Chromatographic analysis of bisphosphonates

Pharmacokinetics of coadministration of levothyroxine sodium and alendronate sodium new effervescent formulation

No clinically important pharmacokinetic interference of alendronate occurred between a new effervescent formulation of alendronate and levothyroxine when coadministered. The combination does not materially affect levothyroxine absorption.

INTRODUCTION

Concurrent treatment of osteoporosis with alendronate (Aln) and hypothyroidism with levothyroxine (LT4) may be problematic because both drugs are to be taken separately after fasting overnight. The primary objective was to assess pharmacokinetic interactions between a new effervescent formulation of Aln (Aln-NEF) and LT4.

METHODS

A randomized, open-label, 3-way crossover study was conducted in 30 healthy adults (15 women). Subjects were dosed 3 times, separated by 35 days, after overnight fasts, with Aln-NEF alone (70 mg), LT4 alone (600 μg), or Aln-NEF and LT4 concurrently. Samples were analyzed for plasma Aln and serum LT4. Pharmacokinetic drug-drug interaction was assessed using 90% confidence intervals (CIs) for the test/reference ratio of the geometric means for area under the concentration-time curve from time zero to last measureable time point (AUC_0-t ) and maximum concentration (C _max). Results were compared to the default no-effect boundaries of 80 to 125% for the ratio Aln-NEF and LT4 concurrently/Aln-NEF alone and the ratio Aln-NEF and LT4 concurrently/LT4 alone.

RESULTS

Geometric mean ratios (Aln-NEF with LT4/Aln-NEF alone) were 0.927 (90% CI 0.795-1.081) for AUC_0-8 and 0.912 (90% CI 0.773-1.077) for C _max, demonstrating LT4 does not appreciably affect the pharmacokinetics of Aln. Geometric mean ratios (LT4 with Aln-NEF/LT4 alone) were 1.049 (90% CI 0.983-1.119) for AUC_0-48 and 1.075 (90% CI 1.006-1.148) for C _max, demonstrating LT4 is bioequivalent between the 2 treatments. Coadministration of Aln-NEF and LT4 was well tolerated.

CONCLUSIONS

There was no clinically important pharmacokinetic interference between the Aln-NEF formulation and LT4. Aln-NEF does not materially affect LT4 absorption.

Bone-Seeking Matrix Metalloproteinase-2 Inhibitors Prevent Bone Metastatic Breast Cancer Growth

Bone metastasis is common during breast cancer progression. Matrix metalloproteinase-2 (MMP-2) is significantly associated with aggressive breast cancer and poorer overall survival. In bone, tumor- or host-derived MMP-2 contributes to breast cancer growth and does so by processing substrates, including type I collagen and TGFβ latency proteins. These data provide strong rationale for the application of MMP-2 inhibitors to treat the disease. However, in vivo, MMP-2 is systemically expressed. Therefore, to overcome potential toxicities noted with previous broad-spectrum MMP inhibitors (MMPIs), we used highly selective bisphosphonic-based MMP-2 inhibitors (BMMPIs) that allowed for specific bone targeting. In vitro, BMMPIs affected the viability of breast cancer cell lines and osteoclast precursors, but not osteoblasts. In vivo, we demonstrated using two bone metastatic models (PyMT-R221A and 4T1) that BMMPI treatment significantly reduced tumor growth and tumor-associated bone destruction. In addition, BMMPIs are superior in promoting tumor apoptosis compared with the standard-of-care bisphosphonate, zoledronate. We demonstrated MMP-2-selective inhibition in the bone microenvironment using specific and broad-spectrum MMP probes. Furthermore, compared with zoledronate, BMMPI-treated mice had significantly lower levels of TGFβ signaling and MMP-generated type I collagen carboxy-terminal fragments. Taken together, our data show the feasibility of selective inhibition of MMPs in the bone metastatic breast cancer microenvironment. We posit that BMMPIs could be easily translated to the clinical setting for the treatment of bone metastases given the well-tolerated nature of bisphosphonates. Mol Cancer Ther; 16(3); 494-505. ©2017 AACR.

Alendronate sodium

This chapter is a review on physical and chemical properties, methods of preparation, analysis, as well as pharmacodynamics and pharmacokinetics of Alendronate sodium (4-amino-1-hydroxybutane-1,1-diphosphonic acid sodium salt), a bone metabolism regulator, indicated for the treatment of excessive bone resorption and osteoporosis.

Differences between bisphosphonates in binding affinities for hydroxyapatite

Bisphosphonates (BPs) inhibit bone resorption and are widely used for the treatment of bone diseases, including osteoporosis. BPs are also being studied for their effects on hydroxyapatite (HAP)-containing biomaterials. There is a growing appreciation that there are hitherto unexpected differences among BPs in their mineral binding affinities that affect their pharmacological and biological properties. To study these differences, we have developed a method based on fast performance liquid chromatography using columns of HAP to which BPs and other phosphate-containing compounds can adsorb and be eluted by using phosphate buffer gradients at pH 6.8. The individual compounds emerge as discrete and reproducible peaks for a range of compounds with different affinities. For example, the peak retention times (min; mean +/- SEM) were 22.0 +/- 0.3 for zoledronate, 16.16 +/- 0.44 for risedronate, and 9.0 +/- 0.28 for its phosphonocarboxylate analog, NE10790. These results suggest that there are substantial differences among BPs in their binding to HAP. These differences may be exploited in the development of biomaterials and may also partly explain the extent of their relative skeletal retention and persistence of biological effects observed in both animal and clinical studies.

Complexation of bisphosphonates with ytterbium(III): application of phosphate and ATP detection assay based on Yb(3+)-pyrocatechol violet

The coordination chemistry of bisphosphonates with Yb(3+) was investigated to evaluate the potential of the UV-vis based detection method using the Yb(3+)-pyrocatechol complexation reaction as a sensor for bisphosphonates. The complexation chemistry of Yb(3+) with phosphate and ATP analogs was previously described (E. Gaidamauskas, K. Saejueng, A.A. Holder, S. Bharuah, B.A. Kashemirov, D.C. Crans, C.E. McKenna, J. Biol. Inorg. Chem. 13 (2008) 1291-1299), and we here studied the complexation chemistry of bisphosphonates in this system. The spectrophotometric assay yields direct evidence for formation of a 4:3 metal to ligand complex at neutral pH. Direct evidence for Yb(3+):methylenebis(phosphonate) complexes with 1:1 and 1:2 stoichiometry was also obtained by potentiometry at acidic and basic pH. Direct evidence for complex formation was obtained using (1)H NMR spectroscopy although the stoichiometry was not accessed at neutral pH. Our results suggest that the spectroscopic observation of the YbPV complex can be used to conveniently measure concentrations of bisphosphonates down to 2-3 microM.

A simple and rapid high-performance liquid chromatography method for determination of alendronate sodium in beagle dog plasma with application to preclinical pharmacokinetic study

A simple and rapid high performance liquid chromatographic (HPLC) method for quantifying alendronate in beagle dog plasma was developed, validated and applied to a pharmacokinetic study. The sample preparation involved coprecipitation with CaCl(2) and derivatization with o-phthalaldehyde. Chromatographic separation was achieved on a Diamonsil C(18 )(250 x 4.6 mm, 5 microm) using acetonitrile-0.4% EDTA-Na(2) (16:84, v/v) containing 0.034% of NaOH as mobile phase. The fluorimetric detector was operated at 339 nm (excitation) and 447 nm (emission). The linearity over the concentration range of 5.00-600 ng/mL for alendronate was obtained and the lower limit of quantification was 5.00 ng/mL. For each level of quality control samples, inter-day and intra-day precisions were less than 8.52 and 7.42% and accuracies were less than 9.07%. The assay was applied to the analysis of samples from a pharmacokinetic study. Following the oral administration of 70 mg alendronate sodium to beagle dogs, the maximum plasma concentration (C(max)) and elimination half-life were 152 +/- 27.3 and 1.75 +/- 0.267 h, respectively. The method was demonstrated to be highly feasible and reproducible for pharmacokinetic studies.

Metal complexation chemistry used for phosphate and nucleotide determination: an investigation of the Yb3+-pyrocatechol violet sensor

Metal complexation reactions can be used effectively as sensors to measure concentrations of phosphate and phosphate analogs. Recently, a method was described for the detection of phosphate or ATP in aqueous solution based on the displacement by these ligands of pyrocatechol violet (PV) from a putative 2:1 (Yb3+)2PV complex. We have not been able to reproduce this stoichiometry and report this work in order to correct the coordination chemistry upon which sensor applications are based. In our work, colorimetric and spectrophotometric detection of phosphate was confirmed qualitatively (blue PV+Yb3+; yellow+Pi); however, the sequence of visual changes on the titration of PV with 2 equiv. of Yb3+ and back titration with ATP as described previously could not be reproduced. In contrast to the linear response to Pi that was reported previously, the absorbance response at 443 or 623 nm was found to be sigmoidal using the recommended 2:1 Yb3+:PV solution (100 microM:50 microM, pH 7, HEPES). Furthermore, both continuous variation titration and molar ratio analysis (Job plot) experiments are consistent with 1:1, not 2:1, YbPV complex stoichiometry at pH 7 in HEPES buffer, indicating that the deviation from linearity is produced by excess Yb3+. Indeed, using a 1:1 Yb3+:PV ratio produces a linear response in DeltaAbs at 443 or 623 nm on back titration with analyte (phosphate or ATP). In addition, speciation analysis of the Yb-ATP system demonstrates that a 1:1 complex containing Yb3+ and ATP predominates in solution at microM metal ion and ATP concentrations. Paramagnetic 1H NMR spectroscopy directly establishes the formation of Yb3+-solute complexes in dilute aqueous solution. The 1:1 YbPV complex can be used for the colorimetric measurement of phosphate and ATP concentrations from approximately 2 microM.

Determination of bisphosphonate active pharmaceutical ingredients in pharmaceuticals and biological material: a review of analytical methods

Bisphosphonates is a class of chemical compounds finding extensive medical applications against bone disorders including osteoporosis, Pagets' disease, etc. Non-N-containing members include etidronate, clodronate and tiludronate, while N-containing bisphosphonates include active pharmaceutical compounds such as pamidronate, neridronate, olpadronate, alendronate, ibandronate, risedronate and zoledronate. The present study covers 20 years of analytical research on this group of compounds, focusing on bioanalytical and pharmaceutical QC applications. A wide range of analytical techniques is presented and critically discussed including among others liquid and gas phase separations, electrophoretic, electroanalytical, automated and enzymatic approaches.

High-performance liquid chromatography method for determining alendronate sodium in human plasma by detecting fluorescence: Application to a pharmacokinetic study in humans

A high-performance liquid chromatographic (HPLC) method was developed using diethylamine (DEA) solid-phase extraction (SPE), 9-fluorenylmethyl derivative (FMOC) and fluorescence detection for quantifying alendronate in human plasma. Sample preparation involved a manual protein precipitation with trichloroacetic acid, a manual coprecipitation of the bisphosphonate with calcium phosphate and derivatization with 9-fluorenylmethyl chloroformate in citrate buffer at pH 11.9. Liquid chromatography was performed on a Capcell Pak C(18) column (4.6 mm x 150 mm, 5 microm particles), using a gradient method starting with mobile phase acetonitrile/methanol-citrate/pyrophosphate buffer (32:68, v/v). The total run time was 25 min. The fluorometric detector was operated at 260 nm (excitation) and 310 nm (emission). Pamidronate was used as the internal standard. The limit of quantification was 1 ng/ml using 3 ml of plasma. The intra- and inter-day precision expressed as the relative standard deviation was less than 15%. The assay was applied to the analysis of samples from a pharmacokinetic study. Following the oral administration of 70 mg of alendronate sodium to volunteers, the maximum plasma concentration (C(max)) and elimination half-life were 40.94 +/- 19.60 ng/ml and 1.67 +/- 0.50 h, respectively. The method was demonstrated to be highly feasible and reproducible for pharmacokinetic studies including bioequivalence test of alendronate sodium in humans.

Analytical methods for the quantification of ibandronate in body fluids and bone

The accurate determination of bisphosphonate levels in bone and biological fluids is important in both clinical and pharmacological/toxicological studies. Ibandronate is a potent nitrogen-containing bisphosphonate containing a tertiary amine group, which does not easily form chromophore derivatives that can be detected by UV light or fluorescence emissions. The current report describes the methodology and validation of a GC-MS assay for ibandronate in serum/plasma and urine, a similar, modified GC-MS method for measurement of bone ibandronate levels, and an ELISA for ibandronate determination in serum/plasma. The range of quantification for the GC-MS was 1-100 ng/ml and 2-7500 ng/ml in plasma or serum and urine, respectively, and 50-1600 pg/ml (potentially 10-320 pg/ml depending on sample size) for the ELISA in plasma or serum. These assays were comparable. The practical application of the assays in preclinical and clinical studies is briefly reviewed.

Pharmacokinetics/pharmacodynamics of bisphosphonates: use for optimisation of intermittent therapy for osteoporosis

Bisphosphonates suppress osteoclast-mediated bone resorption and are widely used in the management of osteoporosis. Daily oral administration of alendronic acid and risedronic acid have been shown to reduce the risk of vertebral and non-vertebral fractures. Once-weekly regimens with these bisphosphonates are pharmacologically equivalent to daily regimens. Regimens with treatment-free intervals longer than 1 week present an attractive therapeutic option as they may offer additional patient convenience and long-term adherence to treatment. However, until recently, such regimens, usually referred to as intermittent or cyclical, have not shown any convincing antifracture efficacy in clinical trials, probably because of the empirical manner in which the design of these regimens has been approached. Investigation of pharmacokinetics/pharmacodynamics of bisphosphonates may help in the design of effective intermittent dosage regimens. Bisphosphonates are poorly absorbed from the gastrointestinal tract and about 50% of the absorbed drug is taken up selectively by the skeleton, while the rest is excreted unaltered in urine. Bisphosphonates exert their action at the bone surface, where they are taken up by the osteoclasts during bone resorption. Therefore, when describing the pharmacokinetics of bisphosphonates in relation to the pharmacodynamics, the amount of bisphosphonate at the skeleton should be accounted for. Few of the reported clinical pharmacokinetic studies addressed this issue. This is partly due to the absence of study design elements to account for skeletal binding of the drugs. Pharmacokinetic studies have also been hampered by technical difficulties in determining the concentration of bisphosphonates in serum and urine. Moreover, most clinical pharmacokinetic (but also pharmacokinetic/pharmacodynamic) studies have primarily used noncompartmental analysis, leaving out the distinct advantages of modelling and simulation techniques. Clinically, the primary action of bisphosphonates can be assessed by the measurement of biochemical markers of bone resorption. Recent studies indicate that the pattern of these markers during bisphosphonate treatment may be predictive of antifracture efficacy; however, only limited data are available for the development of pharmacokinetic/pharmacodynamic models that are able to predict the response of these markers to different treatment regimens with bisphosphonates. Recently, pharmacokinetic/pharmacodynamic models for response to bisphosphonates have been described and, at present, some of them are being used in the design of bisphosphonate regimens with long drug-free intervals.

Determination of bisphosphonates by ion chromatography–inductively coupled plasma mass spectrometry

An ion chromatography-inductively coupled plasma mass spectrometry (IC-ICP-MS) was introduced in the analysis of bisphosphonates. Two compounds (alendronic acid and etidronic acid) were separated on a Dionex AS-7 anion-exchange column with dilute nitric acid employed as the mobile phase. The analytes were detected at m/z 31, as they contain phosphorus. The detection limits achieved were 0.20 mg l(-1) for alendronic acid and 0.05 mg l(-1) for etidronic acid. Since the determination of phosphorus by ICP-MS is difficult due to polyatomic interferences at m/z 31 (15N16O+, 14N16O1H+, and 12C1H(3)16O+), a detailed study of the influence of plasma parameters on phosphorus and background signal was performed.

Semi-automatic liquid chromatographic analysis of olpadronate in urine and serum using derivatization with (9-fluorenylmethyl)chloroformate

The semi-automatic bioanalytical assays for olpadronate [(3-dimethylamino-1-hydroxypropylidene)bisphosphonate] involves a protein precipitation with trichloroacetic acid and a double co-precipitation with calcium phosphate for serum samples and a triple calcium co-precipitation for urine samples. These manual procedures are followed by an automated solid-phase extraction on a cation-exchange phase. The procedure is continued either directly, at high olpadronate levels in urine, or after off-line evaporation under nitrogen and reconstitution in water on the same robotic workstation. The continued automatic procedure comprehends derivatization with (9-fluorenylmethyl)chloroformate, ion-pair liquid-liquid extraction and ion-pair HPLC with fluorescence detection at 274/307 nm. The intra- and inter-day precisions for urine and serum samples are typically in the 5-8% range for different olpadronate concentrations [levels near the lower limit of quantification (LLQ) excluded]. The LLQ is 5 ng/ml olpadronate for a 2.5-ml urine sample and 10 ng/ml for a 1-ml serum sample, respectively.

Semi-automatic liquid chromatographic analysis of pamidronate in urine after derivatization with 1-naphthylisothiocyanate

An existing sensitive chromatographic assay for pamidronate in urine has considerably been automated. Using the same sample processor, the solid-phase extraction (SPE) was automated separately from the derivatization with 1-naphthylisothiocyanate, the two-fold ion-pair liquid-liquid-extraction and the treatment with hydrogen peroxide for the 2-20 ng/ml concentration range. The automatic procedure was preceded by a triple calcium precipitation and interrupted by evaporation of the SPE eluate under nitrogen. For the 0.5-5 microg/ml concentration range one automatic sequence was used by avoiding evaporation during the sample treatment. In addition to the labour-saving of the semi-automatic procedure, the daily sample-throughput was improved compared to the existing manual assay. Further, the validation showed marginal improvements in the precision, accuracy and lower limit of quantification.