Ifeanyi T Nzekwe1 
,
Anselm C Okere1,
Ifeanyi E Okoye1,
Kokonne E Ekere2,
Adaobi A Ezenwa1,
Chukwuma O Agubata3
For correspondence:- Ifeanyi Nzekwe Email: it.nzekwe@unizik.edu.ng Tel:+2348066555469
Accepted: 26 June 2020 Published: 31 July 2020
Citation: Nzekwe IT, Okere AC, Okoye IE, Ekere KE, Ezenwa AA, Agubata CO. Bioassay-guided optimization of lipid-based erythromycin microparticles. Trop J Pharm Res 2020; 19(7):1351-1358 doi: 10.4314/tjpr.v19i7.2
© 2020 The authors.
This is an Open Access article that uses a funding model which does not charge readers or their institutions for access and distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0) and the Budapest Open Access Initiative (http://www.budapestopenaccessinitiative.org/read), which permit unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited..
Purpose: To optimize erythromycin microparticles by in vitro bioassay methods based on its antibacterial activity.
Methods: The microparticles were produced by high shear homogenization. The effects of different lipid-to-surfactant ratios were studied. The hydrodynamic size of the different batches was evaluated using dynamic light scattering while bioactive drug load per batch was assessed in agar using bioassay methods. The antimicrobial activities of selected batches were tested ex vivo by determination of reduction in bacteraemia following administration of the microparticles to infected animals.
Results: All batches had particles with hydrodynamic sizes < 8.5 microns. Batch 7 with a 2: 5: 2.5 (drug: surfactant: stearic acid) ratio, represents the optimized batch with a hydrodynamic size of 2281 nm, a bioactive drug loading capacity (BLC) of 4.67 ± 0.70 % and bioactive drug entrapment efficiency (BEE) of 10.51 %. The “microparticle MIC” against Staphylococcus aureus was 1.74 x 10-3 µg/ml. Despite containing lower amounts of erythromycin than the pure sample, the microparticles achieved comparable reduction in bacteraemia, with the optimized batch exhibiting lower variation in bacteraemia than the pure drug.
Conclusion: Erythromycin microparticles have been successfully optimized with the aid of bioassay methods which has the advantage that only the bioactive drug concentration is factored in. This method eliminates problems posed by inadequate or non-discriminating chemical assay methods.
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