Formulation Design and Evaluation of an Emulgel Containing Terminalia arjuna Bark Extract for Transdermal Delivery

Background: Terminalia arjuna is used in various indigenous system of medicine such as Ayurveda, Siddha, and Unani. The traditional medical forms provide drug delivery with peaks often above the required dose and face problems such as first‑pass metabolism, stability, and low therapeutic efficacy. To enhance topical delivery and to allow for controlled release, the use of T. arjuna bark extract emulgel was explored. Objective: The objective of this study is to design and develop novel emulgel formulation of T. arjuna bark extract for transdermal delivery. Materials and Methods: Pseudoternary phase diagram was developed using aqueous titration method. Appropriate amount of oil, surfactant, and cosurfactant were mixed together in accordance with obtained emulsion region in the phase diagram. The emulsion was prepared and incorporated in gel base. The four different formulations were evaluated for physical examinations, rheological studies, skin irritation studies, in vitro release, and ex vivo release studies. Results: The phase diagram at Km value 3 showed better emulsion existence regions. Formulation F3 showed maximum release, wherein the amount of the extract released after 720 min was 91.43%. Skin irritation test on albino rats resulted no allergic symptoms such as inflammation, redness, and irritation up to 72 h. All the prepared emulgel formulations were found to be stable on storage. Conclusion: It can be concluded that T. arjuna bark extract emulgel can be used for transdermal delivery for the treatment of chronic ailments such as pulmonary hypertension.