Fast LC Method for Determination of Cefditoren Pivoxil and Its Related Impurities in Bulk and Pharmaceutical Formulations

 

R. Narendra Kumar*, G. Nageswara Rao and P.Y. Naidu

School of Chemistry, Andhra University, Visakhapatnam.

*Corresponding Author E-mail: narenrokkam@yahoo.co.in

 

ABSTRACT:

A Fast LC method has been developed and subsequently validated for the determination of Cefditoren pivoxil and its related impurities in bulk and pharmaceutical formulation. Separation was achieved in Gradient mode using Hypersil BDS, C18, 100 x 4.6 mm, 3µm column with mobile phase A containing Ammonium formate buffer (pH adjusted to 6.0±0.05 with formic acid solution) and mobile phase B containing Methanol and Acetonitrile (40:60 v/v) at different time intervals as eluent at a flow rate 1.2ml/min. UV detection was performed at 230nm. The method is simple, rapid, and selective and stability indicating .The described method is linear over a range of 200.34µg/mL to 1520.56µg/mL. The method precision for the determination of assay was below 2.0% RSD .The Percentage recoveries of Active Pharmaceutical Ingredient (API) from dosage form is 99.2. LOD and LOQ of all related impurities of Cefditoren pivoxil was established and ranged from 0.0431µg/ml - 0.1843µg/ml for LOD and 0.1292µg/ml - 0.6014µg/ml for LOQ .The method is useful in the quality control of bulk manufacturing and also in pharmaceutical formulations.

 

 

1.0 INTRODUCTION:

Cefditoren pivoxil is a is a pivaloxymethyl ester of Cefditoren pivoxil is 3rd generation cephalosporin derivative belonging to the class of 3-(2-substituted vinyl) cephalosporin, used in the treatment of broad-spectrum and highly active not only against a variety of gram-positive and gram-negative bacteria. Cefditorenpivoxil is [6R-[3-(Z), 6a, 7b(Z)]]-7-[[(2-amino-4- thiazolyl) (methoxyimino) acetyl] amino]-3-[2-(4-methyl-5-thiazolyl) ethenyl]8-oxo-5-thia1-azabicyclo [4.2.0] oct-2-ene-carboxylic acid, pivaloyloxy-ethyl ester. The empirical formula is C25H28N6O7S3 and its molecular weight is 620.73. It is a amorphous light yellow colored powder. Freely soluble in dilute hydrochloric acid. The chemical structure (Fig-1) is given below 1-4

Fig-1 Cefditoren pivoxil

 

It is official in pharmacopoeia and very few liquid chromatography procedures have been reported for the determination of Cefditoren pivoxil in Bulk and Pharmaceutical dosage forms. However there are limited publications concerning the analysis of Cefditoren pivoxil in presence of its intermediates in bulk and Pharmaceutical dosage forms. So it is felt necessary to develop a Fast LC method, which would serve as a rapid and reliable method for the determination of Cefditoren pivoxil in respective related impurities in bulk and pharmaceutical dosage forms. In the proposed method, related impurities were well separated and eluted before 18min. Finally the method was thoroughly validated for the Assay and its related impurities.

 

2.0 EXPERIMENTAL:5-7

2.1 Instrumentation: Waters HPLC equipped with Quaternary pump and PDA detector was used. The output signal was monitored and integrated using waters Empower 2 software.

 

2.2 Solutions preparation:

2.2.1 Mobile Phase A:

Preparation of pH 6.0 Buffer solution:

About 3.16 g of Ammonium formate accurately weighed and dissolve in 1800 mL of milli-Q water in a suitable container and adjusted the pH of the solution to 6.0 ± 0.05 with dilute formic acid solution (if necessary) and diluted to 2000ml with milli-Q water mixed well and filter through 0.2µm nylon membrane filter.

 

2.2.2 Mobile phase B:

Mix Methanol and Acetonitrile in the ratio 40:60(v/v) and filtered through 0.2µm nylon membrane filter.

 

2.2.3 Diluent (0.1 N Methanolic Hydrochloride):

Add about 8.6mL of 35% hydrochloric acid in 1000 mL volumetric flask and diluted to volume with Methanol and mixed well.

 

2.2.4 Preparation of Blank:

About 10mL Acetonitrile taken in 25 mL volumetric flask and diluted to volume with diluent and mixed well.

 

2.2.5 Preparation of Standard solution (1000µg/ml): About 128mg of Cefditoren pivoxil working standard was accurately weighed and transferred in to a 100mL volumetric flask and dissolved in 40ml of acetonitrile and sonicated to dissolve and diluted to volume with diluent and mixed well. Solution was filtered through 0.45µm nylon membrane filter prior to use.

 

2.2.6 Preparation of Test Solution: Twenty tablets were taken weighed and powdered. Sample equivalent to about 100mg of Cefditoren was accurately weighed and transferred in to a 100mL volumetric flask 40ml of acetonitrile was added and sonicated for 20min with intermediate shaking and add 30ml of diluent and sonicated for 10 minutes with intermediate shaking and diluted to volume with diluent and mixed well and centrifuge the portion of sample at 2500 RPM for 10 minutes using centrifuge tube with cap and Solution was filtered through 0.45µm nylon membrane filter prior to use .

 

2.2.7 Chromatographic Conditions:

A Hypersil BDS C18 (100 x 4.6mm;3µm packing) column was  used  for  analysis  at   column

temperature 25şC with Sample injection Volume was 20µL.The photodiode array detector was set to a

wavelength of 230nm for the detection. The mobile phase was pumped through the column as per the

gradient composition given below at a flow rate of 1.2mL/min.

 

Time in minutes

% of

Mobile phase-A

% of

Mobile phase-B

0.0

50.0

50.0

8.0

50.0

50.0

12.0

40.0

60.0

18.0

50.0

50.0

 

3.0    RESULTS AND DISCUSSION:

3.1 Method development: 8-24

3.1.1 Separation of Known degradant impurities:

To develop a suitable and robust RRLC method for the determination of Cefditoren pivoxil different mobile phases and columns were employed to achieve the best separation and resolution. The method development was started with a Peerless basic C18 100 x 4.6mm, 5µ column using a mobile phase -A (pH6.0 buffer):mobile phase-B (Methanol: Acetonitrile 50:50)(v/v)) in the ratio 60:40.In the above condition elution was very broad for Cefditoren pivoxil Early elution with little separation was observed. with mobile phase consisting of mobile phase -A (pH6.0 buffer):mobile phase -B (Methanol:Acetonitrile 50:50)(v/v)) in the ratio 55:45 using column Zorbax XDB, C18,100 x 4.6 mm,1.8 µm, resolution of impurities was not good. Finally the mobile phase consisting of mobile phase -A (pH6.0 buffer) : mobile phase -B (Methanol: Acetonitrile 40:60)(v/v)) in the ratio 50:50 was found to be appropriate, allowing good separation and symmetrical peak at a flow rate of 1.2mL/min using Hypersil BDS C18, 100 x 4.6 mm, 3.0 µm.The Chromatogram of Cefditoren pivoxil sample spiked with the related compounds using the proposed method is shown in Fig.2.In the proposed method the  resolution is more than 2 between the Cefditoren pivoxil and impurity-C and impurity-B .System suitability results of the method are presented in Table 1. Cefditoren pivoxil and its related compounds show significant UV absorbance at Wavelength 230 nm. Hence this wavelength has been chosen for detection in the analysis of Cefditoren pivoxil.

 

Fig -2 TYPICAL CHROMATOGRAM OF Cefditoren pivoxil AND ITS RELATED IMPURITIES

 

TABLE-1 SYSTEM SUITABILITY REPORT

Compound

Tailing Factor a

Resolutiona

%RSDa

Theoretical Plates

Cefditoren pivoxil

1.1

----

0.1

5493

Impurity C

1.1

2.3

0.2

5389

a Number of samples analyzed six.

 

3.1.2         Column Selection 25-26

Based on the retention time and separation of the compounds Hypersil BDS, C18, (100x 4.6mm, 3µm)

Column was selected as suitable column for the analysis of Cefditoren pivoxil.

 

3.2          Method Validation27-28

The developed RRLC method of Cefditoren pivoxil is extensively validated for assay and its related impurities using the following parameters.

 

3.2.1) SPECIFICITY:

Placebo Interference:

A study to establish the interference of placebo was conducted. Assay was performed on Placebo in triplicate equivalent to about the weight of placebo in portion of test preparation as per test method. Chromatograms of placebo solutions showed no peaks at the retention time of Cefditoren pivoxil peak and its related impurity peaks. This indicates that the excipients used in the formulation do not interfere in estimation of Cefditoren pivoxil and its related impurities in Cefditoren pivoxil tablets.

 

Interference from degradation products:

A study was conducted to demonstrate the effective separation of degradants from Cefditoren pivoxil peak. separate portions of Drug product, Drug substance and Placebo were exposed to following stress conditions to induce degradation. Stressed samples were injected into the chromatographic system with photo diode array detector by following test method conditions. All degradant peaks were resolved from Cefditoren pivoxil peak in the chromatograms of all samples. The chromatograms of the stressed samples were evaluated for peak purity of Cefditoren pivoxil using Empower software. In all forced degradation samples, Cefditoren pivoxil peak Purity angle is less than purity threshold. The results are given under Table-4. From the above results it is clear that the method can be used for determining the stability of Cefditoren pivoxil as bulk and pharmaceutical formulations.

 

TABLE-2 RESULTS FOR PRECISION OF TEST METHOD

Test No

% Assay

200mg

01

99.1

02

98.9

03

99.5

04

99.6

05

98.8

06

99.3

Average

99.2

% RSD

0.3

 

3.2.2 Preparation of Degradation samples for Specificity Study:

For Acid degradation Cefditoren pivoxil sample was refluxed with 0.01N HCl at 70şC for 10 min on Mantel and then neutralized by adjusting pH to 7.0 with 0.01N NaOH .The Solution was further diluted to required concentration with diluent.

For alkali degradation Cefditoren pivoxil sample was stressed with 0.01N NaOH on bench top for 10minutes and then neutralized by adjusting pH to 7.0 with 0.01N HCl .The Solution was further diluted to required concentration with diluent.

 

For Oxidative degradation Cefditoren pivoxil sample was refluxed 1%H2O2 by heating on water bath at 40şC for 1hour .The Solution was further diluted to required concentration with diluent.

For Photolightic Stress the samples were exposed to UV at 254nm for 47hrs and visible light for 166hrs meeting the specification of ICH i.e. UV (200watt/m2) and Visible (1.2million Lux hours).

For Thermal Degradation Samples were exposed to temperature at 105şC for 14hrs.

The above stressed samples i.e. Photolightic and Thermal stress samples solutions were prepared to required concentration with diluent.

 

3.2.3) Precision of Test Method:

a) Active Ingredient:

The precision of test method for Active Substance was conducted by assaying six samples of Cefditoren pivoxil tablets. The Average % assay of Cefditoren pivoxil in Cefditoren pivoxil tablets was found to be 99.2% for 200mg tablets and RSD was found to be 0.3%. The results were given in Table-2.

 

b) Related impurities:

The precision of test method of all known impurities of Cefditoren pivoxil was evaluated by spiking all known impurities at target concentration level on Tablets. The Relative standard deviations of all known impurities were calculated and found to be less than 4.0%. The results were given in Table-3.

 

3.2.4 Limit of Detection and Limit of Quantitation :

A study to establish the Limit of detection and limit of quantitation of Cefditoren pivoxil related impurities were conducted.

Limit of detection and limit of quantitation were established based on signal to noise ratio. A series of solutions having Cefditoren pivoxil related impurities were injected. Limit of detection for related impurities were established by identifying the concentration which gives signal to noise ratio about 3. Limit of quantitation was established by identifying the concentration which gives signal to noise ratio about 10.

 

Precision of Cefditoren pivoxil related impurities at about Limit of Quantitation were conducted. Six test preparations of Cefditoren pivoxil tablets having related impurities at about Limit of quantitation was prepared and injected into the chromatographic system. The %RSD at LOQ level was calculated for all known impurities and found to be less than 5.0%.

 

Accuracy of Cefditoren pivoxil related impurities at about Limit of Quantitation was conducted. Test solutions spiked with related impurities at about Limit of Quantitation was prepared in triplicate and injected into chromatographic system and calculated the % recovery. The mean recovery of Cefditoren pivoxil related impurities at about Limit of Quantitation was ranged from 97.2 to 103.0% .The results are given under Table-5

 

3.2.5       Linearity of Detector Response:

a) Active Ingredient:

Linearity of detector response for Cefditoren pivoxil was established by plotting a graph to concentration versus average area and determining the correlation coefficient. A series of solutions of Cefditoren pivoxil standard were prepared in the concentration range of about 200.342µg/mL to 1520.560µg/mL A graph was plotted to concentration in µg/mL on X- axis versus response on Y-axis. The detector response was found to be linear with a correlation coefficient of 0.999.  Linearity graph is shown in Fig-3.

 

TABLE-3 RESULTS FOR PRECISION OF TEST METHOD FOR RELATED IMPURITIES

S. No

% Impurity

Cefditoren Sodium

Imp-A

Imp-B

Imp-C

Imp-E

Imp-F

1

1.1333

1.4336

1.3030

2.6812

3.0829

0.9948

2

1.1429

1.4494

1.3154

2.7063

3.1069

0.9764

3

1.1291

1.4340

1.3015

2.6765

3.0808

0.9463

4

1.1327

1.4428

1.3074

2.6889

3.0923

0.9353

5

1.1359

1.4470

1.3125

2.6977

3.1004

0.9226

6

1.1288

1.4412

1.3066

2.6851

3.0914

0.8994

Average

1.1338

1.4413

1.3077

2.6893

3.0925

0.9458

% RSD

0.5

0.5

0.4

0.4

0.3

3.7

 

TABE -4 TABLE RESULTS FOR SPECIFICITY [INTERFERENCE FROM DEGRADATION PRODUCT]

Stress Condition

% Degradation

Purity Angle

Purity Threshold

Purity Flag

Acid Stress

1.44

0.022

0.216

No

Base Stress

21.47

0.026

0.217

No

Oxidation Stress

1.65

0.022

0.218

No

Photolightic Stress

1.29

0.020

0.219

No

Thermal Stress

14.82

0.022

0.218

No

Exposed to humidity at 25°C/ 90% RH for 240Hrs

0.65

0.022

0.219

No

Stressed with water by Heating on Mantle at 85oC for 10minutes.

4.36

0.019

0.222

No

 

TABLE-5 TABLE RESULTS FOR LOD AND LOQ OF RELATED IMPURITIES

Impurity Name

Limit of detection (LOD) a

Limit of Quantitation (LOQ) a

%RSD a

% Recovery a

Conc. µg/mL

Conc. µg/mL

Cefditoren sodium

0.0431

0.1292

0.8

99.6

Imp-A

0.1308

0.4428

1.8

102.6

Imp-B

0.0761

0.2536

1.0

98.2

Imp-C

0.0910

0.2931

3.1

101.8

Imp-E

0.1280

0.4332

2.1

103.0

Imp-F

0.1843

0.6014

2.4

97.2

a Number of samples analyzed are six

 

          Impurity-Cefditoren sodium                                           Impurity-A                                                       Impurity –B

 

 

            Impurity -C                                                    Impurity-E                                                                      Impurity-F

 

Fig-3 Cefditoren pivoxil RELATED IMPURITIES AND IT’S CHEMICLE NAMES

Cefditoren Sodium: Sodium (6R,7R)-7-[(Z)-2-(2-aminothiazol-4-yl)-2-methoxyiminoacetylamino] -3-[(Z)- 2-(4-Methylthiazol-5-yl)ethenyl]-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylate.

Impurity-A :2,2 –Dimethylpropanoyloxymethyl(2R)-2-{(R)-{[(2Z)-2-(2-amino-1,3-thiazol-4-yl) -2-(methoxyimino)ethanoyl]amino} (carboxy)methyl]-5-[(Z)-2-(4-methyl-1,3-thiazol-5-yl)ethenyl] -3,6-dihydro-2H-1,3-thiazine-4-carboxylate.

Impurity-B : 2,2-Dimethylpropanoyloxymethyl(6R,7R)-7-[(Z)2-(2-aminothiazol-4-yl) -2-methoxyiminoacetylamino]-3-methyl-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylate.

    

Impurity-C : 2,2 Dimethylpropanoyloxymethyl(6R,7R)-7-[(Z)2-(2-aminothiazol-4-yl) -2-methoxyiminoacetylamino]-3-[(Z)-2-(4-methylthiazol-5-yl]ethenyl]-8-oxo-5-thia-1-azabicyclo[4.2.0] oct-3-ene-2-carboxylate .

Impurity-E:2,2-Dimethylpropanoyloxymethyl(6R,7R)-7-[(Z)2-(2-aminothiazol-4-yl)-2-methoxyiminoacetylamino]-3-[(E)-2-(4-methylthiazol-5-yl]-8-oxo-5-thia-1-azabicyclo[4.2.0] oct-2-ene-2-carboxylate.

Impurity-F: 2,2-Dimethylpropanoyloxymethyl (6R, 7R)-7-[(2Z)-[2-[{(2,2-dimethylpropanoyl)oxy] methyl}amino]-1,3-thiazol-4-yl](methoxyimino)acetyl amino]-3-[(Z)-2-(4-methylthiazol-5-yl) Ethenyl]-8-oxo-5-thia-1-azabicyclo [4.2.0] oct-2-ene-2-carboxylate.

 

TABLE-6 ACCURACY IN THE ASSAY DETERMINATION OF Cefditoren pivoxil

Spike level

Average ‘mg’ of Cefditoren pivoxil added a

Average ‘mg’ of Cefditoren pivoxil Recovered a

Average %recovery* a

25%

25.12

24.92

99.2

50%

50.23

50.01

99.6

75%

75.21

74.93

99.6

100%

100.27

99.54

99.3

150%

150.23

149.82

99.7

a Number of samples analyzed at each spike level are three.

 

TABLE-7: ACCURACY FOR THE DETERMINATION OF Cefditoren pivoxil RELATED IMPURITIES

Spike level

a Cefditoren Sodium

a IMP -A

a IMP -B

µg/ml added

µg/ml found

Avg % Recovery

µg/ml added

µg/ml found

Avg % Recovery

µg/ml added

µg/ml found

Avg % Recovery

50 %

4.9182

4.7773

97.1

4.9852

5.5020

110.4

8.1246

8.5370

105.0

75 %

7.3774

7.1077

96.3

7.4778

8.1397

108.9

12.1868

13.1907

108.2

100 %

9.8365

9.5530

97.1

9.9704

10.6483

106.8

16.2491

16.5440

101.8

125%

12.2956

11.8937

96.7

12.4630

13.2617

106.4

20.3114

21.4360

105.5

 

Spike level

a IMP -C

a IMP -E

a IMP -F

µg/ml added

µg/ml found

Avg % Recovery

µg/ml added

µg/ml found

Avg % Recovery

µg/ml added

µg/ml found

Avg % Recovery

50 %

4.3919

4.7387

107.9

4.7435

4.4383

93.6

4.6894

4.4627

95.2

75 %

6.5878

7.1303

108.2

7.1153

7.6610

107.7

7.0341

6.9343

98.6

100 %

8.7837

9.4330

107.4

9.4870

9.1907

96.9

9.3788

8.9733

95.7

125%

10.9797

11.7540

107.1

11.8588

11.7807

99.3

11.7234

11.8200

100.8

a Number of samples analyzed at each spike level are three

 

TABLE-8 STABILITY DATA OF Cefditoren pivoxil IN STANDARD AND TEST SOLUTIONS

BENCH TOP STABILITY

Time in Days

% Assay of Standard preparation

Difference from Initial

% Assay of test preparation

Difference from Initial

Test - 1

Test - 2

Test - 1

Test – 2

Initial

78.6*

NA

100.5

100.9

NA

NA

1

75.4

3.2

93.6

94.2

6.9

6.7

REFRIGERATOR STABILITY

Time in Days

% Assay of Standard preparation

Difference from Initial

% Assay of test preparation

Difference from Initial

Test - 1

Test - 2

Test - 1

Test – 2

Initial

78.6*

NA

100.5

100.9

NA

NA

1

76.2

2.4

97.8

98.4

2.7

2.5

2

76.4

2.2

97.6

98.0

2.9

2.9

* Potency of Cefditoren pivoxil on as is basis

 

 

b) Related impurities:

Linearity of detector response of all known Cefditoren pivoxil Related impurities is established by plotting a graph to concentration versus area of Cefditoren pivoxil related impurities and determining the correlation coefficient. A series of solutions of Cefditoren pivoxil related impurities in the concentration ranging from Limit of Quantitation level to about 150% of target concentration level of Cefditoren pivoxil known impurities were prepared and injected into the chromatographic system.

 

The detector response was found to be linear from Limit of quantitation to 150% of target concentration level of Cefditoren pivoxil known Impurities. Linearity graph is shown in Fig-5

 

3.2.6) Accuracy:

a) Active Ingredient:

A study of recovery of Cefditoren pivoxil from spiked placebo was conducted at five different Spike levels i.e. 25%, 50%, 75%, 100% and 150%. Samples were prepared by mixing placebo with Cefditoren pivoxil raw material equivalent to about of the target initial Concentration of Cefditoren pivoxil. Sample solutions were prepared in triplicate for each spike level and assayed as per proposed method. The Slope, intercept, % recovery and Correlation Coefficient were calculated and given in Table-6.The mean Recoveries of Cefditoren pivoxil from spiked were found to be in the range of 99.2-99.7%.

 

FIG-4 LINEARITY OF DETECTOR RESPONSE GRAPH OF Cefditoren pivoxil

 

FIG-5 LINEARITY OF DETECTOR RESPONSE GRAPH OF Cefditoren pivoxil RELATED IMPURITIES

 

b) Related impurities:

A study of recovery of Cefditoren pivoxil related impurities in spiked samples of Cefditoren pivoxil test preparation was conducted. Samples were prepared in triplicate by spiking of all known impurities in test preparation at 50%, 75%, 100% and 125% of the target concentration level of Cefditoren pivoxil known Impurities. The average % recovery for Cefditoren pivoxil Related Impurities was Calculated and given in Table-6. Cefditoren pivoxil related impurities from spiked were found to be in the range of 93.6-110.4%

3.2.7) Ruggedness:

A study to establish the stability of Cefditoren pivoxil in standard was conducted on bench top and Refrigerator at Initial, 1 day and 2 days. The assay of Cefditoren pivoxil in standard solution was estimated against freshly prepared standard each time. The difference in % assay of Standard from initial to 1 day was calculated and given in Table-6. From the above study, it was established that the standard preparation was not stable for a period of 1day on bench top and stable for 2-days in Refrigerator.

 

A study to establish the stability of Cefditoren pivoxil in Test Solution was conducted on bench top and Refrigerator at Initial, 1 day and 2-days. The assay, of Cefditoren pivoxil in test solutions was estimated against freshly prepared standard each time. The difference in % assay of test from initial to 1 day and

 

2-days was calculated and given in Table-7. From the above study, it was established that the Test Solution was not stable for a period of 1-day on bench top and stable for 2-days in refrigerator Refrigerator.

 

3.2.8 ) Robustness:

A study to establish the effect of variation in mobile phase composition, Flow, Temperature and pH of buffer in mobile phase was conducted. Standard and test solutions spiked with known related impurities of Cefditoren pivoxil prepared as per proposed method were injected into chromatographic system. The System suitability parameters, % Assay and RRT’s of all individual known impurities were evaluated. From the above study the proposed method was found to be Robust.

 

4.0 ACKNOWLEDGEMENTS:

The authors wish to thank the Orchid Healthcare for providing the samples of Cefditoren pivoxil.

 

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Received on 12.05.2010        Modified on 20.05.2010

Accepted on 24.05.2010        © AJRC All right reserved

Asian J. Research Chem. 3(4): Oct. - Dec. 2010; Page 943-949