclusion, the NLC formulation remarkably improved the oral bioavailability of VIN and demonstrated a promising perspective for oral delivery of poorly water-soluble drugs.

Effect of Fascioliasis on the pharmacokinetic parameters of triclabendazole in human subjects

OBJECTIVES

To study the clinical efficacy of Triclabendazole (TCBZ) on Egyptian patients infected with Fasciola and understand the effect of Fascioliasis on the pharmacokinetics of TCBZ.

METHODS

The pharmacokinetics of TCBZ administered as a single oral dose (10 mg/kg) was investigated in both infected and parasite--free Egyptian subjects. After oral administration, TCBZ is metabolized to a sulphone and sulfoxide derivatives. The latter is responsible for the fasciolicidal activity of TCBZ, and it could be used as a marker of drug bioavailability. Blood samples were collected following the oral administration, and TCBZ sulfoxide plasma concentrations were determined by a sensitive and specific HPLC method.

RESULTS

Pharmacokinetic parameters (Cmax, AUC0-48, t1/2 and tmax) for TCBZ sulfoxide were calculated. In patients; the mean Cmax was 9.11 +/- 1.3 microg/ml, the mean AUC(0-48) was 91 +/- 10.5 microg h ml(-1), the mean t1/2 was 7.4 +/- 0.6 h, and the tmax was 3.0 +/- 0.4 h. In normal subjects, the mean Cmax was 8.48 +/- 0.92 microg/ml, the mean AUC(0-48) was 85 +/- 6.55 microg h ml(-1), the mean t1/2 was 6.2 +/- 0.357 h, and the tmax was 3 +/- 0.4 h. No significant difference could be detected in the patients as compared to normal subjects, which would suggest that Fascioliasis does not affect any of the studied parameters. No eggs in faeces could be detected following TCBZ treatment. Also, most of the clinical investigations showed significant decline back to the normal ranges post-treatment which indicates complete curing and high TCBZ efficacy.

CONCLUSION

Fasioliasis as an infective condition widely spread in Egypt has no significant effect on the pharmacokinetic parameters of the orally administered TCBZ and at the same time it is very effective against the parasite which strongly and safely suggests the use of this medication for the treatment of this infection.

Spectrophotometric and liquid chromatographic determination of fenofibrate and vinpocetine and their hydrolysis products

Several spectrophotometric and HPLC methods are presented for the determination of fenofibrate, vinpocetine and their hydrolysis products. The resolution of either fenofibrate or vinpocetine and their hydrolysis products has been accomplished by using numerical spectrophotometric methods as partial least squares (PLS-1) and principal component regression (PCR) applied to UV spectra; and graphical spectrophotometric methods as first derivative of ratio spectra (1DD) or first (1D) and second (2D) derivative spectrophotometry for vinpocetine and fenofibrate, respectively. In addition HPLC methods were developed using ODS column with mobile phase consisting of acetonitrile-water (80:20, v/v, pH 4) with UV detection at 287 nm for fenofibrate and a mobile phase consisting of acetonitrile-10 mM KH2PO4, containing 0.1% diethylamine (60:40, v/v, pH 4.6) with UV detection at 270 nm for vinpocetine. The proposed methods were successfully applied for the determination of each drug and its hydrolysis product in laboratory-prepared mixture and pharmaceutical preparation. The proposed HPLC and derivative spectrophotometric methods were used to investigate the kinetics of acidic and alkaline hydrolytic processes of each drug. The pH-rate profile of hydrolysis of each drug in Britton-Robinson buffer solutions was studied.