Ocular pharmacokinetics of acetazolamide from intravitreal implants by high-performance liquid chromatography coupled to tandem mass spectrometry

Glaucoma, a leading cause of irreversible blindness, affects about 70 million people globally. Its treatment focuses on reducing intraocular pressure. Acetazolamide, a potent anti-glaucoma drug, is currently used only systemically due to low solubility and permeation, which cause severe side effects. Developing topical medications with acetazolamide requires robust analytical methods for its detection in biological samples. In this context, this study aimed to develop a method to quantify acetazolamide in rabbit vitreous humor samples. The method involved a simple, fast, inexpensive, and environmentally friendly protein precipitation step for sample preparation, needing just 50 μL of sample and 200 μL of organic solvent, with adequate recovery. This was combined with high-performance liquid chromatography coupled to tandem mass spectrometry, enabling highly sensitive (LOQ of 5 ng/mL) quantification within only 5 min. The method proved to be selective, precise, and accurate, with well-fitted analytical curves, with no carryover, and no matrix effect impacting reliability. The method was successfully applied to analyze vitreous humor samples from rabbits in pharmacokinetic studies, monitoring drug release from intravitreal implants. Results showed a controlled release profile, with a maximum drug concentration (Cmax) of 426.01 ± 64.57 ng/mL, time to reach Cmax (Tmax) of 28 days, and area under the curve (AUC0–42 and AUC0-∞) of 7722.66 ± 1125.96 ng days/mL and 8998.11 ± 1311.92 ng days/mL, respectively. The device demonstrated significantly slower elimination, ensuring therapeutic levels for an extended period when compared to intravitreal injection.