Formulation and Evaluation of Effervescent Buccal Tablets of Fentanyl for Breakthrough Pain Management

Breakthrough cancer pain requires rapid-onset opioid formulations capable of delivering timely and predictable analgesia. Fentanyl, a potent synthetic opioid analgesic, is especially suitable for transmucosal administration owing to its high lipophilicity, potent receptor affinity, and rapid systemic absorption. The present research aimed to design, develop, and comprehensively evaluate effervescent buccal tablets (FBTs) of fentanyl incorporating dynamic pH modulation and mucoadhesive polymers to optimize dissolution kinetics and enhance transmucosal permeation. Effervescent systems were engineered by incorporating citric acid and sodium bicarbonate, which generated carbon dioxide upon contact with moisture. This reaction established a transient acidic microenvironment to increase fentanyl solubility, followed by pH neutralization facilitating permeation of the unionized drug across the buccal epithelium. Formulation performance was assessed through a series of in vitro evaluations including dissolution studies, mucoadhesive strength measurement, swelling index determination, and drug content uniformity testing. The optimized FBT formulation achieved over 95% drug release within 30 minutes and demonstrated consistent mucoadhesive strength of 0.42 N, ensuring adequate mucosal residence time. Additionally, the dynamic pH cycling contributed to enhanced dissolution and permeation compared to conventional oral transmucosal lozenges. These findings support the feasibility of effervescent buccal tablets as a promising, patient-centric platform for the rapid management of breakthrough pain in oncology settings. Future clinical investigations will be critical to establish in vivo pharmacokinetic and pharmacodynamic correlations and further validate therapeutic outcomes.