Obstructive Sleep Apnea (OSA) is a sleep-related breathing disorder characterized by recurrent collapse of the upper airway during sleep, in which the palatopharyngeal muscle plays a key role in pathophysiology. Although continuous positive airway pressure (CPAP) remains the standard treatment, adherence is often suboptimal. Botulinum toxin type A (BoNT-A), a peripheral neuromodulator, has been proposed as a potential therapeutic alternative by inducing chemodenervation and muscle volume reduction, thereby potentially increasing upper airway patency. This study aims to evaluate the efficacy and safety of BoNT-A injection into the palatopharyngeal muscle in patients with moderate to severe OSA. This is a prospective, single-arm, interventional clinical trial with pre- and post-intervention assessment. We hypothesize that the intervention will result in a significant reduction in the Apnea-Hypopnea Index (AHI), along with improvements in secondary outcomes such as excessive daytime sleepiness and oxygenation parameters.