Stability and Compatibility of Tegaserod From Crushed Tablets Mixed in Beverages and Foods

Marie-Noëlle Carrier; Olivier Garinot; Christian Vitzling

Disclosures

Am J Health Syst Pharm. 2004;61(11) 

In This Article

Methods

Preparation of suspensions of tegaserod began with thorough crushing of tegaserod maleate tablets containing 6 mg of the drug basea in an aluminum foil pouch with the back of a metal teaspoon. The number of tablets crushed and the volume of vehicle used varied by experiment. The media tested included tap water, apple juice,b orange juice,c milk,d applesauce,e yogurt,f and a chocolate-hazelnut spread.g For stability testing, the powder that resulted from crushing one 6-mg tegaserod tablet was added to 50 mL of beverage (resulting in a liquid suspension of tegaserod 0.12 mg/mL) or to 1 tablespoon of food. For degradation product testing, the powder that resulted from crushing five 6-mg tegaserod tablets was added to 25 mL of beverage (resulting in liquid suspension of tegaserod 1.2 mg/mL) or to 1 tablespoon of food. For tests for completeness of a dose and suspension homogeneity, the powder produced by crushing one 6-mg tegaserod tablet was added to 50 mL of beverage in a glass or to 125 g of yogurt, 130 g of applesauce, or 1 tablespoon of chocolate-hazelnut spread. For in vitro dissolution tests, the powder from one crushed 6-mg tegaserod tablet was added to 50 mL of beverage or 1 tablespoon of food (applesauce only). Vehicles without tegaserod were used as controls.

The following numbers of identical suspensions were prepared for each experiment: one sample of each food vehicle for homogeneity testing; two samples of each beverage vehicle for stability, degradation product, and homogeneity testing; and six samples of each vehicle for dissolution testing. All samples were prepared at room temperature (20-25 °C) before being stored at tested temperatures for tested lengths of time.

Stability Tests. Each 50-mL tegaserod suspension (one crushed tegaserod tablet in water, apple juice, orange juice, or milk) was shaken vigorously by hand for 5-10 times in a 100-mL amber glass volumetric flask. Each preparation of one crushed tegaserod tablet in food (1 tablespoon of applesauce, yogurt, or chocolate-hazelnut spread) was mixed with a spatula in a 250-mL amber glass container until completely homogenized (by visual inspection). The tegaserod suspensions and mixtures were allowed to stand at the specified storage temperatures for the specified storage times. Immediately before assay, each tegaserod-beverage sample was rehomogenized by manual shaking (5-10 times) at 20-25 °C, and the flask was filled to the 100-mL mark with methanol.h For extraction, 100 mL of methanol was added to the tegaserod-food mixtures. Each sample (tegaserod-beverage or tegaserod-food) was then mixed at 20-25 °C for 30 minutes on a magnetic stir platei at approximately 850 rpm, 10 minutes in a sonicator,j and 30 minutes on a magnetic stir plate at approximately 850 rpm. A portion of the methanol solution was centrifuged at 2500 rpm at 20-25 °C for 15 minutes, and 20 µL of the resulting clear solution was injected into the HPLC system.k Each sample was assayed in duplicate.

Degradation Product Determination. Each 25-mL tegaserod suspension (five crushed tegaserod tablets in water, apple juice, orange juice, or milk) was shaken vigorously by hand 5-10 times in a 50-mL amber glass volumetric flask. Each preparation of five crushed tegaserod tablets in food (1 tablespoon of applesauce, yogurt, or chocolate-hazelnut spread) was mixed with a spatula in an amber glass centrifugation tube until it was completely homogenized (by visual inspection). The tegaserod suspensions and mixtures were allowed to stand at the specified storage temperatures for the specified storage times. Immediately before assay, each tegaserod-beverage sample was rehomogenized by manual shaking (5-10 times) at 20-25 °C, and the flask was filled to the 50-mL mark with acetonitrile.l For extraction, 50 mL of water-acetonitrile (50:50 by volume) was added to the tegaserod-food mixtures. Each sample (tegaserod-beverage or tegaserod-food) was then mixed at 20-25 °C for 30 minutes on a magnetic stir plate at approximately 850 rpm, 10 minutes in a sonicator, and 30 minutes on a magnetic stir plate at approximately 850 rpm. A portion of the extraction solution was centrifuged at 2500 rpm at 20-25 °C for 15 minutes, and 25 µL of the resulting clear solution was injected into the HPLC system. Each sample was assayed in duplicate. For the alternative HPLC method for the determination of degradation products, 10 µL was injected and tested in duplicate.

Test for Completeness of a Dose. Each 50-mL tegaserod suspension (one crushed tegaserod tablet in water, apple juice, orange juice, or milk) was homogenized by stirring with a metal teaspoon and was transferred to a 100-mL amber glass volumetric flask (to simulate the patient drinking the contents of the glass, the empty glass was not rinsed); the volumetric flask was then filled to the 100-mL mark with methanol for extraction and testing. Extraction was performed as described for the stability tests. This test was performed in duplicate.

Test for Suspension Homogeneity. Each 50-mL tegaserod suspension (one crushed tegaserod tablet in water, apple juice, orange juice, or milk) was homogenized by stirring with a metal teaspoon. Fifteen milliliters (30% of the total volume of the mixed suspension) was withdrawn from the glass immediately after stirring and transferred to a 100-mL amber glass volumetric flask, which was immediately filled to the 100-mL mark with methanol. This test was done in duplicate. Each tegaserod-food preparation was mixed with a spatula until completely homogenized (by visual inspection). Approximately one third of the mixture was withdrawn with a teaspoon or spatula and transferred to an amber glass bottle, and 100 mL of methanol was added. This process was repeated three times for analysis of the entire mixture. Each sample was then mixed at 20-25 °C for 30 minutes on a magnetic stir plate at approximately 850 rpm, 10 minutes in a sonicator, and 30 minutes on a magnetic stir plate at approximately 850 rpm. A portion of the methanol solution was centrifuged at 2500 rpm at 20-25 °C for 15 minutes, and 20 µL of the resulting clear solution was injected into the HPLC system. Each sample was analyzed in duplicate.

In Vitro Dissolution Test. Each 50-mL tegaserod suspension (one crushed tegaserod tablet in water, apple juice, or orange juice) was added to 450 mL of dissolution medium (purified waterm). Each 1-tablespoon preparation of tegaserod in applesauce was added to 500 mL of dissolution medium and the temperature maintained at 37 °C (±0.5 °C). After the transfer, the spoon and the spatula were rinsed in dissolution medium in the vessel to ensure complete transfer. In vitro dissolution was tested with USP Dissolution Apparatus 2, and the paddlen was rotated at 50 rpm. All tests were performed on six samples, each prepared from one tegaserod tablet and mixed as described previously. Dissolution of crushed tablets without any beverage or food vehicle was performed by adding the powder directly to 500 mL of dissolution medium (three samples) and by adding the dissolution medium to the powder (three samples). No significant difference was observed, so mean results for six samples are reported. Five milliliters of each sample was withdrawn from the dissolution vessel after 5, 15, 30, and 60 minutes of rotation. Each portion was centrifuged at 2500 rpm at 20-25 °C for 10 minutes and diluted with acetonitrile (50:50 by volume), and 50 µL of each diluted sample was injected into the HPLC system.

For HPLC measurement of tegaserod and degradation products, the initial time point (time zero) was considered to be approximately one minute after sample preparation. For each determination, two samples of each vehicle tested (beverage or food) were examined three days after storage at 5 °C (±3 °C), which is the recommended storage temperature for all the selected beverages and foods except the chocolate-hazelnut spread (20-25 °C). Two samples stored at 20-25 °C were also tested at the three-day time point for additional information on the stability of tegaserod in these substances. If the results warranted further investigation, two samples each were tested at additional time points and temperatures. Specifically, beverages were tested at 1 hour (storage at 20-25 °C) and 24 hours (storage at 5 °C and 20-25 °C) after preparation, and foods were tested at 24 hours (storage at 20-25 °C) after preparation.

For stability and homogeneity tests, the instrumentation included a constant-flow solvent-delivery system,o a C8 columnp maintained at 30 °C with a column heater,o a variable-volume injector,o an ultraviolet light detectorq set at 220 nm, and an analogue-to-digital converterr linked to a chromatography data acquisition system.s The mobile phase consisted of acetonitrile and aqueous 0.05 M ammonium carbamate (55:45 by volume) delivered at a flow rate of 2 mL/min.

For determination of degradation products (water, apple juice, and applesauce), a slight modification of the HPLC method developed by Novartis Pharmaceuticals for the purity of tegaserod tablets was used. The instrumentation included a constant-flow solvent-delivery system, a C8 column maintained at 40 °C with a column heater, a variable-volume injector, an ultraviolet light detector set at 220 nm, and an analogue-to-digital converter linked to a chromatography data acquisition system. The mobile phases consisted of acetonitrile:aqueous 0.05 M ammonium carbamate:triethylamine adjusted to pH 8 with concentrated phosphoric acid (200:800:0.5 by volume) (mobile phase A) and acetonitrile:aqueous 0.05 M ammonium carbamate:triethylamine adjusted to pH 8 with concentrated phosphoric acid (700:300:0.5 by volume) (mobile phase B), delivered at a flow rate of 1.5 mL/min on a linear gradient: time zero, A = 90%, B = 10%; time 20 minutes, A = 5%, B = 95%; time 24 minutes, A = 0%, B = 100%; time 34 minutes, A = 0%, B = 100%; and time 36 minutes, A = 90%, B = 10%.

For some of the beverages and foods tested (orange juice, milk, yogurt, and chocolate-hazelnut spread), these HPLC conditions did not allow for the selective separation of components of the matrix from potential degradation products of tegaserod. Therefore, the samples were analyzed with an alternative HPLC method. The instrumentation included a constant-flow solvent-delivery system, a C18 columnt maintained at 40 °C with a column heater, a variable-volume injector, an ultraviolet light detector set at 220 nm, and an analogue-to-digital converter linked to a chromatography data acquisition system. The mobile phases consisted of water:acetonitrile: trifluoroacetic acid (900:100:1 by volume) (mobile phase A) and water: acetonitrile:trifluoroacetic acid (100: 900:1 by volume) (mobile phase B) delivered at a flow rate of 1 mL/min on a linear gradient: time zero, A = 80%, B = 20%; time 12 minutes, A = 10%, B = 90%; time 15 minutes, A = 10%, B = 90%; time 16 minutes, A = 80%, B = 20%; and time 22 minutes, A = 80%, B = 20%.

In vitro dissolution tests were performed according to the method developed by Novartis Pharmaceuticals for tegaserod tablets. The HPLC method used in assay determination was modified by using mobile phase consisting of acetonitrile:aqueous 0.2 M diammonium hydrogen phosphate adjusted to pH 4.6 with phosphoric acid (40:60 by volume) delivered at a flow rate of 2 mL/min.

One control suspension (vehicle without a crushed tegaserod tablet) was prepared for each beverage or food and was analyzed as the sample. Resulting chromatograms were compared for interference by any peak.

For assay and homogeneity testing, a 400-µg/mL (expressed in terms of tegaserod drug base) stock solution of tegaserod hydrogen maleate reference substanceu was prepared in methanol on each day of HPLC. The standard solution of tegaserod was prepared by diluting the stock solution with methanol to a concentration of 60 µg/mL. The standard solution was injected in duplicate after approximately every fourth sample as a one-point external standard.

For degradation product testing, a 300-µg/mL (expressed in terms of tegaserod base) stock solution of the same reference substance was prepared in acetonitrile:water (50:50 by volume) on each day of HPLC. The standard solution of tegaserod was prepared by diluting the stock solution with acetonitrile:water (50:50 by volume) to a concentration of 12 µg/mL. The standard solution was injected in duplicate after approximately every fourth sample as a one-point external standard.

For in vitro dissolution testing, a 120-µg/mL (expressed in terms of tegaserod drug base) stock solution of the same reference substance was prepared in acetonitrile:water (50:50 by volume) on each day ofHPLC analysis. The standard solution of tegaserod was prepared by diluting the stock solution with acetonitrile:water (50:50 by volume) to a concentration of 6 µg/mL. The standard solution was injected in duplicate after approximately every third sample as a one-point external standard.

Tegaserod was considered to be stable in a vehicle if certain acceptance criteria were met for the time points examined. The values of acceptance for stability were 90-110% of the theoretical concentration at time zero and not more than 3% less than the initial concentration after storage. The value of acceptance was ≤0.5% for degradation product 515-91 and ≤0.2% each for other, unknown degradation products, for a total of not more than 1% for all unknown degradation products. Values of acceptance for the completeness-of-dose study for the entire sample were 90-110% of the theoretical content.

aZelnorm, Novartis Pharmaceuticals Corporation, East Hanover, NJ, lot F006 0398.
bAuchan store brand, Croix, France, lot L11.
cTropicana Pure Premium, Tropicana France, Villepinte, France, lot L297.
dHalf-skim milk, Auchan store brand, Croix, lot 21035V103039.
eGolden Apple Baby Food, Blédina, Villefranche-sur-Saone, France, lot LNHZHP.
fPlain yogurt, Danone, Paris, France.
gNutella, Ferrero France, Mont-Saint-Aignan, France, lot 1451B.
hHPLC-grade methanol, reference no. 525102, Carlo Erba, Rodano, Italy.
iVariomag Multipoint HP15, H+P Labortechnik, Oberschleissheim, Germany.
jBransonic 8200-E3, Branson Ultrasonics, Soest, Netherlands.
kAlliance 2690 separations module and ultraviolet light detector model 2487, Waters Corp., Milford, MA.
lHPLC-grade acetonitrile, reference no. RH1016, Rathburn, Walkerburn, UK.
mMilli-Q Academic System, Millipore Corp., Billerica, MA.
nRotating paddle, AT 7, Sotax, Allschwil, Switzerland.
oAlliance 2690 separations module, Waters.
pBrownlee Spheri-5 RP-8 column, 5-µm particle size, 100 × 4.6 mm (for assay) or 220 × 4.6 mm (for degradation products),PerkinElmer Inc., Norwalk, CT.
qUltraviolet light detector model 2487, Waters.
rChromatography server, LabSystems, Altrincham, UK.
sXChrom version 2.10, LabSystems.
tNucleosil 100-5 C 18 AB column, 5-µm particle size, 250 × 4 mm, Macherey-Nagel, Düren, Germany.
uNovartis Pharma, Basel, Switzerland, lot 2990005001.

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