Variation in the pharmacokinetics of glucosamine in healthy individuals.

OBJECTIVES: Clinical trial data for the efficacy of glucosamine in OA are conflicting. Reportedly, Rotta-manufactured glucosamine products are more likely to be effective, and a possible explanation is greater bioavailability than other brands. Specifically, the aim was to compare the steady-state pharmacokinetics of Rotta- and non-Rotta-manufactured glucosamine products in healthy volunteers and examine the interindividual variability. METHODS: In a crossover design, healthy adult participants ingested 1500 mg/day of a Rotta (DONA powder sachets; imported by Mylan Health, Carole Park, QLD, Australia) and a non-Rotta (glucosamine sulphate 1500 mg one-a-day tablet; Blackmores, Warriewood, NSW, Australia) glucosamine product/brand individually for 6 days. Blood samples were collected immediately before and for 12 h after the ingestion of the last dose of each brand and analysed to determine plasma levels of glucosamine. The pharmacokinetic parameters at steady state [including the minimum (Css min) and maximum (Css max) plasma concentration of glucosamine, time to reach Css max post-dosing (Tss max) and area under the plasma concentration vs time curve (AUCss 0-12)] for each brand were calculated and statistically compared. RESULTS: Fourteen participants [mean age 35.5 years (s.d. 8.8)] were recruited (64.2% males). No significant differences were observed in the pharmacokinetic parameters between the two brands. However, for both brands, the coefficient of variation for Css min, Tss max and AUCss 0-12 exceeded 20%, indicating considerable differences in the parameters between participants. No significant association of the pharmacokinetic parameters was observed with various dosing- and participant-related variables. CONCLUSION: Substantial interindividual differences in the absorption and elimination of glucosamine could be a cause of variable clinical outcomes in OA. TRIAL REGISTRATION: The study was registered with the Australian New Zealand Clinical Trials Registry (http://www.ANZCTR.org.au/ACTRN12618000699268p.aspx), number ACTRN12618000699268p.

Synthesis, in vitro inhibitory activity, kinetic study and molecular docking of novel N-alkyl-deoxynojirimycin derivatives as potential α-glucosidase inhibitors.

A series of novel N-alkyl-1-deoxynojirimycin derivatives 25 ∼ 44 were synthesised and evaluated for their in vitro α-glucosidase inhibitory activity to develop α-glucosidase inhibitors with high activity. All twenty compounds exhibited α-glucosidase inhibitory activity with IC50 values ranging from 30.0 ± 0.6 µM to 2000 µM as compared to standard acarbose (IC50 = 822.0 ± 1.5 µM). The most active compound 43 was ∼27-fold more active than acarbose. Kinetic study revealed that compounds 43, 40, and 34 were all competitive inhibitors on α-glucosidase with Ki of 10 µM, 52 µM, and 150 µM, respectively. Molecular docking demonstrated that the high active inhibitors interacted with α-glucosidase by four types of interactions, including hydrogen bonds, π-π stacking interactions, hydrophobic interactions, and electrostatic interaction. Among all the interactions, the π-π stacking interaction and hydrogen bond played a significant role in a various range of activities of the compounds.

[Symptomatic slow-acting drugs in the treatment of osteoarthritis: focus on glucosamine preparations]. / Simptomaticheskie lekarstvennye sredstva zamedlennogo deistviya pri lechenii osteoartrita: fokus na preparaty glyukozamina.

The article discusses the place of symptomatic slow-acting drugs in current guidelines for the treatment of osteoarthritis. Special emphasis is put ot glucosamine preparations, the attitude towards which, until recently, was ambiguous. The results of experimental and clinical studies demonstrating the advantages of crystalline glucosamine sulfate over preparations/food additives of glucosamine hydrochloride are presented. The differences in the pharmacodynamics and pharmacokinetics of glucosamine sulfate and glucosamine hydrochloride, which may be the reason for the ineffectiveness of the latter in clinical trials, are discussed.

Novel 99mTc-Labeled Glucose Derivative for Single Photon Emission Computed Tomography: A Promising Tumor Imaging Agent.

In this study, a d-glucosamine derivative with an isonitrile group (CN5DG) was synthesized and it was chosen to coordinate with 99mTc for preparing 99mTc-CN5DG. 99mTc-CN5DG could be readily obtained with high radiochemical purity (>95%) and had great in vitro stability and metabolic stability in urine. The radiotracer demonstrated a positive response to the administration of glucose and insulin in S180 and A549 tumor cells in vitro, suggesting the mechanism of 99mTc-CN5DG into tumor cells was related to glucose transporters. Biodistribution studies in mice bearing A549 xenografts showed 99mTc-CN5DG had a high tumor uptake and high tumor-to-background ratios. SPECT/CT images further supported its ability for tumor imaging. As a cheap, conveniently made and widely available probe, 99mTc-CN5DG would become a potential "working horse" and be a breakthrough in 99mTc-labeled radiopharmaceuticals for tumor detection.

Disc size markedly influences concentration profiles of intravenously administered solutes in the intervertebral disc: a computational study on glucosamine as a model solute.

PURPOSE: Tests on animals of different species with large differences in intervertebral disc size are commonly used to investigate the therapeutic efficacy of intravenously injected solutes in the disc. We hypothesize that disc size markedly affects outcome. METHODS: Here, using a small non-metabolized molecule, glucosamine (GL) as a model solute, we calculate the influence of disc size on transport of GL into rat, rabbit, dog and human discs for 10 h post intravenous-injection. We used transient finite element models and considered an identical GL supply for all animals. RESULTS: Huge effects of disc size on GL concentration profiles were found. Post-injection GL concentration in the rat disc reached 70% blood concentration within 15 min but remained below 10% in the human disc nucleus throughout. The GL rapidly penetrated post-injection into smaller discs resulting in homogeneous concentrations. In contrast, GL concentration, albeit at much lower levels, increased with time in the human disc with a small outward flux at the annulus periphery at longer periods. CONCLUSIONS: Changes in the disc size hugely influenced GL concentrations throughout the disc at all regions and times. Increases in administered dose can neither remedy the very low concentration levels in the disc center in larger human disc at early post-injection hours nor alter the substantial differences in concentration profiles estimated among various species. The size effect will only be exacerbated as molecular weight of the solute increases and as the endplate calcifies. Extrapolation of findings from animal to human discs on the efficacy of intravenously administered solutes must proceed with great caution.

[Relative bioavailability of glucosamine after oral, intramuscular and transdermal administration of hondroxid maximum preparation in experiment].

A comparison of the relative bioavailability and intensity of penetration of glucosamine sulfate in oral, injection and topical administration of the dosage form Hondroxid Maximum as a cream containing micellar system for transdermal delivery of glucosamine in the experiment by Sprague-Dawley rats was carried out. On the base on the pharmacokinetic profiles data of glucosamine in rat blood plasma with daily administration in 3 times a day for 1 week by cream Hondroxid Maximum 400 mg/kg and the single injection solution of 4% Glucosamine sulfate 400 mg/kg was found that the relative bioavailability was 61.6%. Calculated penetration rate of glucosamine in the plasma through the rats skin in 4 hours, equal to 26.9 µg/cm2 x h, and the penetration of glucosamine through the skin into the plasma after a single dose of cream in 4 hours was 4.12%. Comparative analysis of literature and experimental data and calculations based on them suggest that medicine Hondroxid Maximum, cream with transdermal glucosamine complex in the treatment in accordance with the instructions can provide an average concentration of glucosamine in the synovial fluid of an inflamed joint in the range (0.7 - 1.5) µg/ml, much higher than the concentration of endogenous glucosamine human synovial joint fluid (0.02 - 0.07 µg/ml). By theoretical calculations taking into account experimental data it is shown that the medicine Hondroxid Maximum can reach the bioavailability level of the modern injection forms and exceed the bioavailability level of modern oral forms of glucosamine up to 2 times.

The antiinflammatory action and pharmacokinetics of a novel glucosamine-based di-peptide aminosugar.

PURPOSE: We have previously shown favorable in vitro gut permeability for three novel di-peptide esters of glucosamine (GlcN) likely facilitated by the peptide transporter 1 (PepT1). Herein, we report the development of a novel assay for the determination of bioavailability of the peptide ester of interest, the anti-inflammatory properties of a glycine-valine ester derivative of GlcN (GVG) as well as its pharmacokinetics under healthy and inflammatory conditions. METHODS: A pre-column derivatization (with 9-fluorenylmethoxycarbonyl) HPLC assay was developed to study bioavailability of GVG, GlcN or cleaved GlcN in the rats that were cannulated in their right jugular vein for blood collection. The compounds of interest were orally administered to both healthy and arthritic rats. Serial blood samples and urine were collected and assayed for the compounds. The stability of the GVG was also tested after incubation with the rat feces. Efficacy of GVG was tested in inflamed rats (injection of 0.2 mL of Mycobacterium butyricum in squalene) following GVG (20 and 30 mg/kg/day GlcN equivalent) or GlcN (20 and 90 mg/kg/day) administration. Arthritis index was calculated at the end of the experiment. RESULTS: The assay was linear (ranged between 0.05-20 µg/mL) and reproducible (intra- and inter-day<10%). Among the tested compounds, only GVG showed a significantly higher plasma concentrations and urinary excretion than GlcN (≈3-fold increase). GVG showed a favorable stability in the rat feces. Adjuvant arthritis was completely prevented with doses greater than 20 mg/kg/day with GVG being 3-fold more potent than GlcN. CONCLUSION: The examined glycine-valine-GlcN di-peptide aminosugar is a potent anti-inflammatory compound due to its favorable properties to deliver GlcN into the systemic circulation.

Synthesis, characterization and bioevaluation of technetium-99m labeled N-(2-Hydroxybenzyl)-2-amino-2-deoxy-D-glucose as a tumor imaging agent.

N-(2-Hydroxybenzyl)-2-amino-2-deoxy-D-glucose (NHADG) was synthesized by conjugation of salicylaldehyde to glucosamine. The obtained compound was well characterized via different analytical techniques. Labeling of the synthesized compound with technetium-99m ((99m)Tc) in pertechnetate form ((99m)Tc O4-) was carried out via chelation reaction in the presence of stannous chloride dihydrate. Maximum radiochemical yield of (99m)Tc-NHADG complex (99%) was obtained by using 1 mg NHADG, 200 µg SnCl2.2H2O, at pH 9.5 and reaction time of 15 min. The radiochemical purity of the (99m)Tc-NHADG complex was measured by instant thin layer chromatography (ITLC) and paper chromatography (PC), without any notable decomposition at room temperature over a period of 4h. The biological evaluation results show that the (99m)Tc labeled NHADG conjugate is able to specifically target mammary carcinoma in mice models, thus highlighting its potential as an effective (99m)Tc labeled glucose-derived agent for tumor imaging.

Deciphering the role of glucosamine-6-phosphate in the riboswitch action of glmS ribozyme.

The GlmS ribozyme is believed to exploit a general acid-base catalytic mechanism in the presence of glucosamine-6-phosphate (GlcN6P) to accelerate self-cleavage by approximately six orders of magnitude. The general acid and general base are not known, and the role of the GlcN6P cofactor is even less well understood. The amine group of GlcN6P has the ability to either accept or donate a proton and could therefore potentially act as an acid or a base. In order to decipher the role of GlcN6P in the self-cleavage of glmS, we have determined the preferred protonation state of the amine group in the wild-type and an inactive G40A mutant using molecular dynamics simulations and free energy calculations. Here we show that, upon binding of GlcN6P to wild-type glmS, the pK(a) of the amine moiety is altered by the active site environment, decreasing by about 2.2 from a solution pK(a) of about 8.2. On the other hand, we show that the pK(a) of the amine group slightly increases to about 8.4 upon binding to the G40A inactive mutant of glmS. These results suggest that GlcN6P acts as a general acid in the self-cleavage of glmS. Upon binding to glmS, GlcN6P can easily release a proton to the 5'-oxygen of G1 during self-cleavage of the backbone phosphodiester bond. However, in the G40A inactive mutant of glmS, the results suggest that the ability of GlcN6P to easily release its proton is diminished, in addition to the possible lack of G40 as an effective base.

Quantitation of glucosamine sulfate in plasma by HPLC-MS/MS after administration of powder for oral solution formulation.

A rapid method for the quantification of glucosamine in human plasma using high-performance liquid chromatography coupled to tandem mass spectrometry was developed and validated. The sample preparation includes a simple deproteinization step, using D-[1-¹³C] glucosamine hydrochloride as an internal standard. Chromatographic separation was performed on an ACE Ciano column using isocratic elution with acetonitrile and aqueous 2 mM ammonium acetate containing 0.025% formic acid (80:20). Selected reaction monitoring was performed using the transitions m/z 180.1 → m/z 72.1 and m/z 181.0 → m/z 74.6 to quantify glucosamine and internal standard, respectively. The method was validated and proved to be linear, accurate and precise over the range 50-5000 ng/mL of glucosamine. Recovery rates higher than 90% were obtained for both glucosamine and internal standard. No matrix effect was detected in the samples. The validated method was successfully applied to a pharmacokinetic study after oral administration of a powder for oral solution formulation containing glucosamine sulfate.

The glucosamine controversy; a pharmacokinetic issue.

Glucosamine (GlcN) is a naturally occurring aminosugar that is widely used to treat osteoarthritis despite controversial clinical trial results. Animal studies, on the other hand, unequivocally suggest anti-inflammatory and disease modifying effects for GlcN. Many explanations have been offered as to the root of the controversy. They include superiority of a crystalline sulphate salt over HCl, industry bias, insensitive assessment metrics and poor methodology. Herein, we rule out a difference in bioequivalence between GlcN salts and that of chemically equivalent doses and suggest additional factors; i.e., inconsistency in the chemical potency of some products used, under-dosing of patients as well as variable and erratic bioavailability indices for the lack of GlcN efficacy observed in some studies. Clinical trials using higher doses of pharmaceutical grade GlcN or formulations with greater bioavailability should yield positive results.

Cellular binding and uptake of fluorescent glucose analogs 2-NBDG and 6-NBDG occurs independent of membrane glucose transporters.

The classical methods for determining glucose uptake rates in living cells involve the use of isotopically labeled 2-deoxy-d-glucose or 3-O-methyl-d-glucose, which enter cells via well-characterized membrane transporters of the SLC2A and SLC5A families, respectively. These classical methods, however, are increasingly being displaced by high-throughput assays that utilize fluorescent analogs of glucose. Among the most commonly used of these analogs are 2-NBDG and 6-NBDG, which contain a bulky 7-nitro-2,1,3-benzoxadiazol-4-yl-amino moiety in place of a hydroxy group on d-glucose. This fluorescent group significantly alters both the size and shape of these molecules compared to glucose, calling into question whether they actually enter cells by the same transport mechanisms. In this study, we took advantage of the well-defined glucose uptake mechanism of L929 murine fibroblasts, which rely exclusively on the Glut1/Slc2a1 membrane transporter. We demonstrate that neither pharmacologic inhibition of Glut1 nor genetic manipulation of its expression has a significant impact on the binding or uptake of 2-NBDG or 6-NBDG by L929 cells, though both approaches significantly impact [3H]-2-deoxyglucose uptake rates. Together these data indicate that 2-NBDG and 6-NBDG can bind and enter mammalian cells by transporter-independent mechanisms, which calls into question their utility as an accurate proxy for glucose transport.

The human pharmacokinetics of oral ingestion of glucosamine and chondroitin sulfate taken separately or in combination.

OBJECTIVE: As part of the National Institutes of Health (NIH)-sponsored Glucosamine/Chondroitin sulfate Arthritis Intervention Trial (GAIT) our objective here was to examine (1) the pharmacokinetics (PK) of glucosamine (GlcN) and chondroitin sulfate (CS) when taken separately or in combination as a single dose in normal individuals (n=29) and (2) the PK of GlcN and CS when taken as a single dose after 3 months daily dosing with GlcN, CS or GlcN+CS, in patients with symptomatic knee pain (n=28). METHODS: The concentration of GlcN in the circulation was determined by established fluorophore-assisted carbohydrate electrophoresis (FACE) methods. The hydrodynamic size and disaccharide composition of CS chains in the circulation and dosage samples was determined by Superose 6 chromatography and FACE. RESULTS: We show that circulating levels of CS in human plasma are about 20 microg/ml. Most significantly, the endogenous concentration and CS disaccharide composition were not detectably altered by ingestion of CS, when the CS was taken alone or in combination with GlcN. On the other hand, the Cmax (single-dose study) and AUC values (multiple-dose study) for ingested GlcN were significantly reduced by combination dosing with CS, relative to GlcN dosing alone. CONCLUSIONS: We conclude that pain relief perceived following ingestion of CS probably does not depend on simultaneous or prior intake of GlcN. Further, such effects on joint pain, if present, probably do not result from ingested CS reaching the joint space but may result from changes in cellular activities in the gut lining or in the liver, where concentrations of ingested CS, or its breakdown products, could be substantially elevated following oral ingestion. Moreover, since combined dosing of GlcN with CS was found to reduce the plasma levels seen with GlcN dosing alone, any improved pain relief by combination dosing cannot be explained by higher circulating concentrations of GlcN.

The effects of oral glucosamine on joint health: is a change in research approach needed?

OBJECTIVE: Oral glucosamine (GlcN) has been widely studied for its potential therapeutic benefits in alleviating the pain and disability of osteoarthritis (OA). Its popularity has grown despite ongoing controversy regarding its effectiveness vs placebo in clinical trials, and lack of information regarding possible mechanisms of action. Here, we review the state of knowledge concerning the biology of GlcN as it relates to OA, and discuss a framework for future research directions. METHODS: An editorial "narrative" review of peer-reviewed publications is organized into four topics (1) Chemistry and pharmacokinetics of GlcN salts (2) Biological effects of GlcN salts in vitro (3) Therapeutic effects of GlcN salts in animal models of OA and (4) GlcN salts in the treatment of clinical OA. RESULTS: Data reporting potent pleiotropic activities of GlcN in in vitro cell and explant cultures are discussed in the context of the established pharmacokinetic data in humans and animals. The available clinical trial data are discussed to place the patient in the context of controlled research on disease management. CONCLUSIONS: Future research to determine therapeutic mechanisms of GlcN salt preparations will require use of standardized and clinically relevant in vitro assay systems and in vivo animal models for testing, as well as development of new outcome measures for inflammation and pain pathways in human OA.

Variation in Plasma Levels of Glucosamine With Chronic Dosing: A Possible Reason for Inconsistent Clinical Outcomes in Osteoarthritis.

PURPOSE: Glucosamine is widely used by patients with osteoarthritis (OA) to provide symptomatic relief and to delay disease progression. However, clinical studies have reported inconsistent clinical outcomes. The current study hypothesized that the reported inconsistent clinical results could be, in part, due to variable bioavailability and elimination of glucosamine. This study therefore aimed to determine steady-state minimum plasma concentrations (Css min) of glucosamine to examine the variability among patients taking the supplement. METHODS: Patients with OA who had been taking glucosamine for at least 1 week were recruited. Patients' blood samples were collected 24 h after the ingestion of the previous dose to determine Observed Css min and after a 5-day washout period to determine the endogenous glucosamine levels (GlcNend). The Actual Css min was calculated by using the following equation: Actual Css min = Observed Css min - GlcNend. The glucosamine plasma concentrations were determined by using a previously developed HPLC method. FINDINGS: Ninety-one participants (age range, 42-89 years; mean [SD] age, 68.2 [7.6] years) were recruited (70% females). There was substantial (106-fold) variation, with a 45% coefficient of variation, between the Actual Css min levels (3-320 ng/mL) in participants. No significant association of Actual Css min was observed with various dose- and patient-related variables. IMPLICATIONS: The observed high variability in steady-state plasma concentrations indicates substantial inter-patient differences in the absorption and elimination of glucosamine, which could be a cause for inconsistent clinical outcomes in patients with OA.

Joint inflammation increases glucosamine levels attained in synovial fluid following oral administration of glucosamine hydrochloride.

OBJECTIVE: To compare synovial glucosamine levels in normal and inflamed equine joints following oral glucosamine administration and to determine whether single dose administration alters standard synovial parameters of inflammation. METHODS: Eight adult horses were studied. On weeks 1 and 2, all horses received 20mg/kg glucosamine hydrochloride by nasogastric (NG) intubation or intravenous injection. On weeks 3 and 4, 12h after injection of both radiocarpal joints with 0.25 ng Escherichia coli lipopolysaccharide (LPS) to induce inflammation, glucosamine hydrochloride or a placebo was administered by NG intubation. Plasma samples were collected at baseline and 5, 15, 30, 60, 120, 360, 480 and 720 min after dosing. Synovial fluid (SF) samples were collected within 48 h before dosing and 1, 6 and 12h post-dosing. Glucosamine was analyzed by Liquid Chromatography Electrospray Tandem Mass Spectrometry (LC-ESI/MS/MS). Clinicopathological evaluation of SF parameters included white blood cell (WBC) count and total protein (TP) analyses. RESULTS: No significant differences between groups were observed in SF baseline levels of WBC and TP at any stage of the study. SF WBC and TP significantly increased following IA LPS. The mean (+/-SD) maximal SF glucosamine levels (422.3+/-244.8 ng/mL) were significantly higher (>fourfold) in inflamed joints when compared to healthy joints (92.7+/-34.9 ng/mL). Glucosamine did not have any effect on standard SF parameters of inflammation. CONCLUSION: Synovial inflammation leads to significantly higher synovial glucosamine concentrations compared to levels attained in healthy joints following oral administration of glucosamine hydrochloride. Whether these higher levels are translated into a therapeutic effect on the joint tissues remains to be elucidated.

Optimal 99mTc radiolabeling and uptake of glucosamine sulfate by cartilage. A potential tracer for scintigraphic detection of osteoarthritis.

Glucosamine sulfate (GS) is used in treatment of human osteoarthritis, but no data for(99m)TcGS scintigraphy are available. Radiolabeling of GS was performed using the (99m)TcO(4)(-)/tin method. We applied two procedures for separation of free (99m)Tc using PD10 and G10 columns. In each eluted fraction, GS content was estimated by the Elson/Morgan method. For optimal radiolabeling, we varied the amount of GS, tin, (99m)Tc activity, and pH. For uptake age matched human rib cartilage (males, 78 and 63 years old) and 5-10 µCi/well of (99m)TcGS were used. Uptake was monitored up to 72 h. Also, washout of the tracer 3 h and 24 h after uptake was investigated. At pH 2, using PD10 column, the uptake of (99m)TcGS amounted to 100.8 ± 2.9%, n = 6 at saturation time of 72 h. Uptake was age-dependent; at pH 5, it amounted to 99.8% as compared to 66.1% at 78 vs 63 years old. When the amount of tin was varied at pH 2, the tracer uptake amounted to 21.37% (1 mg) vs 45.99% (2.5 mg) at saturation. At pH 7, the amount of needed tin was much lower and amounted to 42.50 ± 2.50% using 0.1 mg vs 25.11 ± 1.90% using 0.05 mg. Although the uptake at pH 7 (0.1 mg tin) is comparable with that at pH 2 (2.5 mg tin), the washout of the tracer amounted only to 4.10 ± 1.25% and 2.05 ± 0.65% after 3 h and 24 h, respectively. During degeneration of cartilage, incorporation of (99m)TcGS is high and could therefore be a promising tracer not only to target osteoarthritis but also to monitor the effects of therapy.

Glucosamine sulfate effect on the degenerated patellar cartilage: preliminary findings by pharmacokinetic magnetic resonance modeling.

Normal and degenerated cartilages have different magnetic resonance (MR) capillary permeability (K(trans)) and interstitial interchangeable volume (v(e)). Our hypothesis was that glucosamine sulfate treatment modifies these neovascularity abnormalities in osteoarthritis. Sixteen patients with patella degeneration, randomly distributed into glucosamine or control groups, underwent two 1.5-Tesla dynamic contrast-enhanced MR imaging studies (treatment initiation and after 6 months). The pain visual analog scale (VAS) and American Knee Society (AKS) score were used. A two-compartment pharmacokinetic model was used. Percentages of variations (postreatment-pretreatment/pretreatment) were compared (t-test for independent data). In the glucosamine group, pain and functional outcomes statistically improved (VAS: 7.3 +/- 1.1 to 3.6 +/- 1.3, p < 0.001; AKS: 18.6 +/- 6.9 to 42.9 +/- 2.7, p < 0.01). Glucosamine significantly increased K(trans) at 6 months (-54.4 +/- 21.2% vs 126.7 +/- 56.9%, p < 0.001, control vs glucosamine). In conclusion, glucosamine sulfate decreases pain while improving functional outcome in patients with cartilage degeneration. Glucosamine sulfate increases K(trans), allowing its proposal as a surrogate imaging biomarker after 6 months of treatment.

Bioequivalence study of 500 mg glucosamine sulfate in Thai healthy volunteers.

BACKGROUND AND OBJECTIVE: Glucosamine sulfate is widely used to relieve symptoms from osteoarthritis. The present study was conducted in order to determine pharmacokinetic and assess the in-vivo bioequivalence of two different hard capsule formulations of glucosamine sulfate when administered as equal dose of 500 mg. The two formulations contained different salt form where reference product is NaCl and test product is KCl. MATERIAL AND METHOD: A randomized, single dose, two-treatment, two-period, two-sequence crossover study was conducted. Twenty-four healthy volunteers were recruited at Siriraj Clinical Research Unit. Each subject received a dose of 500 mg glucosamine sulfate of both formulations with at least one-week washout period. Blood samples were collected over 24 h after the oral administration. The plasma fractions were analyzed for glucosamine using a liquid chromatography-mass spectrometry (LC-MS/MS). RESULTS: Twenty-four volunteers were enrolled in the present study Pharmacokinetic parameters were determined using the non-compartment model. The 90% confidence intervals of the mean ratios (test/reference) of C(max) (93.69%; ranged from 86.68%-113.32%) and AUC(0-t), (97.73; ranged from 87.38%-112.62%) fell within the acceptable range (80-125%) for bioequivalent eligibility. Both preparations were well tolerated and had a few non-serious adverse events. CONCLUSION: The glucosamine sulfate containing KCl (test product) is bioequivalent to glucosamine sulfate containing NaCl (reference product) in terms of rate and extent of absorption.

Comparative Analyses of Pharmaceuticals or Food Supplements Containing Chondroitin Sulfate: Are Their Bioactivities Equivalent?

INTRODUCTION: Oral supplementation of chondroitin sulfate (CS) and glucosamine (GlcN), symptomatic slow-acting molecules, is recommended by European Society for Clinical and Economic Aspects of Osteoporosis and Osteoarthritis and Musculoskeletal Diseases (ESCEO) and other European Union (EU) guidelines for the restoration of the articular cartilage surface in patients affected by osteoarthritis (OA). They are commercialized as pharmaceutical grade products and as food supplements in combination with plant extracts hyaluronic acid, methylsulfonylmethane, and other components. Food supplements do not need to undergo the strict regulatory controls of pharmaceutical grade products; thus, composition and contaminants that could be present may not be evidenced before commercialization and these uncertainties may give rise to concerns about the bioactivity of these formulations. METHODS: In this paper 10 different food supplements (FS) from diverse European countries were analyzed in comparison with two pharmaceutical grade products (Ph) using updated analytical approaches and biochemical cell-based assays. The purity, the titer, and the origin of CS in Ph and FS samples were initially assessed in order to successively compare the biological function. Both food supplements and pharmaceutical formulations were tested in vitro, using the same final CS concentration, on primary chondrocytes and synoviocytes in terms of (i) cell viability, (ii) activation of the NF-κB-mediated inflammation pathway, (iii) cartilage oligomeric matrix protein (COMP-2), IL-6, and IL-8 production. RESULTS: All the FS presented a certain insoluble fraction; the CS and the GlcN contents were lower than the declared ones in 9/10 and 8/10 samples, respectively. All FS contained keratan sulfate (KS) at up to 50% of the total glycosaminoglycan amount declared on the label. Primary cells treated with the samples diluted to present the same CS concentration in the medium showed cytotoxicity in 7/10 FS while Ph preserved viability and reduced NF-κB, COMP-2, and secreted inflammatory cytokines. CONCLUSION: Among all samples tested, the pharmaceutical grade products demonstrated effective modulation of biomarkers counteracting the inflammation status and improving viability and the physiological condition of OA human primary chondrocyte and synoviocyte cells. In contrast to that, most FS were cytotoxic at the tested concentrations, and only 3/10 of them showed similarities to Ph sample behavior in vitro. FUNDING: This work was partially supported by PON01_1226 NUTRAFAST, MIUR Ministero dell'Università e della Ricerca Scientifica. Bioteknet financed two short-term grants for graduate technicians. The journal's Rapid Service and Open Access fees were funded by IBSA CH.