Coenzyme Q10 (CoQ10) is a natural antioxidant of the oil-soluble benzoquinone group that is involved in electron transport in mitochondria. CoQ10 possesses ...
Pharmaceutical Chemistry Journal, Vol. 46, No. 4, July, 2012 (Russian Original Vol. 46, No. 4, April, 2012)
EFFECT OF POLYETHYLENEGLYCOL ON COENZYME Q10 BIOAVAILABILITY FROM NANOSYSTEMS IN VITRO M. V. Karlina,1 V. M. Kosman,1 O. N. Pozharitskaya,1 A. N. Shikov,1 V. G. Makarov,1 J. Heinämäki,2 J. Yliruusi,2 and R. Hiltunen2 Translated from Khimiko-Farmatsevticheskii Zhurnal, Vol. 46, No. 4, pp. 42 – 45, April, 2012. Original article submitted March 23, 2011.
Coenzyme Q10 (CoQ10) is a natural antioxidant of the oil-soluble benzoquinone group that is involved in electron transport in mitochondria. CoQ10 possesses a broad spectrum of pharmacological activity. However, its insolubility in water and low bioavailability upon peroral administration are significant disadvantages. The present work was aimed at a biopharmaceutical evaluation of nanosystems (NS) with CoQ10 that are suitable for peroral administration and exhibit increased bioavailability in vitro. Solid NS of CoQ10 with polyethyleneglycol (PEG) carriers of various molecular weights (1,500; 6,000; 35,000) were prepared in order to increase the dissolution rate of CoQ10. The NS particle sizes were in the range 48.4 – 200.3 nm. The influences of the PEG molecular weight and the ratio of NS components were evaluated using dispersion analysis. Regression equations describing the effects of these factors on the drug-release and dissolution rates were obtained by processing the results. Response surfaces that adequately described drug dissolution were plotted. Key words: coenzyme Q10, nanosystem, bioavailability.
tion [5]. Therefore, the creation of drugs based on CoQ10 that are convenient to administer and exhibit improved bioavailability is necessary. The rate of absorption of drugs that are practically insoluble in water and intended for peroral administration is often determined by their dissolution rate in the gastro-intestinal tract. A convenient method for increasing the dissolution rate is to decrease the particle size to the nano-scale. Nanosystems (NS) can improve the bioavailability and provide targeted drug delivery. NS can be used as delivery systems for various administration pathways, including peroral [6 – 9]. The goal of the present work was a biopharmaceutical evaluation of CoQ10 NS that are suitable for peroral administration and possess increased bioavailability in vitro.
Coenzyme Q10 (CoQ10, ubiquinone) is an oil-soluble benzoquinone (Fig. 1) that is involved in electron transport in mitochondria [1]. It is a natural antioxidant and a natural metabolite of humans. CoQ10 stimulates the metabolism of fats for energy and the enrichment of fatty tissue with oxygen. This reduces effectively the weight of obese people and normalizes the blood lipid composition. CoQ10 participates in regulation of the glucose level, improvement of blood rheological properties, and stimulation of hematopoietic and immunomodulation processes [2]. Accumulated clinical experience enables the use of CoQ10 to be recommended not only as an effective drug in complex therapy of cardiovascular diseases but also as a preventative agent for them [3]. The biosynthesis of CoQ10 declines progressively with age although its consumption increases during physical and emotional tension and oxidative stress in the pathogenesis of various cardiovascular diseases [4]. CoQ10 is practically insoluble in water. This reduces its bioavailability from various forms upon peroral administra1 2
O CH3
CH3O
CH3O
St. Petersburg Institute of Pharmacy, St. Petersburg, 195067, Russia. University of Helsinki, Faculty of Pharmacy, P. O. Box 56, FI-00014 Helsinki, Finland.
O
CH3
10
H
Fig. 1. Structural formula of coenzyme Q10 (MW = 863.34).
241 0091-150X/12/4604-0241 © 2012 Springer Science+Business Media, Inc.
M. V. Karlina et al.
Amount of coenzyme Q10 released, %
242 70 60 50 40 30 20 10 0
0
1
2
Q10 substance Q10+PEG 1,500 1:10
Time, h
3
4
Q10+PEG 6,000 1:10 Q10+PEG 1,500 1:5
5
Q10+PEG 6,000 1:5 Q10+PEG 35,000 1:10
Fig. 2. Release of coenzyme Q10 from NS (averages).
64
64
Fig. 3. Response surface describing release of coenzyme Q10 as a function of PEG molecular weight and ratio of NS components.
EXPERIMENTAL PART We used CoQ10 substance (Coenzyme Q10, Quim Dis, France) and polyethyleneglycols (PEG) with MW 1,500; 6,000; and 35,000 (Fluka, Germany). NS were prepared by a fusion method. For this, the calculated amounts of PEG 1,500; 6,000; or 35,000 and CoQ10 were melted, mixed, cooled, and ground. Particle size in the NS was determined by photon-correlation spectroscopy on a Zetasizer 3000HSA instrument (Malvern Instruments, Worcestersire, UK). CoQ10 release rate from the NS was evaluated using the Dissolution Test on a rotating stirrer instrument (DT 600,
24 1500
nt
ra
tio
1:10
ne
ra nt ne po m
3000 5100 11800 23400 PEG molec 1:5 ular weight 35000
Co
24 1500
34
3000 5100 11800 PEG mo lecular w eigh
po
1:10
m
34
44
t
23400
Co
44
Dissolution rate, 1/h
54
tio
Release, %
54
350001:5
Fig. 4. Response surface describing dissolution rate of coenzyme Q10 as a function of PEG molecular weight and ratio of NS components
Erweka, Germany) at 37 ± 1°C and rotation rate 100 rpm. The dissolution medium was biphasic water—octanol (3:1) of total volume 400 mL. A weighed portion of test product was placed into a hard gelatin capsule. Samples (3 mL each) were taken at given time points (15, 30, and 45 min and 1, 2, 3, 4, and 5 h). The volume was restored using the same solvent. Experiments were performed in triplicate. Direct spectrophotometry in the UV region was used for quantitative analysis. Optical density of resulting solutions was measured on a Shimadzu spectrophotometer (Japan) at the wavelength maximum (275 nm) in a 1-cm cuvette. The
Effect of Polyethyleneglycol on Coenzyme Q10 Bioavailability
TABLE 1. Particle Sizes of Nanosystems of CoQ10 with PEG Nanosystem
107.3 ± 0.9
Q10+PEG 6,000 1:10
200.3 ± 1.8
Q10+PEG 6,000 1:5
117.1 ± 0.6
Substance Q10+PEG 1,500 1:5 Q10+PEG 1,500 1:10 Q10+PEG 6,000 1:5 Q10+PEG 6,000 1:10 Q10+PEG 35,000 1:10
Data given as average ± standard deviation.
reference solution was octanol. Optical density of a standard solution of CoQ10 was measured in parallel. The content of CoQ10 was calculated using the external standard method. Dispersion analysis and graphical display of the results were carried out using the Statgraphics applied programs (STSC Inc.). RESULTS AND DISCUSSION Solid NS in which the carrier was PEG of different molecular weights were prepared in order to increase the dissolution rate of CoQ10. Table 1 presents the particle sizes in the resulting NS. NS using PEG 35,000 typically had the smallest particle size. The obtained NS were evaluated in the dissolution test that to a first approximation enabled the bioavailability of the drugs to be estimated. The dissolution medium was water—octanol, the use of which was advantageous and effective for studying compounds that were slightly soluble in water [10]. Figure 2 shows the results. Table 2 lists the dissolution rate constants that were calculated by a least-squares method. Dispersion analysis was used to estimate the effects of PEG molecular weight (factor A) and the ratio of NS components (factor B). Factor A was studied on three levels: A1 (MW 1,500); A2 (MW 6,000); and A3 (MW 35,000). Factor B examined component ratios in the NS for B1 (1:5) and B2 (1:10). The response function was Y1, the dissolution rate constant (h–1), and Y2, the release in 3 h (%). Because a significant increase of CoQ10 concentration in solution was not found after 3 h of release, further studies were limited to 3 h. Regression equations describing the effects of the factors on dissolution rate Y1 and release Y2 were obtained by processing the experimental results: 2
Y1 = – 7.88 + 10.52A + 13.48B + 2.95A – 10.63AB,
Constants
Nanosystem
48.4 ± 4.9
Q10+PEG 35,000 1:10 *
TABLE 2. Rate Nanosystems
Particle size, nm
Q10+PEG 1,500 1:5
243
(1)
Y2 = – 64.08 + 86.35A + 31.04B – 14.10A2 – 14.59AB. (2) The dispersion analysis indicated that both models provided information. The determination coefficient of Y1 was R2 = 0.9991; of Y2, R2 = 0.9957. The significance level of the models according to the Fisher criterion was 0.00001. Factor A, PEG molecular weight, had high and significant ef-
of
CoQ10
Dissolution
from
Rate constant of dissolution, h – 1
9.4231 8.4433 11.2012 17.1862 18.0299 13.4446
fect (81.3%) on CoQ10 release whereas factor B, the component ratio, was slightly less significant (13.2%). Factor A had a significant effect (37.3%) on the dissolution rate whereas that of factor B was much less (12.3%). Response surfaces were constructed using Eqs. (1) and (2). The release of CoQ10 and its dissolution rate were plotted as functions of PEG molecular weight and ratio of NS components (Figs. 3 and 4). CoQ10 was released most completely and fastest from NS with PEG 6,000 and component ratio 1:10. According to the literature, the bioavailability of CoQ10 is increased by forming microspheres with lecithin and phospholipids [11] and producing self-emulsified delivery systems [12]; inclusion complexes with cyclodextrin [13]; and solid dispersions with poloxamers [14], polyvinylpyrrolidones [15], etc. However, self-emulsified delivery systems and microspheres presuppose liquid drug forms. The particle size of CoQ10 in inclusion complexes with cyclodextrins was greater than 900 nm [13]. Stable particles of CoQ10 in solid dispersions with poloxamers and improved bioavailability were observed only after adding aerosil to the system [14]. We were able to produce stable binary NS of CoQ10 and PEG of particle sizes 48.4 – 200.3 nm. Particles less than 500 nm in size overcame the immune barrier of M-cells of Peyer’s patches in the gastro-intestinal tract mucosa and delivered the active ingredient directly into the systemic circulation [16]. It could be supposed that the created NS would possess increased bioavailability in vivo. Further studies could confirm this hypothesis. REFERENCES 1. G. P. Littaru and L. Tiano, Mol. Biotechnol., 37(1), 31 – 37 (2007). 2. S. O. Klyuchnikov and E. S. Gyetneva, Pediatriya, 3(87), 103 – 110 (2008). 3. V. L. Lakomkin and O. V. Korkina, Kardiologiya, 12, 51 – 55 (2002). 4. V. I. Kapel’ko, Ross. Med. Zh., 11(21), 1185 – 1188 (2003). 5. R. Wajda and J. Zirkel, J. Med. Food, 10, No. 4, 731 – 734 (2007). 6. A. N. Shikov, O. N. Pozharitskaya, I. Miroshnyk, et al., Int. J. Pharm., 377(1 – 2), 148 – 152 (2009).
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