Ahmed Abduljabbar , Ahmed AA Alsaad, Suhair Murtada

Department of Pharmaceutics, College of Pharmacy, University of Basrah, Iraq;

For correspondence:-  Ahmed Abduljabbar   Email: ahmed.jabbar@uobasrah.edu.iq

Received: 4 February 2026        Accepted: 15 May 2026        Published: 31 May 2026

Citation: Abduljabbar A, Alsaad AA, Murtada S. Influence of excipient selection on carbamazepine solubility and stability in solid-state pharmaceutics: Developing a predictive model for optimized drug formulations. Trop J Pharm Res 2026; 25(5):597-605 doi: https://dx.doi.org/10.4314/tjpr.v25i5.1

© 2026 The authors.
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Abstract

Purpose: To determine the effect of excipient choice on solubility and stability of carbamazepine (CBZ), so as to develop a model for optimal drug formulation. Methods: Four excipients, namely polyvinylpyrrolidone (PVP), hydroxypropyl methylcellulose (HPMC), polyethylene glycol (PEG) and lactose, were chosen. Carbamazepine was mixed with each of the excipients in a 1:1 (w/w) ratio to form a solid dispersion through solvent evaporation technique, in which a solution of both CBZ and the excipient is evaporated to dryness. Solubility was determined by dissolution profile and physical and chemical stability of the formulations was determined using differential scanning calorimetry (DSC), powder x-ray diffraction (PXRD) and Fourier Transform Infrared spectrophotometer (FTIR). Results: The DSC analysis showed excipients bearing different melting point of 120, 125, 130 and 118 oC, for PVP, HPMC, PEG and lactose, respectively. Polyvinyl pyrrolidone, HPMC and lactose had 45, 47 and 46 % crystallinity, respectively. The degree of crystallinity was lowest in PEG at 42 %. The solubility-enhancing effect of PVP was significantly higher than that of HPMC and lactose (p < 0.05). In contrast to PEG, PVP was less efficient with a mean difference of 2.1 (p = 0.001). The significantly higher solubility enhancement ability indicates that PEG possesses a better solubility efficiency compared with other surfactants. Conclusion: The finding has revealed that both PVP and PEG improve the solubility of CBZ, while HPMC, on the other hand, and improves the stability of the medicine.

Keywords: Excipient, Solubility, Stability, Solid-State Pharmaceutics, Carbamazepine

Impact Factor
Thompson Reuters (ISI): 0.6 (2023)
H-5 index (Google Scholar): 49 (2023)