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Mhango EKG, Sveinbjornsson BR, Snorradottir BS, Gizurarson S. Incompatibility of antimalarial drugs: challenges in formulating combination products for malaria. Drug Deliv 2024; 31:2299594. [PMID: 38180033 PMCID: PMC10773615 DOI: 10.1080/10717544.2023.2299594] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Accepted: 11/10/2023] [Indexed: 01/06/2024] Open
Abstract
Lipophilic drugs require more advance formulation, especially if the intention is to make solutions or semisolid formulations. This also accounts for most antimalarial drugs. Although some of these antimalarial drugs are soluble in lipid vehicles, few of them, such as lumefantrine (LF), are also poorly soluble in oily vehicles. Trying to dissolve and formulate LF as a liquid formulation together with other antimalarial drugs is, therefore, a major task. When mixed in solution together with artemether (AR), precipitation occurs, sometimes with LF precipitating out on its own, and sometimes with AR precipitating out alongside LF. In this study, it was hypothesized that the use of fatty acids could lead to enhanced solubility in lipid formulation. Addition of the fatty acid solved the dissolution challenges, making LF soluble for over a year at room temperature (21-23 °C); but further research is needed to test the mechanism of action of the fatty acid. In addition, design of experiments (MODDE® 13) revealed that the amount of fatty acid in the formulation was the only significant factor for LF precipitation.
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Affiliation(s)
- Ellen K. G. Mhango
- Faculty of Pharmaceutical Sciences, School of Health Sciences, University of Iceland, Reykjavik, Iceland
- Department of Pharmacy, School of Life Sciences and Allied Health Professions, Kamuzu University of Health Sciences, Blantyre, Malawi
| | | | - Bergthora S. Snorradottir
- Faculty of Pharmaceutical Sciences, School of Health Sciences, University of Iceland, Reykjavik, Iceland
| | - Sveinbjorn Gizurarson
- Faculty of Pharmaceutical Sciences, School of Health Sciences, University of Iceland, Reykjavik, Iceland
- Department of Pharmacy, School of Life Sciences and Allied Health Professions, Kamuzu University of Health Sciences, Blantyre, Malawi
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Neusaenger AL, Yao X, Yu J, Kim S, Hui HW, Huang L, Que C, Yu L. Amorphous Drug-Polymer Salts: Maximizing Proton Transfer to Enhance Stability and Release. Mol Pharm 2023; 20:1347-1356. [PMID: 36668815 PMCID: PMC9906740 DOI: 10.1021/acs.molpharmaceut.2c00942] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
An amorphous drug-polymer salt (ADPS) can be remarkably stable against crystallization at high temperature and humidity (e.g., 40°C/75% RH) and provide fast release. Here, we report that process conditions strongly influence the degree of proton transfer (salt formation) between a drug and a polymer and in turn the product's stability and release. For lumefantrine (LMF) formulated with poly(acrylic acid) (PAA), we first show that the amorphous materials prepared by slurry conversion and antisolvent precipitation produce a single trend in which the degree of drug protonation increases with PAA concentration from 0% for pure LMF to ∼100% above 70 wt % PAA, independent of PAA's molecular weight (1.8, 450, and 4000 kg/mol). This profile describes the equilibrium for salt formation and can be modeled as a chemical equilibrium in which the basic molecules compete for the acidic groups on the polymer chain. Relative to this equilibrium, the literature methods of hot-melt extrusion (HME) and rotary evaporation (RE) reached much lower degrees of salt formation. For example, at 40 wt % drug loading, HME reached 5% salt formation and RE 15%, both well below the equilibrium value of 85%. This is noteworthy given the common use of HME and RE in manufacturing amorphous formulations, indicating a need for careful control of process conditions to ensure the full interaction between the drug and the polymer. This need arises due to the low mobility of macromolecules and the mutual hindrance of adjacent reaction sites. We find that a high degree of salt formation enhances drug stability and release. For example, at 50% drug loading, an HME-like formulation with 19% salt formation crystallized faster and released only 20% of the drug relative to a slurry-prepared formulation with 70% salt formation. Based on this work, we recommend slurry conversion as the method for preparing ADPS for its ability to enhance salt formation and continuously adjust drug loading. While this work focused on salt formation, the impact of process conditions on the molecular-level interactions between a drug and a polymer is likely a general issue for amorphous solid dispersions, with consequences on product stability and drug release.
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Affiliation(s)
- Amy Lan Neusaenger
- School
of Pharmacy, University of Wisconsin, Madison, Wisconsin 53705, United States
| | - Xin Yao
- School
of Pharmacy, University of Wisconsin, Madison, Wisconsin 53705, United States
| | - Junguang Yu
- School
of Pharmacy, University of Wisconsin, Madison, Wisconsin 53705, United States
| | - Soojin Kim
- School
of Pharmacy, University of Wisconsin, Madison, Wisconsin 53705, United States
| | - Ho-Wah Hui
- Drug
Product Development, Bristol Myers Squibb, Summit, New Jersey 07901, United States
| | - Lian Huang
- Drug
Product Development, Bristol Myers Squibb, Summit, New Jersey 07901, United States
| | - Chailu Que
- Drug
Product Development, Bristol Myers Squibb, Summit, New Jersey 07901, United States
| | - Lian Yu
- School
of Pharmacy, University of Wisconsin, Madison, Wisconsin 53705, United States,Department
of Chemistry, University of Wisconsin, Madison, Wisconsin 53706, United States,
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Preparation and structure analysis of non-covalent interactions directed 11 adducts from 2-amino-5-methylthiazole and organic acids. J Mol Struct 2022. [DOI: 10.1016/j.molstruc.2022.133031] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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