D-optimal mixture design optimized solid formulation containing fruits extracts of Momordica charantia and Abelmoschus esculentus

Fruit extracts of Momordica charantia L. (Cucurbitaceae) and Abelmoschus esculentus (L.) Moench (Malvaceae) have shown promising antidiabetic activities in clinical trials. However, they remain underutilized due to insufficient standardization and lack of formulation containing their mixture. This study’s overall purpose was to develop and optimize a capsule dosage form containing dried fruit extracts of M. charantia and A. esculentus. The design of the experiment involved two steps; first, response surface methodology (RSM) with a five-level two-factor central composite rotatable design (CCRD) was employed to determine the optimal dose of a mixture of extracts for adequate glycemic control. The extract of M. charantia and A. esculentus were the independent variables while fasting plasma glucose (FPG) was the dependent factor. In the second step, a D-optimal mixture design was applied to study the interaction effect of the optimal dose and selected excipients on granules flowability and capsules’ disintegration time. Moreover, a second-order quadratic model determined the interrelationship of excipients and the desired capsules’ quality attributes. The validity of the predicted models was confirmed. The findings indicated that a combined dose of 175 A. esculentus and 281 M. charantia (mg/kg) significantly reduced the FPG level compared to vehicle at day 14 (mean difference -2.7 ± 0.21, p < 0.001). This dose was used to make a 600 mg capsule (DM083) with 76% drug loading. The DM083 had 40.4 ± 0.62 mg GAE/gDW total polyphenols, 12 peaks HPLC fingerprint, and 26.6 ± 4.75 min average disintegration time. Together, these findings showed that a mixture of M. charantia and A. esculentus fruit extracts could be formulated in a stable capsule dosage form with acceptable quality standards. Further biological studies such as toxicity assays and long-term efficacy studies of the developed capsules could be carried out before large-scale commercial production.