1. HPLC ANALYSIS OF AZITHROMYCIN SUSPENSIONS AND TABLETS
Alex Okaru, M.Pharm.
Department of Pharmaceutical Chemistry, SOP, UoN

2. Co-Authors: K.O. Abuga, PhD., F.N. Kamau, PhD. and S.N. Ndwigah, PhD.
Department of Pharmaceutical Chemistry, SOP, UoN

3. Introduction Azithromycin
Azithromycin (AZT) is a dibasic 15-membered ring macrolide derivative
pKa1 ( ) -C3’-N(CH3)2 of desosamine
pKa2 ( )-C9a –NCH3
Figure 1: Structure of AZT

4. Study justification
Azithromycin is indicated for the management of ENT, eye and atypical infections among others.
 AZT is listed as an essential drug by WHO and MoH, Kenya
Shortcomings of existing analytical methods gave impetus for research.
Need for a better validated LC method for quality control of AZT products

5. Objectives Develop and validate a LC method for the analysis of AZT
Apply the developed method in the assay of some commercial samples of AZT in the city of Nairobi.

6. Optimized LC chromatographic conditions of the developed method
Column: Waters XTerra® 5 μm C18, 250×4.6mm ID.
Mobile Phase: ACN-0.1M Potassium phosphate pH M TBAOH-Water (25:15:1:59, % v/v/v/v).
Column temperature: 43 °C, Detection λ: 215 nm, Flow rate: 1.0 ml/min; Inj. Vol. : 20μl

7. DAZT-DecladinosylAZT, AZA-Azathromycin, AZT-Azithromycin, NDMAZT-N-demetylazithromycin, EAIE-Erythromycin A iminoether, EAO-Erythromycin A oxime
Figure 2: Typical chromatogram of the working mixture obtained under optimized chromatographic conditions

8. Sample preparation procedure
Tablet powder equivalent to 250 mg AZT was transferred into a 50 ml volumetric flask followed by addition of 25 ml acetonitrile then sonicated for 15 min, filled to the mark with distilled water and filtered through a 0.45 µm membrane filter.
Suspension equivalent to 40 mg/ml weighed in 5 ml volumetric flasks. This was followed by addition of 2.5 ml of acetonitrile then sonicated for 15 min, filled to the mark with distilled water and filtered .
Azithromycin raw material was prepared using the procedure described for the standard solution in the USP (2012).

9. Analysis of samples
The online drug PPB register listed 77 products with only two brands of AZT manufactured locally
Two brands (all tablets) did not appear on the online register
Test samples randomly purchased from pharmacies within Nairobi CBD.
Samples analysed using the developed and validated LC method.
Nine AZT suspensions analysed -5 premixed, 4-powder.
13 tablet brands analysed
Zithromax® donated by Pfizer, Raw material-Skylight Chemicals Ltd

10. Assay results Product Code Formulation % Content Remarks I Tablet
93.6 (1.55) C
94.8 (1.04) II
110.3(0.16)
109.1(0.12)
III
98.5 (0.46
99.2 (0.31) IV
97.2 (0.19)
97.6 (0.19) V
102.0 (1.51)

11. VI
Tablet
109.9 (0.32) C
107.3 (0.26)
VII
105.1 (1.60)
104.3 (1.28)
VIII
Suspension (M)
110.0 (0.61)
Suspension(M)
109.3 (0.47) IX
96.4 (0.72
96.1 (0.18) X
69.3 (1.68) NC XI
89.3 (0.39)
XII
81.4 (0.46)
XIII
99.8 (0.31)
XIV
83.3 (0.15) XV
87.0 (1.13)

12. P-Powder for reconstitution, M-Premixed, C-Complied, NC- Did not comply
XVI
Tablet
103.3 (1.33) C
XVII
Suspension (P)
88.6 (0.16) NC
XVIII
105.5 (0.36)
XIX
Suspension (M)
87.79 (1.32) XX
98.7 (0.66)
Raw material
Powder
94.7 (0.09)
Zithromax®
99.6 (0.71)
96.4 (1.48)

13. Summary of results Formulation Number Failure (%) Tablets 13 23.1
Suspension 9
44.4

14. II XIX
Figure 3: Typical chromatograms of samples analysed (II=Tablet sample, XIX= Suspension sample)

15. Analytical findings
Content for premixed suspensions was relatively lower compared dry powders for reconstitution.
One of the 3 tablet brands that did not meet the assay specifications was listed in the online PPB register.
Need for post market surveillance to ensure good products are in circulation
Limitations: Batch to batch comparison not possible, limited sample area, suspicion, convenience sampling.

16. Conclusion and recommendations
A simple, fast, isocratic LC method for the analysis of AZT was developed and validated.
Market has poor quality AZT is a matter of public health concern
Post market surveillance to curb poor quality products and counterfeits

17. Acknowledgements Director NQCL Mr. Rotich (NQCL)and Mr. Mugo (UoN)
Pfizer Laboratories: Dr. Maina, Ms. Winnie, Mr. Seroney, Dr. Epaphrodite.
Skylight Chemicals: Dr. Weru
Drug Analysis Research Unit staff
Chairman and staff at The Department of Pharmaceutical Chemistry, UoN.