Formulation design and optimization of cationic-charged liposomes of brimonidine tartrate for effective ocular drug delivery by design of experiment (DoE) approach

Abstract

Objective

The present study was aimed to design and optimize brimonidine tartrate (BRT) loaded cationic-charged liposome formulation with enhanced trans-corneal drug permeation, prolonged corneal residence, and sustained drug release for effective ocular delivery.

Methods

Design of experiment (DoE) based formulation optimization was done by three-factor, three-level Box–Behnken design selecting lipid, cholesterol, and drug content as independent variables and particle size (PS), polydispersity index (PDI), zeta potential (ZP), entrapment efficiency (EE%), and cumulative % drug release (CDR) as response variables. The optimized formulation consisting of 79.2 mM lipid, 36.2 mM cholesterol, and 15.8 mg/mL drug was prepared by thin film hydration-sonication method using EPCS:DOTAP (1:1) as lipid component and characterized for all desired critical quality attributes (CQAs), drug release kinetics, TEM, DSC, XRD analysis, ex vivo trans-corneal drug permeation, and physical stability studies.

Results

The optimized liposome formulation exhibited experimentally observed responses close to predicted values having 150.4 nm (PS), 0.203 (PDI), 30.62 mV (ZP), and 55.17% (EE). The observed CDR (%) was 36.15% at 1 h and 91.13% at 12 h exhibiting sustained drug release profile and followed Higuchi drug release kinetics. The TEM, DSC, and XRD studies revealed spherical, nanosized, small unilamellar vesicles effectively entrapping BRT in liposomes. The ex vivo permeation study across goat cornea recorded apparent permeability (P_app) 1.011 ± 0.07 cm.min⁻¹ and steady-state flux (J_ss) 17.63 ± 1.22 µg.cm⁻².min⁻¹ showing >2-fold enhanced drug permeation as compared to BRT solution.

Conclusion

The developed liposomal formulation possessed all recommended CQAs in optimal range with enhanced trans-corneal drug permeation and remained physically stable in 3 months stability study.

Keywords:

• Brimonidine tartrate
• cationic charged liposome
• ocular drug delivery
• design of experiment (DoE)
• Box–Behnken design (BBD) optimization
• trans-corneal drug permeation
• formulation optimization of liposome
• drug release kinetics of liposome

Acknowledgements

The authors are thankful to M/s. Piramal Healthcare India for gift sample of BRT, M/s. Lipoids GmbH Germany for providing EPCS and DOTAP samples, AIIMS New Delhi India for carrying out the TEM studies, and UGC-DAE Consortium Indore India for carrying out XRD studies.

Disclosure statement

The authors declare that they have no conflict of interest.

Additional information

Funding

This work was supported by the All India Council for Technical Education, New Delhi (8023/BOR/RID/RPS-123/2010).